Intertidal water column meiofauna in relation to wave intensity on an exposed beach

Abstract

Since the 1970s, various studies have shown that some meiofaunal taxa frequently occur in the water column. Water currents or any process that disturbs the sediments are possible factors that can facilitate the passive entry of meiofauna in the water column. Wave action has been predicted as one of these factors (Armonies, 1994), suggesting a correlation between the number of eroded specimens and wave intensity should exist. As a test of this prediction, replicated samples were taken in the water column, swash sediment and back-swash water in an exposed beach (Island of Sylt, northern Wadden Sea). Wave height and period were measured to characterise the energy regime. Samplings were carried out over a nine day period in August 2000, at diurnal mid-tide time. Wave height and period varied significantly among collections. Densities of nematodes, harpacticoids, nauplii, platyhelminthes, ostracods and bivalve larvae in the water column, swash sediment and back-swash water varied significantly among collections. Nevertheless, no significant correlation was found between water column density and wave characteristics. Density of meiofauna in the water column was not correlated with density in the sediment or in back-swash water. Therefore wave intensity did not explain the variability of meiofaunal densities present in the water column.