Infaunal communities of Baltic upper circalittoral muddy sediment not dominated by bivalves

This habitat is distributed on Baltic aphotic bottoms with at least 90% coverage of muddy sediment according to the HELCOM HUB classification. Sessile/semi-sessile epibenthic macrofauna are generally not present and infaunal polychaetes/crustaceans/echinoderms/or insect larvae dominate in terms of biomass. This habitat typically occurs below approximately 20 m depth and is present in all energy exposure classes and in all the Baltic sub-basins. Four  associated biotopes have been identified: these are characterized by infaunal polychaetes where species such as Polydora ciliata, Lagis koreni, Capitella capitata, Scoloplos (Scoloplos) armiger constitute at least 50% of the infaunal biomass; by infaunal crustaceans  where the benthic amphipods Monoporeia affinis and/or Pontoporeia femorata dominate;  or where  insect larve where (Chironomidae) or echinoderms dominate the biomass. M. affinis is an important food source for several fish species, such as cod (Gadus morhua), herring (Clupea harengus), smelt (Osmerus eperlanus) and fourhorn sculpin (Myoxocephalus quadricornis). In favourable conditions, M. affinis and Pontoporeia femorata can occur in great abundances, even several thousand individuals per square meter. 

Indicators of quality:  

Both biotic and abiotic indicators have been used to describe marine habitat quality. These include: the presence of characteristic species as well as those which are sensitive to the pressures the habitat may face; water quality parameters; levels of exposure to particular pressure, and more integrated indices which describe habitat structure and function, such as trophic index, or successional stages of development in habitats that have a natural cycle of change over time. There are no commonly agreed indicators of quality for this habitat, although particular parameters may have been set in certain situations e.g. protected features within Natura 2000 sites, where reference values have been determined and applied on a location-specific basis. Diversity, abundance and biomass of fauna may be indicators of quality.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats