Mudflats

Mudflats - John Miller - Explore Kent

Current Status

Mudflats are sedimentary intertidal habitats created by deposition in low energy coastal environments, particularly estuaries and other sheltered areas. Their sediment consists mostly of silts and clays with a high organic content. Towards the mouths of estuaries where salinity and wave energy are higher, the proportion of sand increases. Mudflats are intimately linked by physical processes to, and may be dependent on, other coastal habitats such as soft cliffs and saltmarshes. They commonly appear in the natural sequence of habitats between subtidal channels and vegetated saltmarshes. In large estuaries they may be several kilometres wide and commonly form the largest part of the intertidal area of estuaries. However, in many places they have been much reduced by land claim.

The surface of the sediment is often apparently devoid of vegetation, although mats of benthic microalgae are common. These produce mucilage that binds the sediment. Under nutrient-rich conditions, there may be mats of the macroalgae Enteromorpha spp or Ulva spp.

Mudflats are highly productive areas which, together with other intertidal habitats, support large numbers of predatory birds and fish. They provide feeding and resting areas for internationally important populations of migrant and wintering waterfowl, and are also important nursery areas for flatfish

With 8,408 hectares of intertidal mudflat, Kent holds a high proportion of the region's resource for this habitat, most of which is covered by at least one conservation designation (SSSI, SPA, etc.). Most of this is contained within the Thames, Medway and Swale estuaries on the North Kent Coast.

Factors

  • ‘Coastal squeeze' resulting from a combination of sea level rise and hard coastal defences.
  • Land claim
  • Barrage Schemes
  • Diffuse and point pollution
  • Dredging for navigation
  • Fishing and bait digging
  • Introduction of non-native species

Current Action

  • Important areas of mudflats are designated as SSSI, SPA and/or Ramsar sites.
  • The Environment Agency has an ‘Encroachment Policy for Tidal Rivers and Estuaries' which is supported by English Nature, the RSPB and the Wildlife Trusts. This policy maintains a presumption against encroachment where this may lead to loss of or damage to ecological integrity of intertidal habitats.

Objectives

  1. Maintain at least the present extent and general distribution of Kent's mudflats.
  2. Maintain, restore and enhance the quality of intertidal mudflats.
  3. Raise awareness, amongst key decision-makers, of the importance of mudflats as an ecological resource.

Relevant Habitat Action Plans

The relevant Kent Habitat Action Plans: