The Deben Estuary is important for its populations of overwintering waders and wildfowl and also for its extensive and diverse saltmarsh communities. Several estuarine plants and invertebrates with a nationally restricted distribution are also present.
The Estuary extends for over 12km in a generally south-easterly direction. It is sinuous, relatively sheltered and narrow, particularly at its mouth which is protected by shifting sand banks. Much of the intertidal area is occupied by mudflats with more sandy deposits occurring where exposed Red Crag erodes from cliffs.
The numbers of Redshank Tringa totanus overwintering on the Estuary are of international importance and the summer breeding population of this species is of county significance. The site is of national importance for its winter populations of Dark-bellied Brent Goose Branta bernicla, Shelduck Tadorna tadorna and Blacktailed Godwit Limosa limosa with the numbers of Wigeon Anas penelope, Pintail Anas acuta and Grey Plover Pluvialis squatarola approaching this level in some years. The Estuary supports many other species including high numbers of Dunlin Calidris alpina, Curlew Numenius arquata and Mute Swan Cygnus olor.
The Deben Estuary supports approximately 40% of Suffolk’s area of saltmarsh which also displays the most complete range of the vegetation’s community types in the county. These occur in a highly complex mosaic with the variation in the proportions of species being dependent upon several factors including substrate type, frequency of tidal inundation, exposure, position within the Estuary and past management practices.
Low-marsh communities, which are mainly situated towards the head of the Estuary, are characterised by a vegetation dominated by Sea Aster Aster tripolium, Annual Seablite Suaeda maritima, Glasswort Salicornia europea, Sea Poa Puccinellia maritima and Sea Purslane Halimione portulacoides. In places, particularly where steep cliffs abut the mudflats, virtually pure stands of Common Cord-grass Spartina anglica occur. Where the old seawalls have been breached a saltmarsh community that is typical of formerly disturbed sites has established. This is characterised by a mosaic of Sea Poa, Sea-milkwort Glaux maritima, Common Sea-lavender Limonium vulgare, Sea Arrow-grass Triglochin maritima and Sea Plantain Plantago maritima. Varying proportions of these species are also to be found in the more typical mid-marsh communities which became prevalent towards the lower end of the Estuary. There are several areas where upper-marsh occurs, characterised by the presence of Sea Rush Juncus maritimus, Red Fescue Festuca rubra, Saltmarsh Rush J. gerardii and Creeping Bent Agrostis stolonifera.
Sea couch Elymus pycnanthus is mainly confined to sea walls but at the northern-most end of the site it forms extensive stands which show a natural transition to Blackthorn Prunus spinosa scrub on the higher ground. In addition, swamp communities occur in several places along the Estuary, usually as relatively narrow fringes but occasionally forming large stands. Such areas may be dominated by Sea Club-rush Scirpus maritimus, Greater Pond sedge Carex riparia or, most frequently, Common Reed Phragmites australis.
The Estuary supports three nationally scarce plant species, namely Marsh Mallow Althaea officinalis, Shrubby Seablite Suaeda fruticosa and Small Cord-grass Spartina maritima. The nationally rare Mollusc Vertigo augustior and nationally scarce V. pusilla have also been recorded.
This site is currently under consideration for inclusion in the new UK MPA network. Having marine components does not automatically qualify a site to be part of the new MPA network. As such, the marine components of this site, as well as the management efforts, are being evaluated. Check out our MPApedia page on the UK for more information!
For general information on Bann Estuary Area of Special Scientific Interest (regardless of MPA status), click here.
Contacts & Resources
Original data record from World Database on Protected Areas (WDPA) via ProtectedPlanet.net [view record on site].