A bioassay approach to seasonal variation in the nutritional value of sediment

Tested the following hypoptheses: 1) Sediment supports more population growth in the spring and early summer, relative to the late summer and fall. 2) The nutritive value of sediment declines from spring to early fall, and absorption therefore should decrease. Laboratory tests using the deposit-feeding oligochaete Paranais litoralis partially support both hypotheses. Population growth studies of spring and summer sediment show a relatively nutritionally enriched surface sediment layer, suggesting that the sediment is recharged in the late fall and winter, either by particulate organic matter deposition or microbial transformation of previously unabsorbable material. High summer temperature contributes to the negative effect of poor sediment quality. In Flax Pond, Long Island, New York, field studies show summer declines of several species of deposit feeding invertebrates, but caging studies demonstrate that predation is not a likely cause of the crashes. -from Authors