Benthic macroinvertebrates as reference indicators for monitoring of anthropogenic isotope Cs contamination in the marine environment.

Due to the limited studies dealing with isotopes levels in benthic macroinvertebrates other than Mytilus sp. in period 2011-2018, macroinvertebrates and seawater samples from the southern Baltic Sea were collected. Activity of Cs was measured in most common benthic macroinvertebrates inhabiting southern Baltic Sea in the context of choosing the best bioindicators. Taking into account the narrow range of CR coefficients, statistically significant correlation between Cs activities in seawater and species, a high frequency of occurrence and thus high biomass and the common occurrence, only Limecola balthica could potentially serve as indicators for shallow and deep-sea areas accordingly. Widely spread Mytillus trossulus was characterised by large size variability in samples and shows no significant correlation between activities in species and seawater and appears not so common as L. balthica.