The distribution of Zostera and its exploitation by wildfowl in the solent, Southern England

Abstract

In the Solent estuarine system on the central south coast of England, Zostera marina L. occurs both in mainly sublittoral beds on firm substrate around the low-water mark of spring tides, and in large eulittoral beds on mudflats between the low-water mark of neap tides and the uppermost level of the shore. Zostera noltii Hornem. occurs with eulittoral Z. marina on uppershore mudflats and also on exposed sandy shores near the low-water mark of spring tides. Since 1960 the eulittoral Zostera beds have spread widely on mudflats in Portsmouth, Langstone and Chichester Harbours, where they now occupy 430–450 ha. The Zostera beds at the bottom of the shore remain winter-green, but the mudflat Zostera beds shed most of their leaves between November and January. Comparisons are made with localities further east, which show earlier and greater leaf loss. The uppershore Zostera beds in the three harbours comprise an important and favoured autumn and early winter food for Dark-bellied Brent Geese, ( Branta bernicla bernicla (L.)) and Wigeon ( Anas penelope L.), which consume the leaves and rhizomes, and Teal ( Anas crecca L.) which consume the seed. The pattern of occurrence of these three species of birds is, to some extent, related to the availability of Zostera.