The objective of this research is to assess the degree to which deposit feeding populations in field circumstances are limited by food, in the context of changes in nutritional quality of the sediment over spatial and temporal scales. Past research has demonstrated that newly deposited seaweed based detritus contributes substantially to population growth of deposit feeders, but that the particulate organic matter in the sediment also is of great importance. Seasonal studies over the last two years demonstrate that the sediment promotes declining population growth from spring to fall and carbon retention also declines when a deposit feeder ingests spring versus fall sediment. These findings will be extended to experimental studies on the addition of detritus in the field, since a diagnostic marker of lateral transport of detritus is available. The experimental addition studies will be combined with the marker approach as well as with caged controls for predation, to examine the impact of detrital addition and seasonal organic matter change in the sediment on the population growth of the dominant oligochaete worm, Paranais litoralis, and on the behavior of the mud snails, Ilyanassa obsoleta and Hydrobia truncata. Interactions between feeding behavior, sediment deposition and flow will also be examined. This study will be the first to utilize the combined spatial and temporal approach to examine detrital limitation of surface feeding benthic field populations.
