The conservation status of Margaritifera falcata: using GIS to demonstrate the decline of a freshwater mussel in Idaho

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Freshwater mussels are perhaps the most imperiled group of animals in North America. Many scientists have presented convincing evidence regarding the decline of this group. As western landscapes have changed over the past Century, alterations to lotic habitats have taken place, sometimes with severe consequences for benthic organisms. It remains a challenge, however, to impress upon natural resources managers that conservation interventions are needed due to a widespread lack of trend data demonstrating species imperilment. Yet anecdotal evidence continues to accumulate, the results of which suggest that even once widely ranging species may be in decline due to changing land use patterns Here we present the results of a case study concerning the ecological biogeography of M. falcata in Idaho, U.S.A. We’ve used GIS, available locality data, and estimates of historical and contemporary M. falcata distributions to demonstrate the decline of a wide-ranging freshwater mussel. The contemporary distribution of Margaritifera falcata (Gould, 1850) in Idaho has declined between 37 and 57% when compared to estimates of historical distribution. The absence of M. falcata from specific stream reaches is related to land use and is restricted to those streams embedded within relatively undisturbed watersheds. Our results have implications for the conservation of M. falcata in western North America, but, more broadly, our methods are easily adapted to provide information to natural resource managers regarding the status and trend of other aquatic macroinvertebrates of conservation interest.

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ELECTRONIC FILE - Zoology: Invertebrates

NOTE that the copy we have has no date on it. The date comes from the name on the electronic file from Leona Svancara, IDFG.

Citation: Lysne SJ, Krouse BR. [2012]. The conservation status of Margaritifera falcata: using GIS to demonstrate the decline of a freshwater mussel in Idaho. 38 p. Technical report submitted to Idaho Department of Fish and Game, Clearwater Region, Lewiston, ID.