Scientific Importance

Conservation Importance

By definition, the economic value of the biotope complexes relates to their role in conserving, protecting and creating resources valued by man (Penning-Rowsell et al, 1992). In particular these are:

• support for fisheries, as they support large nursery populations of flatfishes and roundfishes prior to their movement offshore and eventual commercial exploitation (e.g. Lockwood, 1982; Elliott et al, 1990);
• support for shellfish and their exploitation, both as a feeding areas for shrimp populations and, in the case of sand flats and sand banks, as areas supporting large populations of cockles, Cerastoderma edule, and more recently razor fish (Ensis sp.) (Eastern Sea Fisheries Joint Committee unpubl.);
• providing minerals for extraction - the subtidal sand banks are exploited for aggregate extraction, possibly for building but also for beach nourishment;
• the subtidal mobile sandbanks may occur in areas subject to oil and gas exploration and exploitation;
• the protection of the physical resource as intertidal sedimentary areas provide integral protection for flood and coastal defences; they absorb wave energy and thus enable seawalls to be lower in protection against high tides and storm surges than otherwise would be the case. Similarly, subtidal sandbanks provide nearshore protection against shore-eroding conditions.

The scientific importance of these areas has been well-defined and their study has focused on:

• the biological functioning of systems, including fundamental research into the carrying capacity of marine systems (e.g. Goss-Custard, 1985) and the biological productivity of coastal areas (e.g. Elliott & Taylor, 1989b);
• they have provided an understanding of the interactions between the biological and environmental (physical) features and thus the features structuring the marine and estuarine system;
• the analysis of physical systems, in this case sediments, which are modified by biological processes such as bioturbation and biosedimentation ; and
• an understanding of the physical nature and dynamics of marine systems, for example the nature of coastal sedimentary cells, the interactions between adjacent cells and their role in coastal protection.

The biological conservation importance of many of these sedimentary habitats centres on their intrinsic value in supporting their own biological communities together with their support for the predators dependent on those communities. It is of note that many intertidal sedimentary habitats and their support for predators, especially wading birds in the case of mudflats, are the primary reason for estuarine areas being designated as SSSI (Special Sites of Scientific Interest) and SPA (Special Protection Areas under the EU Birds Directive). In addition, the intertidal habitats have a conservation importance in protecting other wetland habitats such as saltmarsh and reedbeds.

The conservation importance of these biotope complexes is assessed more fully in Chapter VIII, following from the review of their ecological functioning and sensitivity to environmental change.

Next Section                     References