COMPOSITION AJ\JD DISTRIBLITION OF EPIFAUNA ON PROP ROOTS OF RHIZOPHORA MANGLE L. IN LAKE SURPRISE, FLORIDA by Gary L. Nickelsen A Thesis Submitted to the Faculty of the College of Science lll Partial Fulfillment of the Requirements for the Degree of ~~ster of Science Florida Atlantic University Boca Raton, Florida December 1976 (0 Copyright by Gary L. Nickelsen 1976 11 CO~WOSITION AND DISTRIBUTION OF EPIFAUNA ON PROP ROOTS OF RI-IIZOPHORA MANGLE L. IN LAKE SlffiPRISE, FLORIDA by Gary L. Nickelsen This thesis was prepared under the direction of the candidate's thesis advisor, Dr. G. Alex Marsh, and has been approved by the members of his supervisory committee. It was submitted to the faculty of the College of Science and was accepted in partial fulfillment of the requirements for the degree of Master of Science. SUPERVISORY COMMITfEE: ~~Jttw~ / - · J~~ ·/( . /// c~( ~ ~H ~ t_____., I t/ Sk~ ··m~: Dean, College of Science /97t 111 AC KNO\VLEDGB [ENTS I wish to express my appreciation to Dr. c;. Al ex Iarsh for his assistance in this study and his thorough revie~v of the manuscript . Drs. Ralph ~1. Adams and Sheldon Dobkin are also thanked for their review and criticism of the manuscript. I also \vish to thank Dr. Joseph L. Simon and Mr. Ernest D. Estevez of the University of South Florida for their genuine interest and invaluable assistance in the initial development of t his study. Dr . Manley L. Boss, who initiated several stimulating discussions of my work and offered advice and encouragement throughout this study, is gratefully acknowledged . I would also like to thank Dr. Robert B. Grinun for assistance in identification of algae, and Dr . Tin1othy S. Cotton and Ms. Carol Jones for designing the computer programs us.ed in this study. I am indebted to Mr. Bruce R. Johnson for his honest criticism of the manuscript, and to Mr . Richard E. \Valesky for his valuable opinions and for permission to use his unpublished data . I also thank ~lessrs . Gary A. Pettit and Larry Brown for their assistance 1n the field , and Don and Debra Burgess and Daniel Bell for their aiel 111 constructing the figures used in the manuscript. Credit for the development of the Com­ munity Fullness index is shared with Mr. Gary S. Kleppe 1 of Fordham University. A special thanks goes to ~lr . John Golden for his encouragement and friendship throughout this study. lV Most of all I wish to thank my wife Susan who assisted in the field, typed the manuscript, and contributed to this thesis in many other ways. Her love, patience, and w1derstanding have been unfailing throughout this study. v ABSTRACT Author: Gary L. Nickelsen Title: Composition and Distribution of Epifauna on Prop Roots of Rhizophora mangle L. in Lake Surprise, Flonda Institution: Florida Atlantic University Degree: ~~ster of Science Year: 1976 The invertebrate epifauna associated with prop roots of a single strand of the red mm1grove, Rhizophora mangle L., in Lake Surprise, Florida was sampled in !v~y and November, 1975. A total of 108 species was collected. Dominant species included the amphipods Elasmopus pocillirnanus and Erichthonius brasiliensis, the polychaetes Syllis ~· and Vermiliopsis bermudensis, and the tanaidacean Apseudes propinquus. Fringe roots hosted greater numbers of species and individuals and a greater abundance of sponges and epiphytes thm1 roots 1n the interior of the strand. The root connnuni ty was characterized by three assemblages. The algae-amphi- pod-tanaidacean assemblage was prominent on fringe roots . The sponge- polychaete assemblage (excluding serpulids) was represented well in both areas, but \vas more prominent at the fringe. The bare root-serpulid as- ) sernblage dominated much of the interior. Overall mean qiversi ty (H 5 m1d equitability (E) were 2.60 and 0.65 respectively. Faunal density was 13,200 ind/rn2 of root surface. Vl TABLE OF CONTENTS ACKNO\VLEDGE!v!ENTS lV ABSTRACT ... Vl LIST OF TABLES viii LIST OF FIGURES lX INTRODUCTION . 1 HI\TERIALS AND METHODS 4 Description of Study Area 4 Sampling Stations . 4 Physico-Chemical Sampling Procedure 6 Biotic Sampling Procedure 7 RESULTS 9 Physico-Chemical Conditions 9 Community Composition . 11 Horizontal and Vertical Distribution 23 Seasonal Variation 26 Diversity 32 DISCUSSION . 37 Epiphytes 37 Sessile Fauna 39 Motile Fauna 42 Connnuni ty Structure 48 TI1e Prop Root Counnunity as an Indicator of Environmental Conditions 54 SUM01ARY 59 LITERI\TURE CITED 62 ADDITIONAL REFERENCES USED FOR IDENTIFICATION OF SPECIES 67 Vll LIST OF TABLES 1. Light intensity readings 15 em below the surface. Readings given in lux for each station are means of 4-7 trials . 12 2. Ranking by abundance of all non-colonial epifaunal species collected in this study. Percent and cumulative percent composition, total number of root sections on \-vhich each species occurs (#Sect.), mean density (individuals/m2), and Biological Index (BI) are listed for each species 13 3. Ranking by Biological Index (BI) values of dominant non­ colonial epifaunal species collected in this study. A Amphipod, P = Polychaete, T = Tanaidacean, 1-1 = 1-Iolothurian 21 4.. Ranking by surface area of all sponges attached to mangrove roots collected in this study. Displacement vollUl1e 1s also given for each species . 