Macro-invertebrate communities of chalk shores in Southeastern England

• Autores: J. D. George, A. A. Fincham
• Localización: Scientia Marina, ISSN 0214-8358, Vol. 53, Nº. 2-3, 1989, págs. 373-385
• Idioma: inglés
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• Resumen

  • Chalk shores are of limited occurrence in Europe. In Britain they are mainly confined to the eastern end of the Channel coast and many have already been extensively modified by erosion defence works and developments. Little was known about the invertebrate communities inhabiting intertidal chalk. As a consequence an investigation of chalk shores in southeastern England was carried out, paying particular attention to the region in which it is proposed to dump on the foreshore up to 3.75 million cubic metres of chalk spoil from the Channel tunnel which will link Britain and France. The most frequently encountered shore topography is a gently-sloping, boulder-strewn, wave-cut platform backed by vertical cliffs. In all. 194 species of macro-invertebrate were recorded. The fauna is characterised by the presence of boring species such as piddocks and the polychaete Polydora ciliata. The shores can be divided into six fauna1 zones, often characterised by dominant algal bands. A strandline of algal debris, containing aquatic and semiaquatic invertebrates occurs at the bases of many chalk cliffs. The upper zone of the chalk platform, often consisting of green-algal-covered boulders, is grazed by littorinids. A barnacle/limpet/littorinid-dominated area is the next zone encountered down the shore and is occasionally occluded by mussel beds. Polydora and piddocks appear in abundance in this zone and extend down to the low water mark through fucoid, red and iaminarian algal zones. Within the lower zones assemblages of macro-invertebrates can be recognised under small boulders and overhangs, and amongst algal fronds. Additionally the study revealed characteristic groups of species associated with old piddock burrows and with laminarian holdfasts. It is concluded that the chalk shores of SE England are species-poor compared with rocky shores on the west coast of Britain. This is due partly to the soft friable nature of the chalk substratum, to the high turbidity of the water caused by continuous slow dissolution of the chalk, and to the relatively low winter air and sea temperatures in this part of Britain.