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The ecology of molluscan infauna on the southwestern continental shelf of Florida

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Title:
The ecology of molluscan infauna on the southwestern continental shelf of Florida
Physical Description:
xi, 150 leaves : ill., map ; 29 cm.
Language:
English
Creator:
Bishof, David Edward
Publisher:
University of South Florida
Place of Publication:
Tampa, Florida
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Subjects / Keywords:
Mollusks -- Gulf Coast   ( lcsh )
Dissertation, Academic -- Marine science -- Masters -- USF   ( fts )

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General Note:
Thesis (M.S.)--University of South Florida, 1980. Bibliography: leaves 54-58.

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University of South Florida
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Universtity of South Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 028608357
oclc - 08021203
usfldc doi - F51-00015
usfldc handle - f51.15
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SFS0040007:00001


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THE ECOLOGY OF MOLLUSCAN INFAUNA ON THE SOUTHWESTERN CONTINENTAL SHELF OF FLORIDA by David Edward Bishof A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the Department of Marine Science in the University of South Florida June, 1980 Major Professor: Dr. Norman J. Blake

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Graduate Council University of South Florida Tampa, Florida CERTIFICATE OF APPROVAL MASTER'S THESIS This is to certify that the Master's Thesis of David Edward Bishof with a major in Marine Science has been approved by the Examining Committee on March 18, 1980 as satisfactory for the thesis requirement for the Master of Science degree. Thesis Committee: Major Professor: Dr. Norman J. Blake Member: Jtihn c: Briggs Member: Dr. Harold J. Humm Member: William G. Lyons

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Several fellow students helped in many aspects of this study. Among these were William Jordan, Eric Myers, Esther Peters, Robert Steward, and John Studt. By providing his computer programs and advice on how to use them, Stephen Bloom was very helpful. Larry Doyle graciously provided the sediment data. Paula Bline was a great aid in drafting several of the figures. Discussions with David Camp and Ken Turgeon resulted in many useful suggestions on the analysis of the data. aid in learning how to identify molluscs was rendered by William Lyons, Donald Moore, and Donna Turgeon. The efforts of my major professor, Norman Blake, enabled this investigation to be undertaken. John Briggs, Harold Humm and William Lyons as members of my thesis committee offered innumerable valuable criticisms and advice. My wife, Debby Winters, encouraged and helped this work in so many ways that it would have been impossible to complete it without her. Wanting early encouragement from my parents, it is unlikely that I would have ever developed an interest in science or scholarship. This study was partly funded by a grant from the United States Bureau of Land Management. i i

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TABLE OF CONTENTS LIST OF TABLES .............. LIST OF FIGURES ............ ABSTRACT .... .................................... INTRODUCTION ...... LOCATION AND PREVIOUS STUDIES ............................... f4ATERIALS AND METHODS ....................................... Study Organisms .............. Samp 1 i ng Method .......... An a 1 ys i s .............. RESULTS ................ DISCUSSION ........... Sediments ................................................ . Diversity ..................... Classification ............. ................ LIST OF REFERENCES .................. APPENDICES ..................... APPENDIX 1 Alphabetical listing of taxa of mollusks identified .. APPENDIX 2 Plots of species area curves for all samples .. APPENDIX 3 Species dominance according to McCloskeys index and numbers of each species in each samp 1 e . APPENDIX 4 Composition of sample sediments in one fractions and . percent carbonate composition ... iii Page v vii ix 1 3 8 8 8 12 19 45 47 48 50 53 54 59 60 67 103 131

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Page APPENDIX 5 Mean of the mean grain size, with m1n1mum and maximum mean in which each species was found and total number of indi-viduals of each species collected........................ 133 APPENDIX 6 Mean depth at which each species were found and total number of individuals of each species.................... 142 iv

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LIST OF TABLES Page 1. Station locations and depths in meters................... 10 2. List of five most dominant species at each station. Numbers in columns under station number indicates species rank at that station......................................... 23 3. The mean grain size of the sediments found in the samples along with their classification according to Folk (1954). 24 4. Maximum, minimum, and mean of mean sediment 0 for dominant spec1es................................................... 25 5. Maximum, minimum, and mean depths (m} at'which dominant species were collected................................... 28 6. Simple and partial correlation of species richness (S) and number of individuals (N) versus depth and percent carbonate composition of sediments in samples (CaC03). Number in parenthesis below each correlation coefficient indicates significance................................... 36 7. Alphabetical listing of taxa of mollusks identified...... 61 8. Species dominance according to McCloskey1s index and numbers of each species in each sample from station 1 .... 104 9. Species dominance according to McCloskey1s index and numbers of each species in each sample from station 2 .... 107 10. Species dominance according to McCloskey1s index and numbers of each species in each sample from station 3 .... 109 11. Species dominance according to t4cCl os key 1 s index and numbers of each species in each sample from station 4 .... 112 12. Species dominance according to McCloskey1s index and numbers of each species in each sample from station 5 .... 115 13. Species dominance according to index and numbers of each species in each sample from station 6 .... 117 14. Species dominance a ccording to tkCl os key 1 s index and numbers of each species in each sample from station 7 .... 118 v

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Page 15. Species dominance according to McCloskeys index and numbers of each species in each sample from station 8 .... 121 16. Species dominance according to McCloskeys index and numbers of each species in each sample from station 9 .... 122 17. Species dominance according to McCloskeys index and numbers of each species in each sample from station 10 ... 125 18. Species dominance according to McCloskeys index and numbers of each species in each sample from station 11 .. 127 19. Species dominance according to f1cCloskeys index and numbers of each species in each sample from station 12 ... 129 20. Composition of sample sediments in one 0 fractions and percent carbonate composition ............................ 132 21. Mean of the mean grain size, with minimum and maximum mean in which each species was found and total number of individuals of each species collected .................... 134 22. Mean depth at which each species were found and total number of individuals of each species ................... 143 vi

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LIST OF FIGURES Page 1. of the study area showing station locations........... 4 2. Plots of species area curves according to Holme's (1953) method for winter sampling of stations 1-6................ 20 3. Histogram of the faunal diversity according to Heck's E(s) .. .. ... ... ... .. .. ... .. .. .. ..... ..... . .... 30 4. Histogram of the faunal diversity according to Hurlbert's /j, c 32 5. Histogram of species richness (S) in samples.............. 34 6. Dendrogram ofnormal classification using Morisita's index of similarity and group average sorting................... 37 7. Dendrogramof inverse classification of the dominant species using Morisita's index of similarity and group average sorting.................................................... 41 8. Plots of species area curves for sample 0121.............. 68 9. Plots of species area curves for sample 0221... ........... 69 10. Plots of species area curves for 0321.............. 70 11. Plots of species area curves for sample 0421.............. 71 12. Plots of species area curves for sample 0521.............. 72 13. Plots of species area curves for sample 0621.............. 73 14. Plots of species area curves for sample 0721.............. 74 15. Plots of species area curves for sample 0821............. 75 16. Plots of species area curves for sample 0921.............. 76 17. Plots of species area curves for sample 1121.............. 77 18. Plots of species area curves for sample 1221.............. 78 19. Plots of species area curves for sample 0122.............. 79 vii

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Page 20. Plots of species area curves for sample 0222 ........... 80 21. Plots of species area curves for sample 0322 ............ 81 22. Plots of species area curves for sample 0422 ............. 82 23. Plots of species area curves for sample 0522. ........... 83 24. Plots of species area curves for sample 0622 ............ 84 25. Plots of species area curves for sample 0722 ........... 85 26. Plots of species area curves for sample 0822 ............. 86 27 . Plots of species area curves for sample 0922 ............. 87 28. Plots of species area curves for sample l 022 ............ 88 30. Plots of species area curves for sample 1122 ............ 89 31. Plots of species area curves for sample 1222 ............. 90 31. Plots of species area curves for sample 0123 ............. 91 32. Plots of species area curves for sample 0223 ............ 92 33. Plots of species area curves for sample 0323 ............ 93 34. Plots of species area curves for sample 0423 ............ 94 35. Plots of species area curves for sample 0523 ............. 95 36. Plots of species area curves for sample 0623 .. .......... 96 37. Plots of species area curves for sample 0723 ........... 97 38. Plots of species area curves for sample 0823 ............. 98 39. Plots of. species area curves for sample 0923 ............. 99 40. Plots of species area curves for sample 1023 ............ 100 41. Plots of species area curves for sample 1123 ............ 101 42. Plots of species area curves for sample 1223 ............ 102 viii

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THE ECOLOGY OF MOLLUSCAN INFAUNA ON THE SOUTHWESTERN CONTINENTAL SHELF OF FLORIDA by David Edward Bishof An Abstract Of a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the Department of Marine Science in the University of South Florida June, 1980 Professor : Dr. Norman J. Blake ix

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ABSTRACT A total of 216 taxa of molluscan infauna identified at least to genus level were collected from twelve stations arranged in two transects across the southwestern Florida continental shelf, off Sanibel Island and Clearwater, Florida. Stations were sampled during spring, fall and winter of 1975-1976, and were located with precision navigation. Quan-. titative samples (0.54m2 surface area) were collected using a box corer at each station. Species area curves indicated that sample sizes were barely sufficent to represent communities. Minimum, maximum, and mean depths and sediment grain sizes were determined for each species. Faunal diversity was high in spring and winter and low in fall at shallower {ll-38m) stations. Deeper stations (92-109m) demonstrated a pattern which was the reverse of that found at shallow stations. Diversity correlated negatively with mean sediment grain size but showed no correlation with depth or percent carbonates in sediments. Species richness showed no distinct seasonal pattern, but did correlate negatively with depth. A normal numerical classification of samples showed that depth and sediment grain size were important factors influencing infaunal molluscan community composition. The normal classification demonstrated no distinct difference in fauna from the two transects, indicating both were in the same zoogeographic province. Inverse numerical classification of dominant species, as determined by McCloskey's (1970) index, X

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showed that species distributions \-Jere strongly influenced by depth and sediment composition. Abstract approved: xi Major Professor Associate Professor Department of Marine Science Date of Approval

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INTRODUCTION Benthic infaunal communities of the continental shelf off south western Florida have been sampled as part of several oceanographic research programs, the most notable being the Hourglass program (Joyce and Williams, 1969). The goal of most of these studies was at first to explore and to describe the fauna of the area covered. Later studies emphasized more detailed surveys of the fauna and its distribution, while at the same time continuing to describe the as yet incompletely known fauna. Unfortunately, quantitative analysis of the composition of these communities with respect to sediment types, depth, and seasonal fluctuations has never been done. The present study is an attempt to fill this gap with respect to the infaunal mollusks found in this area. Obtaining a quantitative sample and precisely resampling a location are two major problems encountered by investigators trying to study offshore communities. The present study has attempted to eliminate these problems by using recent developments in quantitative benthic sampling gear and precision navigation. By doing this, it is hoped that a significantly more accurate understanding of the spatial and temporal variations in the benthic molluscan infaunal assemblages in a subtropical-warm-temperate area can be achieved. Boesch (1973) pointed out that at present there are two basic analytical techniques used in marine benthic ecology which have rarely been used in combination with each other. One of these is numerical 1

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classification in which entities are classified relative to each other based on their composition according to various mathematical criteria (Clifford and Stephenson, 1975}. The other popular technique is analysis of "community structure" in which such factors as species diversity, dominance, and distribution are examined (Boesch, 1973}. 2 This study, for the first time, used both of these approaches to analyze offshore benthic molluscan infaunal communities precisely and quantitatively sampled over the course of a year. Nature of bottom deposits is probably the most important abiotic factor influencing composition of infaunal communities (Jones, 1950; Thorson, 1957; Collard and oAsaro, 1973}. Offshore, where such factors as salinity gradients, temperature fluctuations, wave shock, and tidal currents are reduced (Friedrich, 1969}, substrate variations undoubt edly play a greater role in determining the nature of the fauna than inshore. Because of this, a study of the factors affecting infaunal communities would be incomplete without an analysis of their relationship with the sediments in which they are found. Two additional factors having a significant influence on the composition of benthic communities are depth and latitude. With the exception of the Hourglass program (Joyce and 1969}, none of the benthic ecological studies of the southwestern Florida continental shelf have been designed to systematically explore the effects of depth and latitude. The present investigation is des igned to investigate the relationship between these factors and the benthic infaunal communities in the study area

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LOCATION AND PREVIOUS sTUDIES The study area is the continental shelf on the southwest coast of Florida between Sanibel Island on the south and Clearwater on the north and extends to the 100 fathom (183m) isobath (Figure 1). The shelf in this area is approximately 185 km wide with a relatively even slope that is interrupted by small isolated hills, coral reefs, and other types of bioherms (Shepard, 1973). It is covered with a thin layer of sediments which tends to be composed chiefly of quartz near shore with calcareous sediments dominating off shore (Gould and Stewart, 1956). The highly variable Gulf Loop current enters the Gulf of Mexico from the Caribbean through the Yucatan Straits and extends during the summer to just south of the Mississippi river mouth (Maul, 1977). Its influence on the west Florida continental shelf is primarily in the form of eddies (Niiler, 1976). The influence of this current helps explain why the shallow water and estuarine fauna of the northern Gulf is temperate in its zoogeographic characteristics, but the fauna offshore is tropical (Pulley, 1952; Hedgpeth, 1953), a phenomenon which is emphasized by the fact that living coral reefs have been found in the northern Gulf of Mexico (Bright and Pequegnat, 1974; Hopkins et al., 1977; Turgeon and Lyons, 1977; Lyons, 1980). This area has been qualitatively studied in the past as part of several oceanographic e xpeditions. Although the cruises of the Blake did not have any stations directly in the study area, dredge hauls 3

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4 Figure 1. Hap of the study area showing station locations.

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5 85" 8 4" J3" 82" 28"40'+----------_.__ _________ ..__ __ .,;-,.-------'------.-28"40' 28" II 28" i5 GULF OF MEXICO 0 i 27" 27" 26 26" 25"40' .J-------L----.-------.-----------,,----l.25"40' 85" 84 83" 82

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were taken in the southern part of the Gulf (Agassiz, 1888), which greatly increased the knowledge of the fauna found in this region (Moore, 1977). The expeditions of the Albatross were the first to have stations within the study area, and although their primary interest was in finding new fishing grounds, some dredges were taken (Tanner, 1887}. Mollusks from these collections were described and reported with those from the Blake collection by Dall (1886, and 1889). In 1901 and 1902 the Fish Hawk was used to investigate the sponge grounds and sponge fishing between Anclote Anchorage and Key West (Galtsoff, 1954) and in 1917 the Grampus covered the study area investigating the fishery and shrimp grounds (U.S. Bureau of Fisheries, 1919). After this early period of exploration, investigations declined until the early 1950's when the U.S. Fish and Wildlife Service occupied a number of dredge stations using several different exploratory fishing vessels, particularly the Oregon, and Pelican (Bullis and Thompson, 1965). These studies did much to increase the knowledge of the study area, but none of them attempted systematically to resample stations at different times of the year or to use quantitative sampling gear. During this time and previously, there were a large number of workers in the shallow water and inshore environments within the study area (Conrad, 1846; Simpson, 1886; Clench, 1923; Perry, 1940). Although these studies were not primarily directed toward the conti nental shelf communities, they greatly increased understanding of the systematics and distribution of the shell bearing mollusks in the area. The Florida Department of Natural Resources during 1965-1967 con ducted an extensive survey in the study area in which stations were resampled on a monthly basis for the first time (Joyce and Williams, 6

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1969). Neither quantitative sampling gear nor highly precise navi gation were used, but the study is still the most inclusive and detailed of this area to date. Unfortunately, much of the molluscan information gained from it is as yet unpublished (Lyons, personal communication). 7

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MATERIALS AND METHODS Study Organisms The group of organisms used for a study of this nature must possess two properties. First, they must be reasonably ubiquitous in the study area so that one is not put in the position of trying to study communities which are difficult or impossible to find and sample. Also the systematics must be reasonably well understood so that the investigator is not put into the position of trying to analyze communities which are known to exist, but in which the species composition is unknown. Mollusks have been chosen for this study because they meet these two criteria quite well. They are found throughout the ocean in reasonably large numbers (Hyman, 1967; Barnes, 1968), and the systematics of mollusks in the study area, while still needing work, are known sufficiently well enough for them to be identified in most cases (Abbott, 1974; Keen, 1971). Sampling t1ethod The sampling was done along two transects (Figure 1), which were a part of the United States Bureau of Land Management1s Mississippi, Alabama, and Florida Lease Area (MAFLA) project. The southernmost transect was located along north latitude 261 and was composed of six stations out to a depth of 200m. The northern transect Was along north latitude 271 andwasalso composed of six stations out to a depth of 200m, al though not all of t h e s tations w e r e e xactly in line 8

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The reason that the northern stations were not in line was so that several stations from an earlier part of the MAFLA project could be used. The stations were located the first time they were sampled with the LORAC navigation system and in subsequent sampling with DECCA Hi-Fix. Holding the ship on location with an accuracy of thirty meters was attempted using these highly accurate navigation systems This was done by using ships (R V Columbus Islen and R V Gyre) equipped with twin propellers and bow thrusters used to correct the position of the ship between each replicate taken. Table l shows a list of the station locations and their depths. These transects were chosen as the pattern for the sampling program so that effects such as depth, distance from shore, and latitude could be evaluated as efficiently as possible. The southern transect (stations l -6) located off Sanibel was sampled on May 28-29, 1975, September 15-16, 1975, and January 29, 1976. The northern transect (stations 7-12) located off Clearwater, were sampled on July 22-23, 1975, September 16-17, 1975, and January 29, 1976 for a total of three samplings at each station. Unfortunately, station 10 on the Clearwater transect was not sampled in the first season so it is the only station that was only sampled twice. The rationale behind these three samplings was that a detailed under standing of the seasonal variation occurring in the study area would have required frequent samplings which would take years to analyze. One of the project's primary goals, however, was to qui c kly generat e and analyze data from this area These two conflicting goals led to the compromise of three samplings per year, hopefully producing under standing of the m a gnitude of seasonal variation while still being within the investigator's ability for quick analysis 9

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10 Table 1. Station locations and depths in meters Station Lat. N. Long. W. Depth (m) 1 26' 82 15' 11 2 26' 82 25' 18 3 26' 82 58' 38 4 26' 83 23' 53 5 26' 83 50' 92 6 26' 84 15' 168 7 27' 83 09' 19 8 27' 83 27'30" 33 9 2]052'30" 83 34' 34 10 27'30" 83 42'30" 37 11 27'30" 83 53' 44 12 2JC57' 84 48' 190

