Clubshell ('Pleurobema clava') and Northern Riffleshell ('Epioblasma torulosa rangiana').

摘要

The clubshell (Pleurabema clava) and northern riffleshell (Epioblasma torulosa rangiana) were listed as endangered species on 22 February 1993 (50 CER 17). Both were widespread throughout most of the Ohio River and Maumee River drainages prior to 1800. The clubshell was apparently very common. These species now exist in eight to ten isolated populations each, most of which are small and peripheral. The largest remaining clubsheLl population is in the Tippecanoc River of Indiana, and that of thc northern riffleshell is in French Creek, Pennsylvania. Both species are threatened by runoff and channelization, domestic and commercial pollution, in-stream sand and gravel mining, impoundment, and zebra/quagga mussel infestation.