RECRUITMENT OF THE SQUAT LOBSTER PLEURONCODES MONODON ON THE CONTINENTAL-SHELF OFF CENTRAL CHILE

A benthic megafaunal study off Concepcion Bay, central Chile (36 degre es 32'S, 73 degrees W), provided abundance and bathymetric distributio n data of the newly recruited squat lobster Pleuroncodes monodon (Deca poda, Galatheidae). The megafauna was surveyed 8 times between July 19 91 and April 1992, with an Agassiz trawl at depths of 40, 64, and 96 m along a transect across the continental shelf. Recruits of P. monodon (carapace length (CL) 3-10 mm) were first sampled in all depth strata in early March, and then in April. April density (1 ind/m(2)) and mea n size (6.1 mm CL) were significantly higher than March density (0.07 ind/m(2)) and mean size (5.3 mm CL). Depth did not affect abundance an d its significant effect on mean size was conditional on month effect. We interpret these results as evidence that the main pulse of recruit ment occurred simultaneously across the continental shelf transect in April, and that larvae settling in April have a larger size than larva e settling in March. Recruitment appears to be associated with late su mmer development of the giant sulfur bacteria Thioploca spp., suggesti ng an ecological relationship. Moreover, the observed recruitment occu rred in late summer to early fall when the oceanographic regime in the area shifts to a postupwelling regime.