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So that the successive samplings of the stations could be easily distinguished, two digits were put after the station number. The first indicated which year of the MAFLA project the sample was taken. Since all samples reported here were taken in the second year, this number is 2 for all of them. The second number indicates during which of the three sampling periods the sample was taken. An example of this is 0921 which indicates the sample taken at station 9 in the first sampling period of the second year. A box corer similar to the one described by Bouma and Marshall (1964) was used to collect the samples. It is believed that of all sampling gear available for use on soft offshore bottoms, a box corer is the most efficient because it takes a sample of precise surface 11 area and uniform thickness (Smith and Howard, 1972). Box corers have two major weaknesses. One is that it produces a bow wave which tends to wash some of the fauna away from the edge of the core (Jumars, 1975). The bow wave effect unfortunately is a problem with all benthic sampling gear (Mcintyre, 1976), but it is believed that box corers suffer this problem less than other sampling devices (Hessler and Jumars, 1974). The second weakness is that box corers cannot sample epifauna living on hard substrates. The present investigation is concerned with only infauna living on soft bottoms so that this second weakness is not a problem. The corer measured 21.3 x 30.5 em in surface area with a maximum thickness of 42 em. Nine replicate cores were taken for each sampling at each station for the purpose of microfaunal analysis and a tenth core for sediment analysis. Some of the cores were subsampled for other analysis. A fter these

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subsamples were taken, the nine cores had a combined surface area of 0.54m2. The top fifteen centimeters of sediment in each core was removed and sieved in 500 mm nitex tube sieves. The sediment that remained after sieving was placed in cloth bags. The sample bags were then placed in a fifteen percent MgS04 solution in seawater for a minimum of thirty minutes to narcotize the animals. Once the animals were narcotized, the samples were transferred to ten percent buffered formalin for fixation and storage. In the laboratory the samples were stained with rose bengal and carefully sorted to remove as many of the animals as possible. The mollusks were separated from the rest of the organisms and identified, usually to species and at least to family. Analysis In studying any community through samples drawn from it, the question arises has the community been adequately sampled? In order to answer this question the cumulative number of species found can be plotted against the cumulative size of the sample. If the curve that results, which is called a species area curve, approaches an asymptote with a slope of zero, the community has been adequately sampled (Myintyre, l97lb). Species area curves were plotted in two ways. The first was a modification of the method used by Holme (1953) which is designed to avoid the problem of species that are encountered in early replicates and not identified, but are identified when they are encountered in later samples, causing the species area curve to increase longer than it should. The tendency for later identification of previously 12

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unidentifiable material is usually caused by either the first specimens being in poor condition or by the identifier increasing in skill with experience. Holme avoided the problem by randomizing the order in which the replicates are plotted. In the present investigation the problem was avoided by randomizing the order in which the replicates were identified. A more accurate picture of how the species were accumulated is obtained by this technique. Ursin (1960) pointed out that simple randomizing can lead to problems if most of the species are from one of the replicates, because the position of that replicate in the randomized order will substantially determine the nature of the slope. The second method used here was designed to avoid this problem. A area curve was plotted for each of five different random orderings of the replicates. The mean of the five randomized orders was then plotted, which has the effect of smoothing out any anomalies caused by an uneven distribution of the species (Ursin, 1960). Both of these techniques were plotted with the aid of an IBM 370 computer equipped with a CALCOMP 563 plotter and the program SPAREA (Bloom et al., 1977). Sediment grain size analysis was performed on the top five centimeters of two five-centimeter diameter subcores, one taken from the first replicate box core in a sample and one from the tenth box core in the sample. The analysis was done by wet sieving the subcores in a five 0 sieve to remove the silt and clay fractions. The remaining sediments were oven dried and then dry sieved through a set of one interval sieves. The mean 0 size for each sample was then calculated according to the method described by Folk and Ward (1957) with the aid of the computer program SEDANA (Bloom et al., 1977). 13

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Faunal and sedimentary data were combined to determine the range in mean size of sediments in which each of the species were found. The mean of the mean grain size of the sediments in which each species was found was then calculated according to the formula: where Fs is the mean of the mean sediment grain size of the sediment in which species s is found, si is the number of individuals of species sin sample i, and fi is the size of the sediments from sample i. Only species which were identified to at least the genus level were used. The depth at which the samples were taken was combined with the faunal data to find the range in depth at which each of the species was found. The average depth at which the species were found was calculated using the formula: 14 in which Ds is the mean depth at which species s was found, si is the number of individuals belonging to species sin sample i, and zi is the depth at which sample i was taken. This was done for all of the species that were identified to at least the genus level. The data were analyzed for faunal diversity which is believed, despite its criticisms (Hurlbert, 1971), to be a useful tool if used properly. In order to avoid the problem of diversity indices with questionable interpretations, two were chosen that specific ecological value. Hurlberts (1971) method for calculating the probability of

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15 interspecific encounters was one of these indices. It is calculated according to the formula: in which N is the total number of individuals in a sample and Ni is the number of individuals belonging to species i. This index makes. the assumption, which is never completely satisfied, that all of the animals are equally motile. However the index does give an idea of what, for example, predators looking for their prey are likely to have to deal with in a given community. The second index used is that of Heck et al. (1975) which is a technique for calculating the number of species that would be found in a sample of a specified size drawn randomly from the sample population. It is calculated according to the formula: ( !i)-1 ( N-Ni) E =S-n t.... n 5 in which E is the expected number of species that would be found in a sample composed of n individuals selected at random from a collection containing N individuals and S species. The number of individuals belonging to species sis represented by Ni. A value of twenty was assigned to n for the purposes of this study. The advantage of this index is in comparing samples from communities with varying population diversities. Diversity as measured by the two indices described above as well as species richness were tested for correlation with depth, sediment grain size, and percent carbonate in the sediments. The tests were done using the Pearson product -moment correlation coefficient r

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(Steel and Torrie, 1960; Snedecor and Cochran, 1967). Partial corre-lation was also performed to test for possible spurious correlations. These tests are useful in explaining the role played by three environmental factors in relationship to the faunal diversity and species richness of infaunal mollusks in the study area. 16 Numerical classification of the data was performed using Morisitas (1959) index of similarity as modified by Horn (1966). Morisitas index .was chosen for two reasons. First, since species counts were taken, it was considered desirable to use an index which could use this information. Many similarityindices use presence absence information only, ignoring the information contained in more quantitative data. s index does use counts and gleans as much information from the data as possible. The second reason was that on examining the data it became immediately obvious that the number of individuals in the different samples varied widely, reflecting different faunal diversities at the stations. This index is relatively independent of the size of the samples making it useful for comparing samples taken from communities with varying population densities. Morisitas similarity index with Horn's (1966) modification is calculated for samples drawn from community = and r with x and y number of individuals respectively according to the formula:

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in which X; and Y; represent the number of individuals belonging to species i found in the samples from community and r respectively. The index varies from zero when the samples have no species in common to one when the samples are identical in composition. The numerical classification was done in two ways. One was a "normal classification" in which samples are compared with each other based on their faunal composition. The other was a "inverse classification" in which the species are compared with each other according 17 to their relative distributions in the samples. Group average sorting as described by Lance and Williams (1967}, but used earlier by Sakal and Mitchener (1958), was used to construct hierarchial dendrogram from the similarity matrices. The normal classification was done using only species which had been identified at least to the level of genus. The computer program ORDANA (Bloom et al., 1977) was used to perform the classification described above. The large number of species collected and the fact that many of them are rare in the samples made it impractical to compare them all with each other in the inverse classification. One method for selecting species to be compared would be to select the ones which were most abundant. This technique has the disadvantage of discriminating against the species found at stations where relatively low faunal density is exhibited. Another technique would be to choose the species which were found at the most stations, regardless of their absolute numbers. This method, unfortunately, discriminates against species which are found at few stations but which may be quite numerous when found. McClosky's (1970) dominance index ranks the species found at a station based on their being found consistently and in relatively large

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18 numbers. The five most dominant species from each station according to McCloskeys index were chosen to be used in the inverse numerical classification. By doing so each of the twelve stations was allowed to contribute equally to the analysis regardless of their faunal densities and it allowed for species which are common at only one station to be analyzed. The species in each of the samples are arranged in descending order according to how many individuals of. each species were found in that sample. The total number of species in a sample (S) is then determined and the most abundant species is given a score of S. The next most abundant species is given a score of S-1 and the third most abundant species, a score of S-2. This is continued with ties being averaged until all of the species in a sample have been assigned a score. The dominance rank is determined for each species found at the station by summing all of its scores from the samples taken at that station.

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19 RESULTS Of the 240 identifiable taxa (Appendix 1) twenty-four were identi-. fied only to the level of family. The remaining 216 were identified to at least the level of genus with most being taken to species. The taxonomic list is composed of 129 gastropods, 92 bivalves, 10 scaphopods, 7 polyplacophorans, and 2 aplacophorans. Plots of the species area curve according to Holmes (1953) technique for the samples taken from the southern transect (stations 1-6) during the third sampling period (winter 1976) are displayed in figure 2. The plots show that there is a general decline in the number of species found in a sample with increasing depth and in particular that the point at which the curves ievel off is reached sooner from samples taken from the deepest stations. The results are representative of both transects in all three sampling periods. Plots of the species area curves for all of the samples are presen ted in Appendix 2. These consist of a large plot representing Holmes (1953) method. Note that the smaller plot is square and the larger is rectangular with the larger axis being vertical which causes the larger plot to appear to have a steeper slope than the smaller one, when in fact it does not. A comparison of the results of the two techniques reveals that Ursins method produces a curve which tends to be smoother than Holmes method. Order of dominance as determined by McCloskeys (1970) index for the mollusks from each of the twelve stations is shown in Appendix 3. Two properties of these lists are prominent: the order of species

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Figure 2. Plots of species area curves according to method for winter sampling of stations 1-6. 20

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-0 0:: 20 w m :.?! ::::> z (j) w td 32 n. (j) -0 cr w en ::::> z (j) w l) (j) 0 0: Lt.J ro ::::> z 8 -0 0:: w en. ::::> z 0 0:: w en :;! ::::> z (j) w l) w n. (j) -0 0::: w en ::J z 21 2 COR

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according to t-kCloskey's index is only approximately the same as would be obtained from putting them in order according to the total number of individuals of each species found at a station and most of the species are rare with many represented by only one individual at a station. Table 2 lists in alphabetical order the species which composed the top five dominant species from each of the stations. Note that several of them were dominant at more than one station and the order of species with tied dominance scores is of no importance. 22 The mean grain size of the sediments for all of the samples are listed in Table 3 along with their classification according to Folk's (1954) scale. The total range in sediments was from (very fine sand) in sample 0821 to (very coarse sand) in sample 1121. The northern transect had on the average finer sediments than the southern transect. Depth did not correlate significantly (r = -0.221) with variation in mean sediment grain size but it did correlate significantly (r = 0.728) with percent carbonate composition of the sediments. A complete listing of the percent composition of the sediments from each of the samples in one intervals can be found in Appendix 4. The means of the mean grain size of the sediments in which the dominant species were found and the ranges of the mean grain size of the sediments in which they were found are listed in Table 4. It can be seen from this table that the ranges in general are too wide to be very meaningful. The 216 species which were identified at least to the level of genus have their ranges and mean of the mean grain size listed in Appendix 5 along with the total number of individuals of each species that were collected.

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23 Table 2. List of five most dominant species at each station. Numbers in columns under station number indicates species rank at that station. Species 1 2 3 4 5 6 7 8 9 10 11 12 Abra lioica 5 1 2 2 Acteocina candei 4 3 2 Amygdalum papyrium 4 Barbatia cf. domingensis 5 Bathyarca glomerula 4 Cadulus parvus 4 Caecum bipartitum 5 Caecum cubitatum 2 3 2 Caecum pulchellum 3 Cardiomya perrostrata 5 Cerithiopsis crystallinum 3 Chaetoderma spp. 1 1 Corbula dietziana 3 Crassinella cf. martinicensis 1 1 Crenella divaricata 5 Cyclopecten nanus 3 Diplodonta spp. 3 5 Eulimostraca hemphillii 2 4 Gastrochaena hians 4 Glycymeris subtilis 2 5 Ischnochiton papillosus 3 3 Lyonsia hyalina floridana 5 Olivella spp. 3 5 Parvilucina cf. multilineata 2 2 1 1 1 2 Philine sagra 4 Pitar simpsoni 2 Plicatula gibbosa 5 Semele nuculoides 4 Solemya occidentalis 1 3 Tellina versicolor 4 1 1 3 2 4 4 Thyasira spp. 4 Varicorbula operculata 5 1 Verticordia ornata 5

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Table 3. The mean grain size of the sediments found in the samples along with their classification according to Folk (1954). Station 21 1 1.64 i"1S 2 1. 28 MS 3 -0.07 vcs 4 0.37 cs 5 0.10 cs 6 1.32 MS 7 1. 99 MS 8 3.59 VFS 9 2.88 FS 10 ---11 -0.65 vcs 12 2. 77 FS VCS = very coarse sand CS = coarse sand MS = medium sand FS = f in e sand VFS = very fine sand Sample Period 22 1.58 MS 1.83 MS 1 48 lYlS 0.43 cs 0.19 cs 1. 70 1. 97 MS 2.82 FS 2.74 FS 1.98 MS 0.49 cs 2.60 FS 23 1. 74 MS 1.48 MS 1. 59 MS -0.18 cs 0.33 cs 1.68 MS 2.10 FS 2.91 FS 2.64 FS 2.06 F S -0.51 vcs 2.41 FS 24

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Table 4. Maximum, minimum, and mean of mean sediment 0 for dominant species. 25

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of Mean Number of Species Name 0 Size Minimum Mean Maximum Mean Individua l s Abra lioica 1.82 -0.5 1 2.91 158. Acteocina candei 2.48 -0.18 3.60 139. Amygdalum papyrium 1.27 -0.65 2.91 25. Barbatia cf. domingensis 0.27 0.10 0.33 4. Bathyarca glomerula 2.37 1. 70 2. 77 7. Cadul us parvus 0.46 -0.18 1.98 14. Caecum bipartitum 2.60 -0.65 3.60 163. Caecum cubitatum 2.41 -0.51 3.60 179. Caecum pu1chellum 2.51 -0.51 2.91 205. Cardiomya perrostrata 1.60 -0.18 2.74 20. Cerithiopsis crystallinum 2.59 2.41 2. 77 13. Chaetoderma spp. 2.14 1.32 2. 77 52. Corbula dietziana 0.62 -0.65 2.06 24. Crassine11a cf. martinicensis 0. 61 -0.65 2.88 66. Crene11a divaricata 1.41 -0.65 3.60 33. Cyc1opecten nanus 1.36 -0.51 2. 77 24. Diplodonta spp. 1. 61 -0 . 65 3.60 77. Eu1imostraca hemphi1lii 1. 79 1.28 2.91 72. Gastrochaena hians 0.47 -0.65 1. 74 16. G1ycymeris subtilis 0.97 0.10 1. 70 12. Ischnochiton papil1osus 1.40 -0.65 1.99 170. Lyonsia hyalina floridana 1.99 -0.51 3.60 42. Olivella spp. 1. 53 -0.18 2.10 46. Parvilucina cf. multilineata 2.35 -0.65 3.60 559. Philine sagra 1.96 -0.51 2.88 35. Pitar simpsoni 0.48 -0.65 2.64 22. Plicatula gibbosa 1.55 0.33 1. 74 32. Semele nuculoides 0.27 -0.18 1.99 15. So1emya occidentalis 1. 78 -0.51 2.74 183. Tellina versicolor l. 76 -0.65 3.60 426. Thyasira spp. 1.39 -0.18 2. 77 17. Varicorbula operculata 1.95 -0.51 3.60 394. Verticordia ornata 1.85 -0.18 2. 77 10. N m

PAGE 39

The mean, maximum, and minimum depth at which each of the dominant species was found is listed in Table 5. It can be seen from this table that unlike the case of the sediments, the range in depth$ at which the dominant species found tend to be narrow enough to be useful. The same information on depth is listed for all of the species which were identified to at least the level of genus in Appendix VI. Faunal diversity (il and E(s)) and species richness are shown in 27 the form of histograms (Figures 3, 4 and 5). Both diversity indices had relatively small ranges in value compared to species richness which fluctuated quite widely. There was no significant correlation between depth and diversity or between percent carbonate composition of the sediments and diversity according to either index used. Species richness and total number of individuals in the samples did correlate with both depth and percent carbonate; however since depth and percent carbonate had high correlation w ith each other partial correlations were run which showed that the correlation between both species richness and total number of individuals with percent carbonate was spurious (Table 6). The values of both diversity indices did correlate with mean grain size, with E(s) yielding a correlation coefficient of -0.739 and L1 yielding a value of -0.518. Both-correlation coefficients are significant at a 0.01 level of probability. The. normal numerical classification of the samples produced the d endrogramshm-Jn in Figure 6. The corres ponding depth s and mean s e di sizes are listed next to the sample number on the figure. Examination of the dendrogramreveals that thesamples fall into six groups, A through F Group A is made up of all three samples from stations twelve and

PAGE 40

Table 5. Maximum, minimum, and mean depths (m) at which dominant species were collected. 28

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Numbe r of Species Name Depth Minimum Depth Maximum Depth Indi viduals Abra lioica 80.1 11.0 189.6 158. Acteocina candei 31.7 11.0 53.3 139. Amygdalum papyrium 39.9 29.3 53.3 25. Barbatia cf. domingensis 91.3 89.6 92.0 4 Bathyarca glomerula 183.1 167.6 189.6 7 Cadulus parvus 65.8 37.2 167.6 1 4 Caecum bipartitum 29.9 11.3 42.1 163. Caecum curitatum 35.3 29.3 43.6 179. Caecum pulchellum 33.2 11.3 43.6 205. Cardiomya perrostrata 37.9 17.4 53.3 20. Cerithiopsis crystallinum 189.6 189.6 189.6 1 3. Chaetoderma spp. 178.5 161.5 189.6 52. Corbula dietziana 38.6 11.0 53.3 2 4 Crassinella cf. martinicensis 41.7 18.3 53.3 66. Crenella divaricata 37.8 29.3 53.3 33. Cyclopecien nanus 103.9 19.2 189.6 24. Diplodonta spp. 26.8 11.0 53.3 77. Eulimostraca hemphillii 21.4 11.0 38.4 72. Gastrochaena hians 34.5 11.0 53.3 1 6. Glycymeris subtilis 129.5 89.6 167.6 1 2. Ischnochiton papillosus 21.1 1 1. 0 92.0 170. Lyonsia hyalina floridana 36.2 17.7 53.3 42. Olive11a spp. 24.7 11.0 92.0 46. Parvilucina cf. multilineata 35.9 11.0 189.6 559. Philine sagra 38.5 29.3 92.0 35. Pitar simpsoni 47.3 11.0 92.0 22. Plicatula gibbosa 17.2 11.0 92.0 3 2 Semele nuculoides 61.3 1 8.3 92.0 15. Solemya occidentalis 16.6 11.0 53.3 183. Tellina versicolor 22.9 11.0 53.3 426. Thyasira spp. 122.3 18.3 189.6 17. Varicorbula operculata 33.3 11.0 53.3 394 Verticordia ornata 139.3 11.3 189.6 10. \0

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Figure 3. Histogram of the faunal diversity according to Heck's E(s) 30

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16 1 2 -8 4 0 1 6 12 8 4 0 r-r--C\1 ,., C\1 C\1 C\1 ,._ ,._ ,._ 0 0 0 C\1 0 N rt> N C\1 0 0 r--C\1 N N N N co co co 0 0 0 N N 0 N !'() N N N N 0 0 r--1--,., C\1 m 0 r--C\1 0 N rt> N C\1 0 0 C\1 ,., C\1 ,., C\1 C\1 C\1 C\1 C\1 N ,., ,., ,., 'It 'It 'It 0 0 0 0 0 0 SAMPLE r-N C\1 N 8 8 1--r--,____ N rt> N N C\1 C\1 C\1 C\1 C\1 (.0 0 r---C\1 C\1 (.0 0 ,., C\1 (.0 0 31

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Figure 4. Histogram of the faunal diversity according to Hurlbert's 32

PAGE 45

0121 0 0 0122 0\23 0221 0222 0223 0321 (J} 0322 0323 042\ IT1 0422 0423 0521 0522 0523 0621 0622 0623 0 N 0 t> 0 (J) 0 Cl) 0 I I I I I I I I I I I I J J I J I I J I I 0721 0 0 0722 0723 0821 0822 0823 0921 0922 0923 1021 1022 1023 II 21 1122 1123 1221 1222 1223 0 N I Q l> I 0 m I Q Cl) _l J I I I I I J I I J I I _I J I 0 w w

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34 Figure 5. Histogram of species richness (S) in samples.

