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Diseases of Aquatic Organisms

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DAO 91:57-66 (2010)  -  DOI:

Ulcerative disease outbreak in crayfish Orconectes propinquus linked to Saprolegnia australis in Big Muskellunge Lake, Wisconsin

Lisa Krugner-Higby1,*, Danielle Haak2, Pieter T. J. Johnson3, Jeffery D. Shields4, William M. Jones III4, Kimberly S. Reece4, Tim Meinke2, Annette Gendron1, James A. Rusak2,5

1Research Animal Resources Center, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA
2Center for Limnology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
3Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309, USA
4The Virginia Institute of Marine Science, The College of William & Mary, Gloucester Point, Virginia 23062, USA
5Present address: Dorset Environmental Science Centre, Ontario Ministry of the Environment, Dorset, Ontario P0A 1E0, Canada

ABSTRACT: Crayfish populations in the area of the North Temperate Lakes Long Term Ecological Research (LTER) project, Wisconsin, USA, have been monitored for >25 yr. In 2005, native crayfish Orconectes propinquus from Big Muskellunge Lake were found with ulcerated lesions in the cuticle. In 2006, lesions occurred in 9.5% of sampled crayfish from the lake (n = 3146). Ulcers generally occurred on the appendages of affected individuals but varied in location and severity. The prevalence of ulcers varied widely among sites, sample depths, and sampling dates, ranging from <2% to >20%. The prevalence of ulcers in crayfish increased from a minimum in early June to a maximum in late July and August. In aquarium trials, healthy crayfish representing either O. propinquus or O. rusticus co-housed with ulcerated crayfish did not develop ulcers within 4 wk of exposure. Gross and histopathologic analyses of ulcerated crayfish revealed the presence of filamentous hyphae in the lesions while hemocytic infiltrates, melanotic reactions and silver-stained sections indicated that the ulcers had an oomycete etiology. Excised samples of ulcerated crayfish cuticle grown in culture developed an oomycete that was identified as Saprolegnia australis by PCR amplification and sequence analysis of 2 different DNA fragments. This is the first report of the occurrence of ulcers in wild crayfish associated with S. australis infection in the USA. The advent of the outbreak and its underlying ecological causes are still under investigation.

KEY WORDS: Shell disease · Epidemiology · Mortality · Aphanomyces · Saprolegnia · Crayfish

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Cite this article as: Krugner-Higby L, Haak D, Johnson PTJ, Shields JD and others (2010) Ulcerative disease outbreak in crayfish Orconectes propinquus linked to Saprolegnia australis in Big Muskellunge Lake, Wisconsin. Dis Aquat Org 91:57-66.

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