Significant areas of the seabed had been suffering from anaerobic conditions – a clear indicator of eutrophication – but such problems have now almost completely disappeared from the Western Black Sea, where conditions are now similar to those that prevailed until the 1960s. Fish stocks in these waters are still out of balance, however – mainly as a result of over-fishing.
Reduced phosphorus - improved ecological status
Phosphorus is now the limiting factor for algal growth (eutrophication) and phosphorus inputs into the Black Sea have been halved since around 1990. This seems to be the main reason for ecological improvements in the Western Black Sea.
Since the fact that phosphorus is the limiting factor for eutrophication in the Black Sea, efforts to reduce phosphorus emissions should be continued and strengthened.
The current relatively low inputs of nitrogen and phosphorus to the Black Sea are partly due to the economic recession affecting the former communist countries, which has resulted in:
- dramatic reductions in the application of mineral fertilizers
- closures of large livestock farms (significant point sources of agricultural pollution)
- closures in nutrient-discharging industries (e.g. fertilizer industry)
Economic development as the challenge
These trends have been favourable in environmental terms, but desirable economic developments in these countries are likely to lead to increases in nutrient emissions in the future. The challenge will therefore be to cancel out these possible increases by actively reducing emission levels from both point sources and diffuse sources, in order to keep nutrient inputs at their current low levels while also allowing for the effects of economic development in countries in the middle and lower regions of theDanube Basin.