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Community composition of crustaceans and gastropods on Caulerpa prolifera, Halodule wrightii, and Thalassia testudinum

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Title:
Community composition of crustaceans and gastropods on Caulerpa prolifera, Halodule wrightii, and Thalassia testudinum
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Book
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English
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Gibson, Jennifer A
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University of South Florida
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Tampa, Fla.
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Subjects / Keywords:
Amphipod
Cymadusa compta
Epiphytic algae
Seagrass
Epifauna
Dissertations, Academic -- Biology -- Masters -- USF   ( lcsh )
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

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ABSTRACT: A survey was conducted in monospecific beds of two seagrasses, Halodule wrightii Ascherson and Thalassia testudinum Banks ex König and the macroalgae Caulerpa prolifera (Forsskål) Lamouroux in Lassing Park, Tampa Bay, Florida (USA) to examine epifauna communities and to determine factors influencing the abundances of epifauna in this area including surface area of the vegetation or amount of epiphytic algae growing on each type of vegetation. This survey addressed three questions: 1) Does the amount of epiphytic algae differ among seagrasses, T. testudinum and H. wrightii, and the macroalga, C. prolifera? 2) Is there a difference between community composition, measured by epifauna density or species dominance, on each type of vegetation? 3) Is there a correlation between the amount of epifauna and the amount of either epiphytic algae or blade/frond surface area for each of the three types of vegetation? Field surveys were conducted in June and October 2004 inmonospecific beds of C. prolifera, H. wrightii, and T. testudinum. The amount of epiphytic algae on C. prolifera was found to be an order of magnitude lower than the amounts found on either seagrass species over both sampling dates, although the amount of C. prolifera surface area was roughly double that of the seagrasses in October 2004. Although all three vegetation species supported epifauna communities composed mainly ofperacarids and gastropods, there were differences in the amount of epifauna found on each type of vegetation. Three major findings of this survey include: 1) evidence for a positive relationship between the amount of epifauna and amount of blade/frond surface area, including vegetation with higher amounts of surface area supporting higher amounts of epifauna, 2) no relationship between the amount of epifauna and amount of epiphytic algae on submerged vegetation, and 3) when the amount of surface area of all vegetation species was similar the epifauna communities weresimilar in species composition. Together these lend support to the theory that surface area of vegetation (and therefore possibly habitat complexity) is an important factor in determining the abundance and community composition of epifauna in seagrass and macroalgae beds in Lassing Park, Florida.
Thesis:
Thesis (M.S.)--University of South Florida, 2007.
Bibliography:
Includes bibliographical references.
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by Jennifer A. Gibson.
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Title from PDF of title page.
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Document formatted into pages; contains 51 pages.

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usfldc doi - E14-SFE0002001
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ABSTRACT: A survey was conducted in monospecific beds of two seagrasses, Halodule wrightii Ascherson and Thalassia testudinum Banks ex Knig and the macroalgae Caulerpa prolifera (Forssk¢l) Lamouroux in Lassing Park, Tampa Bay, Florida (USA) to examine epifauna communities and to determine factors influencing the abundances of epifauna in this area including surface area of the vegetation or amount of epiphytic algae growing on each type of vegetation. This survey addressed three questions: 1) Does the amount of epiphytic algae differ among seagrasses, T. testudinum and H. wrightii, and the macroalga, C. prolifera? 2) Is there a difference between community composition, measured by epifauna density or species dominance, on each type of vegetation? 3) Is there a correlation between the amount of epifauna and the amount of either epiphytic algae or blade/frond surface area for each of the three types of vegetation? Field surveys were conducted in June and October 2004 inmonospecific beds of C. prolifera, H. wrightii, and T. testudinum. The amount of epiphytic algae on C. prolifera was found to be an order of magnitude lower than the amounts found on either seagrass species over both sampling dates, although the amount of C. prolifera surface area was roughly double that of the seagrasses in October 2004. Although all three vegetation species supported epifauna communities composed mainly ofperacarids and gastropods, there were differences in the amount of epifauna found on each type of vegetation. Three major findings of this survey include: 1) evidence for a positive relationship between the amount of epifauna and amount of blade/frond surface area, including vegetation with higher amounts of surface area supporting higher amounts of epifauna, 2) no relationship between the amount of epifauna and amount of epiphytic algae on submerged vegetation, and 3) when the amount of surface area of all vegetation species was similar the epifauna communities weresimilar in species composition. Together these lend support to the theory that surface area of vegetation (and therefore possibly habitat complexity) is an important factor in determining the abundance and community composition of epifauna in seagrass and macroalgae beds in Lassing Park, Florida.
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Community Composition of Crustaceans and Gastropods on Caulerpa prolifera Halodule wrightii and Thalassia testudinum by Jennifer A. Gibson A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Biology College of Arts and Sciences University of South Florida Major Professor: Susan S. Bell, Ph.D. Clinton J. Dawes, Ph.D. Margaret O. Hall, Ph.D. Date of Approval: March 19, 2007 Keywords: amphipod, Cymadusa compta epiphytic algae, seagrass, epifauna Copyright 2007, Jennifer A. Gibson

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i Table of Contents List of Figures ii List of Tables iii Abstract vi Introduction 1 Materials and Methods 5 Study Site 5 Experimental Design and Data Collection 5 Data Analysis 9 Results 11 Vegetation and Epiphytic Algae 11 Epifauna 16 Community Composition 34 Relationship Between Epiphytes and Ep ifauna or Surface Area and Epifauna 40 Discussion 45 References Cited 49

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ii List of Figures Figure 1 Map and aerial photo (LAB INS 2004) showing the location of Tampa Bay, Florida and Lassing Park within Tampa Bay (27o45’N, 82o37’W). 6 Figure 2 View of the X-sampler used to collect epifauna samples, in the open position. 7 Figure 3 Mean (SE) amount of surface area (cm2) of vegetation per sample (0.09m2 bottom area) for June and October 2004 samples. 12 Figure 4 Mean (SE) dry weight (g) of epiphytic algae per sample (0.09m2 bottom area) for June and October 2004 samples. 14 Figure 5 Mean (SE) abundances of epifauna per sample (0.09m2 bottom area) for June and October 2004 samples. 19 Figure 6 Mean (SE) abundances of ep ifauna per surface area of vegetation blades/fronds (cm2) for June and October 2004 samples. 24 Figure 7 Mean (SE) abundances of epif auna per amount of epiphytic algae (g) for June and October 2004 samples. 28 Figure 8 Multi-Dimensional Scale plot of epifauna communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum per sample (0.09m2 bottom area), June 2004. 36 Figure 9 Multi-Dimensional Scale plot of epifauna communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum per sample (0.09m2 bottom area), October 2004. 37 Figure 10 Number of total epifauna per sample (0.09m2 bottom area) vs. dry weight of epiphytic algae (g) per sample (0.09m2 bottom area) for June and October 2004 samples. 41 Figure 11 Number of total epifauna per sample (0.09m2 bottom area) vs. surface area of blades/fronds (cm2) per sample (0.09m2 bottom area) for June and October 2004 samples. 43

