Biodiversity & Conservation

The biotope is an important feeding area for many fish species, notably flatfish and gobies. Flatfish, including sole, Solea solea, dab, Limanda limanda, flounder, Platichthys flesus, and plaice, Pleuronectes platessa, feed on polychaetes and their tails (e.g. of Hediste diversicolor and Arenicola marina), bivalve young and siphons (e.g. of Macoma balthica) and crustaceans (see review by Elliot et al., 1998). Flatfish may remove one third of the annual biomass of Arenicola marina by eating of tail tips. This has the effect of reducing productivity but not abundance and the lugworms must divert energy from growth and reproduction to regeneration (Barnes & Hughes, 1992).
The high productivity of intertidal mudflats also provides a valuable feeding resource for birds. Direct observation and analysis of the diet of wading birds indicated that Hediste diversicolor constitutes the main prey of about 15 waders and is the dominant prey for the avocet Recurvirostra avosetta, the grey plover Pluvialis squatarola, the curlew sandpiper Calidris ferruginea, the bar-tailed godwit Limosa lapponica and the curlew Numenius arquata (see Goss-Custard et al., 1977 and review by Zwarts & Esselink, 1989). Bivalves, including Cerastoderma edule and Mya arenaria, are also predated by several bird species, mainly waders, ducks and gulls (Meire, 1993). The main predator of bivalves in estuaries is probably the oystercatcher, Haemotopus ostralegus. Drinnan (1957) (cited in Meire, 1993) estimated that oystercatchers remove 22% of the cockle population in Morecambe Bay, UK.

The biotope is exploited by bait diggers (Anon, 1999), the principal target species being the polychaetes, Hediste diversicolor and Arenicola marina.
There are also likely to be commercial fisheries for bivalve species, e.g. Cerastoderma edule (Hall & Harding, 1997), and shrimps (Anon, 1999).
The biotope is at risk from land reclamation. For example, land claim for urban infrastructure and industry has removed approximately 25% of Great Britain's estuarine intertidal flats (Anon, 1999).