Active emergence of meiofauna from intertidal sediment

Abstract

Laboratory experiments were conducted to test for active meiofaunal emergence from intertidal sediment in the absence of currents. Copepoda, Ostracoda, Plathelrninthes and Polychaeta actively left submerged glass jars containing undisturbed sandy sediment. Ostracoda and juvenile Bivalvia moved to the sediment surface and climbed out of the glass jars while other taxa left the jars by swimming. In no case d ~ d Nematoda or Ohgochaeta leave the sediment. During a single nocturnal high tide, 87 % of Copepoda, 67 U/o of Ostracoda and 42 % of Plathelminthes may leave the sediment. Emigration rates are significantly smaller during diurnal high tides. Copepoda were randomly d~st r i buted in the water column 10 to 50 cm above the bottom and Plathelminthes between 10 and 40 cm There are specific differences in the emigrahon rates of plathelmlnth taxa. Diatom-feeders, copepodfeeders and unspecific predators emerged In sign~ficantly higher proportions than did nematodefeeders and bacteria-feeders. Results suggest high mobility and high transport rates of intertidal meiofauna above the sediment