Nematode-Based Effect Assessment in Freshwater Sediments

Abstract

Sediments provide a habitat for a very diverse fauna and considerably contribute to important ecosystem services of aquatic ecosystems. Especially soft (fine and sandy) sediments are known to be hotspots of chemical contamination. Their assessment can aid in identifying the causes of environmental stress and to trigger management actions to improve ecosystem health of the respective ecosystems. Achieving a “good ecological status” of surface waters, as required by the European Water Framework Directive, strongly depends on recognition of the chemical status of sediments. The recently developed NemaSPEAR[%]-index is a proven monitoring tool using freshwater nematodes, which are one of the most abundant and species-rich invertebrates in soft sediments, to detect chemical-induced changes in benthic communities. Using defined class boundaries, the NemaSPEAR[%] can help to categorize sediment samples according to their ecological status. Overall, the index can be a valuable tool for the classification and to prioritize environmental samples in terms of sediment management decisions. However, in situ assessments of benthic communities should be supported by sediment toxicity tests based on relevant species for these habitats. The well-established model organism Caenorhabditis elegans is a suitable representative of free-living (nematode) communities, and standardized test protocols are available to be used as supportive line-of-evidence for the assessment of environmental samples in a weight-of-evidence approach.