Model estimates of the impact of bioirrigation activity of Marenzelleria spp. on the Gulf of Finland ecosystem in a changing climate

Drastic changes have occurred in the Eastern Gulf of Finland ecosystem after recent invasion and establishment of polychaete Marenzelleria spp. Possible mechanisms of these changes are explored with the help of three-dimensional ecosystem model SPBEM. Relative significance of bioirrigation activity is studied by comparison of two climate change scenario simulations, which include or disregard Marenzelleria effects. The novel results obtained with this approach demonstrate that on a system level biogeochemical consequences of both implemented climate changes scenario and polychaete activity are equivalent to a weakening of “vicious circle” of the Baltic Sea eutrophication. The eutrophication-mitigating effects of the Marenzelleria invasion into the Eastern Gulf of Finland, revealed by the long-term field measurements, are explained by simulation-based considerations.