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Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   Aphelochaeta spp. and Polydora spp. in variable salinity infralittoral mixed sediment

Physical habitat description

Salinity Reduced (18-30ppt), Variable (18-35 ppt), Low (<18ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Sandy gravelly muddy mixed sediment
Zone Infralittoral
Depth Band 0-5 m, 5-10 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 SS.SMx.SMxVS.AphPol <I>Aphelochaeta</I> spp. and <I>Polydora</I> spp. in variable salinity infralittoral mixed sediment

  • 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.


In sheltered muddy mixed sediments in estuaries or marine inlets with variable or reduced/low salinity communities characterised by Aphelochaeta marioni and Polydora ciliata may be present. Other important taxa may include the polychaetes Nephtys hombergii, Caulleriella zetlandica and Melinna palmata, tubificid oligochaetes and bivalves such as Abra nitida. Conspicuous epifauna may include members of the bivalve family Cardiidae (cockles) and the slipper limpet Crepidula fornicata. This biotope is often found in polyhaline waters.


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Polychaeta 4 1-20 %
Harmothoe 2 Common 41-60 %
Eteone longa 2 Frequent 41-60 %
Hediste diversicolor 1 41-60 %
Nephtys hombergii 8 Common 61-80 %
Scoloplos armiger 1 21-40 %
Polydora ciliata 10 Abundant 61-80 %
Pygospio elegans 1 Frequent 21-40 %
Streblospio shrubsolii 2 21-40 %
Aphelochaeta marioni 33 Common 81-100 %
Caulleriella zetlandica 5 Common 41-60 %
Capitella capitata 1 Occasional 41-60 %
Mediomastus fragilis 2 41-60 %
Melinna palmata 4 Common 21-40 %
Ampharete 1 Common 21-40 %
Lanice conchilega 1 Frequent 21-40 %
Tubifex 2 Frequent 21-40 %
Tubificoides 3 Frequent 41-60 %
Cirripedia 14 Common 21-40 %
Carcinus maenas 3 1-20 %
Crepidula fornicata 27 41-60 %
Cardiidae 50 41-60 %
Cerastoderma edule 1 41-60 %
Abra nitida 3 Common 41-60 %

Similar biotopes or habitat types

In areas of mixed sediment, where A. marioni occurs in high numbers, it may be difficult to separate AphTubi from AphPol, requiring classification on sediment characteristics and associated species in addition to the abundance of A. marioni.

PolCvol is similar to AphPol but occurs in muddier estuarine conditions.

CreMed may be distinguished from AphPol by the abundance of C. fornicata and its sediment characteristics. AphPol may also be found in reduced salinity conditions.

As salinity increases AphPol may grade into MelMagThy with those species characteristic of the latter increasing in abundance.

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