Finnish Institute of Marine Research and Finnish Environment Institute inform:

Large algal mats probable in late July in the Gulf of Finland and in the Archipelago Sea

Bluegreen algae prognosis 2007

According to a prognosis made by the Finnish Environment Institute and the Finnish Institute of Marine Research, the risk of blue-green algae blooms in the Gulf of Finland is considerable in this summer. In the Bothnian Sea and in the Bothnian Gulf the risk of surface algal mat formation is low.

In the eastern Gulf of Finland, the phosphorus concentrations during the spring have been higher than in the previous two years. The main reason to the high phosphorus level is the phosphorus which was released from the sea bottom during poor oxygen conditions and raised to the surface layer by heavy autumn and winter storms and thereby made available to algae. However, the circumstances for bluegreen algal mat formation are not as favourable as in the worst years. For instance in 2004 the risk of bluegreen algal blooms in the Gulf of Finland was higher than this year and surface mats were then actually found in large quantities.

In summer 2007, the most abundant blooms will probably occur in the Gulf of Finland and in the southern part of the Archipelago Sea as well as in the central and southern parts of the Baltic proper. The peak blooming under average weather conditions will occur in late July. If the early summer weather is calm and warm, blooms may already occur in early July.  The weather during the summer determines whether the expected wide surface bloom mats will be formed or not.

Heavy bluegreen algae blooms may in favourable conditions occur even beyond the areas shown in the map, and they may also be driven by currents to the coast. On the other hand, if the summer is cold and windy, the bluegreen algae will remain mixed with the surface water and the visible algae mats will be fewer and smaller. After mid-August the bluegreen algae situation will depend more on the development of the nutrient situation during the summer, and it may thus deviate from the prognosis.

The algae bloom risk estimate is based on prognoses made with ecosystem models, using last winter's nutrient situation as input data. The prognosis also takes into account the development of nutrient concentrations during the spring. The algae prognosis describes the risk of blooming in average weather and current conditions for those bluegreen algae that form surface mats.  

A report on the algae situation will be given on every Wednesday from 6 June to the end of August.

Map:

Bluegreen algae prognosis 2007 (RGB).jpg

Bluegreen algae prognosis 2007 (CMYK).jpg

More information

Finnish Environment Institute (SYKE), Mr Heikki Pitkänen, leading research scientist, phone +358 40 582 3181, forename.lastname@ymparisto.fi

Finnish Institute of Marine Research, Mr Tapani Stipa, research scientist, phone +358 40 505 8090, forename.lastname@fimr.fi

Finnish Institute of Marine Research, Mr Seppo Kaitala, algae monitoring coordinator, phone +358 400 609 269, forename.lastname@fimr.fi