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0 0121 0122 0123 0221 0222 0223 0321 0322 en l> 0323 3: f! 0421 rn 0422 0423 0521 0522 0523 0621 0622 0623 0 I I J I I J N 0 -' en 01 0 I I I I I I 0 I I I I (JI 0 I I 0 0721 0722 0723 0821 0822 0823 0921 0922 0923 1021 1022 1023 1 1 2 1 1122 1123 12 21 1222 1223 0 I N 0 I J I en I I I I I J I I (JJ 0 I I 0 I (JI 0 I w U'1

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. Table 6. Simple and partial correlation of species richness (S) and number of individuals (N) versus depth and percent carbonate composition of sediments in samples (CaC03). Number in parenthesis below each correlation coefficient indicates significance. Depth CaC03 control= control= Depth CaC03 CaC03 Depth s -0.663 -0.525 -0.481 -0.083 (0.000) (0.001) (0.004) (0.642) N -0.636 -0.434 -0.518 0.054 (0.000) (0.009) (0.002) (0.761) 36

PAGE 49

Figure 6. Dendrogramof normal classification using index of similarity and group average sorting. 37

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DEPTH SAMPLE 190 2.41 1223 190 2.77 1221 I 68 I 70 0622 A 190 2.60 1222 I 68 I 32 0621 92 0. 19 0522 92 0.10 0521 168 I .68 0623 -----44 0. 49 II 22 44 -O. 65 I I 21 53 -0. 18 0423 8 53 0.37 0421 38 -0.07 0321 92 0.33 0523 53 0.43 0422 -c---3 -=,--2 o s---ro 2-3 -5----,9---i:lo ___ o723-33 9. 91 0823 34 2.88 0921 33 3.59 0821 37 1.98 1022 34 2. 74 0922 E 33 2.82 0822 38 I. 59 0323 38 1.48 0322 I I I. 64 0121 ___ o223. F 17 I. 83 0222 19 1.99 0721 19 1.97 0722 17 II I I I. 28 I. 74 I. 58 0221 0123 0122 100 38 I I I I I 1--1--1------I I 1---I J I I -I I I I I 75 50 25 0 LEVEL OF Sl M I LARITY

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six and two of the samples from station five. These are the deepest stations sampled ranging in depth from 92 to 190 meters, and have sediments which range from fine to coarse sand. Group B is composed of all of the samples from stations four and eleven plus one sample each from stations five and three. All samples except the one from station five came from depths between 38 and 53 meters. Sediments from the samples in this group consisted of coarse to very coarse sand. The presence of single samples from stations three and five in this group can be explained by their depth and sedimentary properties. The sample from station three in this group has sediments with a mean particle diameter that is 1.5 than the other two samples from station three. Since this sample is from a station in the general depth range of group B and has sediments which also fall into the range of group B, it is not at all surprising to find that it has fauna with an affinity for group B. One sample from station five is in this group although the other two samples from this station are in group A. Station five is the shallowest station with the coarsest sediments in group A. These two factors explain how one of the samples from station five can break away from the rest and join a group from lesser depth but with similar sediments. Groups C and D are each made up of one sample from stations seven and ten respectively. Why these samples did not fall into the larger groups that the rest of the samples from these stations are found in cannot be explained by the available information. Group E consists of all of the samples from stations eight and nine and the remaining samples from stations ten and three albng with one sample from station one. These samples with the exception of the 39

PAGE 52

40 sample from station one all came from depths of between thirty and forty meters. The group is characterized by sediments composed of medium to very fine sand. The fauna of this group appears to be distinct from that of group B, which consists of stations that are from slightly deeper water, primarily because of the finer sediments characterizing group E. All of the samples from station two and the remaining two samples from stations one and seven comprise group F. These samples are distinguished by sediments made up of medium_ sand and having come from depths of eleven to nineteen meters which are the shallowest of any group. The inverse numerical classification of the dominant species formed .. eight groups, A through H (Figure 7). Next to each of the species names on the dendrogram are the average depths at which they were found and the mean of the mean sediment grain sizes of the sediments in which each species \-Jas found. Although it was possible to have up to sixty species by taking the five most dominant species from each of the twelve stations, many species were dominant at more than one station and as a result only thirty-three species are shown. Group A consists of six species which were generally found in samples with medium to fine sand from the deepest stations. The average depth at which the species were found ranged from 104 to 188 meters. Of the six species in this group two, a bivalve, Verticordia ornata, and a gastropod, Cerithiopsis crystallinum, are carnivores. The three remaining bivalves in this group, Bathyarca glomerula, Cyclopecten and Thyasira spp., are filter feeders, and Chaetoderma spp. are deposit feeding aplacophorans.

PAGE 53

Figure 7. Dendrogram of inverse classification of the dominant species using Morisita's index of similarity and group average sorting. 41

PAGE 54

DEPTH 138.4 182.2 188.4 122. 0 103. 5 177. 8 129. 5 91. 3 33. 3 35. 8 35. 3 33. 2 29. 9 31. 6 79. 9 22.9 24. 7 21 4 16 6 2 I I 17. 2 26. 8 61. 3 47. 3 65.8 34.5 38. 6 41. 7 38.5 36.2 39. 9 37.9 37.8 I 9 2 4 2.6 I. 4 I 4 2 I I 0 0 3 I. 9 2 3 2 4 2 5 2 6 2.5 I 8 I 8 I. 5 I. 8 I 8 I. 4 I 5 I. 6 0 3 0 5 0.5 0.5 0 6 0 6 2.0 2 0 I. 3 I. 6 I 4 SPECIES Verticordia ornata BatiJyarca glomerula Cerit!Jiopsis crysto/linum TIJyasira spp. Cyclopecten nanus CIJae loderma spp. Glycymeris sudlilis Barbatia domingensis Varicorbula opercula/a Parvilucina cf. multilneata Caecum cubitatum Caecum pulciJe/lum Caecum bipartilum Acleocina candei A bra lioica Tel/ina versicolor Olive/la spp. Eulimostraca HempiJillii Solemya occidentalis lsciJnociJiton papillosus Plicalula gibbosa Diplodonla spp. Semele nuculoides Pitar simpsoni Cadulus parvus Gaslro ciJ aena IJians Corbula d ietziana Crassinella cf. martinicensis PIJiline sagra Lyonsia IJyalina floridana Amygdalum papyrium Cardiomya perrostrata Crenella divaricata 100 l _I I I J 1-1--f-1-l r f----f.r I 75 50 25 0 LEVEL OF SIMILARITY

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43 Two filter feeding bivalves, Glycymeris subtilis and Barbatia domingensis, made up group B. They were found at average depths of 130 and 91 meters respectively, and in sediments consisting of coarse sand. This group overlap$ group A in its depth range but not in its sediment associations. Varicorbula operculata, a filter feeding bivalve, is the sole member of group C. It is characterized by being found at an average depth of 33 meters and in sediments which generally consisted of medium grade sand. Neither of these two characteristics would appear to be unusual enough to explain operculata having a distribution which is distinct enough from the other species distributions that it should be placed in a group by itself. What does seem to operculatas uniqueness is that it was found in nineteen of the thirty-five samples, which gives it a distribution that overlaps that of many of the other species but which is distinct from all of them. Group D contains three members of the gastropod genus Caecum, C. cubitatum, pulchellum, and. bipartitum all of which are grazers. The group also contains a filter feeding bivalve, Parvilucina cf. multilineata, and a deposit feeding gast ropod, Acteocina candei. All organisms in this showed a preference for fine sand and depths of about 30 meters. Abra lioica, a deposit feeding bivalve, is the sole member of group E, indic ating that like Varicorbul a operculat a it exhibited a very distinct distribution pattern. This can be verified by looking at its range in depth (Table 5) which was from 11. 0 to 190 m eters. None of the oth e r spe cies exhibi ted a s great a rang e in d e p th. Group F is trophically the most. diverse. It contains a deposit

PAGE 56

feeding bivalve, Tellina versicolor, and three filter feeding bivalves, Solemya occidentialis, Plicatula gibbosa and Diplodonata spp. A carnivorous gastropod, Olivella spp., and a parasitic gastropod, Eulimostraca hemphillii, are contained in this group, along with a poly placophoron grazer, Ischnochition papillosus. The organisms in this group were found at average depths that were the shallowest of any group, ranging from 17 meters to 27 meters. Their sediment preferences were for medium sand. Two deposit feeders, a bivalve, Semele nuculoides, and a scaphopod, Cadulus parvus, and four filter feeding bivalves, Pitar simpsoni, Gastrochaena hians, Corbula and Crassinella cf. martinicensis, compose group G. These organisms were found on the average in ments composed of coarse sand and at depths of 35 to 60 meters. Group H contains two carnivores, a gastropod, Philine sagra, and a bivalve, Cardiomya perrostrata, and three filter feeding bivalves, Lyonsia hyalina floridana, Amygdalum papyrium, and Crenella divaricata. These mollusks were found at depths which averaged from 36 to 40 meters and in sediments which consisted of medium sand. Depth preferences of this group overlap with group G but sediment preferences do not. 44

PAGE 57

DISCUSSION The richness of the molluscan infauna in this region is well demonstrated by the data. Five classes of mollusks were represented by 240 identifiable taxa found in samples which had a combined surface area of only 18.4m2. One of these classes, the aplocophorans, have only once previously been reported from the Gulf of Mexico (Treece, 1979). The mollusks belonged to virtually every trophic level available to a benthic marine animal. The abundance of mollusks combined with their taxanomic and trophic diversity is evidence that they play a significant role in the ecology of their communities, and demonstrates the validity of choosing mollusks for use in a study of the ecology of this region. The molluscan infaunal richness in the study area, as stated above, has been demonstrated by this investigation. It should be understood, however, that the total molluscan faunal richness (infaunal and epifaunal) in the study area has not been exhaustively sampled. The Hourglass project brought up over 1,000 mollusk species from essentially the same region (Lyons, personal communication). The discrepancy between the results of this project and of the Hourglass project are believed to be caused by two factors. The first is that box corers are unable to sample hard substrate epifauna and, in fact, no attempt was made to study this type of molluscan fauna. The other factor is that with each sample consisting of 0.54m2 of bottom surface area the larger molluscs, especially carnivores which are rare in terms of individuals per m2 (Elton, 1927), will tend to be missing 45

PAGE 58

entirely. Large carnivores can play very important ecological roles (Paine, 1971), making the inability to sample them a significant weakness of the technique used here. As a result of this fact, any further discussion of the molluscan fauni of the study area should be understood to be only concerned with the species which a box corer was able to capture. The faunal data produced by this study contained little in the 46 way of zoogeographical surprises. The region that was studied is generally considered to have Caribbean affinities in its offshore waters (Pulley, 1952; Hedgepeth, 1953; Lyons and Collard, 1974; Lyons, 1980) and in fact that is what was found. This fact is undoubtedly influenced by the Gulf Loop Current which brings Caribbean water well up into the Gulf of Mexico (Niiler, 1976). The main exception to the Caribbean character of the fauna was that the fauna from the deeper stations on the ends of the transects weremorecharacteristic of deeper waters than of more localized zoogeographic provinces. If a sample taken at a station contained a large enough area of the bottom to accurately represent the resident community, its species area curve (Appendix 2) should approach an asymptote with a slope of zero (Holme, 1953). Unfortunately, a horizontal asymptote is seldom approached for any of the samples, which tends to put any further analysis of the communities in doubt. In most cases, however, the species area curves are leveling off and it is believed that the sample size was adequate, although barely so. The potential problem is at its greatest when different samples are being compared. To eliminate the problem in the future it would be advisable for any studies of a similar nature to use samples larger than 0.5m2 A comparison of the

PAGE 59

two types of graphs shows that Ursins technique did smooth out irregularities in the curves. This is especially true in the early part of the curve before an asymptote is approached; otherwise, the two methods produce very similar results. Consequently, this investigator will tend to use only Ursins technique in the future. Sediments The sediment analysis for the three samples taken at each station reveals another potential problem. As stated earlier, one of the primary goals of the project was to sample precisely the fauna at each of the stations on a repetitive basis. It would be unreasonable to expect the sediment samples taken at a station during the course of a year, no matter how precisely done, to yield identical results. However, it would be reasonable to expect the sediments to change very little in the course of a year, especially on a level bottom area such as the study area. This is exactly what happened for the most part. Most of the 35 samples have mean grain sizes that are less than one half of a class different from the other samples taken at the stations. Unfortunately, in 4 of the 35 samples there is a change of more than one half of a class. There are three possible explanations for these changes. The first possibility is that the sediments did change at the stations between samplings. Changes in sediments are possible and, in fact, hurricane Eloise passed through the northern Gulf of Mexico just after the early fall sampling and could have caused some changes in sediments. Only one of the four anomalous samples could possibly be explained as a result of change s caused by Eloi se. It s eems unli k ely th a t changes in sample sedime nts were cau se d by a ctu a l changes in the sediments at the stations, especially since two other 47

PAGE 60

possible explanations are much more likely. The second possibility is that the samples were not taken at the same location, which could have been caused by one of two factors. One of these is that the ship was not held on station but allowed to drift. Since it usually took about one hour to take all of the box cores for a sample, the ship could have drifted off station. The ship was not supposed to drift, however, but was held in pos.ition by correcting the position location betv1een every box core drop. Another reason could be that the navigation system was not calibrated correctly. However, miscalibration was avoided by carefully calibrating the navigation system on a surveyed location at the beginning and end of each cruise so that it could be used at its greatest precision which was greater than required for the project. The third possibility is that the nature of the bottom is such that at some of the stations a very short distance can make a significant difference in the type of sediments brought up. This phenomenom was observed at some stations where very slight changes in the position of the ship caused substantial changes in the nature 48 of the cores being brought up. It is my opinion that the patchy nature of the bottom at some stations, combined with the fact that it is impossible to hold the ship absolutely on station without movement, is what caused variations in sediments in a few samples. Diversity The measurement of faunal diversity using the indices of both Heck et al. (1975) and Hurlbert (1971) produced similar results, but E(s) tended to vary over a relatively wider range than Neither of these indices could be correlated with depth. The lack of correlation

PAGE 61

with depth is somewhat surprising since both numbers of individuals and species richness decreased with depth. The two indices used were insensitive to these changes in that they remained fairly constant 49 over the entire range of depth. This finding, although over a smaller range in depth, is similar to those of Sanders and Hessler (1969). Both diversity indices do correlate with mean sediment grain size, showing a tendency toward higher diversity where coarser sediments are encoun-tered. The histograms of diversity measurements (Figure 3) reveal an interesting pattern. The first three stations on each transect (stations 1, 2, 3, 7, 8, and 9) have highest faunal diversity in the early summer and winter samplings. The three deepest stations (stations 5, 6, and 12) have the opposite, with higher diversity in the early fall and low diversity in the early summer and \'linter. The remaining three stations, which are located between these two groups, show no such pattern. These patterns appear to be more than coincidental and are believed to be characteristic of the communities found at these stations. These patterns may be reflecting reproductive cycles within the communities. Even organisms in the relatively unvarying deep sea have been observed to be seasonal in reproductive patterns (Schoener, 1968). The communities at the shallow stations could be spawning in a distinctively different annual pattern from the deep stations, with intermediate depth stations not clearly belonging to either pattern. Different annual spawning patterns might have caused fluctuations in measurements of diversities as a second order effect. Size measure-' ments of the organisms during different seasons might give a clue as whether or not the presence of absence of juveniles corresponds to

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the changes in diversity. Such measurements, at least for dominant species, should be included in any future studies of this nature. Two diversity indices were used in the hope that each one would shed a different light on the communities being studied. The index of Heck et al., (1975), as stated earlier, displayed a relative degree of variation that was larger than that displayed by Hurlbert's (1971) index. Otherwise the two indices did not produce meaningfully different results. In future studies this investigator would recommend the use of either, but not both, of these indices. Classification The groups that were found as a result of the normal classification relate well to the two of depth and mean sediment grain size. In general the groups were composed of samples with similar sediments from similar depths. This is not at all surprising in the light of present knowledge of benthic communities (Thorson, 1957). The magnitude of change in mean grain size necessary to cause samples to split into separate groups, although variable, seems to be on the order of one class. Changes in depth appear to act in a proportional manner as might be expected so that a change from 25 to 50 meters depth has a greater effect than from 100 to 125 meters. If the difference in latitude between the transects were to have an appreciable effect on the nature of the communities, the groups found by the normal classification would tend to contain only samples from one transect. Two of the groups consisted of only one sample and therefore could not have samples from both transects. Of the remaining four groups all four contain samples from both transects, indicating that the difference in latitude between transects (approximately 1') 50

PAGE 63

is not sufficient to distinguish the communities found along them. The. lack of distinction between the two transects agrees with the generally held belief that the study area is contained entirely within the province and therefore should not have.any marked faunal inconsistencies The fact that it required 6 groups to classify 35 samples from 12 stations indicates that the study area cannot be described by a few types of communities, typified by one or two dominant species, sensu Thorson (1957). Two theories (sometimes call definitions) as to what a community consists of may explain these results. Mills (1969) states that a community is 11a group of organisms occurring in a particular environment presumably interacting with each other and with the e nviron ment, and separable by means of ecological survey from other groups ... The second theory is that communities or associations are merely parts of continuously varying assemblages of species which vary in response to complex environmental gradients (Whittaker, 1970). Either of these theories allows for an infinite number of different community types and can therefore explain the large number of groups found by the normal classification. It is outside the realm of this investi gation to test which of these two theories is closest to the truth. A test of the theories would require careful sampling between t\'IO distinct assemblages on a scale which could detect whether th e y were distingu i shable or inte rgrade into each other The inverse classification clearly shows that species are influence d in their distri butions by the paramet ers of sediment and depth. The contribution of th e two paramet e r s appe a r s to b e more clearly defined relative to depth and sediment type than the groups formed by 51

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the normal classification. The reason for this may be that the sediment and depth preferences used in the inverse analysis are means while that for the normal analysis represent single data points. It 52 is not surprising that using a mean seems to smooth out anomalies which show up with individual measurements. Rhoads and Young (1970) have pointed out that deposit feeders and suspension feeders often have distinctively different distributions, but in some cases deposit feeders and suspension feeders are found together (Young and Rhoads, 1971). Whether or not the distribution of the molluscan fauna in the study area is noticeably influenced by its trophic level is a question which this study can address. If species are segregating based on feeding type, then groups formed in the inverse classification of dominant species should contain either deposit feeders or filter feeders, but not both. Two of the eight groups from the inverse classification contain only one species and cannot represent more than one trophic level. Of the six remaining groups, two are composed of filter feeders with no deposit feeders and four contain both. This evidence supports the conclusion that the molluscan infauna from the study area does not segregate by trophic level in what Rhoads and Young (1970) called "trophic group amensalism."