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iii List of Tables Table 1 Results of a two-factor ANOVA on surface area of seagrass, Halodule wrightii and Thalassia testudinum blades and the fronds of the macroalgae Caulerpa prolifera for June and October 2004 samples. 13 Table 2 Results of a two-factor ANO VA on the amount of epiphytic algae found on the seagrass, Halodule wrightii and Thalassia testudinum blades and macroalgae, Caulerpa prolifera fronds for June and October 2004 samples. 15 Table 3 Peracarid crustacean and ga stropod species, and their feeding group (for the majority of species), collected in epifauna samples in June and October 2004 on three types of vegetation: Caulerpa prolifera Halodule wrightii and Thalassia testudinum 17 Table 4 The percentage of peracari d crustacean and gastropod epifauna found in each feeding group, collected in epifauna samples in June and October 2004 on three types of vegetation: Caulerpa prolifera Halodule wrightii and Thalassia testudinum 18 Table 5 Results of a two-factor ANO VA on the abundance of total epifauna per sample (0.09m2) on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 20 Table 6 Results of a twofactor ANOVA on the abundan ce of total peracarids per sample (0.09m2) on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 21 Table 7 Results of a two-f actor ANOVA on the abundance of C. compta per sample (0.09m2) on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 22 Table 8 Results of a two-factor ANOVA on the abundance of total gastropods per blade/frond surface area of Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 26

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iv Table 9 Results of a two-f actor ANOVA on the abundance of Bittium varium per blade/frond surface area of Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 27 Table 10 Results of a two-factor ANO VA on the abundance of total epifauna per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 29 Table 11 Results of a two-factor ANO VA on the abundance of total peracarids per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 30 Table 12 Results of a two-f actor ANOVA on the abundance of Cymadusa compta per amount of epiphyt ic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 31 Table 13 Results of a two-fact or ANOVA on the abundance of total gastropods per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii, and Thalassia testudinum for June and October 2004 samples. 32 Table 14 Results of a twofactor ANOVA on the abundance of Bittium varium per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii, and Thalassia testudinum for June and October 2004 samples. 33 Table 15 Results of the June 2004 BIOENV analysis of the re lative amount of influence that the three vegeta tion characteristics: number of blades/fronds, surface area of blades/fronds (cm2), and/or amount of epiphytic algae (g) have on the peracarid and gastropod communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum 38 Table 16 Results of the October 2 004 BIOENV analysis of the relative amount of influence that the three vegetation characteristics: number of blades/fronds, surface ar ea of blades/fronds (cm2), and/or amount of epiphytic algae (g) have on the peracarid and gastropod communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum 39 Table 17 Regression slopes and R2 values for the relationships between the amount of epifauna and the amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 42

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v Table 18 Regression slopes and R2 values for the relationships between the amount of epifauna and the amount of vegetation blade/frond surface area (cm2) of Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. 44

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vi Community Composition of Crustaceans and Gastropods on Caulerpa prolifera Halodule wrightii and Thalassia testudinum Jennifer A. Gibson ABSTRACT A survey was conducted in monospecific beds of two seagrasses, Halodule wrightii Ascherson and Thalassia testudinum Banks ex Knig and the macroalgae Caulerpa prolifera (Forsskl) Lamouroux in Lassing Park, Tampa Bay, Florida (USA) to examine epifauna communities and to de termine factors influencing th e abundances of epifauna in this area including surface area of the vegeta tion or amount of epiphytic algae growing on each type of vegetation. This survey addre ssed three questions: 1) Does the amount of epiphytic algae differ among seagrasses, T. testudinum and H. wrightii, and the macroalga, C. prolifera ? 2) Is there a difference between community composition, measured by epifauna density or species domin ance, on each type of vegetation? 3) Is there a correlation between the amount of epifauna and the amount of either epiphytic algae or blade/frond surface area for each of th e three types of vegetation? Fiel d surveys were conducted in June and October 2004 in monospecific beds of C. prolifera H. wrightii and T. testudinum The amount of epiphytic algae on C. prolifera was found to be an order of magnitude lower than the amounts found on either seagrass species ov er both sampling dates, although the amount of C. prolifera surface area was roughly double that of the seagrasses in October 2004. Although all three vegetation species supported epifauna communities composed mainly of

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vii peracarids and gastropods, there were differe nces in the amount of epifauna found on each type of vegetation. Three major findings of th is survey include: 1) evidence for a positive relationship between the amount of epifauna and amount of blade/frond surface area, including vegetation with higher amounts of surface area supporting higher amounts of epifauna, 2) no relationship be tween the amount of epifauna and amount of epiphytic algae on submerged vegetation, and 3) when the amount of surface area of all vegetation species was similar the epifauna communities were simi lar in species composition. Together these lend support to the theory that surface area of vegetation (a nd therefore possibly habitat complexity) is an important factor in determining the abundance and community composition of epifauna in seagrass and m acroalgae beds in Lassing Park, Florida.

