Time lags between the deposition and meiobenthic assimilation of phytodetritus

Abstract

Radiolabelled phytodetritus was continuously produced in the watercolumn from Jan to June, by the addition of 14C-bicarbonate. Allmeiobenthos reached specific activities higher than in the sediment;recently produced detritus was more readily assimilated than oldersedimentary carbon. The proportion of assimilated detritus differedgreatly between two faunal group in the top 5 cms of the sediment.First, the harpacticoids asimilated almost exclusively labelled phytoplankton,with a time lag of less than 2 mo. The rest of meiobenthic specieshad remarkably lower specific activities, 10-30 {%} of phytoplankton.It appears that most of the organic carbon in the diet of these faunahad been produced prior to January. I suggest that these 2 meiobenthicgroups were segregated by depth in the surface mms and that the lowspecific activity fauna utilized a alrge buried reservoir of olderdetritus.