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SUMMARY 1. The southeastern Gulf of Mexico was repetitively sampled for the first time in a quantitative manner using a boxcorerand precision navigation. 2. Benthic mollusks from these samples consisted of 240 taxa belonging to five classes. 3. The total sample size of 0.54m2 was enough to represent the communities adequately although, barely so. 4. The mean of the mean sediment grain size and range of sizes of the sediments in which each species \'/as found was determined. 5. The average depth and the range in depth at which each species was found was determined. 6. Faunal diversity was found to be independent of depth and species richness and negatively correlated with mean sediment 0 size. 7. Faunal diversity exhibited distinct seasonal fluctuations at most stations. 53 8. Numerical classification of samples revealed that depth and sediment are key factors in controlling the communities' characteristics. 9. Numerical classification of dominant species showed that depth and sediments are also key factors in controlling their distributions.

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. 54 LIST OF REFERENCES Abbott, R. T. 1974. "American Seashells." 2nd ed. 663 pp. 24 pls. Van Nostrand Reinhold, New York. Agassiz, A. 1888. Three cruises of the United States Coast and Geodetic Survey Steamer B1 ake. Vol. l. Bull Mus. Comp. Zoo l 14: l-314. Barnes, R. D. 1968. "Invertebrate Zoology." 2nd ed. 743 pp. W.B. Sanders, Philadelphia. Bloom, S.A. and S. L. Santos, and J. G. Field. 1977. A package of computer programs for benthic community analysis. Bull. Mar. Sci., 27 (3): 577-580. Boesch, 0. F. 1973. Classification and community structure of macrobenthos in the Hampton Roads area, Virginia. Mar. Biol. 21 :226 244. Bouma, A. H. and N. F. Marshal. 1964. A method for obtaining and analyzing undisturbed oceanic sediment samples. Mar. Geol., 2:81-99. Bright, T. J. and L. H. Pequegnat. Eds. 1974. "Biota of the West Flower Garden Bank." 435 pp. Gulf Publishing Co., Houston, Texas. Bullis, H. R. and J. R. Thompson. 1965. Collections by the exploratory fishing vessels Oregon, Combat, and Pelican made during 1956-1960 in the southwestern north Atlantic. U.S. Fish Wildl. Serv. Spec. Sci. Rep. No. 510:130 pp. Clench, W. J. 1923. The marine shells of Sanibel, Florida. Nautilus, 37: 52-56. Clifford, H. T. and W. Stephenson 1975: "An introduction to numerical classification." 229 pp. Academic Press, New York. Collard, S.B. and C. N. D'Asaro. 1973. Benthic invertebrates of the eastern Gulf of in "A Summary of Knowledge of the Eastern Gulf of Pg. IIIGl-IIIG28. State Univ. Sys. Fla. Inst. Oceanogr., St. Petersburg, Fla. Conrad, T.A. 1846. Catalogue of shells inhabiting Tampa Bay and other parts of the Florida coast. Am. J. Sci., 52: 393-400.

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Dall, W. H. 1886. Reports on the results of dredging-in the Gulf of Mexico (1877-78) and in the Caribbean Sea (1879-80) by the steamer 11Blake. 11 29. Report on the Mollusca, part I. Brachiopoda and Pelecypoda. Bull. Mus. Comp. Zool., 12: 171-318 pls. 1-9. Dall, W.H. 1889. Reports on the results of dredging in the Gulf of Mexico (1877-78) and in the Caribbean Sea (1879-80) by the steamer 11Blake.11 29 Report on the Nollusca, part II. Gastropoda and Scapopoda. Bull. Mus. Comp. Zool., 18: 1-492, pls. 10-40. Elton, C.S. 1927. 11Animal Ecology.11 209 pp. Macmillian, New York. Folk, R. L. 1954. The distinction between grain size and mineral composition in sedimentary rock nomenclature. J. Geol., 62: 344-359. -----and w ; C. Ward 1957. Brazos River Bar. A study in the significance of grain size parameters. J. Sediment. Petrol., 27(1): 3-26. 55 Friedrich, H. 1969. 11Marine Biology. 11 474 pp. Univ. Hashington Press. Sea ttl e. _Galtsoff, P.S. 1954. Historical sketch of the explorations in the Gulf of Mexico. U.S. Fish Wild. Serv. Fish. Bull. 89: 3-36. Heck, K. L., Jr. G. van Bell. and D. Simberloff. 1975. Explicit calculation of the rarefacation diversity measurement and the determination of sufficient sample size. Ecology 56(6): 1459-1461. Hedgpeth, J.W. 1953. An introduction to the zoogeography of the northwestern Gulf of Mexico with reference to the invertebrate fauna. Publ. Inst. Mar. Sci. Univ. Tex. 3: 107-224. Hessler, R. R. and P. A. Joumars. 1974. Abyssal community analysis from replicate box cores in the central north Pacific. Deep Sea Res. 21 : 185-209. Holme, N.A. 1953. The biomass of the bottom fauna in the English Channel off Plymouth. J. mar. biol. Ass. U.K., 32: 1-49. Hopkins, T.S. and D.R. Blizzard, and O.K. Gilbert. 1977. The molluscan fauna of the Florida Middle Grounds with comments on its zoogeographical affinities. Northeast Gulf Sci., I(I): 39-47. Horn, H.S. 1966. of 110Verlap11 in comparative ecological studies. Am. Nat., 100: 419-424. Hurlbert, S.H. 1971. The nonconcept of species diversity: a critique and alternative parameters. Ecology, 52(4): 577-586.

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Hyman, L.H. 1967. 11The Invertebrates: Mollusca I." 792 pp. McGrawHill Ne\'1 York. Jones, N.S. 1950. Marine bottom communities. Biological reviews of the Cambridge philosophical Society, 25(3): 283-313. Joyce, E.A., Jr. and J. Williams. 1969. Memoirs of the Hourglas cruises: rationale and pertinent data. Fla. Dept. Nat. Resour. Mar. Res. Lab., 1 (1): 50 pp. Jumars, P.A. 1975. Environmental grain and polycheate species diversity in a bathyal benthic community. Mar. Biol., 30: 253266. Keen, A.t1. 1971. "Sea Shells of Tropical America.11 2nd ed. 1064 pp. Stanford Univ. Press, Stanford. Lance, G.N. and W.T. Williams. 1967. A general theory of classificatory sorting strategies I. Hierarchial systems. Comput. J., 9: 373-380. Lyons, W.G. and S.B. Collard. 1974. Benthic invertebrate communities of the eastern Gulf of Mexico, in Proceedings of Marine Environ mental Implications of Offshore Drilling in the Eastern Gulf of f1exico pg. 157-165. State Univ. Sys. Fla. Inst. Oceanogr., St: Petersburg, Fla. Lyons, W.G. 1980. f1olluscan Communities of the West Florida Shelf. Bull. Am. Malacol. Union, (1979): 37-40. McCloskey, G.A. 1970. The dynamics of the community associated with a marine scleractinian coral. Int. Revue. ges. Hydrobiol., 55(1): 13-81. Mcintyre, A.D. 197la. Efficiency of benthos sampling gear. Pg . 140146, in 11Methods for the Study of Marine N.A. Holme and A.D. tkintyre, Eds. Blackwell Scientific Publications, Oxford. -----197lb. Design of sampling programs. Pg. 1-ll, in 11Methods for the Study of Marine Benthos." N.A. Holme and A.D. Mcintyre, Eds. Blackwell Scientific Publications Oxford. Maul, G.A. 1971. The annual cycle of the Gulf Loop Current. Part I: Observations during a one-year series. J. Mar. Res., 35(1): 29-47. E.L. 1969. The community concept in marine zoology, with comments on continua and instability in some marine communities: a review. J. Fish. Res. Bd. Can. 26: 1415-1428. 56

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Moore, D.R. 1977. From the first cruise of the "Blake" to the present day -one hundred years of progress in the study of Gulf and Caribbean marine molluscs . Bull. Am. Malacol. Union (1977) 63-68. Morisita, M. 1954. Measuring of interspecific association and similarity between communities. Mem. Fac. Sci. Kyusha Univ., Ser. E (Biol.), 3(1): 65-80. Niiler, P.P. 1976. Observations of low-frequency currents on the West Florida Continental Shelf. Mem. Soc. Roy. Sci. Liege, 10: 331-358. Paine, R.T. 1971. A short-term experimental investigation of resource partitioning in a New Zealand rocky intertidal habitat. Ecology, 52(6): 1096-1106. Pulley, T.E. 1952. "A zoogeographic study based on the bivalves of the Gulf of Mexico." 215 pp. Unpublished Ph.D. thesis, Harvard University. Rhoads, D.C. and O.K. Young. 1970. The influence of deposit-feeding organisms on sediment stability and community trophic structure J. mar. Res. 28(2): 150-261. Sanders, H .L. and R.R. Hessler. 1969. Ecology of the deep-sea benthos. Science, 163: 1419-1424. Schoener, A. 1968. Evidence for reproductive periodicity in the deep sea. Ecology, 49(1): 81-87. Shepard, F.P. 1973. "Submarine Geology." 3rd ed., 517 pp. Harper and Row, New York. Simpson, C.J. 1886. Record of a two days dredging cruise in Tampa Bay, Florida. Nautilus, 1:44, 52-53. Smith, K.L. and J.D. Howard. 1972. Comparison of a grab sampler and large volume corer. Limnol. Oceanogr., 17(1): 142-145. Snedecor, G.W. and W.G. Cochran. 1967. "Statistical 6th ed. 593 pp. Iowa State Univ. Press, Ames. Sakal, R.R. and C.D. Michener. 1958. A statistical method for evalu ating systematic relationships. Univ. Kans. Sci. Bull., 38: 1409-1438. Steel, R.G.D. and J.H. Torrie. 1960. "Principles and Procedures of Statistics." 481 pp. McGraw-Hill, New York. 57

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Tanner, Z.L. 1887. Report rin the work of the U.S. Fish Commission steamer Albatross for the year ending December 31, 1885. U.S. Comm. Fish and Fisheries, Rept. of the Commissioner for 1885 App. A, 89 pp., 5 pls., Washington. Thorson, G. 1957. Bottom communities in 11Treatise on 1"1arine Ecology and Paleoecology ... Vol. I, Ecology, Geol. Soc. Am. Mem. 67: 461-534. Treece, G.D. 1979. Four new records of aplacophorous mollusks from the Gulf of Mexico. Bull. Mar. Sci., 29(3): 344-364. Turgeon, D.O. and W.G. Lyons. 1977. A tropical marine molluscan assemblage in the northeastern Gulf of Mexico, Bull. Am. t4alacol. Union, (1977): 88-89. United States Bureau of Fisheries. 1919. Report of the U.S. Com missioner of Fisheries for the fiscal year ending June 30, 1917. pp. 80, Washington. Ursin, E. 1960. A quantitive investigation of the echinoderm fauna of the central North Sea. Meddr. Danm. Fisk-og Havanders. N.S., 2(24), 204 pp. 58 Whittaker, R.H. 1970. 11Communities and Ecosystems ... 162 pp. Mad4illan, London. Young, O.K. and D.C. Rhoads. 1971. Animal-sediment relations in Cape Cod Bay, Massachusetts I. A transect study. Mar. Biol; 11: 242-254.

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59 APPENDICEs

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APPENDIX 1 Alphabetical listing of taxa of mollusks identified. 60

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APPENDIX 1 Table 7. Alphabetical listing of taxa of mollusks identified. Abra aegualis Abra lioica Aeanthochitona pygmaea Acteocina candei Acteocina spp. Acteon candens Acteon punctostriatus Alvania auberiana Alvania spp. Amygdalum papyrium Amygdalum sagittatum Anachis iontha Anachis obesa Anadara transversa Anodontia alba Anomia sim"j?le'X CLS:Aplacophora FAtt: Arci dae Arcinella cornuta Arcoosis adamsi Arene tricarinata Argopecten gibbus Atys riiseana Bactrocythara spp. Barbatia cf. domingensis Bathyarca glomerula Brachycythara barbarae Brachycythara biconica Bull a striata i dae Bushia spp. Cadulus parvus Cadulus guadridentatus Cadulus spp. Caecum bipartitum Caecum cornucopiae Caecum cubitatum Caecum floridanum Caecum imbricatum Caecum pulchellum Caecum strigosum Calliostoma fascinans Calliostoma jujubinum Calliostoma spp. Calotrophon ostrearum Calyptraea centralis 61

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APPENDIX 1 Table 7 {cont'd). Cardiomya costellata Cardiomya perrostrata Cardiomya spp. F A.'1: Cerithi i dae Cerithiopsis crystallinum Cerithiopsis taeniolata Cerithium atratum Cerodrillia simpsoni Chaetoderma spp. Chaetopleura apiculata Chama congregata Chama macerophylla Chione cancellata Chione grus Chione latilirata Chlamys benedicti Cochliolepis FAN:Columbellidae Conus jaspideus stearnsi Cooperella atlantica Corbula dietziana Costellaria spp. Crassinella cf. martinicensis Crassinella lunulata Crenella divaricata Crepidula fornicata Cryoturris citronella Cryoturris fargoi Cryoturris filifera Cryoturris guadrilineata Cryoturris spp. Cyclopecten nanus Cyclostremiscus spp. Cylichna spp. FAM:Cylichnidae Cymatoica orientalis Dacrydium vitreum Dentalium bartletti Dentalium ceratum Dentalium lagueatum Dentalium semistriolatum Dentalium sowerbyi Dentalium spp. Dentalium texasianum Diplodonta spp. Divaricella dentata 62

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Table 7 (cont'd). APPENDIX 1 Dosinia elegans Epitonium novangliae Ervilia concentrica Erycina emmonsi Eucrassatella speciosa Eulima bifasciatus Eulimostraca hemphillii Eulimostraca spp. Eupleura sulcidentata Fasciolaria lilium hunteria Finella dubia FAM:Fissurellidae Gastrochaena hians Glans dominguensis Glychymeris subtilis Glyphostoma hendersoni Glyphoturris spp. Gouldia cerina Greguriella coralliophaga Haminoea succinea Henrya spp. Hiatella arctica Ischnochiton boogii Ischnochiton floridanus Ischnochiton hartmeyeri Ischnochiton papillosus Ischnochiton spp. Ithycythara lanceolata Ithycytha ra spp. Kurtziella atrostyla Kurtziella spp. Laevicardium pictum FAt4: Lepton i dae L i rna pe 11 uc ida Ilnlcitula setifera Limea bronniana FAM:Limidae Linga amiantus Linga leucocyma Linga sombrerensis Lioberus castaneus Lucina nassula Lucina radians FAM:Lucinidae Lyonsia hyalina floridana Macoma cf. extenuata Macrocallista maculata 63

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Table 7 (cont'd) APPENDIX 1 Marginella eburneola Marginella hartleyanum Marginella spp. Melanella arcuata 1 ane 11 a s pp. Microdrilla comatotropis Mitrella lunata Mitrolumna biplicata Modulus modulus Murex cabritii Murex glyptus Murex pomum Musculus lateralis Myse 11 a spp. Nannodiella melanitica Nannodiella spp. Nassarius spp. Natica canrena Natica livida Nati ca pusi 11 a Natica spp. FAM:Naticidae Nemocardium peramabile Nemocardium tinctum Niso aeglees Nucinella adamsi Nucula cf. fernandinae Nucula crenulata Nuculana acuta Nuculana carpenteri Nuculana spp. Ocenebra minirosea Oceanida spp. Odostomia seminuda Odostomia spp. Oliva sayana Oliva spp. 01 ivella spp. Opalia spp. Parvilucina blanda Parvilucina cf. multilineata FAM:Pectinidae Philine sagra FAM:Pinnidae Pitar cordatus Pitar simpsoni 64

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Table 7 (contd). APPENDIX 1 Pitar spp. Platycythara elata Pleuromeris tridentata Plicatula gibbosa Polinices duplicatus Polinices lacteus Psarostola glypta Psarostola minor Pteromeris perplana Pyrgocythara spp. Pyrunculus caelatus Retusa sulcata Rimosodaphnella morra Rimula frenulata Rimula spp. Rissoina bryerea Rissoina multicostata Rubellatoma rubella Scaphander spp. Scissurella spp. Seila adamsi Semele bellastriata Semele nuculoides Semele purpurascens Sigatica carolinensis Sigatica semisulcata Sinum perspectivum Solariella lacunella Solariella spp. Solecurtus sanctaemarthae Solemya occidentalis Strombus alatus Tellina aeguistriata Tellina alternata Tellina sguamifera Tellina versicolor Terebra dislocata Terebra glossema Terebra spp. Thelecythara floridana Thyasira spp. Trachycardium egmontianum Trigonostoma tenerum 65

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Table 7 (cont'd). APPENDIX 1 Triohora decorata Triphora spp. Turbo castanea Turboni 11 a spp. FAM:Turridae Turritella acropora Varicorbula operculata Verticordia ornata Vitreolina bermudezi Volvulella persimilis Volvulella recta Zebina browniana 66

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67 APPENDIX 2 Plots of species area curves for all samples.

