Effects of Copper Contamination on Recolonisation of Subtidal Marine Soft Sediments – an Experimental Field Study

Recolonisation patterns of soft-bottom macrofauna on defaunated Cu-spiked sediments were studied in a field experiment at 63 m depth in the Oslofjord, Norway. Field experiments studying colonisation patterns of contaminated sediments are ecologically relevant since settling and metamorphosis of pelagic larvae are generally considered the most critical phases in the development of marine benthic assemblages. Total faunal abundance and the density of the polychaetes Pectinaria koreni and Prionospio cirrifera decreased significantly at sediment Cu-concentrations of 300 mg kg−1. Also the polychaetes Pseudopolydora paucibranchiata, Capitella capitata, Chaetozone setosa, Harmothoe spp., the bivalve Thyasira sarsi and the brittlestar Ophiura affinis were significantly negative correlated to increased sediment Cu-content. Although these species were affected negatively, most of the 116 taxa within the experimental trays showed no response over the entire range of Cu sediment concentrations. Most field studies on recolonisation have been performed in the intertidal or shallow subtidal. These environments are often dominated by robust organisms while animals living in deeper waters are more sensitive to disturbance. The experimental system developed could easily be used at depths between 20 and 100 m to study effects of toxic compounds separately or as mixtures, or colonisation and succession processes of uncontaminated sediments in general.