22 5. Ranking by Biological Index (BI) of dominant species at fringe and interior areas for May and November collections. A= Amphipod, P = Polychaete, T = Tanaidacean, 1-1 = 1-Iolothurian 25 6. Summary of Community Fullness values for May and November collections. Subtotals represent contributions of indi- cated taxa to "fullness" of conunw1ity . 35 Vlll LIST OF FIGURES 1. 111ap of area showing collecting site (X) and stations (A-F in top insert) in Lake Surprise . 5 2. Approximately bi-weekly surface salinities at Lake Surprise and total monthly rainfall at Royal Pa1Jn Station, Ever- glades Na tional Park, April 1975-December 1975 10 3. Distribution and abundance of major non-colonial taxa on fringe mangrove roots. A = Amphipods, P = Polychaetes, T = Tanaidaceans, I Isopods, G = Gastropods, 0 =All Others . 27 4. Distribution and abundance of major non-colonial taxa on interior mangrove roots. A = Amphipods, P = Polychaetes, T = Tanaidaceans, I Isopods , G = Gastropods, 0 = All Others . 28 5. Distribution and abundance of sponges and epiphytic algae on fringe mangrove roots . 29 6. Distribution and abw1dance of sponges and epiphytic algae on interior mangrove roots 30 7. Abundance of polychaetes (including serpulids) in relation to sponge surface area on mangrove root sections with in­ significant (> .5 ml displacement volLUTie) algal cover. Solid line is estimated line of best fit . 44 8. Abundance of amphipods in relation to algal 2olume on mangrove root sections with insignificant (> .5 em) sponge cover. Solid line is estimated line of best fit ..... 46 9. Species frequency curve for mangrove prop root community in Lake Surprise . 55 LX INfRODUCf ION ' The mangrove commw1ity 1s a major tropical ecosystem. According to McGill (1958) the many species of mangroves dominate nearly 75% of the world's shoreline between 25°N and 25°S latitude. In south Florida, three species of mangroves (Rhizophora mangle, Avicennia germinans and Lagw1cularia racemosa) occupy 700 square miles along the coasts. The red mangrove (Rhizophora mangle L.) typically dominates the intertidal zone of protected areas and plays a vital role in the ecology of estu- arine areas (Heald et al. , 197 4) . "-Jhe widespread occurrence of tropical mangrove communities has stimulated many studies of the trees themselves and of the flora and fauna associated with them. Davis (1940) discussed the role of mangroves in accwrrulating sediments and building land areas. Davis also gave a general accow1t of the ecology of several mangrove co1nmunities in Florida. Other studies include an investigation of the structure and Inetabolism of the red mangrove (Galley et al., 1962); the zonation of Indo-West Pacific (Jvtacnae, 1967, 1968) and South African (Macnae, 1963) mangroves and their associated flora and fauna; and the zonation of the epibenthic and infauna living on and in the mud in mangrove swamps (Wal sh, 1967; Rutzler, 1969; Sasek.unar, 1974). Odum (1970) and Odum and Heald (1972) 1 described the complex tropic structure of an entire mangrove community and Heald and Odum (1970) discussed the importance of mangrove ecosys- tems to sport and commercial fisheries. 1 2 One aspect of mangrove ecology that has received relatively lit- tle attention is the often diverse and abundant epibiota associated with prop roots of ~· mangle. Burkholder and Almodovar (1973) investigated quantitatively the distribution and productivity of marine algae attached to the prop roots of red mangroves in Puerto Rico, and Rehrn (1974) studied qualitatively the distribution and ecology of marine epiphytes on ~· mangle from Tampa to Key Largo, Florida. Many other studies of the man- grove community have made reference to the epifatma, but detailed in- vestigations of the ecology of anDnals living on red mangrove roots are generally lacking. ~~ttox (1949) studied the ecology of the mangrove osyter Ostrea rhizophorae in Puerto Rico, and Robertson (1959) described the molluscan fauna of mm1groves in the Bahamas. The only comprehensive studies that have exrunined community struc- ture and distribution of prop root epifauna and the ecological factors governing these communities are those of Kolehmainen (1973) and Kolehmainen et al. (1974) in Puerto Rico. Descriptions of faunal dis­ tribution were restricted primarily to the phylum level m these studies. Species diversity was indicated merely by numbers of species present. , The importance of red mangroves to various fisheries has been well docwnented (Idyll et al., 1968; Odum, 1970; Heald and Odum, 1970; Odum and Heald, 1972; Heald et al., 1974). Leaves, as they decompose after falling into the \vater, form the foundation of a detritus food chain. They become protein enriched \vi th coatings of bacteria and fungi ! and are ingested by detritivores.