AA.A1G1 Baltic photic rock and boulders dominated hydroids (Hydrozoa)


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic bottoms in the photic zone with at least 90 % coverage of rock, boulders or stones of more than 63 mm in diameter. Epibenthic cnidarians cover at least 10%, and more than other perennial attached erect groups. Out of the attached epibenthic cnidariand hydroids represent at least 50 % of the biomass.

Physical environment       

Substrate is rock and/or boulders.

Characteristic species        


Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Known from Russia waters

Correspondence with other classification systems               

HELCOM 1998: Sublittoral level soft rock bottoms with little or no macrophyte vegetation Sublittoral level stony bottoms with little or no macrophyte vegetation

EUNIS 2012:
A3.4 : Baltic exposed infralittoral rock
A3.5 : Baltic moderately exposed infralittoral rock
A3.6 : Baltic sheltered infralittoral rock