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1 Introduction Marine epifauna in macrophyte beds act as an important link in the food web between primary producers and secondary consumers, such as small fish and crabs (Schneider and Mann 1991). Epifauna are found in vegetated habitats around the world including seagrass beds, algae beds, kelp forest s, and drift algae. Different species of epifauna have developed various feeding strate gies and predator avoidance tactics to adapt to the specific vegetative hab itats in which they live. One habitat in which epifauna have been widely studied is coastal seagrasses. Seagrass systems are composed of one or more species of seagrass and may have one or more species of macroalgae as well. Previous studies have shown seagrass systems to have primary production rates of 0.2 to 18.7 g C m-2 d-1 (similar to coral reefs which have primary production rates of 5 to 20 g C m-2 d-1) (Dawes 1998). Seagrass beds may also support other primary producers including attached macroalgae microalgae, and drift algae (Klumpp et al. 1992). Epifauna have been shown to use thes e highly productive seagrasses and algae as a food source (Dawes 1998). Previously it was tho ught that epifauna of seagrass systems used seagrass detritus as their main source of food (Darnell 1967, Odum and de la Cruz 1963, Fenchel 1970). More recently, Bologna and He ck (1999) and Moncreiff and Sullivan (2001) have shown that epiphytic alg ae, not detritus or living seagrass blades, are the main source of food for these epifauna, although the diets of epifauna may vary by species (Morgan and Kitting 1984, Duffy and Hay 1994, Cruz-Rivera and Hay 2000, Cruz-Rivera and Hay 2003,

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2 Sotka et al. 2003). Epiphytic algae have b een shown to have primary productivity rates equal to or exceeding the primary productivity rates of the seagrass on which they live (Morgan and Kitting 1984, Jensen and Gibson 1986, Moncreiff et al. 1992, Dawes 1998, Moncreiff and Sullivan 2001). It is reasonabl e to assume that the epiphytic algae on submerged vegetation are suffici ently abundant enough to serve as an important food source for small consumers living in and among seag rass beds. Therefore a higher abundance of epifauna on vegetation that supports higher numbe rs of readily consumable epiphytic algae should be expected. Along with using seagrass beds as a food s ource, epifauna also use seagrass beds as structure for protection from predators. Previo us studies have shown that epifauna prefer habitats with more complex structure, such as that provided by highly branched macroalgae, seagrass short shoots with a high number of blades, or epiphytes growing on seagrass (Hacker and Steneck 1990, Knowles and Be ll 1998, Bostrm and Mattila 1999, Edgar and Klumpp 2003). Hacker and Sten eck (1990) concluded that bran ched and filamentous algae provide complex three-dimensional structures with many small crevices which could be used by epifauna to avoid predators while leathe ry-type algae lack such complexity and thus do not offer many refuges for epifauna. Ther efore systems with high complexity and high productivity of seagrass and epiphytes should be the most highly ut ilized by epifauna species. Two seagrasses, Halodule wrightii and Thalassia testudinum and one type of macroalgae, Caulerpa prolifera present different habitat struct ural complexity for epifauna based on their morphology. The two seagrasses ha ve flat blades that grow only from the rhizomes at short shoots with H. wrightii producing multiple thin (around 1mm wide) blades per short shoot and T. testudinum producing three to seven (u p to 15mm wide) blades per

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3 short shoot (Dawes 1998). Caulerpa prolifera offers a structural habitat of fronds up to approximately 15mm wide that present a wavy to whirled configuration growing from both the rhizoid and also from other fronds (Daw es 1974). In a previous study Snchez-Moyano et al. (2001) showed that fronds of C. prolifera provided a habitat with high structural complexity, supporting a rich community of epifauna although they did not look at a possible relationship between the amount of epifauna and epiphytic algae cover. Therefore, there are marked differences among macrophyte morphology. Along with using the structural complexity of the vegetation as a habitat, epifauna may also take advantage of the chemical com position characteristics of the vegetation that could offer protection from predators. Caulerpa prolifera is known to produce a secondary compound, caulerpenyne, which may act as a defe nse mechanism to prevent grazing (Vest et al. 1983, Meyer and Paul 1992, Snchez-Moyano et al. 2001). Experi ments testing the effectiveness of caulerpenyne as an antiher bivory defense have had mixed results. McConnell et al. (1982) showed that caulerpe nyne effectively deters sea urchins from feeding on C. prolifera In contrast, Meyer and Paul ( 1992) found that caulerpenyne coated on algal pieces actually stim ulated fish feeding. If C. prolifera exhibits an effective antiherbivory chemical defense against large gr azers or omnivores then the epifauna that live on and among C. prolifera fronds may be indirectly prot ected from any predators that avoid grazing on C. prolifera. Distributional studies have revealed that epifauna are commonly habitat generalists (Edgar and Klumpp 2003) and are able to move from one type of vegetation habitat to another (Virnstein and Curran 1986, Howard 1987) These mobile epifauna have been shown to move between different macrophytes in order to find optimal habitats for feeding and predator avoidance (Stoner 1980, Main 1987, Hacker and Steneck 1990, Duffy and Hay

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4 1991, Bostm and Mattila 1999, Parker et al. 2001, Edgar and Klumpp 2003). With this ability to move from one habitat to anothe r, epifauna should be able to move from unsuitable habitats to more suitable habitats su ch as those with a higher availability of food and/or more protection from predators, pr ovided either directly through structural complexity or indirectly because of reduced herbivory on the habitat macrophyte. Thus, if there is a difference in the amount of food and/or protecti on offered by a macrophyte species then one would expect to find more epifa una moving to, and staying within, the more suitable habitat offered by that vegetation. Monospecific areas of Caulerpa prolifera Halodule wrightii and Thalassia testudinum coexist within Lassing Park, Tampa Bay, Florida. Here I describe a survey conducted in these areas designed to answer th e following questions: 1) Does the amount of epiphytic algae differ among the three dominant macrophytes: T. testudinum H. wrightii, and C. prolifera ? 2) Is there a difference among community composition, measured by epifauna density or species dominance, on each type of vegetation? and 3) Is there a correlation between the amount of epifauna a nd either epiphytic algae or the amount of blade/frond surface area for each of th e three types of vegetation?

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5 Materials and Methods Study Site The survey was conducted in Lassing Park, Tampa Bay, Florida (27o45’N, 82o37’W) (Figure 1). Lassing Park has a mean depth of 0.53m, the temperature ranged from 18.14oC32.53oC and salinity ranged from 22.1‰-29.3‰ ove r the course of the study. Both monospecific beds and mixed areas of the seagrasses Thalassia testudinum and Halodule wrightii as well as the macroalgae Caulerpa prolifera are all present within this area. Further information on the study site is available in Bell et al. (1993). Experimental Design and Data Collection Areas of monospecific seagrasses Thalassia testudinum Halodule wrightii and the macroalga Caulerpa prolifera were located throughout Lassing Park. In order to determine if there was a difference in the amount or co mposition of epifauna or epiphytic algae among the three types of vegetation, fifteen samples of both vegetation and epifauna were collected from monospecific areas within each type of vegetation. These samples were collected in summer (June 3 and 4) and fall (October 9 and 10), 2004. Both the vegetation and epifauna samples were taken from the same location within the monospecific beds. First, the epifauna samples were collected using an Xsampler (Figure 2), similar to one used by Virnstein et al. (1987) consis ting of two 0.5mm mesh screens fixed to frames. The two frames were configured in order to sample a consistent bottom area of 0.09m2. When used

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6 Figure 1. Map and aerial photo (LABINS 2004) showing the location of Tampa Bay, Florida and Lassing Park within Tampa Bay (27o45’N, 82o37’W).

