Sand and mud communities in the Dovey estuary

Abstract

This paper presents results of an ecological study towards high-tide level near the mouth of the Dovey estuary, carried out in 1925–6. The area was treated as an extension of the sea floor, the only comparable work at that time being submarine. Petersen (1918) showed that on the bed of shallow seas the fauna could be grouped into “animal communities”, whose constitution was determined by depth, distance from shore, shelter and salinity. Analysed with regard to distance from high-water mark, and degree of shelter, the fauna of this part of the estuary shows Petersen's Macoma community over most of the area, with a Corophium community at high tide in the more sheltered part. Davis (1925), in the North Sea, substituted “soil associations” as an alternative ecological unit, a certain grade of soil carrying its typical fauna wherever it might be found. The two groupings already found in the Dovey estuary clearly emerged as soil associations, after adoption of a reliable method for analysis of fine-grade soils. Up to the present, oceanographers have used sieves or elutriation for soil analysis. Up to the present, oceanographers have used sieves or elutriation for soil analysis. These methods are unsatisfactory for examinations of estuarine soils, with their large proportion of fine material.