Algal blooms in the Danish coast causes the death of fish


11.04.2011.Soyuz anglers Denmark announces the start of the flowering period of sea water, which is accompanied by mass mortality of fish. Brown water, saturated many unicellular algae has always characterized the spring to the east of Jutland.

In the early spring season sea trout fishing almost always historically been characterized by poor catches. The reason probably lies in an unusually extensive algal blooms in February and March, caused by the multiplication of toxic phytoplankton Chatonella, that at high concentrations it can cause even death of the fish. In this regard, the Danish Union of Fishermen encourages its members to immediately report sightings of dead fish on the coast and, if possible, to accompany your posts photographs.

Studies show that the concentration of single-celled algae Chatonella from 0.5 to 1 million units per liter of water to kill the fish. These algae are believed to inhibit the absorption of oxygen by the fish. After contact with critical concentrations Chatonella fish becomes passive, changed behavior, stops eating, floating on the surface, gasping for breath, and eventually dies.

At present in the sea water off the coast of Denmark, there is increased concentration of unicellular algae. The highest concentration of Chatonella was awarded in March, 19 million cells per liter of water, which is approximately 40 times higher than a critical value. Of course, this has led to massive loss of trout and its prey. In March, been many cases of detection on the coast of Jutland dead trout and cod in the country on the coast of Jutland. Coastal fishermen fishers also report will reduce catches of trout. This led to the fish, obviously, sensing danger, moved away from the coast to the open sea, at great depth, where she became out of reach for coastal fishing.

Assessment of water clarity on how using Secchi disk shows the approximate concentration of algae in 0.5 million (white disc standard size is not visible to a depth of 4 m), which is critical. Chattonella first appeared in Danish waters in 1998 on the west coast, where the mass deaths caused garfish. That same year, the alga has caused great damage to cage aquaculture in Norway, causing massive fish kills in coastal cages.

Since Chattonella in mass quantities in these regions appear almost every year in early spring, but its concentration in the spring of 2011, even compared to previous years is unusually large. Chatonella can grow at very low temperatures of the water and therefore can be used to supply a large amount of nutrients that are not used by other species of algae due to the late start of the growing season.

Thanks to his abilities Chattonella able to change the composition of plant communities, both in the short and long term, which may be difficult to predict a negative impact on flora and fauna in Danish waters.

Fisheries Federation of Sports of Russia

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