In 1997 a survey was undertaken to determine ecology and life history of the BAP short-listed aquatic mollusc Anisus vorticulus. This work (Willing & Killeen 1998) included monthly sampling (between April and September) of ditches at North Cove and Carlton Marshes, Suffolk. The results gave new information on the life history and ecology, but the snail’s unpredictable occurrence prevented an unambiguous description of the life cycle. Previous work had not proved conclusive in establishing the habitat factors that correlated well with the species’ presence. This report describes continuation of the East Anglian work with the following objectives: repeat parts of the 1997 survey to refine the description of the species’ life history and to monitor the fate of the snails within the ditches sampled previously to determine the effects of ditch age on their abundance; undertake monthly monitoring of selected ditches at North Cove and Carlton Marshes, Suffolk and at Halvergate, Norfolk.
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