MEIOFAUNA AND SEDIMENT CHLOROPLASTIC PIGMENTS ON THE CONTINENTAL-SHELF OFF LOUISIANA, USA

Organic matter derived from phytoplankton blooms in the euphotic zone represents an important component of the flux of material to the botto m sediments. The relationship between the supply of phytodetritus to b ottom sediments and the horizontal and vertical distribution of meiobe nthos in the continental shelf of the Gulf of Mexico off the coast of Louisiana, U.S.A., was studied in February 1992. A total of 13 station s located in two areas was visited. One area (''off Mississippi''; eig ht stations) was adjacent to the Mississippi River mouth and was direc tly influenced by the river plume, while the other (''off Cocodrie''; five stations) was situated west of the Mississippi River mouth. The s ediment chloroplastic pigment contents (Chl a and total pigments) were significantly higher off Mississippi, as were densities of harpactico id copepods, while nematodes were significantly more abundant off Coco drie. Vertical profiles of sediment pigments, harpacticoid, nematode, and total meiobenthic densities were also markedly different in the tw o areas. Densities of total meiobenthos, nematodes, and harpacticoids correlated significantly with the sediment total pigment and Chl a con tents off Cocodrie, while no significant correlations were detected of f Mississippi. This is an indication that meiofaunal abundances in the latter area, exposed to a constant supply of sedimenting organic matt er, seem to be controlled by factors other than the abundance of phyto detritus as expressed by the sediment chloroplastic pigment content. C opyright (C) 1996 Elsevier Science Ltd