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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 Moderately exposed, Sheltered, Extremely sheltered
Tidal streams Weak (>1 kn)
Substratum Sandy mud
Zone Infralittoral
Depth Band 5-10 m, 10-20 m
Other Features

Biotope origin

Derived using data from Various
Faunal group Infauna

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 or coarser sediments, dense populations of the polychaete Melinna palmata may occur, often with high numbers of Magelona spp. and the bivalve Thyasira flexuosa (although the latter may be present in variable abundances or absent in some cases). Other important taxa may include Chaetozone gibber, Nephtys hombergii, Galathowenia oculata, Euclymene oerstedii, Ampelisca tenuicornis, Ampharete lindstroemi, Abra alba, and Phoronis spp. In addition the polychaete Aphelochaeta spp. and the gastropod Turritellinella tricarinata 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. This biotope may also exist in a continuum with SS.SMu.CSaMu.AfilKurAnit.


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
Pagurus bernhardus 23 Occasional 61-80%
Virgularia mirabilis 20 Occasional 41-60%
Melinna palmata 19 Abundant 81-100%
Myxicola infundibulum 12 Frequent 41-60%
Mya truncata 10 41-60%
Chaetozone gibber 10 Abundant 61-80%
Cerianthus lloydii 8 Occasional 41-60%
Hydractinia echinata 8 Occasional 41-60%
Magelona filiformis 7 Common 61-80%
Amphiura filiformis 5 41-60%
Kurtiella bidentata 5 41-60%
Thyasira flexuosa 5 41-60%
Carcinus maenas 4 Rare 41-60%
Nemertea 4 Common 81-100%
Ampharete lindstroemi 3 Frequent 61-80%
Euclymene oerstedii 3 Abundant 61-80%
Galathowenia oculata 3 Common 61-80%
Nephtys hombergii 3 Common 61-80%
Thyasira flexuosa 3 Frequent 81-100%
Abra alba 2 Common 61-80%
Ampelisca tenuicornis 2 Common 61-80%
Harpinia antennaria 2 Frequent 61-80%
Magelona alleni 2 Frequent 61-80%
Nucula nitidosa 2 61-80%
Phoronis 2 Common 61-80%
Spio filicornis 2 Frequent 61-80%
Nematoda 1 Frequent 61-80%
Aphelochaeta marioni 1 Common 41-60%
Varicorbula gibba 1 61-80%
Notomastus latericeus 1 Occasional 61-80%
Phaxas pellucidus 1 61-80%
Tharyx 1 Common 41-60%
Turritellinella tricarinata 1 Common 41-60%

Similar biotopes or habitat types

The current biotope displays some similarity to SS.SSa.CMuSa.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 SS.SMu.SMuVS.AphTubi and it is possible that SS.SMu.ISaMu.MelMagThy occupies an intermediate position between SS.SMu.SMuVS.AphTubi and SS.SSa.CMuSa.AalbNuc.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SMu.ISaMu.MelMagThy Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud
2004 (04.05) SS.SMu.ISaMu.MelMagThy Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud
1997 (97.06) Part of SS.IMS.FaMS.SpiSpi Spio filicornis and Spiophanes bombyx in infralittoral clean or muddy sand

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