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7 Figure 2. View of the X-sampler used to co llect epifauna samples, in the open position.

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8 in the field, the sampler was opened the maximum amount (encompassing a bottom area of 0.09m2), lowered onto the monospecific vegetati on, and closed to trap epifauna and vegetation between the frames. The vegetation tra pped in the sampler was then clipped at its base and the trapped epifauna and clipped vegeta tion were rinsed into a glass jar and stored in 10% formalin with Rose Bengal. After each epifauna sample was collected a companion core of vegetation was collected using a 16cm diameter PVC corer at each site within a distance of 0.6m of the epifauna sample. The vegetation from the core was returned to the lab where the June 2004 samples were preser ved in 5% formalin and the October 2004 samples were frozen until further processing. In the laboratory the epifauna samples we re rinsed over a 0.5mm sieve, sorted using a dissecting microscope, and all taxa were id entified. Peracarid crus taceans and gastropods were then identified to genus, and species when possible. Each of the vegetation samples were rinsed free of sand and the surface area of all blades/fronds within the core was measured to the nearest 0.1cm2. Epiphytic algae on seagrass and algae blades/fronds were removed with a scalpel blade, dried at 60oC for 5 days, and weighed to the nearest 0.0001g. Thus for both summer and fall, data on the number of blades/fronds per sample (0.09m2 bottom area), surface area of blades/fronds per sample, amount of epiphytic algae (g) per sample, and total numbers of all epifauna identi fied to species, when possible, per sample was available for further analysis.

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9 Data Analysis A two-way ANOVA was used to determine if there were significant differences in the amount of blade/frond surface area per sample epiphytic algae per sample, and epifauna abundances between sampling dates and among ve getation types. Because early analysis revealed the dominance of one peracarid species, Cymadusa compta and one gastropod species, Bittium varium across all samples, all epifauna collected over both dates were divided into the following groups for statistical tests: total epifauna, total peracarids, total number of C. compta total remaining peracarids (a ll species of peracarids except C. compta ), total gastropods, and total number of B. varium The epifauna were tested using the two-way ANOVA as abundances of epifauna per sample (0.09m2 bottom area), per blade/frond surface area (cm2), and per epiphytic algae (g). Regression analysis of epifauna to vegetation surface area and epifauna to epiphytic algae was used to determine any relationship between the amount of epifauna and the amount of surface area or epiphytic algae present. Similarities in the epifauna species a ssemblages among the three vegetation types, Caulerpa prolifera Halodule wrightii and Thalassia testudinum were plotted using nonmetric Multi-Dimensional Scaling (MDS) ordi nation using the Bray Curtis similiarity measure to calculate similarities among replicat e samples. One way analyses of similarities (ANOSIM) was used to test for differences in species assemblages among the three vegetation types. Similarity percentages-spec ies contributions (SIMPER) analysis was used to determine the contribution of each epifauna species to the dissimilarity of the epifauna communities among C. prolifera H. wrightii and T. testudinum Vegetation characteristics were included to assess thei r influence on the epifauna a ssemblages for each type of

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10 vegetation using a Biodata-Environmental ma tching (BIOENV) analysis (Clarke and Warwick 2001).

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11 Results Vegetation and Epiphytic Algae In June 2004 the amount of vegetation in Lassing Park as measured by total surface area per 0.09m2 of bottom area was similar between al l three types of vegetation ranging from 135cm2 to 680cm2 for Caulerpa prolifera 114cm2 to 474cm2 for Halodule wrightii and 214cm2 to 713cm2 for Thalassia testudinum In October 2004 AVOVA revealed that the amount of C. prolifera was greater than in June 2004 (p<0.001) while the amount of seagrasses did not change significantly. The total surface area of T. testudinum was significantly lower than C. prolifera and significantly higher than H. wrightii in October 2004 but not significantly different than the total surface area of T. testudinum in June 2004 (Figure 3). There was a signi ficant interaction between date s and vegetation type (p<0.003) (Table 1). When compared between dates, the amount of epiphytic algae found on each of the three types of vegetation did not differ (2 -way ANOVA). However, in both June and October, 2004 the mean amount of epiphytic algae found on Caulerpa prolifera was significantly less than that found on either seagrass (p=0.002). The mean amount of epiphytic algae in June and October 2004, on C. prolifera was an order of magnitude lower than that recorded for Halodule wrightii and Thalassia testudinum The mean amount of epiphytic algae found on T. testudinum and H. wrightii was similar between seagrass species and over both dates (Figure 4). There was no in teraction between date and vegetation type (Table 2).

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12 0 200 400 600 800 1000 1200 1400 1600Mean (+/SE) Surface Area of Blades/Fronds (cm2) per sample (0.09m2 bottom area) A C B A A A C Caulerpa proliferaHalodule wrightiiThalassia testudinum Figure 3. Mean (SE) am ount of surface area (cm2) of vegetation per sample (0.09m2 bottom area) for June and October 2004 samples. Solid areas represent June 2004 samples, striped areas represent October 2004 samples. Results of a two-way ANOVA; means with the same letter are not significantly different (p<0.05).

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13 Table 1. Results of a two-factor ANOVA on surface area of seagrass, Halodule wrightii and Thalassia testudinum blades and the fronds of the macroalga Caulerpa prolifera for June and October 2004 samples. Source df SS MS F P Sampling Date 1 3339757.538 3339757.538 40.725 <0.001 Vegetation Species 2 3917796.28 1958898.140 23.887 <0.002 Sampling Date x Vegetation Species 2 2826253.881 1413126.940 17.231 <0.003 Residual 83 6806699.342 82008.426 Total 88 16932890.94 192419.215

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14 0 0.05 0.1 0.15 0.2 0.25 0.3Mean (+/SE) Dry Weight(g) of Epiphytic Algae per sample (0.09m2 bottom area) A B A B B B Caulerpa proliferaHalodule wrightiiThalassia testudinum Figure 4. Mean (SE) dry weight (g) of epiphytic algae per sample (0.09m2 bottom area) for June and October 2004 samples. Solid ar eas represent June 2004 sa mples, striped areas represent October 2004 samples. Results of a two-way ANOVA; means with the same letter are not significantly different (p<0.05).

