Multivariate statistical approach to the temporal and spatial patterns of selected bioindicators observed in the North Sea during the years 1995?1997

Abstract

A comprehensive database, containing biological and chemical information, collected in the framework of the bilateral interdisciplinary MARS project ("biological indicators of natural and man-made changes in marine and coastal waters") during the years 1995-1997 in the coastal environment of the North Sea, was subjected to a multivariate statistical evaluation. The MARS project was designated to combine a variety of approaches and to develop a set of methods for the employment of biological indicators in pollution monitoring and environmental quality assessment. In total, nine ship cruises to four coastal sampling sites were conducted; 765 fish and 384 mussel samples were analysed for biological and chemical parameters. Additional information on the chemical background at the sampling sites was derived from sediment samples, collected at each of the four sampling sites. Based on the available chemical data in sediments and black mussel (Mytilus edulis) a pollution gradient between the selected sites, was established.The chemical body burden of flounder (Platichthys flesus) from these sites, though, did not reflect this gradient equally clear. In contrast, the biological information derived from measurements in fish samples displayed significant a regional as well as a temporal pattern. A multivariate bioindicator data matrix was evaluated employing a factor analysis model to identify relations between selected biological indicators, and to improve the understanding of a regional and temporal component in the parameter response. In a second approach, applying the kmeans algorithm on the data matrix, two significantly different clusters of samples, characterised by the current health status of the fish, were extracted. Using this classification a temporal, and in the second order, a less pronounced spatial effect was evident. In particular, during July 1996, a clear sign of deteriorating environmental conditions was extracted from the biological data matrix.

Parasites of flounder Platichthys flesus (L.) from the German Bight, North Sea, and their potential use in ecosystem monitoring

“…For the sampling locations of the present study, a contamination gradient between the sites-Elbe > Outer Eider > Helgoland and Elbe > Inner Eider > Helgolandcould be established in respect of the chlorinated-hydrocarbon residues in the muscle and the liver of flounder and in respect of heavy-metal residues in sediments and blue mussel (Schmolke et al 1999). Corresponding gradual differences also could be observed when flounder parasites were considered.…”

“…At the infra-community level, lowest values of parasite species richness and species diversity were found in fish from the Elbe estuary, when compared to fish from the other sites. When data were pooled, even gradual differences were observed among the sites, which corresponded to a contamination gradient (Elbe > Outer Eider, Inner Eider > Helgoland) established by Broeg et al (1999) and Schmolke et al (1999). Despite seasonal variation in the ecological measurements, these differences were found in both seasons.…”

The use of innate immune responses as biomarkers in a programme of integrated biological effects monitoring on flounder (Platichthys flesus) from the southern North Sea

“…This gradient could be established when the residue data were based on the fat content of the liver, which is considered to reflect the chemical burden of the habitat . From sediment analysis, however, such a clear gradient could not be established, and when residue data from flounder based on wet weight were considered for analysis, individual flounder could not be related to different sample sites by means of residue analysis (Schmolke et al 1999). This is most probably a consequence of a strong reduction of heavy metal as well as PCB influx into the southern North Sea during the last decade, which resulted in a decrease in heavy metal and PCB content in the sediment of between 45% and 85% (De Jong et al 1999).…”

“…When considering heavy metal and chlorinated hydrocarbon contaminations in flounder muscle, very low residues were found in animals from all the sites, and there was no 'clean' site with all the residues 'below detection limit' (Schmolke et al 1999;Dizer et al 2003). In this situation, when analysing immunological data in their response to pollution, clear differences between sampling locations which could be confirmed in all the sampling campaigns could not be established in the present study.…”

Parasites of the flounder Platichthys flesus (L.) from the German Bight, North Sea, and their potential use in ecosystem monitoring

“…This approach was followed in a study by Broeg et al (1999) who, in the framework of biological-effects monitoring, investigated the parasites of the flounder Platichthys flesus (L.) at different locations in the German Bight for their potential use as bio-indicators of pollution effects and, for the first time, supplemented the parasitological data by well known biochemical and histochem-ical biomarkers recommended by the ICES Advisory Committee on the Marine Environment (ACME) for application in biological-effects monitoring programmes (ICES 1996(ICES , 2002.…”