FAU Institutional Repository http://purl.fcla.edu/fau/fauir This paper was submitted by the faculty of FAU’s Harbor Branch Oceanographic Institute. Notice: ©1978 Rosenstiel School of Marine and Atmospheric Science, University of Miami. This manuscript is available at http://www.rsmas.miami.edu/bms and may be cited as: Gore, R. H., Scotto, L. E., & Becker, L. J. (1978). Community composition, stability, and trophic partitioning in decapod crustaceans inhabiting some subtropical sabellariid worm reefs: Studies on decapod crustacea from the Indian River region of Florida, IV. Bulletin of Marine Science, 28(2), 221‐248. BULLETIN OF MARINE SCIENCE, 28(2): 221-248, 1978 COMMUNITY COMPOSITION: STABILITY, AND TROPHIC PARTITIONING IN DECAPOD CRUSTACEANS INHABITING SOME SUBTROPICAL SABELLARIID WORM REEFS STUDIES ON DECAPOD CRUSTACEA FROM THE INDIAN RIVER REGION OF FLORIDA. IV Robert H. Gore, Liberta E. Scotto, and Linda J. Becker ABSTRACT A 2-year study consisting of quantitative and qualitative collections, both day (1974) and night (1975), was made on the decapod and stomatopod crustaceans inhabiting, or associating peripherally with, some sabellariid worm reefs on the central eastern Florida coast. The reefs investigated all occurred in the surf zone or just inside dredged and maintained inlets of the Indian River region, from St. Lucie Inlet northward to Sebastian Inlet. Quantitative and qualitative sampling indicated that at least 96 species of decapod and stomatopod crustaceans, in 52 genera and 22 families, may occur within, or in habi- tats adjacent to, the sabellariid biotope. The Quantitative Survey obtained 51 species, lO- II of which comprised nearly 90% of all collected individuals, and were sufficiently recur- rent to be labelled common. These 10-11, plus the next 13 species in abundance (= 24) contained 97% of all collected individuals and were considered characteristic of the decapod and stomatopod fauna on central eastern Florida sabellariid reefs. The remaining 27 species accounted for approximately 3% of all collected individuals and were designated as uncommon. The sabellariid-inhabiting macrocrustacean community is dominated numerically by three species, the porcellanid crab Pachycheles l1lonilifer, and the xanthid and grapsid crabs, Menippe nodifrons and Pachygrapsus transversus, respectively. To- gether, these three species made up 65% of all collected individuals obtained during quantitative sampling. Three other species, the pistol shrimp Synalpl1eus jritzmuelleri, and the xanthid crabs Pilumnlls dasypodus and Panopeus bermudensis, accounted for another 15% of all individuals coltected from these reefs. Species composition and rela- tive abundance and occurrence of the numerically important decapod crustaceans on these reefs was similar over both years of the study. Nutritional modes among the first three species suggested that trophic partitioning occurs. Gut content analyses and predator- prey relationships among the six most numerous species indicated that all feed to some extent on the sabellariid worms which construct the substratum of the biotope. The sabellariid bioherm thus offers hard substratum, protection, and food for these decapod species allowing them to utilize the surf zone habitat, an area where they would not normally be found. Persistence of the sabellariid biotope, and predictability of decapod species composition may account in some measure for the observed stability in the decapod community on these reefs. Two of the three most abundant species, Pachycheles l1lonilifer and Menippe nodifrons, are zoogeographically limited in their northern range to the Indian River region of Florida, and neither of these species occurs in large numbers outside of the sabellariid biotope. Their distribution along the central eastern Florida coastline appears to follow that of the sabellariid worm itself. Members of the polychaete worm family dwelling tubes which, as development and Sabellariidae have long been noted for the increased settlement continues, eventually ability to form extensive "reefs" or bioherms coalesce to form large colonies within and in shallow marine waters. Species in the just seaward to the surf zone on shores family utilize sand particles and a muco- exposed to the open sea. Such colonies proteinaceous cement to construct their often support large associated faunas com- 221 222 BULLETIN OF MARINE SCIENCE, VOL. 28, NO.2, 1978 posed principally of crustaceans and molluscs (Rivosecchi, 1961; Achary, 1971; Fausto- Filho and Furtado, 1970; Gruet, 1970, 1971, 1972a, 1972b, 1973; Wilson, 1971). Nearly all of these studies have been carried out on Sabel/aria alveolata (Linne), a tem- perate-water European species. In the New World, Phragmatopoma lapidosa Kinberg, 1867, is a