Abundance and Food Preferences of Amphipods (Crustacea: Amphipoda) in the Eastern Gulf of Finland, Baltic Sea

Abstract

This paper focuses on the group of the estuarine Baltic amphipods describing abundance and biomass of their representatives in the shallow- and deep water communities of the eastern part of the Gulf of Finland and assessing their food habits. Actuality of this study is determined by an increase in the number of species and abundance of amphipods in the ecosystem of the Gulf of Finland in recent years, mainly due to invasion of new species. Altogether 10 species of amphipods were recorded at 43 sites in 2013-2015. Invasive species of amphipods were dominated by biomass (40 % of the total benthic biomass) and occupied an important position in the coastal food chain of the gulf. The most abundant species such as Pontogammarus robustoides, Gmelinoides fasciatus and Gammarus tigrinus attributed to be omnivorous or carnivorous animals, changing their diet during ontogenesis. Adult males of these species preyed actively upon coexisting species of invertebrates reducing their abundance. At the same time, young and middle-sized individuals of amphipods, consuming a significant amount of detritus and algae, promote their rapid transformation, making this resource more available to the other consumers

Keywords

• Amphipoda
• Amphipoda
• abundance
• biomass
• diet
• trophic position
• ontogenetic shift