Finland To See Just Slight Risk Of Blue-Green Algal Blooms In Sea Areas This Summer

(CORDIS) — The risk of blue-green algal blooms off the coast of Finland, especially in the Gulf of Finland and around its mouth, is mainly moderate this summer, environmental researchers have reported, and the risk is much lower in comparison to last summer.

The team, from the Finnish Environment Institute’s (SYKE) Marine Research Centre, note that although in the southern reaches of the Archipelago Sea and in the northern parts of the Baltic proper there will be a considerable risk of algal blooms, in the Gulf of Bothnia no major blooms are forecast. It is the southern Baltic Sea that faces the greatest risk of blue-green algal blooms.

In very high densities, algal blooms can discolour the water and outcompete, poison, or asphyxiate other life forms in the sea. As algae are sensitive to different changing environmental factors, scientists can draw conclusions about the overall state of the ecosystem based on their presence.

In the end, it is the summer weather that determines at what time and where major surface accumulations occur. Warm and calm weather increases the risk of major surface accumulations, yet if the summer is cold and windy, blue-green algae mix with the water and there is little surface accumulation.

The team’s prognosis is based on estimates made on the average sea current, wind and temperature conditions, nutrient concentrations in the previous winter and changes in nutrient concentrations during the spring.

But it is not just in sea areas where algal blooms can appear; lakes can also find themselves covered in the tangled weed too. To this end, the researchers will also come up with a prognosis for 34 of Finland’s largest lakes. The prognostic model under development will mainly depict whether the risk of algal blooms is greater or smaller, on average, than in previous years.

The prognostic model will calculate current nitrogen and phosphorus loads originating in fields, forests and other sources, the migration of nutrients in waterbodies, and nutrient concentrations in each lake sized 1 hectare or larger. The likelihood of algae occurrences will be calculated on the basis of nutrient concentrations.

‘Thus far, the algae prognoses for lakes have been uncertain, since the prognostic model does not include all factors influencing the growth of algae. Current algae prognoses mainly enable us to predict whether the risk of algal blooms in a given lake is larger or smaller than in previous years,’ says Bertel Vehviläinen, senior hydrologist at SYKE’s Freshwater Centre.

These algae prognoses for lakes are supported by the EU-funded GISBLOOM (‘Tools for evaluation and management of eutrophication’) project. The project’s central aim is to develop map-based online tools for forecasting algal blooming and facilitating river basin management.

The bloom period is expected to peak in late July and early August; from now until the end of August, SYKE will provide weekly updates on the algae situation in the Baltic Sea and in inland waters.