Infaunal communities in Baltic infralittoral sand not dominated by bivalves

This is a Baltic Sea benthic habitat in the photic zone where at least 90% of the substrate is sand according to the HELCOM HUB classification. There is a lack of macrovegetation or epibenthic macrofauna but crustaceans, polychaetes and insect larvae may dominate the infauna. The habitat is present in areas of high energy associated with wave action or currents.

Where polychaetes dominate the infauna two associated biotopes with different dominant species of polychaetes (at least 50% of the biomass of the infaunal polychaetes) can be identified. ‘Baltic photic sand dominated by lugworms (Arenicola marina)’ (AA.J3M2) usually at a depth of 1 – 5 meters, in high exposure and in salinities over 10 psu. It is distributed in only in the western Baltic Sea, in the Sound and the Belt Sea. ‘Baltic photic sand dominated by multiple infaunal polychaete species: Pygiospio elegans, Marenzelleria spp. and Hediste diversicolor’ (AA.J3M4) distributed in the whole Baltic Sea. Where crustaceans dominate the infauna one associated biotope has been identified: ‘Baltic photic sand dominated by sand digger shrimp (Bathyporeia pilosa)’ (AA.J3N3). Depth of this biotope is typically from 1 to 10 meters, and it is encountered in areas of moderate to high wave exposure with salinity over 4 psu. Another biotope ‘Baltic photic sand dominated by midge larvae (Chironomidae)’ (AA.J3P1) is identified by a large representation of Midge larvae (Chironomidae).

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 are potential indicators of quality.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats