Differential variability in time and space of numbers in suspension and deposit feeding benthic species in a tidal flat area.

Evidence from a tidal flat ecosystem in the Dutch Wadden Sea is presented, substantiating a hypothesis formulated by Levinton (1972) and stating that both the food supply and the numbers of suspension feeding marine zoobenthic species fluctuate more heavily, spatially as well as temporally, than those of deposit feeders. During the year and also from day-to-day, concentrations of chlorophyll-a and particulate organic matter fluctuated more heavily in the water above tidal flats than in the top layer of the bottom. From year to year, the numbers of suspension feeding species (as the bivavles Mytilus edulis, Mya arenaria and Cerastoderma edule ) fluctuated more heavily than those of deposit feeding species (as Arenicola marina, Heteromastus filiformis, Scoloplos armiger and Nereis diversicolor ). Also from place to place, the numbers of suspension feeding species were more variable than those of deposit feeders