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Marine Habitat Classification

Description of biotope or habitat type

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   Hartlaubella gelatinosa and Conopeum reticulum on low salinity infralittoral mixed substrata

Physical habitat description

Salinity Reduced (18-30ppt), Low (<18ppt)
Wave exposure Very sheltered, Extremely sheltered
Tidal streams Moderately strong (1-3 kn)
Substratum Boulders, cobbles and mixed sediments
Zone Infralittoral
Depth Band 0-5 m
Other Features

Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.

Distribution of habitat IR.LIR.IFaVS.HarCon <I>Hartlaubella gelatinosa</I> and <I>Conopeum reticulum</I> on low salinity infralittoral mixed substrata

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.


Upper estuarine mixed hard substrata colonised by very sparse communities of animals with low species richness and with a few seaweeds in very shallow water. In the Tamar estuary the hydroid Hartlaubella gelatinosa and bryozoan Conopeum reticulum are found on stones. In the River Dart the bryozoan Amathia imbricata is most abundant. The mussel Mytilus edulis, the crab Carcinus maenas and the hydroid Obelia dichotoma can be present. A similar brackish-water rocky biotope is recorded from the Bann Estuary, Northern Ireland. There are considerable differences in species composition between sites, but all occur in brackish turbid-water conditions. More information required to validate this description.


Insufficient information to describe neighbouring biotopes.

Temporal variation


Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Hartlaubella gelatinosa 33 Frequent 81-100%
Obelia dichotoma 22 Rare 81-100%
Conopeum reticulum 11 81-100%
Amathia imbricata 11 81-100%
Carcinus maenas 11 Occasional 81-100%
Mytilus edulis 11 Rare 81-100%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code
1996 (6.95) SCR.HarCon (part)

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