The European river lamprey Lampetra fluviatilis (L., 1758) (Petromyzontidae) as a component of the Neva Bay bottom coenoses

The presence of larvae of the European river lamprey Lampetra fluviatilis was reported for the first time from in macrobenthic communities of the Neva Bay of the Gulf of Finland (St. Petersburg, Russia). It has been shown that ammocoetes inhabit several areas, at depths to 12 meters. Apart from ammocoetes, the communities with lamprey larvae contain abundant oligochaetes, bivalves, and less commonly chironomid larvae. At some sites, the number of larvae was up to 80 specimens/m2, while their biomass was over 90% of the total of the community. The abundance of macrozoobenthos in these sites is generally low (average abundance 190 specimens/m2, biomass – 70 g/m2), which is usual in autumn. Intestines of the ammocoetes constantly contained large quantities of diatoms representing common phytoplankton of the Gulf of Finland.