Density-dependent population dynamics in juvenile Panulirus argus (Latreille): The impact of artificial density enhancement

The use of artificial structures to enhance marine animal populations, or as an aid to fishing, is widespread and increasing. While most investigators have studied the efficacy of artificial structure by measuring population abundance of the target species, or by comparison of the resulting community structure with that of natural communities, the effect of habitat enhancement on the processes creating such patterns is largely unknown. We enhanced density with the addition of artificial structures to examine the effect of local population density on the population dynamics (e.g., movement, mortality, and nutritional condition) of juvenile Caribbean spiny lobster (Panulirus argus) at natural and habitat-manipulated sites in the Florida Keys (USA). We artificially enhanced lobster density using small, scattered crevice-bearing structures that mimicked the natural shelters sought by juvenile lobsters. Enhanced density had no measurable effect on juvenile lobster mortality from predation or nutritional condition (as measured by hemolymph refractive index), but it increased the short-term residency of juvenile lobsters. The gregarious nature of spiny lobsters coupled with access to abundant prey may make them robust to high population density.