Beltringharder Koog

An area of some 3,345ha was enclosed in 1987. 853ha (c16%) was reintegrated with the sea in 1988-89 principally to make up for losses when the original sea bank enclosed the tidal land. Two sea gates work together to produce a tidal range of 40cms, which follow the natural tidal cycles. This replacement area (for tidal land lost at Nordstrand), before reintegration contained saltwater tidal lagoons and extensive fresh-water habitats to compensate for the lost habitats.

The tidal range of the lagoons was reduced to 40 cm, which exposed only 140 ha of mud flat at low tide. Benthic invertebrates tended to occur at lower densities here compared with the Wadden Sea. Semi-quantitative predictions of the effects of the habitat loss were made by knowledge of the ecology of each species, the plans for the embanked area and data from other reclaimed sites. Of the important waterfowl that used the area prior to the reclaim, only the herbivorous species Wigeon and Barnacle Goose showed increases in the reclaimed area and, even with the remaining intertidal habitats, shorebirds showed a large decline. Only Redshank used these areas for feeding at high tide and the reduction in tidal range, reduced invertebrate densities and enclosure by tall embankments rendered the remaining area unsuitable for shorebirds. As a result of the embankment built to control tidal flows, the numbers of Brent Geese, Shelduck and most shorebird species decreased in the area surrounding the embankment when compared with pre-embankment numbers. Most species elsewhere in the German part of the Wadden Sea increased or were stable over the same period.

References

Atkinson, P.W., Crooks, S., Grant, A. & Rehfisch, M.M. 2001. The Success of Creation and Restoration Schemes in Producing Intertidal Habitat for Waterbirds. English Nature Research Report, 425 English Nature.