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(I) 't... () 8 APPENDIX 2 SPECIES AREA CURVE Sample 0121 0 0 2 4 SAMPLES 6 8 Figure 8. Plots of species area curves for sample 0121. 68

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4 0 0 APPENDIX 2 SPECIES AREA CURVE Sample 0221 m 8 ;a 4 2 4 6 SAMPLES 8 Figure 9. Plots of species area curves for sample 0221. 69

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70 APPENDIX 2 SPECIES AREA CURVE Sample 0321 {3 (I) f!j 9:l 16 40 0 2 4 6 8 SAMPLES Figure 10. Plots of species area curves for sample 0321.

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32 24 (f) ...... (;) !l:: 16 8 APPENDIX 2 SPECIES AREA CURVE Sample 0421 0 2 4 SAMPLES 6 8 Figure 11. Plots of species area curves for sample 0421. 71

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12 APPENDIX 2 SPECIES AREA CURVE Sample 0521 72

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12 1 0 tl) 156 4 2 0 0 Figure 13. APPENDIX 2 SPECIES AREA CURVE Sample 0621 .12 ..... 0 2 SAMPLES 6 2 4 6 8 SAMPLES Plots of species area curves for sample 0621. 73

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lE Cr) APPENDIX 2 SPECIES AREA CURVE Station 0721 Figure 14. Plots of species area curves for sample 0721. 74

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24 20 4 APPENDIX 2 SPECIES AREA CURVE Station 0821 2 SAMPLES 6 0 2 4 6 8 SAMPLES Figure 15. Plots of species area curves for sample G821. 75

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28 20 t3 (I) ....... 12 4 0 APPENDIX 2 SPECIES AREA CURVE Sample 0921 2 fa (I) 't ml 4 4 SAMPLES 6 8 Figure 16. Plots of species area curves for sample 0921. 76

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28 20 f3 (r) ...... (.') 12. l5 4 0 Figure 17. APPENDIX 2 SPECIES AREA CURVE Sample 1121 .... 012 4 2 SAMPLES 6 2 4 6 SAMPLES 8 Plots of species area curves for sample 1121. 77

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78 APPENDIX 2 12 SPECIES AREA CURVE Sample 1221 10 8 55 '() 12 2 't 0 0 2 4 6 8 SAMPLES Figure 18. Plots of species area curves for sample 1221.

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APPENDIX 2 SPECIES AREA CURVE Sample 012 2 2sAMPLES 6 0 2 4 6 8 SAMPLES Figure 19. Plots of species area curves for sample Cl22. 79

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32 24 8 APPENDIX 2 SPECIES AREA CURVE Sample 0222 0 2 4 SAMPLES 6 8 Figure 20. Plots of species area curves for sample 0222. 80

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APPENDIX 2 SPECIES AREA CURVE Sample 0322 0 0 2 4 SAMPLES 6 8 Figure 21. Plots of species area curves for sample 0322. 81

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28 til P;j 'to-. () 20 l5 <: 12 4 0 0 Figure 22. APPENDIX 2 SPECIES AREA CURVE Sample 0422 f3 (f) .... 0 {5 12 2 SAMPLES 6 2 4 6 SAMPLES 8 Plots of species area curves for sample 0422. 82

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(I) '-t5 APPENDIX 2 16 SPECIES AREA CURVE Sample 0522 12 0 8 4 (I) 0 2 4 SAMPLES 6 8 Figure 23. Plots of species area curves for sample 0522. 83

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20 16 t3 C/) 8 < 4 0 0 Figure 24. APPENDIX 2 SPECIES AREA CURVE Sample 062 2 20 {a ti 12 .... () 9:i 4 2 SAMPLES 6 2 4 6 SAMPLES 8 Plots of species area curves for sample 0622. 84

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32 24 APPENDIX 2 SPECIES AREA CURVE Sample 0722 85

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24 16 APPENDIX 2 SPECIES AREA CURVE Sample 0822 Figure 26. Plots of species area curves for sample 0822. 86

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APPENDIX 2 SPECIES AREA CURVE 28l Sample 092 2 20 4 0 2 e I 0 4 6 8 SAMPLES Figure 27. Plots of species area curves for sample 0922. 87

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(f) llJ {f) 't.... tt 12 4 0 APPENDIX 2 SPECIES AREA CURVE Sample 102 2 C!t 0 0 0 2 I 2 SAMPLES 6 4 SAMPLES 6 8 Figure 28. Plots of species area curves for sample 1022. 88

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28 20 Cr) e5 12 4 0 Figure 29. APPENDIX 2 SPECIES AREA CURVE Sample 1122 G 8 ....... (I) ..... 1:) 12 4 2 SAMPLES 6 2 4 6 SAMPLES 8 Plots of species area curves for sample 1122. 89

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90 APPENDIX 2 SPECIES AREA CURVE 12 Sample 1222 10 8 (1)6 ""- 'S (I) 2 't) m4 2 SAMPLES 6 0 0 2 4 6 8 SAMPLES Figure 30. Plots of species area curves for sample 1222.

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28 (I) 't.... R:: Lt12o 0 APPENDIX 2 SPECIES AREA CURVE Sample 0123 2 4 SAMPLES 2 SAMPLES 6 6 8 Figure 31. Plots of species area curves for sample 0123. 91

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APPENDIX 2 SPECIES. AREA CURVE Sample 0223 Figure 32. Plots of species area curves for sample 0223. 92

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24 "' 16 8 0 0 Figure 33. APPENDIX 2 SPECIES AREA .CURVE Sample 0323 '() 24 16 8 2 SAMPLE.S 6 2 4 6 SAMPLES 8 Plots of species curves for sample 0323. 93

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94 APPENDIX 2 SPECIES AREA CURVE Sample 0423 (J) 16 8 "c) a 2 SAMPLES 6 0 0 2 4 6 8 SAMPLES Figure 34. Plots of species area curves for sample 0423.

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24 20 16 12 CJ) "" 8 4 0 0 Figure 35. APPENDIX 2 SPECIES AREA CURVE Sample 0523 24 fa 16 Ct) ..... () t!i i 8 2 SAMPLES 6 2 4 6 SAMPLES 8 Plots of species area curves for sample 0523. 95

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12 10 8 2 APPENDIX 2 SPECIES AREA CURVE Sample 0623 0 Figure 36. Plots of species area curves for sample 0623. 96

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28 20 4 APPENDIX 2 SPECIES AREA CURVE Sample 0723. 2 SAMPLES 6 0 2 4 6 8 SAMPLES Figure 37. Plots of species area curves for sample 0723. 97

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Ct) 't... (:) 8 4 0 0 Figure 38. APPENDIX 2 SPECIES AREA CURVE Sample 0823 24 t1 S3 16
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99 APPENDIX 2 SPECIES AREA CURVE Sample 0923 12 -...... lt fa 4 (I) 12 "a I 4 2 SAMPLES 6 0 0 2 4 6 8 SAMPLES Figure 39. Plots of species area curves for sample 0923.

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28 24 APPENDIX 2 SPECIES AREA CURVE Sample I 023 100

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101 APPENDIX 2

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102 APPENDIX 2 12 SPEClES AREA CURVE Sample 1223 10

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APPENDIX 3 Species dominance according to McCloskey's index and numbers of each species in each sample. 103

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APPENDIX 3 Table 8. Species dominance according to McCloskey's index and numbers of each species in each sample from station 1. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Solemya occidentalis 118.0 80 15 37 28 Parvilucina cf. multilineata 116.0 58 25 22 11 Ischnochiton papillosus 112.5 138 4 73 61 Tellina versicolor 112.0 40 19 10 11 Plicatula gibbosa 108.0 29 7 9 13 Diplodonta spp. 106.5 28 8 12 8 Calyptraea centralis 98.5 21 13 4 4 Cerithium atratum 87.5 25 1 13 11 Lioberus castaneus 84.5 9 3 2 4 Crepidula fornicata 67.5 15 12 0 3 Oceanida spp. 65.5 10 0 4 6 Chione cance11ata 59.0 6 1 1 4 Olive11a spp. 59.0 6 1 1 4 Acanthochitona pygmaea 58.5 8 0 5 3 Ischnochiton spp. 55.0 6 0 3 3 Turboni11a spp. 53.0 7 5 1 1 Gastrochaena hians 49.5 5 1 0 4 Eulimostraca hemphillii 47.0 4 1 1 2 Gouldia cerina 47.0 4 1 1 2 spp. 46.0 4 0 2 2 Anadara transversa 45.0 4 2 l l Atys riiseana 42.5 8 0 0 8 Anachis iontha 42.0 4 0 1 3 Kurtzi ell a spp. 38.5 8 0 7 1 Crassine11a lunulata 37.5 3 l 0 2 Kurtziel1a atrostyla 37.5 3 1 0 2 ...... 0

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APPENDIX 3 Table 8 (cant d). Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Oliva sayana 33.5 3 2 1 0 Corbula dietziana 32.5 3 1 1 1 Ischnochiton floridanus 32.5 3 0 0 3 FAM:Leptonidae 32.5 3 0 0 3 Anachis obesa 29.5 4 4 0 0 Eulima bifasciatus 29.5 4 4 0 0 Varicorbula operculata 29.5 4 4 0 0 Natica livida 26.5 3 3 0 0 Caecum bipartitum 26.0 2 0 0 2 sen a adams; 26.0 2 0 0 2 Odostomia seminuda 24.0 2 2 0 0 Abra lioica 23.0 2 1 0 1 Chione grus 23.0 2 1 0 1 Chaetopleura apiculata 22.5 3 0 3 0 Volvulella persimilis 21.0 2 1 1 0 Archinella cornuta 21.0 2 0 1 1 Chama congregata 21.0 2 0 1 1 Ischnochiton boogii 21.0 2 0 1 1 Glyphoturris spp. 20.0 2 0 2 0 Acteocina candei 11.5 1 1 0 0 Chama macerophylla 11.5 1 1 0 0 Cyclostremiscus spp. 11.5 1 1 0 0 Eupleura sulcidentata 11.5 1 1 0 0 Haminoea succinea 11.5 1 1 0 a 11.5 1 1 0 0 Pitar simpsoni 11.5 1 1 0 0 ..... Semele bellastriata 11.5 1 1 0 0 0 U1

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APPENDIX 3 Table 8 (cont'd). Species Name Rank Score Total Number Number of Individuals Each Sample P e r iod of Individuals 21 22 23 Strombus a1atus 11.5 1 1 0 0 Terebra dis1ocata 11.5 1 1 0 0 A1vania spp. 11.5 1 0 0 1 FAI"1:Arcidae 11.5 1 0 0 1 Caecum pu1che11um 11.5 1 0 0 1 Ca1otrophon ostrearum 11.5 1 0 0 1 Conus jaspideus stearnsi 11.5 1 0 0 1 Cryoturris guadri1ineata 11.5 1 0 0 1 Lucina nassula 11.5 1 0 0 1 Marginell a spp. 11.5 1 0 0 1 Me1ane11a spp. 11.5 1 0 0 1 Murex pomum 11.5 1 0 0 1 Sinum perspectivum 11.5 1 0 0 l Terebra spp. 11.5 1 0 0 1 Verticordia ornata 11.5 1 0 0 1 Linga amiantus 1 0 0 0 Sigatica carolinensis 9.5 1 0 1 0 Trachycardium egmontianum 9.5 1 0 1 0 Vitreolina bermudezi 9.5 1 0 1 0 Zebina browniana 9.5 1 0 l 0

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APPENDIX 3 Table 9. Species dominance according to McCloskey's index and numbers of each species in each sample from station 2. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Tellina versicolor 81.0 176 20 92 64 Eulimostraca hemphillii 75.0 40 8 6 26 Olivella spp. 70.5 19 3 7 9 Acteocina candei 55.5 14 0 6 8 Varicorbula ooercu1ata 53.0 22 0 4 18 Caecum pulchellum 49.5 8 0 5 3 Caecum bipartitum 45.5 23 8 0 15 Finella dubia 40.0 5 0 2 3 Turbonilla spp. 38.5 5 0 3 2 Solemya occidentalis 37.5 8 3 5 0 Laevicardium pictum 36.0 10 6 4 0 Dentalium bartletti 35.5 5 1 1 3 Nannodiella spp. 34.0 4 0 2 2 tre 11 a 1 unata 32.5 6 0 5 1 Oivaricella dentata 29.5 5 0 4 1 Volvulella persimilis 27.0 4 0 0 4 Dosinia elegans 24.5 3 0 1 2 Brachycythara biconica 24.5 3 0 0 3 Cryoturris spp. 23.0 3 0 2 1 Ervilia concentrica 23.0 3 0 2 1 Bushia spp. 18.5 2 0 0 2 Calyptraea centralis 18.5 2 0 0 2 Cooperella atlantica 18.5 2 0 0 2 Dentalium spp. 18.5 2 0 0 2 Nannodiella melanitica 18.5 2 0 0 2 Atys riiseana 17.0 9 9 0 0 ..... 0 ......,

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APPENDIX 3 Table 9 ( cont' d). Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Abra lioica 15.5 2 0 2 0 Acteon punctostriatus 15.5 2 0 2 0 Cryoturris citronella 15.5 2 0 2 0 Lucina nassula 15.5 2 0 2 0 Retusa su1cata 13.5 2 0 1 1 Caecum imbricatum 12.5 2 1 0 1 Dip1odonta spp. 12.5 2 1 0 1 Eulima bifasciatus 11.0 2 1 1 0 Natica 1ivida 10.5 2 2 0 0 Sigatica semisu1cata 10.5 2 2 0 0 Cadulus guadridentatus 7.5 1 0 0 1 Caecum strigosum 7.5 1 0 0 1 Kurtziella spp. 7.5 1 0 0 1 Lyonsia hya1ina f1oridana 7.5 1 0 0 1 Macroca1lista macu1ata 7.5 1 0 0 1 Melane1la spp. 7.5 1 0 0 1 Nati ca pus i 11 a 7.5 1 0 0 1 Anachis iontha 6.0 1 0 1 0 Cerithium atratum 6.0 1 0 1 0 lanceolata 6.0 1 0 1 0 Lima pell uci da 6.0 1 0 1 0 Musculus lateralis 6.0 l 0 l 0 Pitar simpsoni 6.0 l 0 l 0 Sigatica carolinensis 6.0 l 0 l 0 Cardiomya perrostrata 5.0 1 l 0 0 -' 0 co

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APPENDIX 3 Table 9 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sam p l e Per iod of Individuals 21 22 23 Chione cancellata 5.0 1 1 0 0 Epitonium novangliae 5.0 1 1 0 0 Oliva sayana 5.0 1 1 0 0 Terebra dislocata 5.0 1 1 0 0 Table 10. Species dominance according to McCloskey's index and numbers of each species in each sample from station 3. Species Name Rank Score Total Number Number of Individuals Each Sample P e r iod of Individuals 21 2 2 23 Tellina versicolor 119.5 41 6 19 16 Parvilucina cf. multilineata 115.5 39 5 19 15 Diplodonta spp. 98.5 16 4 8 4 Amygdalum papyrium 95.5 15 2 3 10 Crenella divaricata 92.0 13 8 2 3 Crassinella cf. martinicensis 80.0 11 1 4 6 Varicorbula operculata 79.5 12 7 1 4 Acteocina candei 75.5 15 0 5 1 0 Finella dubia 73.5 16 0 3 13 Philine sagra 68.5 12 0 3 9 Cymatoica orientalis 66.0 6 3 2 1 Caecum cubitatum 66.0 12 0 2 10 Gouldia cerina 60.0 8 2 0 6 _.. 0 \0

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APPENDIX 3 Table 10 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Samp 1 e Period of Individuals 21 22 23 Lyonsia hyalina floridana 56.5 17 0 1 16 Abra lioica 55.5 7 5 0 2 Cardiomya perrostrata 55.5 7 1 1 5 Musculus lateralis 54.0 6 1 4 1 Brachycythara biconica 52.0 5 2 0 3 Caecum bipartitum 49.5 11 1 0 10 Caecum pulchellum 47.5 12 0 11 1 Caecum imbricatum 44.5 4 1 1 2 Atys riiseana 42.5 6 5 0 l Solemya occidentalis 41.0 4 0 3 1 Dentalium semistriolatum 40.5 5 l 0 4 Nucula crenulata 36.5 3 2 1 0 Oceanida spp. 36.5 3 2 1 0 Chlamys benedicti 36.5 3 1 2 0 Laevicardium pictum 35.5 6 6 0 0 Eulima bifasciatus 34.5 3 0 1 2 Oliva sayana 34.5 3 0 1 2 Eulimostraca hemphillii 33.5 5 0 0 5 Cadulus guadridentatus 32.5 3 1 0 2 Chione grus 32.5 3 1 0 2 Volvulella persimilis 30.5 4 0 0 4 Dentalium bartletti 26.5 2 0 2 0 Lucina nassula 26.5 2 0 2 0 Acteon punctostriatus 24.5 2 2 0 0 Eulimostraca spp. 24.5 2 2 0 0 Linga amiantus 24.5 2 2 0 0 Melanella arcuata 24.5 2 2 0 0 Zebina browniana 24.5 2 2 0 0 0

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APPENDIX 3 Table 10 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Limea bronniana 22.5 2 0 0 2 Psarostola glypta 22.5 2 0 0 2 Polinices duplicatus 22.0 2 1 1 o Cyciopecten nanus 21.5 2 0 1 1 Lima pe ll uci da 21.5 2 0 1 1 Macoma cf. extenuata 21.5 2 0 1 1 Calyptraea centralis 19.5 2 1 0 1 Ithycythara lanceolata 19.5 2 1 0 1 Cerodrillia simpsoni 12.0 1 0 1 0 Conus jaspideus stearnsi 12.0 1 0 1 0 Ithycythara spp. 12.0 1 0 1 0 Kurtzi e 11 a spp. 12.0 1 0 1 0 Marginel1a eburneo1a 12.0 1 0 1 0 Margine11a hart1eyanum 12.0 1 0 1 0 01 ivella spp. 12.0 1 0 1 0 Rimosodaphne11a morra 12.0 1 0 1 0 Sigatica carolinensis 12.0 1 0 1 0 Te11ina aequistriata 12.0 1 0 1 0 Triphora decorata 12.0 1 0 1 0 Acteocina spp. 10.0 1 1 0 0 Corbula dietziana 10.0 1 1 0 0 Erycina emmonsi 10.0 1 1 0 0 Ischnochiton boogii 10.0 1 1 0 0 Ischnochiton papi11osus 10.0 1 1 0 0 Pteromeris perp1ana 10.0 1 1 0 0 spp. 10.0 1 1 0 0 Henrya spp. 9.5 1 0 0 1

