Factors Regulating Settlement and Microhabitat Use by Spiny Lobsters Panulirus argus

Clumps of highly-branched red algae Laurencia spp. serve as important settling habitat for postlarval spiny lobsters Panulvus argus and as residence for early benthic-stage juveniles. G ~ v e n choice between the 2 most abundant macrophytes in Florida Bay, Laurenna spp. and the seagrass Thalassia testudinum, postlarval and juvenile lobsters chose Laurencia spp. Postlarvae apparently use intricate algal architecture as a cue for settlement, whereas juveniles use both architecture and food abundance in selecting habitat. In tethering experiments, predation on juve~ule lobsters was very high on open sand, much reduced In algal clumps and seagrass, and lowest in dense algal meadows. Predation rates were s~milar day and night both on open sand and In vegetabon. Most lobsters vacated algal clumps located within continuous algal meadows overnight, at a rate significahtly higher than that from isolated algal clumps. We suggest that algal clump d~s tnbubon , postlarval settling behavior, and juvenile interpatch movement and mortality contribute to the highly dispersed distnbution and locally sparse abundances of early benthic juveniles.