Macrozoobenthos of the Pechora Bay in 2020–2021 indicates a likely change of common bivalve molluscs in the Arctic estuary

Abstract The Pechora Bay is a hydrologically and ecologically important area of the Barents Sea but there are still gaps in our knowledge biodiversity area, including macrozoobenthos. In first half twentieth century, was noted as type locality for bivalve mollusc Portlandia aestuariorum . Only few surveys macrozoobenthos have been conducted since last work from this indicated absence P. paper, we described hydrological conditions bay based on data collected field campaigns 2020–2021. All estuarine stations corresponded to monodominant community Macoma balthica poor biomass (27.29 ± 20.82 g m −2 ) species richness (33 recorded 10 stations). seaward most station occupied by marine assemblage dominated polychaetes Nephtys longosetosa Cistenides hyperborea Macrozoobenthos forms an ecocline along gradient salinity. No significant differences macrobenthic abundance, were found between 2 years sampling fauna corresponds well communities sampled 1990s. absent all samples, which supports hypothesis disappearance previously common question driver change remains open requires further investigation.