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APPENDIX 3 Table 10 (contd). Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 FAM:Limidae 9.5 l 0 0 l Murex cabritii 9.5 l 0 0 l Niso aeglees 9.5 l 0 0 l Retusa sulcata 9.5 l 0 0 l Terebra spp. 9.5 l 0 0 l Triphora spp. 9.5 1 0 0 1 Turbonilla spp. 9.5 1 0 0 1 Table 11. Species dominance according to McCloskeys index and numbers of each species in each sample from station 4. Species Name Rank Score Total Number Number of Individuals Each Sample Per iod of Individuals 21 22 23 Crassinella cf. martinicensis 93.0 16 2 8 6 Pitar simpsoni 85.5 10 2 5 3 Tellina versicolor 78.5 17 7 1 9 Cadulus parvus 74.5 10 1 6 3 Abra lioica 66.0 10 3 7 0 Corbula dietziana 60.5 6 0 3 3 Olivella spp. 55.0 6 4 1 1 Varicorbula operculata 54.0 7 1 1 5 Atys riiseana 52.0 4 2 2 0 ...... ...... N

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APPENDIX 3 Table 11 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Kurtziella spp. 47.5 6 0 5 1 Caecum floridanum 44.5 4 0 3 1 Glans dominguensis 44.5 4 0 3 1 Diplodonta spp. 41.5 4 0 1 3 Ischnochiton papillosus 41.0 14 0 14 0 Crenella divaricata 39.5 3 1 2 0 Parvilucina cf. multilineata 35.0 3 1 J 1 Semele purpurascens 33.5 3 0 3 0 Gouldia cerina 32.5 3 l 0 2 Semele nuculoides 32.0 8 0 0 8 Turboni 11 a spp. 30.0 2 0 2 0 Amygdalum papyrium 29.5 4 4 0 0 Brachycythara barbarae 27.0 3 3 0 0 Eulima bifasciatus 27.0 3 3 0 0 Cyclopecten nanus 27.0 3 0 0 3 Caecum imbricatum 25.5 2 0 l 1 Nannodiella spp. 25.5 2 0 l 1 Solemya occidentalis 25.5 2 0 1 1 Thyasira spp. 25.5 2 0 1 1 Verticordia ornata 25.5 2 0 1 1 Laevicardium pictum 24.0 2 1 1 0 Murex cabriti i 24.0 2 1 1 0 Odostomia spp. 24.0 2 1 1 0 Philine sagra 24.0 2 1 1 0 P1atycythara elata 24.0 2 1 1 0 Acteocina candei 23.0 2 0 0 2 Volvulella recta 23.0 2 0 0 2 ..... ..... w

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APPENDIX 3 Table 11 (contd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Cadulus spp. 22.0 2 2 0 0 Gastrochaena hians 22.0 2 2 0 0 Parvilucina blanda 22.0 2 2 0 0 Volvulella persimilis 22.0 2 2 0 0 Cardiomya perrostrata 20.5 2 1 0 1 Eucrassatella speciosa 20.5 2 1 0 1 Arcopsis adamsi 14.5 1 0 1 0 Dentalium sowerbyi 14.5 1 0 1 0 FAM:Fissurellidae 14.5 1 0 1 0 Limatula setifera 14.5 1 0 1 0 Macoma cf. extenuata 14.5 1 0 1 0 Modulus modulus 14.5 1 0 1 0 Musculus latera1is 14.5 1 0 1 0 Ocenebra minirosea 14.5 1 0 1 0 Pleuromeris tridentata 14.5 1 0 1 0 Psarostola glypta 14.5 1 0 1 0 Trigonostoma tenerum 14.5 1 0 1 0 Turbo castanea 14.5 1 0 1 0 Turritella acropora 14.5 1 0 1 0 Chione latilirata 11.0 1 0 0 1 FAM:Columbellidae 11.0 l 0 0 1 spp. 11.0 1 0 0 1 Cylichna spp. 11.0 1 0 0 1 Dentalium bartletti 11.0 1 0 0 1 Limea bronniana 11.0 1 0 0 1 Polinices dup1icatus 11.0 1 0 0 1 Pyrunculus caelatus 11.0 1 0 0 1 __, .J::>

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APPENDIX 3 Table 11 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Semele bellastriata 11.0 1 0 0 1 Lyonsia hyalina floridana 9.5 1 1 0 0 Natica spp. 9.5 1 1 0 0 Nemocardium tinctum 9.5 1 1 0 0 Sigatica carolinensis 9.5 1 1 0 0 Sinum perspectivum 9.5 1 1 0 0 Tellina aeguistriata 9.5 1 1 0 0 Table 12. Species dominance according to McCloskey's index and numbers of each species in each sample from station 5. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Abra lioica 45.5 23 12 6 5 Glycymeris subtilis 33.0 6 1 2 3 Ischnochiton papillosus 33.0 11 0 2 9 Semele nuculoides 22.5 5 1 0 4 Barbatia cf. domingensis 21.0 4 1 0 3 Parvilucina cf. multilineata .19. 5 5 0 0 5 Nucinella adamsi 16.5 5 4 0 1 Dentalium sowerbyi 15.5 3 1 1 1 Dentalium spp. 13.0 2 0 0 2 --' --' Nassarius spp. 13.0 2 0 0 2 ()"1

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APPENDIX 3 Table 12 (cont'd). Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 2 1 22 23 Nuculana spp. 13.0 2 0 0 2 Pitar simpsoni 13.0 2 0 0 2 P1icatula gibbosa 13.0 2 0 0 2 Cadulus parvus 12.0 2 0 2 0 Limea bronniana 11.0 2 0 1 1 Eucrassate11a speciosa 10.0 3 3 0 0 Nemocardium peramabile 10.0 2 1 1 0 So1ariel1a lacunella 10.0 2 1 1 0 Thyasira spp. 10.0 2 1 1 0 Nucu1ana acuta 9.0 2 2 0 0 Ca11iostoma fascinans 5.5 1 0 1 0 Dentalium ceratum 5.5 1 0 1 0 Ith.z::c.z::thara spp. 5.5 1 0 1 0 Kurtzie11a spp. 5.5 1 0 1 0 FAM:Pectinidae 5.5 1 0 1 0 Dacrydium vitreum 5.5 1 0 0 1 Mitro1umna bip1icata 5.5 1 0 0 1 01ivella spp. 5.5 1 0 0 1 Opa1ia spp. 5.5 1 0 0 1 Phil ine sagra 5.5 1 0 0 1 P1euromeris tridentata 5.5 1 0 0 1 FAM:Turridae 5.5 1 0 0 1 Cyclopecten nanus 4.5 1 1 0 0 __,

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APPENDIX 3 Table 13. Species dominance according to McCloskey's index and numbers of each species in each sample from station 6. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Chaetoderma spp. 35.5 24 6 14 4 Abra lioica 32.0 15 6 6 3 CicloQecten nanus 19.0 7 6 0 Thyasira spp. 17.0 8 0 8 0 Glycymeris subtilis 16.0 6 0 1 5 Bathyarca glomerula 14.0 2 0 2 0 Linga sombrerensis 11.0 7 7 0 0 Denta1ium sowerbyi 10.5 2 1 1 0 Verticordia ornata 10.5 2 1 1 0 Dentalium spp. 10.0 2 0 1 1 Limatu1a setifera 10.0 2 0 1 1 Nucu1a cf. fernandinae 10.0 2 0 1 1 Parvi1ucina cf. mu1ti1ineata 10.0 7 0 0 7 Cardiomya spp. 8.0 3 3 0 0 Eucrassate11a SQeciosa 7.0 2 2 0 0 CLS:AQ1acoQhora 7.0 1 0 1 0 FAM:Bu1lidae 7.0 1 0 1 0 Cadu1us parvus 7.0 1 0 1 0 Costellarta spp. 7.0 1 0 1 0 C_y:c 1 i ch n i dae 7.0 1 0 1 0 Dacrydium vitreum 7.0 1 0 1 0 Solariella spp. 7.0 1 0 1 0 Denta1ium Texasianum 6.0 2 0 0 2 Dentalium ceratum 3.5 1 1 0 0 Nannodiella spp. 3.5 1 1 0 0 So1ariella lacunella 3.5 1 1 0 0 ...... ...... ""-'

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APPENDIX 3 Table 13 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Per iod of Individuals 21 22 23 Cadulus spp. 3.0 1 0 0 1 Sci ssure 11 a spp. 3.0 1 0 0 1 Table 14. Species dominance according to McCloskey's index and numbers of each species in each sample from station 7. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Varicorbula operculata 97.0 59 7 14 38 Tellina versicolor 96.5 96 50 41 5 occidental is 82.0 86 16 69 1 Eulimostraca hemphillii 79.0 11 5 2 4 Olive11a spp. 76.0 11 3 2 6 ri i seana 68.0 8 2 3 3 Calyptraea centralis 68.0 11 2 7 2 Dosinia elegans 67.5 10 6 1 3 Acteocina candei 56.5 6 4 2 0 Dentalium bartletti 54.5 7 5 1 1 Turbonilla spp. 45.0 5 4 1 0 Diplodonta spp. 44.5 4 2 2 0 Caecum strigosum 41.5 6 6 0 0 Crassinella cf. martinicensis 41.0 4 3 1 0 _. _. 00

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APPENDIX 3 Table 14 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Caecum bipartitum 37.0 4 4 0 0 Finella dubia 33.5 7 1 0 6 Chione cancellata 33.0 3 3 0 0 Cryoturris fargoi 33.0 3 3 0 0 spp. 33.0 3 3 0 0 Cryoturris spp. 33.0 3 2 1 0 Eulima bifasciatus 27.0 6 0 6 0 Caecum pulchellum 26.5 3 0 2 1 Caecum cornucopiae 25.0 2 2 0 0 Corbula dietziana 25.0 2 2 0 0 Ischnochiton hartmeyeri 25.0 2 2 0 0 Melanella spp. 25.0 2 2 0 0 Polinices duplicatus 25.0 2 2 0 0 Semele nuculoides 25.0 2 2 0 0 Thyasira spp. 25.0 2 2 0 0 Abra lioica 25.0 3 1 0 3 Brachycythara biconica 25.0 3 1 1 1 Gouldia cerina 25.0 3 1 0 2 Lucina nassula 25.0 3 1 l 1 Cryoturris filifera 25.0 3 0 3 0 Volvulella persimilis 25.0 3 0 3 0 Ervilia concentrica 21.5 5 0 0 5 Caecum imbricatum 19.5 2 0 2 0 Dentalium semistriolatum 19.5 2 0 2 0 Sigatica carolinensis 19.5 2 0 2 0 lunata 18.0 2 1 1 0 Scaphander spp. 18.0 3 0 0 3 __, __, \0

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APPENDIX 3 Table 14 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Terebra dislocata 17 .o 2 1 0 1 nanus 15.0 2 0 1 1 Chama congregata 10.0 1 1 0 0 Divaricella dentata 10 .o 1 1 0 0 Eulimostraca spp. 10.0 1 1 0 0 Haminoea succinea 10.0 1 1 0 0 Ischnochiton QaQillosus 10.0 1 1 0 0 Kurtziella spp. 10.0 1 1 0 0 Lucina radians 10.0 1 1 0 0 Natica canrena 10.0 1 1 0 0 Oliva sayana 10.0 1 1 0 0 Oliva spp. 10.0 1 l 0 0 Parvilucina cf. mu1ti1ineata 10.0 1 1 0 0 Sigatica semisulcata 10.0 1 1 0 0 ArgoQecten gibbus 8.0 1 0 1 0 Bulla striata 8.0 l 0 1 0 Conus jasQideus stearnsi 8.0 1 0 1 0 Henrya spp. 8.0 1 0 1 0 Musculus lateralis 8.0 1 0 1 0 Turbo castanea 8.0 1 0 1 0 Acteocina spp. 7.0 1 0 0 1 Mysella spp. 7.0 1 0 0 1 Pi nni dae 7.0 1 0 0 1 Pitar simpsoni 7.0 1 0 0 1 Robellatoma rubella 7 0 l 0 0 l }ellina aeguistriata 7.0 1 0 0 l N 0

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APPENDIX 3 Table 15. Species dominance according to McCloskey's index and numbers of each species in each sample from station 8. Species Name Parvilucina cf. multilineata Caecum cubitatum Aeteoci na candei Tellina versicolor Caecum bipartitum Caecum pulchellum Varicorbu1a opercu1ata Diplodonta spp. Finella dubia Kurtziella spp. Lyonsia hya1ina f1oridana Atys riiseana Abra 1ioica Grene11a divaricata Pitar cordatus Eulimostraca hemphi11ii Brachycythara biconica Turbonil1a spp. Natica canrena Pitar spp. Volvulella persimilis Abra aequa1is Amygdalum papyrium Retusa sulcata Cryoturris spp. FAI1:Lucinidae Rank Score Total Number 63.0 59.0 54.5 54.5 40.0 39.0 36.5 34.0 32.5 31.5 28.0 21.5 21.0 20.5 20.5 18.5 17.5 17.5 14.0 14.0 14.0 12.0 12.0 12 .o 8.5 8.5 of Individuals 140 59 31 32 56 88 9 8 7 8 7 4 27 3 3 4 2 2 2 2 2 2 2 2 1 1 Number of Individuals Each Sample Period 21 22 23 61 20 14 13 31 0 4 4 3 0 l l 0 2 2 0 0 0 l 1 1 2 0 0 0 0 65 29 10 10 0 82 1 1 1 4 1 1 0 l 1 l 2 2 1 1 1 0 1 1 1 1 14 10 7 9 25 6 4 3 3 4 5 2 27 0 0 3 0 0 0 0 0 0 1 1 0 0 __, N __,

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APPENDIX 3 Table 15 (contd) Species Name Rank Score Total Number Number of Individuals Each Sam p l e Period of Individuals 21 22 23 Phil i ne sagra 8.5 1 0 1 0 Sca2hander spp. 7.5 2 0 0 2 Anomia simplex 5.5 1 1 0 0 Gouldia cerina 5.5 1 1 0 0 Lucina nassula 5.5 1 1 0 0 Lucina radians 5.5 1 1 0 0 Macoma cf. extenuata 5.5 1 1 0 0 Anodontia alba 3.5 1 0 0 1 Caecum imbricatum 3.5 1 0 0 1 Dosinia elegans 3.5 1 0 0 1 Mitrella lunata 3.5 1 0 0 1 Table 16. Species dominance according to McCloskeys index and numbers of each species in each sample from station 9. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Parvilucina cf. multilineata 75.0 159 50 7 1 38 Acteocina candei 64.5 61 19 38 4 Caecum cubitatum 57.0 22 9 11 2 Phi line sagra 53.5 14 2 8 4 ...... floridana 48.5 9 2 4 3 N N

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APPENDIX 3 Table 16 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Caecum Bipartitum 75.0 58 46 0 12 Caecum pulchellum 43.5 60 0 54 6 Finella dubia 42.5 24 21 2 1 Lucina nassula 42.5 7 3 2 2 Crassinella cf. martinicensis 41.0 7 4 3 0 Turbonilla spp. 37.5 6 2 3 1 Eulimostraca hemphillii 37.0 6 3 2 1 Kurtziella spp. 35.5 9 0 3 6 Diplodonta spp. 33.5 5 3 2 0 Tellina versicolor 31.0 7 0 5 2 Crenella divaricata 29.5 7 1 6 0 Vericorbula operculata 29,5 5 1 2 2 Atys riiseana 19.5 3 3 0 0 Abra 1ioica 19.0 21 0 0 21 Retusa su1cata 18.0 4 0 1 3 Natica canrena 15.0 2 2 0 0 Natica spp. 15.0 2 2 0 0 Abra aegua1is 14.0 2 0 2 0 Volvu1e11a persimilis 14.0 2 0 2 0 Odostomia spp. 12.0 2 1 1 0 Amygda1um papyrium 10.0 2 1 0 1 Pitar simpsoni 9.0 2 0 0 2 Acteon punctostriatus 6.5 1 1 0 0 Alvania auberiana 6.5 1 1 0 0 Brachycythara barbarae 6.5 1 1 0 0 Posinia e1egans 6.5 1 1 0 0 Henrya spp. 6.5 1 1 0 0 __. N w

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APPENDIX 3 Table 16 (cont'd) Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Lucina radians 6.5 1 1 0 0 Musculus lateralis 6.5 1 1 0 0 Nannodiella melanitica 6.5 1 1 0 0 Anomia simplex 5.5 1 0 1 0 Bushia spp. 5.5 1 0 1 0 Call istoma spp. 5.5 1 0 1 0 Cardiomya perrostrata 5.5 1 0 1 0 Mysella spp. 5.5 1 0 1 0 Sca12hander spp. 5.5 1 0 1 0 Solemya occidentalis 5.5 1 0 1 0 Tellina alternata 5.5 1 0 1 0 Eulima bifasciatus 3.5 1 0 0 1 Terebra spp. 3.5 1 0 0 1

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APPENDIX 3 Table 17. Species dominance according to McCloskey's index and numbers of each species in each sample from station 10. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Parvilucina cf. multilineata 62.0 130 0 87 43 Caecum cubitatum 59.0 85 0 70 15 Caecum pulchellum 55.0 32 0 28 4 Tellina versicolor 51.5 15 0 12 3 Cardiomya perrostrata 44.5 9 0 2 7 Diplodonta spp. 40.5 5 0 3 2 Lyonsia hyalina floridana 40.5 5 0 3 2 Varicorbula operculata 37.5 271 0 1 270 Acteocina candei 36.0 9 0 8 1 Abra lioica 35.5 21 0 1 20 Crenella divaricata 35.0 5 0 4 1 Finella dubia 35.0 4 0 2 2 Turboni 11 a spp. 35.0 4 0 2 2 Kurtzi e 11 a spp. 32.0 4 0 3 l Philine sagra 29.0 4 0 1 3 Natica canrena 27.0 3 0 3 0 Retusa sulcata 27.0 3 0 3 0 Caecum bipartitum 24.0 8 0 0 8 Eulima bifasciatus 23.0 3 0 l 2 Tellina alternata 23.0 3 0 l 2 Cryoturris citronella 21.5 2 0 2 0 01 ivella spp. 21.5 2 0 2 0 Volvulella persimilis 21.5 2 0 2 0 Anomia simplex 19.5 3 0 0 3 Corbula dietziana 19.5 3 0 0 3 Anodontia alba 14.5 2 0 l 1 __, -N U'l

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APPENDIX 3 Table 17 (contd). Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Cryoturris spp. 14.5 2 0 1 1 Eu1imostraca hemphil1ii 14.5 2 0 1 1 Gou1dia cerina 14.5 2 0 1 1 Atys riiseana 13.5 2 0 0 2 Cyclopecten nanus 13.5 2 0 0 2 Acteon punctostriatus 9.5 1 0 1 0 Cadulus parvus 9.5 1 0 1 0 Crassine11a cf. martinicensis 9.5 1 0 1 0 Cryoturris fi1ifera 9.5 1 0 1 0 Haminoea succinea 9.5 1 0 1 0 L i rna pe 11 uc i da 9.5 1 0 1 0 Natica spp. 9.5 1 0 1 0 Rimosodaphne11a morra 9.5 1 0 1 0 Solemya occidenta1is 9.5 1 0 1 0 f3ushia spp. 5.0 1 0 0 1 Macroca11ista macu1ata 5.0 1 o. 0 1

