Recruitment in Nassau grouper Epinephelus striatus:post-settlement abundance, microhabitat features, and ontogenetic habitat shifts

Abstract

Nassau grouper Epinephelus striatus are of considerable ecological and commercial ~mportance throughout the Caribbean, Gulf of Mexico and South Atlantic Bight, yet little is known of their settlement habitat and ontogenetic changes in early juvenile habitat requirements. Suction sampllng in macroalgae, seagrass, and coarse calcareous sand habitats and visual surveys of artificial patch reefs were conducted systematically in 1991 to 1994 during wtntertime onshore movement of late larval-early juvenile Nassau grouper within the vicinity of Lee Stocking Island, Bahamas. Recently settled fish [R = 32 mm total length (TL)] resided within coral clumps (Porites spp.) covered by masses of macroalgae (primarily Laurencia spp.), with highest densities at 8 fish m-2 There was a positive and significant linear relationship between percent algal cover and post-settlement grouper density. Other habitat features such as algal displacement volume, and the numbers of holes, ledges, and sponges did not explain any sigmficant variation in post-settlement density. Visual transects performed 4 to 5 mo after the settlement period (June) indicated that early juveniles (X = 85 mm TL) residing within or adjacent to algal-covered coral clumps were mostly solitary (88%). Growth rates during February to June averaged 10 mm mo-' in 1993. When densities of early juveniles were relatively high in 1991 and 1993 (X = 0.03 fish m-*), there was also a positive and significant linear relationship between percent algal cover and early juvenile density. During 3 separate annual sampling periods, a decrease in early juvenile densities in macroalgal habitats from June to October was matched by a concomitant increase in abundance in artificial patch reefs located seaward of the macroalgal habitat. These habitat-specific abundance patterns suggest that juvenile Nassau grouper exhibit an ontogenetic habitat shift from inacroalgal-Podtes spp. clumps to patch-reef habitats at a size of 120 to 150 mm TL during late summer and early fall. Based on habitat associations observed in this study, E. striatus were classified into 3 stages: (1) post-settlement fish (25 to 35 mm TL) residing exclusively wlthin algal-covered coral clumps; (2) early juveniles (60 to 150 mm TL) residing outside of and adjacent to algal-covered coral clumps; and (3) larger juveniles (>l50 mm TL), which were generally associated with natural and artificial patch reefs.

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

“…Eggleston (1995) found Nassau grouper (Epinephelus striatus) in the Bahamas settle and remain in and around macroalgal clumps for 3-5 months before outgrowing their shelter and moving out to patch reefs. Lipcius et al (1998) found similar shifts in Caribbean spiny lobster (Panulirus argus), describing a movement away from areas with ample food but limited shelter, to a high quality refuge in coral reefs.…”

Ontogeny of microhabitat use and two-step recruitment in a specialist reef fish, the Browncheek Blenny (Chaenopsidae)

“…For example, some apogonids recruit to patch reefs in sandy areas before moving to adult habitats on the reef slope (Finn and Kingsford 2005). Ontogenetic movement between distinct habitats is especially conspicuous among many large reef fishes such as groupers and snappers (e.g., Eggleston 1995;Dahlgren and Eggleston 2000). This has led to the recognition of the importance of distinct nursery areas such as mangroves and seagrass beds as predation refuges for juvenile reef fishes (Nagelkerken et al 2002;Gillanders et al 2003;Aburto-Oropeza et al 2008).…”

Utilization of seagrass habitats by juvenile groupers and snappers in Banten Bay, Banten Province, Indonesia

“…Diel represents time of day (day or night). Non-significant (NS) factors were removed from the model (Eggleston, 1995). The fact that the maximum length of E. coioides found in the seagrass was only 29 cm (while the maximum reported length is ca.…”

“…In Banten Bay (West Java, Indonesia) groupers (Serranidae) and snappers (Lutjanidae) are two commercially and ecologically valuable fish categories that utilise seagrass areas, especially in their juvenile stages (Heemstra & Randall, 1993;Eggleston, 1995). The populations of groupers and snappers and the fishery on these species are under pressure in Banten Bay, because of overexploitation and the use of destructive fishing methods, such as intensive fishing for juveniles by push net fishermen.…”

“…In subtropical and tropical countries areas, seagrass beds form one such habitat type (Bell & Pollard, 1989;Pinto & Punchihewa, 1996;Jenkins et al, 1997) providing its inhabitants with food, protection from predators and shelter from physical disturbances (Nojima & Mukai, 1990;Motta et al, 1995;Jordan et al, 1996). Seagrass beds provide more complex habitat structure than non-vegetated areas and are known to support higher abundance, biomass and species richness than non-vegetated areas (Bell & Pollard, 1989;Eggleston, 1995;Irlandi et al, 1995;Tolan et al, 1997). For instance, Jordan et al (1996) found that fish abundance in seagrass beds in the northern Gulf of Mexico was significantly higher (760%) than in surrounding sand flats.…”