508 Abstract.–Fish assemblages of near- Nearshore hardbottom fishes of shore hardbottom habitats of southeast Florida were quantified at three sites southeast Florida and effects of from April 1994 to June 1996. Random 2 × 15 m transects were visually censused habitat burial caused by dredging within two replicate areas at each site. The hardbottom at one site was buried by a dredge project to widen a beach Kenyon C. Lindeman one year into the study. A total of 394 Division of Marine Biology and Fisheries, transects were sampled. Eighty-six Rosenstiel School of Marine and Atmospheric Science, taxa (77 identified to species) from 36 University of Miami families were censused. Grunts (Hae- 4600 Rickenbacker Cswy., Miami, Florida 33149 mulidae) were the most diverse family E-mail address (for K. C. Lindeman): [email protected] (11 species), followed by the wrasses (Labridae) and parrotfishes (Scaridae) with seven and six species, respectively. David B. Snyder The most abundant species were sail- Continental Shelf Associates, Inc. ors choice (Haemulon parra), silver porgy 759 Parkway St. (Diplodus argenteus), and cocoa damself- Jupiter, Florida 33477 ish (Stegastes variabilis) with mean abundances (individuals/transect) of 4.5, 3.8, and 3.7, respectively. Early life stages (newly settled, early juvenile, and juvenile) represented over 80% of the individuals at all sites. Newly The southeast coast of mainland of tube-building polychaete worms settled stages of over 20 species were Florida is within a biogeographic (Kirtley and Tanner, 1968) and observed in association with hard- bottom reef structure. Outside of la- transition zone of high marine other invertebrate and macroalgal goons, nearshore hardbottom areas are biodiversity (Briggs, 1974; Gilmore, species (Goldberg, 1973; Nelson, the primary natural structures in shal- 1995). This region is also undergo- 1989; Nelson and Demetriades, low waters of mainland Florida’s east ing some of the most rapid human 1992). In southeast Florida, most coast and were estimated to have nurs- population growth of any area of the nearshore hardbottom structures ery value for 34 species of fishes. After one year, burial of approximately five United States (Culliton et al., 1990). are within 200 m of the shore. These ha of hardbottom habitat at one site Due to the economic and recre- habitats are often centrally located lowered the numbers of individuals and ational value of beaches, substan- between mid shelf reefs to the east species by over 30× and 10×, respec- tial marine dredging projects (up to and estuarine habitats within inlets tively. Due to their early ontogenetic 1.5 × 105 m3 of fill/project) are to the west. Therefore, they may stage, many of these species may not be adapted for high mobility in re- commony used to widen beaches serve as settlement habitats for sponse to habitat burial. Dredging ef- that are subject to erosion in the immigrating larvae or as interme- fects may be amplified by burial prior area (ACOE, 1996). Nearshore diate nursery habitats for juveniles to and during spring and summer peri- hardbottom habitats are the pri- emigrating out of inlets (Vare, 1991; ods of peak larval recruitment. mary natural reef structures of this Lindeman, 1997a). Nonetheless, region at depths of 0–4 m and are most administrative reviews have often buried or indirectly affected by concluded that the fish habitat these projects. To date, no quanti- value of nearshore hardbottom and tative studies of the fish fauna of the effects of dredge-based beach these habitats or the effects of beach restoration projects are minimal dredge-and-fill projects on near- (e.g. ACOE, 1996). shore fishes are available (NRC, This study quantifies nearshore 1995). hardbottom fish assemblages on the Nearshore hardbottom habitats southeast coast of mainland Florida of this area are derived from accre- over a 27-month period. The effects tionary ridges of coquina mollusks, of dredge-fill placement were also sand, and shell marl which lithified examined because the hardbottom parallel to ancient shorelines dur- habitat at one site was buried on ing Pleistocene interglacial periods account of a beach restoration (Duane and Meisburger, 1969; project 12 months into the study. Hoffmeister, 1974). The habitat Three primary objectives were ex- Manuscript accepted 28 August 1998. complexity of these limestone struc- amined. First, spatial and temporal Fish. Bull. 97:508–525 (1999). tures has been expanded by colonies attributes of fish assemblages at Lindeman and Snyder: Nearshore hardbottom fishes of southeast Florida 509 Figure 1 Primary study sites for fish surveys of nearshore hardbottom habitats at Jupiter, Florida (26°56'N, 80°04'W). three undisturbed hardbottom sites were character- 1994 through June 1996 (Fig. 1). Sampling at both ized. Second, abundances of different life stages were sites extended approximately 100 m offshore to a compared to assess the potential nursery value of depth of 4 