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15 Table 2. Results of a two-factor ANOVA on the amount of epiphytic algae found on the seagrass, Halodule wrightii and Thalassia testudinum blades and macroalgae, Caulerpa prolifera fronds for June and October 2004 samples. Source df SS MS F P Sampling Date 1 0.0941 0.0941 7.775 0.007 Vegetation Species 2 0.8180 0.4090 33.817 <0.001 Sampling Date x Vegetation Species 2 0.0383 0.0192 1.583 0.212 Residual 83 0.9920 0.0121 Total 88 1.9400 0.0223

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16 Epifauna Major epifauna taxa collected in this study includ ed shrimp, crabs, bivalves, peracarids, and gastropods. Peracarids and gastropods domin ated all samples from all vegetation types on both dates. These peraca rid and gastropod speci es were grouped into five different feeding groups: herbivores th at feed both microand macro-organisms, epifauna that are only carnivores, epifauna that are omnivores, epifauna that are only suspension feeders, and epifauna that are only detritus feeders (Table 3). The majority of epifauna (84%) found in the June and October 2004 samples were generalist herbivores that eat microalgae and/or macroalgae (Table 4). Cymadusa compta an herbivore generalist, was the most abundant of the eleven peracarids present. Bittium varium an herbivore generalist, was the most abundant of the seven gastropod species present in the samples. Total epifauna per sample (0.09m2 bottom area) were found in similar abundances on Caulerpa prolifera in June 2004, Halodule wrightii in June and October 2004, and Thalassia testudinum in June 2004 (Table 5). Both C. prolifera and T. testudinum had significantly higher abundances of total epifauna in October 2004 (p<0.001 and p=0.008 respectively) than in June 2004 (Figure 5). Cymadusa compta showed this same pattern with higher abundances found on C. prolifera (p<0.001) and T. testudinum in October 2004 (p=0.005) than in June 2004. Total peracarids were found in higher abundances on C. prolifera in October 2004 than on C prolifera in June 2004 (p<0.001) or eith er of the seagrasses over both dates. All three of these groups: total epifauna, total peracarids, and C. compta had a significant interaction between vegetation t ype and date (p=<0.001) (Tables 5-7). The remaining peracarids were si gnificantly less abundant on H. wrightii in October 2004 than on any of the other samples

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17 Table 3. Peracarid crustacean and gastropod sp ecies, and their feeding group (for the majority of species), collected in epifauna samples in June and October 2004 on three types of vegetation: Caulerpa prolifera Halodule wrightii and Thalassia testudinum Species Feeding Group Amphipoda Cymadusa compta (Smith) Herbivore Generalist Ampithoe longimana (Smith) Herbivore Generalist Elasmopus levis (Smith) Omnivore Ampelisca sp. Suspension Gammarus mucronatus (Say) Omnivore Erichthonius brasiliensis (Dana) Detritus Only Colomastix sp. Unknown Caprella sp. Omnivore Isopoda Erichsonella attenuata (Harger) Herbivore Generalist Harrieta faxoni (Richardson) Unknown Tanaidacea Hargeria rapax (Harger) Unknown Gastropoda Bittium varium (Pfeiffer) Herbivore Generalist Cerithium muscarum (Say) Herbivore Generalist Caecum pulchellum (Stipson) Herbivore Generalist Astyris lunata (Say) Carnivore Marginella bella (Conrad) Carnivore Nassarius vibex (Say) Carnivore Odostomia laevigata (d'Orbigny) Unknown

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18 Table 4. The percentage of peracarid crus tacean and gastropod epifauna found in each feeding group, collected in ep ifauna samples in June and October 2004 on three types of vegetation: Caulerpa prolifera Halodule wrightii and Thalassia testudinum Feeding Group Total Number of Epifauna Percent of Total Epifauna Herbivore Generalist 12670 84.38 Detritus Feeder 1027 6.84 Carnivore 731 4.87 Omnivore 553 3.68 Suspension Feeder 34 0.23

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19 0 50 100 150 200 250 300 350 400 450Mean (+/SE) Number of Epifauna per Sampl e (0.09m2 bottom area) Total Epifauna Total Peracarids Cymadusa compta Remaining Peracarids Total Gastropods Bittium varium AB AAA C A B A A A A A B A A A C A A A B A AB A A A A A A B A A A A A** *Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Figure 5. Mean (SE) abundances of epifauna per sample (0.09m2 bottom area) for June and October 2004 samples. Solid areas represent June 2004 samples, striped areas represent October 2004 samples. Results of a two-way ANOVA; means with the same letter are not significantly diffe rent (p<0.05), presence of an asterisk in the upper center of the column represents a signifi cant interaction between vegetation type and date for that column.

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20 Table 5. Results of a two-factor ANOVA on th e abundance of total epifauna per sample (0.09m2) on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 250588.9000 250588.9000 25.235 <.001 Vegetation Species 2 171678.156 85839.0780 8.644 <.001 Sampling Date x Vegetation Species 2 173833.8 86916.9000 8.753 <.001 Residual 84 834130.267 9930.1220 Total 89 1430231.122 16070.0130

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21 Table 6. Results of a two-factor ANOVA on th e abundance of total peracarids per sample (0.09m2) on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 177333.611 177333.611 30.033 <.001 Vegetation Species 2 217324.467 108662.233 18.403 <.001 Sampling Date x Vegetation Species 2 185173.489 92586.744 15.681 <.001 Residual 84 495984.533 5904.578 Total 89 1075816.100 12087.821

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22 Table 7. Results of a two-f actor ANOVA on the abundance of C. compta per sample (0.09m2) on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 193210.0000 193210.0000 56.801 <.001 Vegetation Species 2 203503.899 101751.9440 29.913 <.001 Sampling Date x Vegetation Species 2 138924.467 69462.2330 20.421 <.001 Residual 84 285730.533 3401.5540 Total 89 821368.889 9228.8640

