Functioning of Zoobenthic Communities in the Eastern Gulf of Finland During the Rise and Decline of Invasive Marenzelleria spp. (Annelida: Spionidae) Populations

Results of a 10-year study of zoobenthos in the eastern Gulf of Finland are presented. During this period, a gradual decline in biomass of the invasive polychaete species Marenzelleria spp. was observed. Assessment of energy flow through zoobenthic communities and their efficiency in utilizing plankton primary production revealed that at the beginning of the period, when polychaete biomass was high, these indicators were significantly greater than during subsequent population decline. This suggests that the impact of invasive polychaetes on benthic communities of the Gulf can be considered as neutrally complementary.