Abstract

Red crabs occupy a remarkably narrow band along the continental slopes of the Gulf of Mexico (GOM) at depths from 500 - 2,000 m with the majority found at around 900 m, the maximum depth of light penetration (< 1%). While widely distributed through the GOM, greatest abundance of red crabs is in the north-central Gulf off Alabama and Mississippi in close association with the recent Deep Water Horizon oil discharge. Bathymetric distribution of adult red crabs cannot be explained by any of the environmental factors collected to date. Neither sediment type, nor temperature, nor competition with other geryonid species explain observed distribution. Distribution of red crabs may be related to reproductive strategies and mechanisms of larval transport. Females brood their eggs for nine months with spawning occurring in late fall/early winter. Females carrying eggs comprise about 20% of the total population of females in the north-central GOM in spring, summer, and fall. Recruitment is poorly understood, and locations of postlarval settlement areas are unknown. Megalopae have never been captured in the wild, and only a few zoeal stages have been identified from plankton samples. Captured larvae were found in the upper 200 m of the water column where currents can disperse them far from suitable habitat. In this study we use archived nowcast/forecast numerical model data to examine dispersal and retention mecha-nisms. We also estimate the potential impact of the recent oil discharge on the northern Gulf population.

PDF Preview