AQUATIC BEETLE POPULATION-CHANGES ASSOCIATED WITH RECREATING A TROUT FISHERY BY LIMING A LAKE CATCHMENT

Adult populations of water beetles were sampled in an upland loch subject to liming of its catchment prior to the reintroduction of brown trout. Populations generally declined and the commonest species, Hydroporus palustris, was temporarily displaced by Potamonectes depressus elegans before it too declined. The reasons for these changes are discussed.