widely distrib- uted species which occurs primarily in trop- 28° ical marine waters from the vicinity of Santa Catarina, Brazil to the area of Cape Canaveral, Florida (Kirtley, 1966; Kirtley and Tanner, 1968; Fanta, 1968). Although the worms can be found along the eastern coastline of Florida from Biscayne Bay to Cape Canaveral, studies on the species in 30' this area have been devoted mainly to geological aspects of the worm reefs (Multer and Milliman, 1967; Gram, 1968) and the species has received only limited attention from biologists. Eckelbarger (1976) has described the larval development of Phrag- 27° matopoma lapidosa from the Indian River region on the central eastern Florida coast- line, but the only ecological investigations on the species have been brief studies in Figure 1. Map of the Indian River region on the Brazil (N archi and Rodrigues, 1965; Fanta, central eastern Florida coast, with dots showing the location of sabellariid worm reef stations 1968; Fausto-Filho and Furtado, 1970). sampled during 1974-1975. The Canova Beach Kirtley (1974) summarized both biological station was not continuously sampled (see text). and geological studies on P. lapidosa and related genera and species in the family Sabellariidae. more, in press). The decapod and stoma to- pod crustaceans on these reefs form a Large, exposed colonies of Phragmat- particularly noticeable faunal component opoma lapidosa occur throughout the length of the Indian River region of Florida, from estimated to account for approximately 90r" of the associated macroinvertebrate fauna, just north of Jupiter Inlet to slightly south and thus comprise an assemblage which of Melbourne, Florida about 50 km (30 would appear to lend itself to community miles) south of Cape Canaveral. Many of analyses. these colonies consist of discrete, semiiso- This paper reports on the results of a lated units within the larger framework of 2-year survey, begun in January 1974, that the sabellariid biotope. Preliminary investi- was directed toward determining species gations revealed that such colonies sup- composition, abundance, richness and diver- ported a large and varied invertebrate faunal sity of the decapod and stomatopod fauna assemblage consisting primarily of crusta- either inhabiting, or found in proximity to ceans, molluscs, sponges, bryozoans, and these reefs. Predator-prey and trophic re- anthozoans. These colonies also provide lationships in selected decapod species food and cover for small populations of both within the sabellariid biotope in the Indian transient and permanent fish faunas (Gil- River region were also investigated. In this GORE ET AL.: COMMUN1TY STABILlTY IN WORM REEF CRUSTACEANS 223 Figure 2. General view of three sabellariid worm reef stations sampled in the Indian River region: (A) St. Lucie Inlet; (B) Walton Rocks; (C) Ft. Pierce Inlet. The Sebastian Inlet station is similar to that at Ft. Pierce Inlet. All stations photographed at low tide, facing south. The St. Lucie and Wal- ton Rocks stations typify exposed-shore worm reefs; the Ft. Pierce Inlet station illustrates a more pro- tected area. Note the numerous holes and crevices in the worm colonies at each station. 224 BULLETIN OF MARINE SCIENCE, VOL. 28, NO.2, 1978 paper we consider species composition and the trophic relationships of the numerically .•.. o important decapod species In the com- ;>. munity. II) E •..> o ::l ~ '" METHODS Samples were gathered in the Indian River region along the central eastern Florida coast between latitudes 27° and 28°N. Four areas were selected in 1974 for daytime sampling, three of which were also chosen for nighttime sampling in 1975. All con- u o" tained extensive, viable worm reefs. Pro- gressing from south to north these were (1) ,,; Seminole Shores, a beachside residential o Z subdivision just north of S1. Lucie Inlet, Martin County (hereafter called S1. Lucie oo Inlet); (2) Walton Rocks, an exposed series of coquinoid limestone ledges of the Anas- ci. tasia geological formation, located on an en" isolated beach on Hutchinson Island, S1. t:: (':j II) Lucie County, opposite a large nuclear- <.) .::l NNN NNN fueled power plant; (3) inside the mouth '"::l•.. of F1. Pierce Inlet, S1. Lucie County, be- <.) .•.. NNN tween the enclosing granite rip-rap jetties; o and (4) inside Sebastian Inlet, Indian River County, both alongshore and in the channel itself (Figs. 1 and 2). The latter station was eliminated for night sampling in 1975 NNNN because of the extremely swift and danger- ous current which prevails in the Sebastian :;:;-N Inlet channel. The total geographical range r-- 0'1....• of the survey area encompassed approxi- •.. mately 80 km (50 miles) from S1. Lucie to ::lVJ •...• 01) Sebastian Inlets. ::l i The 2-year investigation was divided