A massive summer-kill of the dog-whelk, Nucella lapillus, on the north Cornwall coast in 1995: freak or forerunner?

In the summer of 1995 a massive kill of the dog-whelk, Nucella lapillus, oc curred in Bude Bay on the north Cornish coast. High mortality was detectabl e along 12 km of shoreline. The only other intertidal species affected appe ared to be another neogastropod, Ocenebra erinacea. The cause of the kill i s unknown but the evidence suggests that it occurred in early July followin g an extended period of warm, calm weather in June. Possible causes of this event are discussed: algal toxicity may have been responsible since an alg al bloom was detected offshore in July in the area. Laboratory experiments exposing gastropods to different species and concentrations of microalgae, designed to test whether N: lapillus is more sensitive than Monodonta linea ta and Littorina littorea, gave inconclusive results. No comparable kill ha s occurred in the Bude area for at least 20 y, but it is suggested that nut rients from a newly-constructed, offshore selvage outfall may now stimulate local algal bloom development during calm weather periods.