Climatic impact on community of filamentous macroalgae in the Neva estuary (eastern Baltic Sea)

- The influence of climatic factors on macroalgal community was defined.
- Influence of climatic conditions was different on study sites of different types.
- High direct correlation with temperature was found on protected sites without stagnant events.
- On sites with stagnant conditions the climatic influence was masked.
- Seasonal biomass significantly inversely correlated with annual NAO-index.

In presented study the impact of climatic factors and North Atlantic Oscillation (NAO) on macroalgal community was analysed. Also the factors influencing algal community were defined with help of Principal Component and Classification analysis. It was found that climatic impact may depend on habitat features and that on different sites biomass of macroalgae correlated with different weather factors. Wind and surf may affect biomass of macroalgae adversely on some sites and at the same time on other sites they may accumulate biomass, transferring it is from adjacent areas. High direct correlation with temperature was found on sites which were protected from surf and had no stagnant events. Seasonal biomass inversely significantly correlated with average seasonal wind speed and annual NAO-index.