English Summary

The established criteria were met by few of the coastal areas and open waters investigated in 2002. Nutrient loads were too high, leading to occasional blooms of planktonic algae and undesirable growth of annual macroalgae associated with eutrophication. Many perennial benthic plants were absent due to shading, and severe oxygen depletion was seen in several areas. Furthermore, TBT was found in several areas, and the level of xenobiotic compounds was one of the reasons that these areas failed to meet the criteria in 2002. Nutrient loading to the Danish marine waters must be reduced if we are to achieve permanent improvements in environmental conditions. The load of nitrogen particularly needs to be reduced, but measures must be taken against phosphorus as well. In certain water bodies TBT and other environmentally hazardous substances constitute a great problem that must be dealt with. The nationwide status of the marine environment can be summarised as follows.

Year 2002
The year 2002 was a remarkable year in many ways. The annual mean temperature of 9.2°C measured in Denmark was 1.5°C degrees higher than average compared with 1961-1990, making this the second warmest year since 1874 (together with 1934 and 1989). The precipitation of 867 mm measured in 2002 was the third highest observed since nation-wide measurements began in 1920. Incident light in June, August and September was above normal. In the period July-December the predominant wind direction was easterly or southerly and, accordingly, wind velocities were low. These weather conditions may in part explain the extent of the oxygen depletion that occurred in autumn.

Nutrient loading
The nitrogen load to marine coastal areas in 2002 was 27% larger than in 2001. The corresponding phosphorus load was 18% larger. Agriculture accounted for 81% and 42%, respectively, of the Danish contributions of nitrogen and phosphorus. When variations in run-off are taken into account, nitrogen and phosphorus loads to estuaries and coastal waters have decreased since 1989 by 40% and 75%, respectively. However, in the case of nitrogen the development in total nutrient load measured in tons without regard to run-off shows no significant decreasing trend from 1989 to 2002. The deposition of nitrogen from the atmosphere to Danish waters is estimated to have decreased around 15% since 1989.

Nutrient concentrations
In 2002 nutrient levels in estuaries and coastal areas were 10-25% lower than in 1989-2001 despite the fact that freshwater run-off was 30% above normal compared with 1971-2000.

Effects of nutrient loading
From the early 1980s to 1993 water transparency has increased in estuaries and coastal areas, but since 1993 there has been no change in secchi depth even though chlorophyll concentrations have continued to decrease. In the open parts of the inner Danish waters, secchi depths have increased since the mid-1980s, and chlorophyll concentrations have decreased accordingly. Primary production was high in 2002, similar to values from the 1980s, while having been lower most of the 1990s. Bottom-water oxygen contents in the months of July-November have decreased significantly through the past 20 and 25 years in the estuaries of eastern Jutland and Funen, respectively, and in the waters surrounding the southern Funen islands. Likewise, in the open parts of the inner Danish waters and in the Arkona Sea oxygen contents are significantly lower than in the late 1960s and 1970s. In late summer and autumn 2002 the inner Danish waters underwent the severest oxygen depletion seen in this area. In all, 20,500 km² of seafloor was affected, corresponding to 47% of the total area of the inner Danish waters, including adjacent estuaries. As a result of oxygen depletion benthic fauna disappeared from large areas of the Little Belt to the north and in deep parts of the Little Belt to the south. Along open coasts eelgrass occurred at the same depths as in the preceding year, while the depth limit has decreased in inner and outer parts of the estuaries. Percent cover of algae associated with eutrophication has decreased since 1994 along open coastlines, but is unchanged in estuaries. At the stone reefs in open-water areas of the Kattegat percent cover of algal vegetation in 2002 was significantly lower than average compared with the period 1994-2001.

Heavy metals and xenobiotics
Concentrations of heavy metals found in bivalves in 2002 corresponded to "insignificant or moderate pollution". Elevated concentrations of mercury were seen in the western part of the Limfiorden, and elevated nickel and copper values were found in the bivalve species Mya arenaria in Ringkøbing Fjord. The concentrations of TBT found in Danish estuaries and inner waters in 2002 were so high that effects on marine organisms are inevitable. The occurrence of imposex and intersex in sea snails continues to be widespread in 2002. The problem was greatest in harbours where, as expected, TBT levels were highest. In many coastal areas the common whelk exhibited high levels of imposex, but effects were also seen in open waters in the case of sensitive species. Concentrations of PCB and other chlorinated substances were high enough to pose a threat to the environment.

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