This study monitored population changes of the snail Anisus vorticulus on an approximately monthly basis from May-November 1998 in a single ditch at both Amberley Wildbrooks and Pulborough Brooks. Ditches were studied at each location because although they are relatively close together (3 km apart) these two areas are isolated from each other. The study has sought to: undertake monthly population counts of Anisus vorticulus from May-October; remove samples of A. vorticulus for biometric analysis; record the abundance of all other Mollusca recovered during the survey process; measure other environmental factors including monitoring ditch dimensions, maximum water depth and depth where samples were taken; water hardness/pH and the vegetation structure and identification of dominant/frequent plants.
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