Description of biotope or habitat type
Hediste-dominated gravelly sandy mud shores
Habitat (physical) description
|Salinity||Full (30-35 ppt), Reduced (18-30ppt), Variable (18-35 ppt)|
|Wave exposure||Sheltered, Very sheltered, Extremely sheltered|
|Substratum||Gravelly sandy mud|
|Depth Band||Lower shore, Mid shore, Strandline, Upper shore|
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.
- 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'
Point data based on records in the UK Marine Recorder Snapshot.
Sheltered gravelly sandy mud, subject to reduced salinity, mainly on the mid and lower shore. The infaunal community is dominated by abundant ragworms Hediste diversicolor. Other species of the infauna vary for the sub-biotopes described. They include polychaetes such as Pygospio elegans, Streblospio shrubsolii, and Manayunkia aestuarina, oligochaetes such as Heterochaeta costata and Tubificoides spp., the mud shrimp Corophium volutator, the spire shell Hydrobia ulvae, the baltic tellin Macoma balthica and the peppery furrow shell Scrobicularia plana. Sub-biotopes described in HedMx have equivalent communities in soft muddy sediments, but the sediment here is much firmer due to the gravel component. There are relatively few records in each sub-type, leading to uncertainty over the precise nature of the habitat, particularly regarding sediment type and salinity regime.
It is probable that there are broad transition areas between the sub-biotopes of HedMx, and the corresponding muddy sediment biotopes. The boundaries may be very indistinct, with the HedMx groups present in patches of gravelly mud on areas of mudflat where the main biotopes are their corresponding mud or sandy mud biotopes. Given the small number of records for each of the sub-biotopes, their spatial distribution is still uncertain.
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||Typical abundance - (count per m2)||% of core records where taxon was recorded|
|Hediste diversicolor||62||Abundant||1406||81-100 %|
|Pygospio elegans||2||Common||207||21-40 %|
|Streblospio shrubsolii||4||Common||1099||41-60 %|
|Manayunkia aestuarina||1||Common||1420||21-40 %|
|Heterochaeta costata||3||Common||4198||21-40 %|
|Tubificoides benedii||3||Common||1759||41-60 %|
|Tubificoides pseudogaster||6||Abundant||1796||41-60 %|
|Corophium volutator||5||Common||2704||41-60 %|
|Hydrobia ulvae||2||Common||366||21-40 %|
|Macoma balthica||2||Common||72||21-40 %|
|Scrobicularia plana||2||Abundant||62||41-60 %|
Not applicable or unknown.