Status report on aquatic pollution problems in Europe

Abstract

Due to the high population densities in European countries and the fact that pollution prevention measures are either non-existent or have only recently begun to be implemented, the degree of coastal and freshwater pollution in Europe is quite high in certain regions. A number of examples from the marine and freshwater field are selected to illustrate specific pollution problems and to derive some general conclusions. These examples include studies on fish diseases in the North Sea, where two species of fish, dab ( Limanda limanda) and cod ( Gadus morhua), are frequently afflicted with externally visible diseases. In dab, the disease prevalences amounted to 40% in certain areas. The locations of prevalence “hot spots” led to the conclusion that pollution might be causing the phenomenon. Highest disease prevalences were found in a dumping area for wastes from titanium dioxide production, in certain German, Danish, and British coastal waters, and on the Dogger Bank (an offshore area characterized by high organochlorine and heavy metal residues in fish). For coastal waters off Germany and Denmark contamination of gonads with PCBs in certain fishes was negatively correlated with the viable hatch. Also malformation rates were higher in fish embryos from dumping areas and along shipping routes than from other stations. PCBs were suspected also to be causative factors in the population declines of marine mammals in the Baltic between 1900 and 1970. Mercury contamination was identified as the paramount pollution problem in the Mediterranean where fish for human consumption display high contamination levels. Consequences for human consumption have not yet been evaluated. Studies on biological effects of pollution in the river Rhine were inconclusive despite the fact that this river must be considered to be one of the most heavily polluted river systems in Europe. Skeletal deformities of certain fish occurred in higher prevalences in the polluted stretches of the river than in control areas. On the other hand, the prevalence of neoplasia in fish livers was not unusually high in the polluted river. The example of the river Elbe highlights long term degradation of river water quality and its impact on biota and illustrates the scientific and public debate on the changes. The changes were too slow, and not dramatic enough to elicit immediate preventive action. The scientific debate on biological changes in the river started in 1798 when fishermen complained that their fishery had deteriorated, and continues today as scientists struggle to determine whether fish populations have decreased or not. From these examples it is concluded that scientific evidence for biological changes in marine and freshwater ecosystems is frequently debated and does not provide the basis needed for sound pollution management measures. The ability has to be developed, therefore, to read and interpret the signs of environment deterioration and to collect circumstantial evidence of ecological malfunctions. Precautionary measures to reduce pollution loads have to be taken in order to protect aquatic ecosystems.