Quantitative extraction of living meiofauna from marine and brackish muddy sediments

Abstract

A method for extracting living meiofauna from marine and brackish water mud is proposed and tested. Samples are fitted into tubes and covered with a 2 cm layer of clean coarse sand. Water of appropriate salinity is added until the sample is flooded and the sandy cover is just moist. Sample tubes are closed and stored in the dark. As the samples become anaerobic, the animals migrate upwards into the sandy layer. To extract them, the sandy cover is separated periodically and washed out by 10-fold shaking and rotating in a beaker. The supernatant is decanted through small funnels, and animals are retained on a 40 pm gauze. Total extraction of 1 sample takes about half a n hour. This extraction procedure is compared to grain-by-grain investigation of the whole sample. Within the sites tested, Plathelminthes, Polychaeta, Oligochaeta, Copepoda, and Ostracoda were extracted quantitatively. Extraction of Nematoda and Halacarida was not always complete. In some cases, extraction even yielded significantly higher numbers of Oligochaeta and Plathelminthes than control sorting.

Floating of mud snailsHydrobia ulvae in tidal waters of the Wadden Sea, and its implications in distribution patterns

“…Ten replicate sediment cores having a 10 cm 2 cross-sectional area and 5 cm depth were collected at each of the sites and on each of the dates. In the laboratory, specimens were separated from the bulk of the sediment using a shakingdecantation procedure (see Armonies & Hellwig, 1986), with subsequent sieving of the decanted water through 0.25 mm meshes. The hydrographic plots (Fig.…”

Turnover of postlarval bivalves in sediments of tidal flats in Königshafen (German Wadden sea)

“…Abundance in the sediment was estimated by weekly sample collection (20 replicate cores of 5 cm 2 crosssectional area and 5 cm depth per site and date). Bivalve spat was separated from the sediment using a shaking-decantation procedure (see Armonies & Hellwig, 1986), with subsequent sieving of the decanted water through 0.5-ram mesh.…”

Juvenile-adult distribution of the bivalve Mya arenaria on intertidal flats in the Wadden Sea: why are there so few year classes?

“…At the permanent sites nine or ten cores were taken. Juvenile molluscs were separated from the sediment using a shaking-decantation procedure originally developed for meiofauna (Armonies and Hellwig 1986). Initial sieving through a 0.25-mm screen in July 1995 indicated a minimum spat length of 0.8 mm.…”