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23 except T. testudinum in October 2004. Total gastropods were found in significantly higher abundances on T. testudinum in October 2004 than on any of the other samples. No differences in abundances of B. varium across all vegetation types and between sample dates were noted (Figure 5). When epifauna were standardized to the amount of vegetation surface area (Figure 6) all three vegetation types appear ed to support similar numbers of total epifauna over both sampling dates. Total peracarids were also found in similar nu mbers on all types of vegetation during both June and October 2004 except on Thalassia testudinum where the total peracarids were more abundant in October 2004 than in June 2004 (p=0.048). Cymadusa compta was found in similar numbers on all three types of vegetation in June 2004 and on Halodule wrightii in June and October 2004. Caulerpa prolifera and T. testudinum supported significantly higher numbers of C. compta in October 2004 than in June 2004 (p=0.027 and 0.003 respectively). The remaining peracarids were found in similar abundances on all three types of ve getation over both sampling dates except on H. wrightii which had significantly more remaining peracarids in June 2004 than October 2004 (p=0.001). In June 2004 all three types of ve getation supported similar abundances of total gastropods. In October 2004 all three type s of vegetation supported abundances of gastropods that were similar to those f ound in June 2004 although the number of total gastropods found on C. prolifera was significantly less than H. wrightii (p=0.021) or T. testudinum (p=0.008) (Figure 6). Bittium varium was found in similar abundances across all three types of vegetation and on both dates except on C. prolifera in October 2004, which had significantly less B. varium than C. prolifera in June 2004 (p=0.041) and Thalassia testudinum in October 2004 (p=0.01). The abundan ces of both the total gastropods (Table 8) and B. varium (Table 9) groups showed a significant interaction

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24 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90Mean (+/SE) Number of Epifauna per Surface Area (cm2) per Sample (0.09m2 bottom area) Total Epifauna Total Peracarids Cymadusa compta Remaining Peracarids Total Gastropods Bittium varium A A A B A B A AB A B A B AB A A A A AB A B A AB A B A AB B AB B A B A A A A A B A B A *Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Figure 6. Mean (SE) abundances of epifauna per surface area of vegetation blades/fronds (cm2) for June and October 2004 samples. Solid areas represent June 2004 sa mples, striped areas represent October 200 4 samples. Results of a two-way ANOVA; means with the same letter are not significantly different (p<0.05) presence of an asterisk in the upper center of the column represents a significant interaction between vegetation type and date for that column.

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25 between vegetation type and sample date (p=0.033 for both groups). The epifauna of each sample were also stan dardized to the amount of epiphytic algae (g) found in each sample (0.09m2 bottom area). The epifauna abundances in all groups: total epifauna, total peracarids, Cymadusa compta remaining peracarids, total gastropods, and Bittium varium showed the same trend when compared over the three types of vegetation and both sample dates. After being standardized to the amount of epiphytic algae in each sample, abundances of all epifauna in the a bove mentioned groups we re not statistically different on Caulerpa prolifera Halodule wrightii or Thalassia testudinum in both June and October 2004 with one ex ception. In October 2004, C. prolifera hosted significantly more epifauna per gram of epiphy tic algae than either the C. prolifera samples from June 2004 or the seagrass samples (p 0.006 for all comparisons involving epifauna found on C. prolifera in October 2004). The following groups : total epifauna, total peracarids, C. compta total gastropods, and B. varium showed a significant interac tion between vegetation type and sample date (p .02) (Figure 7) (Tables 10-14).

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26 Table 8. Results of a two-factor ANOVA on the abundance of total gastropods per blade/frond surface area of Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source Df SS MS F P Sampling Date 1 0.000205 0.000205 0.00609 0.938 Vegetation Species 2 0.217 0.109 3.223 0.045 Sampling Date x Vegetation Species 2 0.241 0.120 3.571 0.033 Residual 83 2.796 0.0337 Total 88 3.253 0.0370

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27 Table 9. Results of a two-factor ANOVA on the abundance of Bittium varium per blade/frond surface area of Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 0.0138 0.0138 0.539 0.465 Vegetation Species 2 0.154 0.0770 3.000 0.055 Sampling Date x Vegetation Species 2 0.183 0.0915 3.563 0.033 Residual 83 2.131 0.0257 Total 88 2.279 0.0282

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28 1.00 10.00 100.00 1000.00 10000.00 100000.00 1000000.00 10000000.00Mean (+/SE) Number of Epifauna per Amount of Epiphyti c Algae (g) per Sample (0.09m2 bottom area) Total Epifauna Total Peracarids Cymadusa compta Remaining Peracarids Total Gastropods Bittium varium A A A A B A A A A A B A A A A A B A A A A A B A A A A A B A A A A A B A * * *Thalassia testudinum A Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Thalassia testudinum Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Caulerpa prolifera Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Halodule wrightii Figure 7. Mean (SE) abundances of epifauna per amount of epi phytic algae (g) for June and Oc tober 2004 samples. Solid areas represent June 2004 samples, striped areas represent October 2004 samples. Results of a two-way ANOVA; means with the same letter are not significantly diffe rent (p<0.05), presence of an asterisk in the upper center of the column represents a signifi cant interaction between vegetation type and date for that column.

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29 Table 10. Results of a two-factor ANOVA on th e abundance of total ep ifauna per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 3.398x1012 3.398x1012 4.84200 0.031 Vegetation Species 2 6.862x1012 3.431x1012 4.889 0.010 Sampling Date x Vegetation Species 2 6.699x1012 3.349x1012 4.772 0.011 Residual 82 5.755x1013 7.018x1011 Total 87 7.397x1013 8.503x1011

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30 Table 11. Results of a two-factor ANOVA on the abundance of total peracarids per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 2.204x1012 2.204x1012 4.06200 0.047 Vegetation Species 2 4.425x1012 2.212x1012 4.077 0.021 Sampling Date x Vegetation Species 2 4.364x1012 2.182x1012 4.021 0.022 Residual 82 4.449x1013 5.426x1011 Total 87 5.514x1013 6.338x1011

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31 Table 12. Results of a two-f actor ANOVA on the abundance of Cymadusa compta per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 1.360x1012 1.360x1012 4.231 0.043 Vegetation Species 2 2.719x1012 1.359x1012 4.228 0.018 Sampling Date x Vegetation Species 2 2.693x1012 1.346x1012 4.188 0.019 Residual 82 2.636x1013 3.215x1011 Total 87 3.292x1013 3.784x1011

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32 Table 13. Results of a two-factor ANOVA on the abundance of total gastropods per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii, and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 8.299x1010 8.499x1010 7.26500 0.009 Vegetation Species 2 1.768x1011 8.842x1010 7.558 <.001 Sampling Date x Vegetation Species 2 1.644x1011 8.222x1010 7.028 0.002 Residual 82 9.593x1011 1.170x1010 Total 87 1.372x1012 1.577x1010