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APPENDIX 3 Table 18. Species dominance according to McCloskey's index and numbers of each species in each sample from station 11. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Crassinella cf. martinicensis 78.0 27 15 8 4 Parvilucina cf. multilineata 71.5 12 4 3 5 Corbula dietziana 67.5 9 2 4 3 Gastrochaena hians 66.5 9 2 3 4 Diplodonta spp. 46.0 5 1 2 2 Ischnochiton papi11osus 46.0 5 T 2 2 Gouldia cerina 40.5 8 6 l l Psarostola minor 34.0 5 l 4 0 Varicorbula operculata 34.0 5 0 l 4 Cyclopecten nanus 27.5 3 0 1 2 Erycina emmonsi 25.0 4 0 4 0 Ischnochiton spp. 23.5 3 0 0 3 Pitar simpsoni 23.0 5 5 0 0 Chlamys benedicti 21.5 3 0 3 0 Greguriella coralliophaga 21.5 3 0 3 0 Caecum f1oridanum 21.0 3 3 0 0 Abra lioica 19.5 2 0 0 2 Lyonsia hyalina floridana 19.5 2 0 0 2 Semele purpurascens 19.5 2 0 0 2 Crenella divaricata 19.0 2 2 0 0 Amygdalum papyrium 17.5 2 l 0 1 Tellina versicolor 17.5 2 1 0 1 Rimula frenulata 17.5 2 0 2 0 Triphora decorata 17.5 2 0 2 0 Caecum strigosum 17.0 2 l 1 0 Modulus modulus 17.0 2 l 1 0 Parvilucina blanda 17.0 2 l l _. 0 N ....._,

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APPENDIX 3 Table 18 (cont'd). Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Lima pellucida 16.5 2 0 1 1 Acanthochitona p,:tgmaea 9.0 1 1 0 0 Bushia spp. 9.0 1 l 0 0 Caecum bipartitum 9.0 1 1 0 0 Ca1liostoma jujubinum 9.0 1 1 0 0 Coch1io1epis striata 9.0 1 1 0 0 Glans dominguensis 9.0 1 1 0 0 Hiate11a arctica 9.0 1 1 0 0 Linga 1eucoc,:tma 9.0 1 1 0 0 FAM:Naticidae 9.0 1 1 0 0 Arcopsis adamsi 8.5 1 0 0 1 Caecum cubitatum 8.5 1 0 0 1 Caecum pulchel1um 8.5 1 0 0 1 Cal,:tptraea centra1 i s 8.5 1 0 0 l Crepidu1a fornicata 8.5 1 o 0 1 Kurtziella spp. 8.5 1 0 0 1 FAM:Leptonidae 8.5 1 0 0 1 Macoma cf. extenuata 8.5 l 0 0 l Philine sagra 8.5 1 0 0 1 Rimula spp. 8.5 1 0 0 l Solemya occidenta1is 8.5 1 0 0 1 Tellina sguamifera 8.5 l 0 0 l At,:ts riiseana 8.0 1 0 1 0 Gl,:tphoturris spp. 8.0 1 0 1 0 Murex gl,:tptus 8.0 1 0 1 0 Nemocardium tinctum 8.0 1 0 1 0 Plicatula gibbosa 8.0 1 0 1 0 P,:trgoc,:tthara spp. 8.0 1 0 1 0 N co

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Table 18 (contd) Species Name Rissoina multicostata Solecurtus sanctaemarthae APPENDIX 3 Rank Score Total Number 8.0 8.0 of Individ u a l s 1 1 Number of Individua l s Each Sample P eriod 2 1 22 2 3 0 0 1 1 0 0 Table 19. Species dominance according to McCloskeys index and numbers of each species in each sample from station 12. Species Name Rank Score Total Number Number of Individuals Each Sample Period of Individuals 21 22 23 Chaetoderma spp. 32. 5 28 12 5 11 Abra lioica 32.0 25 8 7 10 Cerithiopsis crystallinum 27.5 13 4 5 4 Bathyarca glomerula 16.5 5 2 2 1 Verticordia ornata 15.0 5 3 2 0 Cyclopecten nanus 11.0 4 3 0 1 Parvilucina cf. multilineata 10.0 5 0 0 5 Amygdalum sagittatum 8.5 2 0 1 1 Glyphostoma hendersoni 8.5 2 0 1 1 Nuculana carpenteri 8.5 2 0 1 1 Dentalium spp. 8.0 3 2 0 1 Cylichna spp. 4.5 1 0 0 1 G1yphoturris spp. 4.5 1 0 0 1 Bactrocythara spp. 4.0 1 0 1 0 Nucula cf. fernandinae 4.0 1 0 l 0 ...... N lO

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APPENDIX 3 Table 19 (cont'd) Species Name Rank Score Total Number of Individuals Nuculana spp. 4.0 1 Vo1vu1el1a recta 4.0 1 Nuculana acuta 3.5 2 Thyasira spp. 3.5 2 Dentalium 1agueatum 1.0 1 Number of Individuals 21 22 0 1 0 1 2 0 2 0 1 0 Each Sample Period 23 0 0 0 0 0 __, w 0

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131 APPENDIX 4 Composition of sample sediments in one fractions and percent carbonate composition.

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132 APPENDIX 4 Table 20. Composition of sample sediments in one fractions and percent carbonate composition. % Sample 00 20 CaC03 0121 2.6 2.2 3.9 11.0 50.0 21.7 8.6 47.7 0122 5.8 2.6 3.9 13.5 38.1 24.3 11.9 42.4 0123 2.1 2.4 3.7 9.8 47.4 25.2 9.5 32.7 0221 0.1 1.1 2.8 23.6 59.8 8.8 3.8 27.7 0222 0.2 0.5 1.4 11.3 54.8 20.5 11.4 28.6 0223 0.3 0.6 1.5 16.3 63.9 13.0 4.5 21.3 0321 14.9 5.8 19.4 37.8 17.6 0.6 3.6 61.3 0322 0.2 0.3 1.6 36.4 40.9 6.0 14.6 43.9 0323 0.2 0.6 2.2 33.7 40.4 6.0 14.8 2.0 34.2 0421 2.3 10.0 19. 7 44.0 15.9 3.4 4.7 90.5 0422 3.1 20.9 21.0 18.6 18.2 5.9 12.5 88.2 0423 2.8 22.9 29.5 28.2 8.1 1.6 6.9 84.8 0521 3.1 15.4 32. 4 27.0 13.0 5.2 4.0 92.0 0522 1.5 16.7 31.8 27.6 8.8 3.9 9.7 92.1 0523 1.9 14.7 32.2 27.2 B. 1 4.5 9.8 1.7 85.4 0621 3.7 7.0 8.3 19.2 28.7 18.8 5.9 8.3 83.0 0622 2.1 5.3 8.3 17.8 24.7 14.1 27.7 91.2 0623 2.1 5.9 7.7 17.2 29.4 15.0 16.0 6.9 84.7 0721 0.2 1.1 2.3 6.7 41.2 37.5 2.3 8.7 43.4 0722 0.5 1.3 2.8 8.0 37.3 40.7 9.2 37.5 0723 0.3 1.0 1.9 5.0 33.9 46.6 11.3 32.0 0821 1.0 0.6 2.0 3.6 8.7 25.2 4.8 54.1 83.3 0822 0.2 1.1 2.3 4.4 10.7 30.1 51.2 83.6 0823 o. 1 0.8 2.5 4.7 9.6 29.0 44.1 9.1 63.9 0921 0.6 0.7 1.5 5.8 22.3 26.7 4.0 38.4 83.5 0922 0.1 0.5 1.1 4.4 18.1 26.0 49.7 80.0 0923 0.2 0.5 1.1 4.4 19.9 31.6 38.6 3.7 69.1 1021 1022 1.0 1.0 3.0 23.5 23.0 14.4 34.1 90.1 1023 1.8 2.4 3.5 11.3 33.7 16.8 27.6 3.0 58.5 1121 17.4 27.5 27.1 12.8 2.1 1.1 2.3 9.7 93.2 1122 8.3 20.8 26.3 16.3 3.2 1.9 23.2 80.7 1123 13.3 29.9 28.2 12.3 3.3 2.4 10.3 84.2 1221 1.1 1.3 2.2 8.5 22.8 20.7 10.4 33.0 88.0 1222 0.6 0.9 2.0 7.6 18.6 23.2 47.0 86.8 1223 0.5 1.3 2.8 10.1 24.0 22.5 33.6 5 2 87.3

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133 APPENDIX 5 Mean of the mean grain size, with minimum and maximum mean in which each species was found and total number of individuals of each species collected.

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APPENDIX 5 Table 21. Mean of the mean grain size, with minimum and maximum mean in which each species was found and total number of individuals of each species collected. Mean of Mean Minimum Number of Species Name 0 Size f4ean Mean Individuals Abra aegualis 3.17 2.74 3.60 4. Abra lioica 1.82 -0.51 2.91 158. Acanthochitona 1.39 -0.65 l. 74 9. Acteocina candei 2.48 -0.18 3.60 139. Acteocina spp. 1.02 -0.07 2. l 0 2. Acteon QUnctostriatus 1.40 -0.07 2.88 6. Alvania auberiana 2.88 2.88 2.88 l. Alvania spp. l. 74 l. 74 l. 74 l. Amygdalum paQyrium 1.27 -0.65 2.91 25. sagittatum 2.50 2. 41 2.60 2. Anachis iontha l. 73 1.58 1.83 5. Anachis obesa l. 64 l. 64 1.64 4. Anadara transversa l. 65 1.58 l. 74 4. Anodontia alba 2.32 l. 98 2.91 3. Anomia simQlex 2.50 2.06 3.60 5. Arcinella cornuta 1.66 l. 58 l. 74 2. Arcopsis adamsi -0.04 -0.51 0.43 2. Argopecten gibbus 1.97 l. 97 1.97 l. Atys riiseana l. 55 -0.07 3.60 45. Bactrocythara spp. 2.60 2.60 2.60 l. Barbatia cf. domingensis 0.27 0.10 0.33 4. Gathyarca glomerula 37 l. 70 2. 77 7. Brachycythara barbarae 0.99 0.37 2.88 4. Brachycythara biconica l. 60 -0.07 2.82 13. Bulla striata 1.97 1.97 1.97 l. -' Bushia spp. 1.42 -0.65 2.74 5. w +=-

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APPENDIX 5 Table 21 (contd). Mean of Mean Minimum Maximum Number of Species Name Size Mean Mean Indi viduals Cadulus parvus 0.46 -0.18 1.98 14. Cadulus quadridentatus l. 15 -0.07 l. 59 4. Cadulus spp. 0.80 0.37 l. 68 3. Caecum bipartitum 2.60 -0.65 3.60 163. Caecum cornucopiae l. 99 l. 99 1.99 2. Caecum cubitatum 2. 41 -0.51 3.60 179. Caecum floridanum -0.12 -0.65 0.43 7. Caecum imbricatum 1. 31 -0.18 2.91 11. Caecum pul chellum 2.51 -0.51 2.91 205. Caecum strigosum 1.47' -0.65 l. 99 9. Calliostoma fascinans 0 .19 0.19 0.19 l. Calliostoma jujubinum -0.65 -0.65 -0.65 l. Calliostoma spp . 2.74 2.74 2.74 l. Calotrophon ostrearum l. 74 l. 74 l. 74 l. Calyptraea centra1is 1.64 -0.51 2.10 37. Cardiomya perrostrata 1.60 -0.18 2.74 20. Cardiomya spp. l. 32 l. 32 1.32 3. Cerithiopsis crystallinum 2.59 2.41 2.77 13. Cerithium atratum l. 66 1.58 1.83 26. Cerodril1ia simpsoni 1.48 1.48 1.48 l. Chaetoderma spp. 2.14 l. 32 2. 77 52. Chaetopleura apiculata l. 58 l. 58 l. 58 3. Chama congregata 1.77 l. 58 l. 99 3 Chama macerophy1l a 1.64 1.64 l. 64 l. Chione cancellata l. 74 1.28 1.99 10. Chione grus 1.30 -0.07 l. 74 5 __, w
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APPENDIX 5 Table 21 (cont'd). Mean of Mean Minimum Number of Species Name 0 Size Individuals Chione latilirata -0.18 -0.18 -0.18 1. benedicti 0.73 -0.07 1.48 6. Cochliolepis striata -0.65 -0.65 -0.65 l. Conus jaspideus stearnsi 1. 73 1.48 l. 97 3. Cooperella atlantica 1.48 1 .48 1. 48 2. Corbula dietziana 0.62 -0.65 2.06 24. Cos tell aria spp. l. 70 l. 70 l. 70 l. Crassinella cf. martinicensis 0. 61 -0.65 2.88 66. Crassinella lunulata 1.71 l. 64 l. 74 3. Crenella divaricata 1.41 -0.65 3.60 33. Crepidula fornicata 1.53 -0.51 l. 74 16. Cryoturris citronella l. 91 1.83 l. 98 4. Cryoturris fargoi l. 99 l. 99 l. 99 3. Cryoturris filifera l. 97 l. 97 l. 98 4. Cryoturris guadrilineata l. 74 l. 74 l. 74 l. Cryoturris spp. l. 74 -0.18 2.82 14. Cyclopecten nanus 1.36 -0.51 2.77 24. Cyclostremiscus spp. 1.64 1.64 1.64 l. Cylichna spp. l. 12 -0.18 2.41 2. Cymatoica orientalis 0. 72 -0.07 l. 59 6. Dacrydi urn vitreum 1.02 0.33 l. 70 2. Dentalium bartletti 1.62 -0.18 2.10 15. Dentalium ceratum 0.76 0.19 1.32 2 Dentalium lagueatum 2. 77 2. 77 2. 77 l. Dental iL'm semistriolatum 1.46 -0.07 l. 97 7. Dentalium sowerbyi 0.68 0.10 l. 70 6. Dentalium spp. 1.66 0.33 2. 77 9. ...... w 0"1

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APPENDIX 5 Table 21 (cont'd). Mean of Mean Minimum Maximum Number of Species Name 0 Size Mean Individuals Dentalium texasianum 1.68 1.68 1.68 2. Diplodonta spp. 1. 61 -0.65 3.60 77. Divaricella dentata 1.80 1.48 1.99 6. Dosinia elegans 2.05 1.48 2.91 15. Epitonium novangliae 1.28 1. 28 1.28 1. Ervilia concentrica 1.96 1.48 2.10 8. Erycina emmonsi 0.38 -0.07 0.49 5. Eucrassatella speciosa 0.45 -0.18 1.32 7. Eulima bifasciatus 1.64 0.37 2.64 22. Eulimostraca hemphillii 1. 79 1. 28 2.91 72. Eulimostraca spp. 0.62 -0.07 1. 99 3. Eupleura sulcidentata 1.64 1.64 1.64 1. Finella dubia 2.33 1.48 3.60 63. Gastrochaena hians 0.47 -0.65 1. 74 16. Glans dominguensis 0.09 -0.65 0.43 5. Glycymeris subtilis 0.97 0.10 1. 70 12. Glyphostoma hendersoni 2.50 2. 41 2.60 2. Glyphoturris spp. 1. 52 0.49 2.41 4. Gouldia cerina 0.90 -0.65 3.60 29. Gregoriella coralliophaga 0.49 0.49 0.49 3. Haminoea succinea 1.87 1.64 1. 99 3. Henrya spp. 2.15 1.59 2.88 3. Hi a tell a arcti ca -0.65 -0.65 -0.65 1. Ischnochiton boogii 1.09 -0.07 1. 74 3. Ischnochiton floridanus 1. 74 1. 74 1. 74 3. Ischnochiton h artmeyeri 1.99 1. 99 1.99 2. Ischnochiton papillosus 1.40 -0.65 1. 99 170. ..... Ischnochiton spp. 0.94 -0.51 1. 74 9. w "'-J

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APPENDIX 5 Table 21 (cont'd). Mean of Mean Minimum Maximum Number of Species Name 0 Size Mean Mean Individuals Ithycythara lanceolata 1.12 -0.07 1.83 3. Ithycythara spp. 0.84 0.19 1.48 2. Kurtziella atrostyla 1. 71 1.64 1. 74 3. Kurtzi ell a spp. 1.86 -0.51 2.91 40. Laevicardium pictum 0.85 -0.07 1.83 18. Lima pellucida 1.14 -0.51 1. 98 6. Limatula setifera 1.27 9.43 1. 70 3. Limea bronniana 0.71 -0.18 1.59 5. Linga amiantus 0.48 -0.07 1.58 3. Linga leucocyma -0.65 -0.65 -0.65 1. sombrerensis 1.32 1.32 1. 32 7. Lioberus castaneus 1.67 1.58 1. 74 9. Lucina nassula 2.34 1.48 3.60 16. Lucina radians 2.82 1.99 3.60 3. Lyonsia hyalina floridana 1.99 -0.51 3.60 42. Macoma cf. extenuata 1. 32 -0.51 3.60 5. Macrocallista maculata 1.77 1.48 2.06 2. Marginella eburneola 1.48 1.48 1.48 1. Marginella hartleyanum 1.48 1.48 1.48 l. spp. 1.93 1. 74 1.99 4. Melanella arcuata -0.07 -0.07 -0.07 2. Melanella spp. 1.80 1.48 l. 99 4. Mitrella lunata 1. 95 1.48 2.91 9. Mitrolumna biplicata 0.33 0.33 0.33 1. Modulus modulus 0.09 -0.65 0.49 3. Murex cabriti i 0.80 0.37 1.59 3. Murex glyptus 0.49 0.49 0.49 1. __. Murex pomum 1. 74 l. 74 1. 74 1. w 00

