Abstract

In the northern part of the Kattegat, western Sweden, a series of marine depressions remain since the last glaciation. One of these, the well-oxygenated Alkor Deep, is about 3 km long and 800 m wide and with a depth of 138 m. Random depth-stratified sampling was made along four transects on the slopes including benthic macrofauna (0.1 m(2) grab samples) and sediment profile imaging. A significant positive correlation was found between depth and the faunal variables abundance and biomass. Deposit feeders such as Maldane sarsi, Heterormastus filiformis and Abra alba were among the dominants and may have been supported by down-slope advected organic material. In many images, pockets and extensive burrows were seen in the sediment that appeared to be constructed by the crustaceans Calocaris macandreae and Maera loveni. The ecological significance of their irrigation of the sediment is discussed. Due to the faunal activity deep down in the sediments of the slopes, the mean apparent redox potential discontinuity (RPD) was found as deep as between 8.0 and 11.3 cm depth, and RPD was significantly positively correlated with water depth. On the slopes there appears to be a balance between the input of organic material and the capacity of the benthic organisms to assimilate that carbon. (C) 2000 Academic Press.

Keywords

sediment profile imaging; bioturbation; deposit feeder; Calocaris; Maera; Melinna; Kattegat

Published in

Estuarine, Coastal and Shelf Science
2000, volume: 50, number: 6, pages: 843-853
Publisher: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

Authors' information