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33 Table 14. Results of a two-f actor ANOVA on the abundance of Bittium varium per amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii, and Thalassia testudinum for June and October 2004 samples. Source df SS MS F P Sampling Date 1 5.552x1010 5.552x1010 7.20900 0.009 Vegetation Species 2 1.166x1011 5.831x1010 7.572 <.001 Sampling Date x Vegetation Species 2 1.073x1011 5.372x1010 6.975 0.002 Residual 82 6.315x1011 7.701x109 Total 87 9.023x1011 1.037x1010

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34 Community Composition In the June 2004 samples there was no a pparent separation of the samples of peracarid and gastropod communities in MDS plots recorded for the three different vegetation types (Figure 8). In all three types of vegetation Cymadusa compta was the most dominant species of peracarid and Bittium varium the most dominant species of gastropod. In October 2004 there was an apparent difference (ANOSIM p=0.001) between the communities found on each type of seagrass (Figure 9). Based on SIMPER analysis of epifauna per sample (0.09m2 bottom area) C. compta the most abundant peracarid, accounted for 33.12% of the difference between the communities found on Halodule wrightii and Thalassia testudinum 55.72% of the difference between communities on Caulerpa prolifera and T. testudinum and 65.55% of the difference between the communities found on C. prolifera and H. wrightii When the vegetation characteristics (num ber of blades/fronds surface area of blades/fronds, and amount of ep iphytic algae per sample (0.09m2 bottom area) from the June samples were included in a BIOENV analysis using the Bray Curtis similarity measure there was little difference among these factors on the epifauna found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum (Table 15). In the October 2004 samples, however, epiphytic algae were responsible for the majority of differences among the communities found on each type of vegetation (Table 16). The results of the ANOSIM analysis of the October samples indicated that the communities found on C. prolifera and H. wrightii and on C. prolifera and T. testudinum were significantly diffe rent with R statistics of 0.884 and 0.722, respectively, and significance le vels of 0.01 respectively. Communities of peracarids and gastropods found on the seagrasses were more similar to each other than to

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35 the the peracarid and gastropod communities found on C prolifera with an R statistic of 0.169 and a significance level of 0.09.

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36 Figure 8. Multi-Dimensional Scale plot of epifauna communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum per sample (0.09m2 bottom area), June 2004.

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37 Figure 9. Multi-Dimensional Scale plot of epifauna communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum per sample (0.09m2 bottom area), October 2004.

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38 Table 15. Results of the June 2004 BIOENV anal ysis of the relative amount of influence that the three vegetation characteristics: number of blades/fronds, surface area of blades/fronds (cm2), and/or amount of epiphytic algae (g) have on the peracarid and gastropod communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum Variable Correlation Surface Area of Blades/Fronds(cm2) and Epiphytic Algae (g) 0.268 Surface Area of Blades/Fronds (cm2) 0.267 Surface Area of Blades/Fronds (cm2), Epiphytic Algae (g), and Number of Blades/Fronds 0.259 Number of Blades/Fronds and Surface Area of Blades/Fronds (cm2) 0.259 Number of Blades 0.164 Number of Blades and Epiphytic Algae (g) 0.163 Epiphytic Algae (g) 0.130

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39 Table 16. Results of the October 2004 BIOENV an alysis of the relative amount of influence that the three vegetation characteristics: number of blades/fronds, surface area of blades/fronds (cm2), and/or amount of epiphytic algae (g) have on the peracarid and gastropod communities found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum Variable Correlation Epiphytic Algae (g) 0.874 Surface Area of Blades/Fronds (cm2), Epiphytic Algae (g), and Number of Blades/Fronds 0.067 Number of Blades/Fronds with Surface Area of Blades/Fronds (cm2) 0.067 Number of Blades with Epiphytic Algae (g) 0.063 Surface Area of Blades/Fronds (cm2) with Epiphytic Algae (g) 0.063 Surface Area of Blades/Fronds 0.062 Number of Blades 0.062

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40 Relationship Between Epiphytes and Epifauna or Surface Area and Epifauna The number of epifauna per sample (0.09m2 bottom area) was compared to the amount of epiphytes per sample from the June and October 2004 samples (Figure 10). The relationship between the amount of epifauna and the amount of epiphytic algae was plotted for the epifauna found on Caulerpa prolifera, Halodule wrightii and Thalassia testudinum for the June and October 2004 samples. These relationships suggest there was no correlation between the amount of epiphytic algae on the vegetation and the amount of epifauna present with regression slopes ranging from -122.9 to 2761.7 and extremely low R2 value (ranging from 0.0019 to 0.1561) (Table 17). When the amount of epifauna present in each sample was compared to the amount of su rface area of the blades/fronds, the epifauna on C. prolifera and H. wrightii in June and October and on T. testudinum in October showed a small positive correlation between the number of epifauna and surface area for each of the three types of vegetation (with regression slopes ranging from -0.0235 to 0.2772) (Figure 11 and Table 18). Low R2 values (ranging from 0.0047 to 0.3233), however, show a poor correlation between the amount of epif auna and surface area per sample.

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41 0 100 200 300 400 500 600 700 800 00.10.20.30.40.50.60.7Epiphytes (g) per sample (0.09m2bottom area) Number of epifauna per sample (0.09m2 bottom area) Caulerpa prolifera Halodule wrightii Thalassia testudinum Caulerpa prolifera Halodule wrightii Thalassia testudinum Figure 10. Number of total epifauna per sample (0.09m2 bottom area) vs. dry weight of epiphytic algae (g) per sample (0.09m2 bottom area) for June and October 2004 samples. Light symbols represent June 2004 samples, da rk symbols represent October 2004 samples.

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42 Table 17. Regression slopes and R2 values for the relationships between the amount of epifauna and the amount of epiphytic algae (g) found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Regression Slope R2 value June Caulerpa prolifera 1662.7 0.0186 Halodule wrightii -23.7 0.0019 Thalassia testudinum -122.9 0.1561 October Caulerpa prolifera 2761.7 0.1321 Halodule wrightii 87.6 0.0065 Thalassia testudinum 72.8 0.0095

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43 0 100 200 300 400 500 600 700 800 0500100015002000Surface Area of Blades (cm2) per sample (0.09m2 bottom area)Number of epifauna per sample (0.09m2 bottom area) Caulerpa prolifera Halodule wrightii Thalassia testudinum Caulerpa prolifera Halodule wrightii Thalassia testudinum Figure 11. Number of total epifauna per sample (0.09m2 bottom area) vs. surface area of blades/fronds (cm2) per sample (0.09m2 bottom area) for June and October 2004 samples. Light symbols represent June 2004 samples, da rk symbols represent October 2004 samples.

