Modelling the effect of climate change on nutrient loading, temperature regime and algal biomass in the Gulf of Finland

Climate changes and the potential related warming can change runoff, nutrient transport, mean wind velocities and water temperatures. These changes will further affect algal growth in a way that can be modelled. The changes to the nutrient load, temperature regime and algal biomass were simulated by three separate models. The simulations were made for the years 2020, 2050 and 2090. The simulated temperature variations and nutrient loading dynamics were used by algal model to predict changes of the algal biomass under the three different climate scenarios. According to the different scenarios, the maximum temperature of the surface water increased by 0.3–6.2 °C, but in the deeper waters (> 40 m) by less than 0.1 °C. The major part of the nutrient loads is anthropogenic and this part did not change in the scenarios. Thus, the changes in the algal biomass were also relatively small. However, the timing and quantity of spring bloom did change noticeably, at most in 2090, two weeks earlier and 20% higher than nowadays.