AA.A2W Baltic photic rock and boulders characterized by microphytobenthic organisms and grazing snails


Author                                     

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. Less than 10 % of the seabed is covered by perennial vegetation or attached epifauna. Microphytobenthic organisms and snails dominate.

Physical environment       

Substrate is rock and/or boulders. Appears in all wave exposure classes.

Characteristic species        

Snails, e.g. Hydrobia spp., Potamopyrgus antipodarum, Theodoxus fluviatilis, Bithynia spp., Radix spp..

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Whole Baltic Sea, most typical in low salinity northern areas of the Baltic Sea

Correspondence with other classification systems               

HELCOM 1998:
2.1 Rocky bottoms

2.1.1 Soft rock

2.1.1.2 Sublittoral photic zone

2.1.1.2.1 Level bottoms with little or no macrophytevegetation

2.1.2 Solid rock (bedrock)

2.1.2.2 Sublittoral photic zone

2.1.2.2.1 Level bottoms with little or no macrophytevegetation

2.2 Stony bottoms

2.2.2 Sublittoral photic zone

2.2.2.1 Level 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


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