m. Nearshore hardbottom of similar depth nearshore hardbottom habitat. Third, effects of and structure at Ocean Ridge, immediately south of dredge burial on numbers of individuals and species the South Lake Worth Inlet (26°31'N, 80°02'W) was were compared between a site subjected to burial and also surveyed for comparative purposes during the a control site. summer of 1995. Weathered limestone outcroppings were common between depths of 0 and 4 m at all sites. These struc- Methods tures have a variety of names (e.g. Anastasia forma- tion outcroppings, coquina reefs, worm reefs) but are Study areas referred to by their most common name, “nearshore hardbottom,” in the present study. In some areas, Fish abundances were quantitatively surveyed on the hardbottom extended 1.75 m above the bottom two nearshore hardbottom sites approximately 2 km and was highly convoluted. Shoreward portions of north (Coral Cove) and 2 km south (Carlin Park) of the hardbottom were exposed at low tide. Epibiota Jupiter Inlet, Florida (26°56'N, 80°04'W) from April consisted of a variety of invertebrates and algae. The 510 Fishery Bulletin 97(3), 1999 most widespread encrusting organism was the reef- In addition to total abundances, early life stages building sabellariid worm Phragmatopoma lapidosa were also enumerated. Fork length was used for size (=P. caudata; Kirtley, 1994), often covering over 50% estimation. Following Lindeman (1986; 1997a), life of the hardbottom at all sites. stages of grunts (Haemulon and Anisotremus) were A beach restoration project occurred at Carlin Park recorded as follows: newly settled (<2 cm), early ju- in March and April of 1995. More than 350,000 m3 of venile (2–5 cm), juvenile (5–15 cm), and adult (>15 beach-compatible sediments were excavated by a cm). For other families, the same newly settled size cutter-head dredge from a site 0.8 km offshore and range (<2 cm) was used. The early juvenile designa- hydraulically pumped along 1.8 km of shoreline. tion was used only for grunts because of the distinct Bulldozers extended the fill seaward to an estimated morphological features of the 2–5 cm size range width of 60 m. An estimated total of 4.9 to 5.7 ha (Lindeman, 1986). Juvenile and adult stages were (12–14 acres) of nearshore hardbottom was buried.1 based on size and pigment patterns reported in the Visual surveys of fishes were conducted for 12 months literature (e.g. Robins and Ray, 1986; Humann, 1994). before burial and 15 months after burial at both Species identifications of the newly settled or juve- Carlin Park (the impact site) and Coral Cove (the nile stages for certain taxa were limited by very simi- control site). Little or no hardbottom was observed lar morphological features (e.g. scarids, kyphosids, in fish surveys at Carlin Park after the project. gerreids, haemulids, clupeids). Some early stage iden- tifications were therefore recorded only at the genus Survey protocol or family level. Collections of small schools of newly settled grunts were made with hand nets at both During each site visit, three to five transects within Jupiter sites in 1994 and 1995 to supplement field two adjacent areas (=6–10 total transects/site) were identifications. All collections were deposited at the censused. These 2 × 15 m transects were randomly Florida Museum of Natural History, University of located at depths ranging from one to four m. Florida. Transects were deployed along random compass headings at random distances between successive Data analyses transects. Random number tables were used prior to site visits to determine the compass headings and To address the first objective of our study, two comple- distances between transects (based on numbers of mentary multivariate methods were used to spatially fin kicks). All fishes observed within one m of each and temporally characterize the assemblages at the side of the transect line were identified and tallied three sites. The second objective was addressed by by a snorkeler. The survey zone extended from the univariate testing of the hypothesis that abundances bottom to the surface and 2 m in front of the observer. of different life stages would not differ significantly Ledges and sand-rock interfaces were examined for within sites. The third objective was examined with fishes. Rocks were not overturned. The proportion of the hypothesis that numbers of individuals and spe- hardbottom to sand was estimated within each cies would not differ significantly between an impact transect. An estimated 35% of the area within all site where allmost all the hardbottom was buried and transects was sand. Surveys were conducted between a control site that was unaffected by the burial. In 0900 and 1700 and avoided twilight periods. To com- univariate analyses, data were standardized as the pare fish abundances at hardbottom and sand ar- mean number of individuals per transect and as the eas, identical transect methods were used at near- mean number of species per transect.