The present research was designed to provide information on the comparative responses of macrofaunal and nematode communities to the disposal of dredged material at a variety of locations, in order to clarify in which circumstances they are both best utilised.
Transect surveys were conducted at 4 major dredged material disposal sites in UK coastal waters and a response to dredgings disposal was observed in both macrofaunal and nematode communities, although there were clear differences in the nature and severity of impact.
Gross effects due to the direct impact of dredgings disposal were detectable with both methods. However, effects beyond the disposal sites arising from the settling of fine particulates were often only discernible with nematode community analyses. Furthermore, the precision of the nematode data was generally higher than that for the macro fauna, largely due to the greater consistency in the quality of samples collected. The same nematode taxa,
Sabatieria pulchra grp. (both breviseta and punctata) and Daptonema tenuispiculum were found to dominate at all disposal sites, despite appreciable environmental differences between locations and variability in the nature of the deposited dredged material. Such consistent patterns were not observed for macrofaunal species; rather, there appeared to be local enhancement of a range of different taxa characteristic of the sediments surrotmding each of
the disposal sites. At two of the disposal sites, however, the presence of some macrofaunal species more typical of estuarine conditions provided strong evidence for the transport of live animals via dredgings disposal. Although it is likely that nematode species are also capable of surviving transport to the site, establishing this was hampered by the lack of zoo geographical information for this group.
These studies have established, for the first time, that nematode communities can provide a sensitive indicator of change in response to dredged material disposal at a variety of locations and have introduced a new monitoring tool for a practice that has wide significance around the UK coast. The implications of the findings for the future monitoring of dredged material disposal and other waste inputs are discussed.