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44 Table 18. Regression slopes and R2 values for the relationships between the amount of epifauna and the amount of vegetation blade/frond surface area (cm2) of Caulerpa prolifera Halodule wrightii and Thalassia testudinum for June and October 2004 samples. Regression Slope R2 value June Caulerpa prolifera 0.2772 0.3233 Halodule wrightii 0.2437 0.0997 Thalassia testudinum -0.0235 0.0047 October Caulerpa prolifera 0.0439 0.0083 Halodule wrightii 0.1276 0.0778 Thalassia testudinum 0.0562 0.0602

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45 Discussion If the number of epifauna found on each t ype of vegetation wa s driven by habitat complexity (measured by the amount of surface ar ea) as has been shown by previous studies (Hacker and Steneck 1990), one would expect the vegetation with the highest amount of surface area to support the highest amounts of epifauna. This was what was observed in both June and October 2004 for the majority of the epifauna groups tested. In June 2004, when the Caulerpa prolifera Halodule wrightii and Thalassia testudinum had similar amounts of surface area per sample, all of the epifauna groups tested were found in similar abundances on all three types of vegetation. In October 2004 the amount of vegetation surface area increased significantly from H. wrightii to T. testudinum to C. prolifera Two groups of epifauna follow this pa ttern with total epifauna and C. compta having significantly higher abundances as amounts of vegetation increased. Total peracarids also had significantly higher abundances per sample on C. prolifera The results of the PRIMER tests combined with measures of ve getation surface area lend support to the theory that structural comple xity may be a factor influencing the species composition of mobile epifauna. In June 2004 when the amount of surface area for the three types of vegetation, Caulerpa prolifera Halodule wrightii and Thalassia testudinum was not significantly different, the epifauna comm unities on the three types of vegetation also showed strong similarity. In October 2004, when the amount of C. prolifera vegetation was greater than that of either seagrass, the epifauna communities found on the two seagrasses

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46 were more similar to each other than e ither was to the epifauna community found on C. prolifera The BIOENV analysis showed that the difference between the epifauna communities found on C. prolifera and the two seagrasses was driven equally by a combination of vegetation surface area and epiphytic algae and by vegetation surface area alone in the June 2004 samples. Overall, the abundances of epifauna for both the June and October 2004 samples support the theory that epifauna abundances may be related to the amount of habitat complexity (represented by the amount of surface area) as set forth by previous studies (Hacker and Steneck 1990, Knowles and Bell 1998, Bostrm and Mattila 1999, Edgar and Klumpp 2003). Although the epifauna collected for this su rvey appear to be influenced by the amount of surface area of Caulerpa prolifera Halodule wrightii or Thalassia testudinum the epifauna may also be influenced by the amount of epiphytic algae found on the vegetation. If the number of epifauna found on each type of vegetation was driven by the amount of epiphytic algae in this system as has been shown previously by Bologna and Heck (1999) and Moncreiff and Sullivan (2001) then the vegetation that supported the highest amounts of epiphytic algae should also support the hi ghest numbers of epifauna. However, in both June and October 2004 while the amount of epiphytic algae on C. prolifera was an order of magnitude less than the amount found on both types of seagrass the number of epifauna per sample found on C. prolifera was equal to or greater than the number of epifauna found on the seagrass. When the number of epifauna were standardized to the amount of epiphytic algae found on each type of vegetation the amount of epifauna found on C. prolifera was one to five orders of magn itude higher than the amount of epifauna found on either of the two seagrasses. Thus, there does not seem to be a strong relationship between the amount of epifauna and epiphytic alga e present in this system.

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47 Information on individual species may add insight into the patterns exhibited by the major taxa present in this survey. After th e epifauna species were categorized by feeding group one of the feeding groups, herbivores that feed on microand macroorganisms, accounted for 84% of all peracarids and gastrop ods that could be put into a feeding group (all except three of the eighteen species identified). This one fe eding group consists of five species including Cymadusa compta the most abundant peracarid species, and Bittium varium the most abundant gastropod species. These species are most likely to be affected by the lack of epiphytes on Caulerpa prolifera and possibly the secondary compounds produced by C. prolifera which have been shown to deter herbivory by fish and therefore be less abundant on C. prolifera compared to the seagrasses. Instead two of these species, C compta and B varium are the most abundant species in the epifauna communities, not only on the seagrasses but also on C. prolifera, even though the latter had an order of magnitude less epiphytic algae compared to the seagrasses. Cymadusa compta is known to eat a variety of foods including macroalgae, microalgae, de tritus, diatoms,vascular plants, and even tunicates (Morgan and Kitt ing 1984, Duffy and Hay 2001, Cruz-Rivera and Hay 2003, ). Because C. compta is such a broad generalist it may be be tter able to deal with the lack of one type of food (micoalgae) and survive well on C. prolifera while species which eat mainly microalgae cannot because of the lack of epiphytic algae. This would explain why C. compta was abundant on C. prolifera while other peracarids and gastropods which rely more on epiphytic algae were less abundant. Overall, this study found varying amounts of evidence to support the possibility of both the amount of blade/frond surface area and th e amount of epiphytic algae influence the amount and community composition found on Caulerpa prolifera Halodule wrightii and Thalassia testudinum Evidence that supports epiphytic algae influencing the amount and

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48 community composition of epiphytes was found in the fact that in the October 2004 the community composition of epifauna was overw helmingly driven by epiphytic algae. However, the major findings of this survey: 1) some evidence for a positive relationship between the amount of epifauna and the amount of blade/frond surface area, including vegetation with higher amounts of surface area supporting higher amounts of epifauna, 2) no relationship between the amount of epifauna and the amount of epiphytic algae on submerged vegetation, and 3) when the amount of surface area of all vegetation species was similar the epifauna communities were simila r in species composition lend support to the theory that surface area of vegetation (and th erefore possibly habitat complexity) is an important factor in determining the abundan ce and community composition of epifauna in seagrass and macroalgae beds in Lassing Park, Florida.

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