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APPENDIX 5 Table 21 (contd). Mean of Mean Maximum Number of Species Name 0 Size Mean Individuals M u sculus lateralis 1.45 -0.07 2.88 10. 1"1yse 11 a spp. 2.42 2.10 2.74 2. Nannodiella melanitica 1. 95 1.48 2.88 3. Nannodiella spp. 1.17 -0.18 1.83 7 Nassarius spp. 0.33 0.33 0.33 2. Natica canrena 2.51 1. 98 3.60 8. Natica livida 1. 50 1.28 1. 64 5. Nati ca pus i 11 a 1.48 1.48 1.48 1 Natica spp. 2.02 0.37 2.88 4. Nemocardium peramabile 0.15 a. 1 a 0.19 2. Nemocardium tinctum 0.43 0.37 0.49 2. Niso aeglees 1. 59 1. 59 1.59 1. Nucinella adamsi a. 14 a. 1 a 0.33 5. Nucula cf. fernandinae 1. 99 1.68 2.60 3. Nucula crenu1ata 0.45 -0.07 1.48 3. Nuculana acuta 1.44 0.10 2. 77 4. Nucu1ana carpenteri 2.50 2.41 2.60 2. Nucu1ana 1. 09 0.33 2.60 3. Ocenebra minirosea 0.43 0.43 0.43 1. Oceanida spp. 1.39 -0.07 1. 74 13. Odostomia seminuda 1. 64 1.64 1. 64 2. Odostomia spp. 1. 60 0.37 2.88 4. Oliva sayana 1. 60 1.28 1. 99 8. Oliva spp. 1. 99 1. 99 1. 99 1. O livella spp. 1.53 -0.18 2.10 46. Opalia spp. 0.33 0.33 0.33 1. Parvilucina blanda 0.14 -0.65 0.49 4. __, w 1.0

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APPENDIX 5 Table 21 ( cont d). Mean of Mean Minimum Maximum Number of Species Name 0 Size Mean Mean Individuals Parvilucina cf. multilineata 2.35 -0.65 3.60 559. Philine sagra 1. 96 -0.51 2.88 35. Pitar cordatus 3.34 2.82 3.60 3. Pitar simQsoni 0.48 -0.65 2.64 22. Pitar spp. 3.21 2.82 3.60 2. Platycythara elata 0.40 0.37 0.43 2. Pleuromeris tridentata 0.38 0.33 0.43 2. Plicatula gibbosa 1. 55 0.33 1. 74 32. Polinices duQlicatus 1. 04 -0.18 1. 99 5. Psarostola glyQta 1.20 0.43 1. 59 3. Psarosto1a minor 0.26 -0.65 0.49 5. Pteromeris QerQlana -0.07 -0.07 -0.07 1. Pyrgocythara spp. 0.49 0.49 0.49 1. Pyrunculus caelatus -0.18 -0. 18 -0.18 1. Retusa sulcata 2.27 1. 48 2. 91 12. Rimosodaphnella morra 1. 73 1.48 1.98 2. Rimula frenulata 0.49 0.49 0.49 2. Rimula spp. -0.51 -0.51 -0.51 1. Rissoina multicostata 0.49 0.49 0.49 l. Rubellatoma rubella 2.10 2.10 2.10 1. ScaQhander spp. 2.48 2.10 2.91 6. Scissurella spp. 1.68 1. 68 1.68 1. Seila adamsi 1. 74 1. 74 1. 74 2. Semele bellastriata 0.73 -0.18 1. 64 2. Semele nuculoides 0.27 -0.18 1.99 15. Semele QUrQurascens 0.05 -0.51 0.43 5. Sigatica carolinensis 1.53 0.37 1.97 6. __, Sigatica semisulcata 1. 51 l. 28 1. 99 3. 0

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APPENDIX Table 21 (cont'd). Mean of Mean Minimum Number of Species Name Size M ean Indiv i d uals Sig num perspectivum 1.05 0.37 1. 74 2. Solariella lacunella 0.54 0.10 1.32 3. Solariella spp. 1. 70 1. 70 1. 70 1. Solecurtus sanctaemarthae 0.49 0.49 0.49 1. Solemya occidentalis 1. 78 -0.51 2.74 183. Strombus alatus 1.64 1.64 1.64 l. Tellina aeguistriata 1. 31 0.37 2.10 3. Tel1 ina alternata 2.21 1. 98 2.74 4. Tellina sguamifera -0.51 -0.51 -0.51 1. Tellina vers icolor 1. 76 -0.65 3.60 426. Terebra dislocata 1. 75 1. 28 2.10 4. Terebra spp. 1.99 1. 59 2.64 3. Thyasira spp. 1.39 -0.18 2. 77 17. Trachycardium egmontianum 1. 58 1. 58 1. 58 1. Trigonostoma tenerum 0.43 0.43 0.43 1. Triphora decorata 0.82 0.49 1.48 3. Triphora spp. 1. 59 1. 59 1.59 1. Turbo castanea 1. 20 0.43 1. 97 2. Turbonilla spp. 1.96 0.43 2.88 32. Turritella acropora 0.43 0.43 0.43 1. Varicorbu1a opercu1ata 1.95 -0.51 3.60 394. Verticordia ornata 1.85 -0.18 2.77 10. Vitreolina bermudezi 1. 58 1. 58 1. 58 1. Volvulella persimilis 1.81 0.37 3.60 21. Volvulella recta 0.75 -0.18 2.60 3. Zebina 0.48 -0.07 1.58 3. ...... .j:::>o ......

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APPENDIX 6 Mean depth at which each species were found and total number of individuals of each species. 142

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APPENDIX 6 Table 22. Mean depth at which each species were found and total number of individuals of each species. Species Name Abra aegualis Abra lioica Aeanthochitona pygmaea Acteocina candei Acteocina spp. Acteon punctostriatus Alvania auberiana Alvania spp. Amygdalum papyrium Amygdalum sagittatum Anachis iontha Anachis obesa Anadara transversa Anodontia alba Anomia simj?"feX Arcinella cornuta Arcopsis adamsi Argopecten gibbus Atys riiseana Bactrocythara spp. Barbatia cf. domingensis Bathyarca glomerula Brachycythara barbarae Brachycythara biconica Bulla striata Bushia spp. _Cadul us parvus Cadulus guadridentatus Mean Depth 34.1 80.1 14.7 31.7 27.9 29.1 29.2 11.3 39.9 189.4 12.5 11.0 11.1 35.6 35.9 11.3 48.4 19.2 26.0 189.4 91.3 183.1 47.3 27.9 19.2 29.7 65.8 32.7 Minimum Depth 34.1 11.0 11.3 11.0 19.2 17.7 29.3 11.3 29.3 189.6 11.3 11.0 11.0 32.6 34.1 11.3 43.6 19.2 11.3 189.6 89.6 167.6 29.3 17.7 19.2 17.7 37.2 17.7 Depth 34.1 189.6 42.1 53.3 36.6 37.2 29.3 11.3 53.3 189.6 17.7 11.0 11.3 37.2 37.2 ll. 3 53.3 19.2 53.3 189.6 92.0 189.6 53.3 38.4 19.2 42.1 167.6 38.4 Number of Individuals 4. 158. 9. 139. 2. 6. l. 1 25. 2. 5. 4. 4. 3. 5. 2. 2. 1. 45. l. 4. 7. 4. 13. l. 5. 14. 4.

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APPENDIX 6 Table 22 (cont'd) n imum Maximum Number of Species Name Mean Depth Depth Depth Individ uals Cadulus spp. 91.3 53.3 167.6 3. Caecum bipartitum 29.9 11.3 42.1 163. Caecum cornucopiae 18.3 18.3 18.3 2. Caecum cubitatum 35.3 29.3 43.6 179. Caecum floridanum 48.4 42.1 53.3 7 Caecum imbricatum 33. 1 17.4 53.3 11. Caecum pulchellum 33.2 11.3 43.6 205. Caecum strigosum 23.6 17.7 43.6 9. Calliostoma fascinans 91.9 92.0 92.0 l. Calliostoma jujubinum 42.0 42.1 42.1 l. Calliostoma spp. 34.1 34.1 34.1 1. Calotrophon ostrearum 11.3 11.3 11.3 l. Calyptraea centralis 16. 1 11.0 43.6 37. Cardiomya perrostrata 37.9 17.4 53.3 20. Cardiomya spp. 161.4 161.5 161.5 3. Cerithiopsis crystallinum 189.4 189.6 189.6 13. Cerithium atratum ]1. 5 11.0 17.7 26. Cerodrillia simpsoni 38.4 38.4 38.4 1. Chaetoderma spp. 178.5 161.5 189.6 52. Chaetopleura apicu1ata 11.3 11.3 11.3 3. Chama congregata 13.6 11.3 18.3 3. Chama macerophyl1a 11.0 11.0 11.0 1 Chione cance1lata 13.9 11.0 18.3 10. Chione grus 27.1 11.0 38.4 5. Chione latilirata 53.3 53.3 53.3 1. Chlamys benedicti 40.6 36.6 43.6 6. Coch1io1epsis striata 42.0 42.1 42.1 1. .......

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APPENDIX 6 Table 22 (cont'd) Minimum Maximum Number of Species Name Mean Depth Depth Depth Individuals Conus jaspideus stearnsi 22.9 11.3 38.4 3. Cooperella atlantica 17.7 17.7 17.7 2. Corbula dietziana 38.6 11.0 53.3 24. Costellaria spp. 167.4 167.6 167.ti 1. Crassinella cf. martinicensis 41.7 18.3 53.3 66. Crassinella lunulata 11.2 11.0 11.3 3. Crenella divaricata 37.8 29.3 53.3 33. Crepidula fornicata 13. 1 11.0 43.6 16. Cryoturris citronella 27.4 17.7 37.2 4. Cryoturris fargoi 18.3 18.3 18.3 3. Cryoturris fi1ifera 23.7 19.2 37.2 4. Cryoturris guadrilineata 11.3 11.3 11.3 1. Cryoturris spp. 22.4 11.3 53.3 14. Cyclopecten nanus 103.9 19.2 189.6 24. Cyclostremiscus spp. 11.0 11.0 11.0 1. Cylichna spp. 121.3 53.3 189.6 2. Cymatoica orienta1is 37.4 36.6 38.4 6. Dacrydium vitreum 129.7 92.0 167.6 2. Denta1ium bart1etti 23.2 17.4 53.3 15. Denta1ium ceratum 126.6 92.0 161.5 2. Dentalium 1agueatum 189.4 189.6 189.6 1. Denta1ium semistrio1atum 32.6 19.2 38.4 7. Dentalium sowerbyi 109.2 53.3 167.6 6. Dentalium spp. 124.7 17.7 189.6 9. Dentalium texasianum 167.4 167.6 167.6 2. Dip1odonta spp. 26.8 1l. 0 53.3 77. ..... .p. \J1

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APPENDIX 6 Table 22 (cont'd) Minimum Maximum Number of Species Name Mean Depth Depth Depth Individ u als Divaricella dentata 17.8 17.7 18.3 6. Dosinia elegans 20.1 17.7 32.6 15. Epitonium novangliae 17.4 17.4 17.4 1. Ervilia concentrica 18.6 17.7 19.2 8. Erycina emmonsi 42.1 36.6 43.6 5. Eucrassatella speciosa 99.7 53.3 161.5 7. Eulima bifasciatus 27.9 11.0 53.3 22. Eulimostraca hemphillii 21.4 11 !) 38.4 72. Eulimostraca spp. 30.4 18.3 36.6 3. Eupleura sulcidentata 11.0 11.0 11.0 1. Finella dubia 30.7 17.7 38.4 63. Gastrochaena hians 34.5 11.0 53.3 16. Glans dominguensis 51.0 42.1 53.3 5. Glycymeris subtilis 129.5 89.6 167.6 12. Glyphostoma hendersoni 189.4 189.6 189.6 2. Glyphoturris spr. 63.9 11.3 189.6 4. Gouldia cerina 34.9 11.0 53.3 29. Gregurie1la coralliophaga 43.5 43.6 43.6 3. Haminoea succinea 22.1 11.0 37.2 3. Henrya spp. 28.9 19.2 38.4 3. Hiatella arctica 42.0 42.1 42.1 1. Ischonochiton boogii 19.7 11.3 36.6 3. Ischnochiton f1oridanus 11.3 11.3 11.3 3. Ischnochiton hartmeyeri 18.3 18.3 18.3 2. Ischnochiton papil1osus 21.1 11.0 92.0 170. Ischnochiton spp. 22.0 11.3 43.6 9. Ithycythara lanceolata 30.8 17.7 38.4 3. __, +::> 0'\

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APPENDIX 6 Table 22 (cont'd) Minimum Maximum Number of Species Name Mean Depth Depth Depth Individuals Ithycythara spp. 65.2 38.4 92.0 2. Kurtziella atrostyla 11.2 11.0 11.3 3. Kurtzie11a spp. 33.3 11.3 92.0 40. Laevicardium pictum 27.8 17.4 53.3 18. Lima pe11ucida 36.4 17.7 43.6 6. Limatula setifera 129.4 53.3 167.6 3. Limea brownniana 62.8 38.4 92.0 5. Linga amiantus 28.1 11.3 36.6 3. Linga leucocyma 42.0 42.1 42.1 1. Linga sombrerensis 161.4 161.5 161.5 7. Lioberus castaneus 11.2 11.0 11.3 9. Lucina nassula 27.3 11.3 38.4 16. Lucina radians 27.2 18.3 34.1 3. Lyonsia hyalina floridana 36.2 17.7 53.3 42. Macoma cf. extenuata 41.5 34.1 53.3 5. Macrocallista maculata 27.4 17. 7 37.2 2. Marginella eburneo1a 38.4 38.4 38.4 1. Marginella hartleyanum 38.4 38.4 38.4 1. t1a rg i ne 11 a s pp. 16.5 11.3 18.3 4. Melanella arcuata 36.5 36.6 36.6 2. Melanella spp. 16.4 11.3 18.3 4 . Mitre11a lunata 19.6 17.7 32.6 9. Mitro1umna biplicata 91.9 92.0 92;0 1. Modulus modulus 46.3 42.1 53.3 3. Murex cabriti i 48.3 38.4 53.3 3. Murex glyptus 43.5 43.6 43.6 l. Murex pomum 11.3 11.3 11.3 1. __, Musculus lateralis 34.8 17.7 53.3 10. -+::> -""-'

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APPENDIX 6 Table 22 (cont'd) Maximum Number of Species Name Mean Depth Depth Depth Individuals 1"\yse 11 a spp. 26.6 19.2 34.1 2 Nannodtella melanitica 21.5 17.7 29.3 3. Na"lnodiella spp. 48.4 17.7 161.5 7. Nassarius spp. 91.9 92.0 92.0 2. Natica canrena 31.9 18.3 37.2 8. Natica livida 13.5 11.0 17.4 5. Natica pusilla 17.7 17.7 17.7 1. Natica spp. 37.2 29.3 53.3 4. Nemocardium 90.7 89.6 92.0 2. Nemocardium tinctum 48.4 43.6 53.3 2. Niso Aeglees 38.4 38.4 38.4 l. Nucinella adamsi 90.0 89.6 92.0 5. Nucula cf. fernandinae 174.7 167.6 189.6 3. Nucul a crenulata 37.1 36.6 38.4 3. Nuculana acuta 139.4 89.6 189.6 4. Nuculana carpenteri 189.4 189.6 189.6 2. Nuculana spp. 124.4 92.0 189.6 3. Ocenebra minirosea 53.3 53.3 53.3 l. Oceanida spp. 17.2 11.3 38.4 13. Odostomia seminuda 11.0 11.0 11.0 2. Odostomia spp. 42.5 29.3 53.3 4. Oliva sayana 23.0 11.0 38.4 8. Oliva spp. 18.3 18.3 18.3 l. Olivella spp. 24.7 11.0 92.0 46. Opalia spp. 91.9 92.0 92.0 l. Parvilucina blanda 48.0 42.1 53.3 4. Parvi1ucina cf. multilineata 35.9 11.0 189.6 559. ...... Philine sagra 38.5 29.3 92.0 35. (X)

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APPENDIX 6 Table 22 (cont'd) Maximum Number of Species Name Depth Depth Depth Individuals Pitar Cordatus 33.6 32.6 34.1 3. Pitar simpsoni 47.3 11.0 92.0 22. Pitar sp. 33.3 32.6 34.1 2. Platycythara elata 53.3 53.3 53.3 2. Pleuromeris tridentata 72.6 53.3 92.0 2. Plicatula gibbosa 17.2 11.0 92.0 32. Polinices duplicatus 32.9 18.3 53.3 5. Psarostola glypta 43.3 38.4 53.3 3. Psarostola minor 43.2 42.1 43.6 5. Pteromeris perplana 36.5 36.6 36.6 1. Pyrgocythara spp. 43.5 43.6 43.6 1. Pyrunculus caelatus 53.3 53.3 53.3 1. Retusa sulcata 32.1 17.7 38.4 12. Rimosodaphnella morra 37.8 37.2 38.4 2. Rimula frenulata 43.5 43.6 43.6 2. Rimula spp. 43.5 43.6 43.6 1. Rissoina multicostata 43.5 43.6 43.6 1. Rubellatoma rubella 19.2 19.2 19.2 1. Scaphander spp. 26. 1 19.2 34.1 6. Scissurella spp. 167.4 167.6 167.6 1. Seil a adamsi 11 .3 11.3 11.3 2. Semele bellastriata 32.1 11.0 53.3 2. Semele nuculoides 61.3 18.3 92.0 15. Semele purpurascens 49.4 43.6 53.3 5. Sigatica carolinensis 26' 5 11.3 53.3 6. Sigatica semisulcata 17.7 17.4 18.3 3. Sinum perspectivum 32.3 11.3 53.3 2. -' Solariella lacunella 114.3 89.6 161.5 3. .::. u:>

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APPENDIX 6 Table 22 (cont'd) Minimum Species Name Mean Depth Depth Solariella spp. 167.4 167.6 Solecurtus sanctaemarthae 43.5 53.6 Solemya occidentalis 16.6 11.0 strombus a 1 atus 11.0 11.0 Tellina aeguistriata 36.9 19.2 Tellina alternata 36.4 34.1 Tellina sguamifera 43.5 43.6 Tellina versicolor 22.9 11.0 Terebra dislocata 16.4 11.0 Terebra spp. 27.7 11.3 Thyasira spp. 122.3 18.3 Trachycardium egmontianum 11.3 11.3 Trigonostoma tenerum 53.3 53.3 Triphora decorata 41.8 38.4 Triphora spp. 38.4 38.4 Turbo castanea 36.2 19.2 Turban ; 11 a spp. 25.3 11.0 Turritella acropora 53.3 53.3 Varicorbu1a opercu1ata 33.3 11.0 Verticordia ornata 139.3 11.3 Vitreo1ina bermudezi 11.3 11 .3 Volvule11a persimi1is 29.5 11.0 Vo1vu1e11a recta 98.6 53.3 Zebina browniana 28.1 11.3 Maximum Depth 167.6 43.6 53.3 11.0 53.3 37.2 43.6 53.3 19.2 38.4 189.6 11.3 53.3 43.6 38.4 53.3 53.3 53.3 53.3 189.6 11.3 53.3 189.6 36.6 Number of Individuals 1. 1. 183 1. 3. 4. 1. 426. 4. 3. 17. 1. 1. 3. 1. 2. 32. 1. 394. 10. 1. 21. 3. 3. ..... U1 0