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Marine Habitat Classification

Description of biotope or habitat type

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   Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered
Tidal streams Moderately strong (1-3 kn)
Substratum Sandy mud
Zone Infralittoral
Depth Band 5-10 m, 10-20 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.SMu.ISaMu.MelMagThy <I>Melinna palmata</I> with <I>Magelona</I> spp. and <I>Thyasira</I> spp. in infralittoral sandy mud

  • 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 infralittoral cohesive sandy mud, in sheltered marine inlets, and occasionally variable salinity environments, dense populations of the polychaete Melinna palmata may occur, often with high numbers of Magelona spp. and the bivalve Thyasira flexuosa. Other important taxa may include Chaetozone gibber, Nephtys hombergii, Galathowenia oculata, Euclymene oerstedii, Ampelisca tenuicornis, Ampharete lindstroemi, Abra alba, and Phoronis sp. In addition the polychaete Aphelochaeta spp. and the gastropod Turritella communis may be common or abundant in some areas. At the sediment surface visible taxa may include occasional Virgularia mirabilis, and mobile epifauna such as Pagurus bernhardus. This biotope is characteristic in many southern UK marine inlets and in some areas e.g. Plymouth Sound during high levels of recruitment when M. palmata often occurs in abundances between 500 to 1000 per m2 moderate numbers of the species often 'overspill' into adjacent biotopes (Allen et al. 2001).


In many areas this biotope is found on or near the boundary between euryhaline and polyhaline waters and in such areas moderately high numbers of Aphelochaeta spp. are often recorded.

Temporal variation

Numbers of M. palmata tend to vary considerably from year to year presumably due to recruitment and/or adult mortality.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Hydractinia echinata 8 Occasional 41-60 %
Virgularia mirabilis 20 Occasional 41-60 %
Cerianthus lloydii 8 Occasional 41-60 %
Nemertea 4 Common 81-100 %
Nematoda 1 Frequent 61-80 %
Nephtys hombergii 3 Common 61-80 %
Spio filicornis 2 Frequent 61-80 %
Magelona alleni 2 Frequent 61-80 %
Magelona filiformis 7 Common 61-80 %
Aphelochaeta marioni 1 Common 41-60 %
Chaetozone gibber 10 Abundant 61-80 %
Tharyx 1 Common 41-60 %
Notomastus latericeus 1 Occasional 61-80 %
Euclymene oerstedii 3 Abundant 61-80 %
Galathowenia oculata 3 Common 61-80 %
Melinna palmata 19 Abundant 81-100 %
Ampharete lindstroemi 3 Frequent 61-80 %
Myxicola infundibulum 12 Frequent 41-60 %
Harpinia antennaria 2 Frequent 61-80 %
Ampelisca tenuicornis 2 Common 61-80 %
Pagurus bernhardus 23 Occasional 61-80 %
Carcinus maenas 4 Rare 41-60 %
Turritella communis 1 Common 41-60 %
Nucula nitidosa 2 61-80 %
Thyasira flexuosa 3 Frequent 81-100 %
Thyasira flexuosa 5 41-60 %
Mysella bidentata 5 41-60 %
Phaxas pellucidus 1 61-80 %
Abra alba 2 Common 61-80 %
Mya truncata 10 41-60 %
Corbula gibba 1 61-80 %
Phoronis 2 Common 61-80 %
Amphiura filiformis 5 41-60 %

Similar biotopes or habitat types

The current biotope displays some similarity to AalbNuc but is found in shallower water, muddier sediments and often in estuarine influenced areas.

In some areas the current biotope may resemble a more diverse, marine version of AphTubi and it is possible that MelMagThy occupies an intermediate position between AphTubi and AalbNuc.

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