Summary of the F-ratio tests comparing species- and season-specific long-term trends modeled across basins or for each basin separately.

Generalized Additive Models (GAM) with a single year-smoother f(Year) for the entire Central Baltic Sea and basin-specific smoothers fbasin(Year) using the F-ratio tests for each species and season. The residual deviance and the residual degrees of freedom (df) are given for each model together with the reduction in deviance and the change in df's, the F-statistic and its probability value. P-values<0.05 (in bold) indicate a better performance of the more complex GAM with basin-specific smoothers.