Skip to Main Content
Effects of severe drought on freshwater mussel assemblagesAuthor(s): Wendell Hagg; Jr. Warren Melvin L.
Source: American Fisheries Society 137:1165-1178, 2008
Publication Series: Miscellaneous Publication
PDF: Download Publication (2.4 MB)
DescriptionWe examined changes in freshwater mussel abundance and species composition at eight sites in Alabama and Mississippi in response to a severe drought in 2000. Five small-stream sites in Bankhead National Forest were heavily impacted by drought; one site dried almost completely, and four sites experienced total or near cessation of flow but retained water in their channels to a large extent. In contrast, three large-stream sites retained flow and experienced only minor streambed exposure, primarily along the stream margins. In small streams, overall mussel density before and after the drought declined by 65-83%, and the magnitude of the decline did not differ among streams regardless of whether the channel dried or remained wetted. Introduced Corbiculafluminea (Asian clam) experienced near total mortality and declined to a greater extent than native unionids. The magnitude of decline was similar among unionid species, and the likelihood of surviving the drought was mostly a function of predrought abundance; differences in drought tolerance among species were not evident. Consequently, assemblage composition changed primarily because of the loss of rare species, resulting in drainagewide homogenization and convergence on a shrinking species pool. In contrast, we found no evidence for changes in the total abundance or composition of mussel assemblages in large streams that continued to flow during the drought. Our results show that mussels are highly sensitive to the secondary effects of drought-most likely the low levels of dissolved oxygen caused by low flow, wann temperatures, and high biological oxygen demand-in addition to the direct drying of their habitat. The postdrought abundances of some species in Bankhead National Forest may now be below the minimum necessary for successful reproduction. These populations, which are isolated by reservoirs, may be in a downward spiral from which they will have difficulty recovering in the absence of immigration.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationHagg, Wendell, R.; Warren Melvin L., Jr. 2008. Effects of severe drought on freshwater mussel assemblages. American Fisheries Society 137:1165-1178, 2008
Keywordsfreshwater mussel, Corbiculafluminea
- Forest linkages to diversity and abundancein lowland stream fish communities
- Freshwater mussels of the Delta National Forest, Mississippi Final Report
- Role of ecological factors and reproductive strategies in structuring freshwater mussel communities
XML: View XML