WA5 Wildlife Toxicology: Forensic Approaches
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() Investigating the link between avian vacuolar myelinopathy and a novel species of cyanobacteria.

Wiley, F1, Birrenkott, A1, Wilde, S2, Murphy, T3, Hope, C3, Hains, J4, Bowerman, W1, 1 Clemson University, Pendleton, SC, USA2 South Carolina Department of Natural Resources, Marine Resources Research Institute, Charleston, SC, USA3 South Carolina Department of Natural Resources, Green Pond, SC, USA4 U. S. Army Corps of Engineers, Calhoun Falls, SC, USA

ABSTRACT- Avian vacuolar myelinopathy (AVM) is a neurological disease affecting bald eagles (Haliaeetus leucocephalus), American coots (Fulica americana), and other waterfowl across the Southeastern U.S. The cause of the disease has not yet been determined, but it is suspected to be a natural or man-made toxin. Previous research established a link between AVM and aquatic vegetation when several pen-raised adult mallards (Anas platyrhynchos) contracted AVM after consuming aquatic vegetation (Hydrilla verticillata and associated material) in a laboratory feeding study. The current research hypothesis is that a species of cyanobacteria growing epiphytically on the vegetation is producing a toxin responsible for AVM. This suspect cyanobacteria is a previously uncharacterized species of the Order Stigonematales that has been identified at every known site of AVM mortality. Research efforts are currently focusing on further elucidating the relationship between the cyanobacteria and AVM induction. Two feeding trials were conducted October-December, 2003. In the first trial, hydrilla containing the suspect Stigonematales species was collected in mid-October from J. Strom Thurmond Lake (JSTL), a reservoir where AVM has previously occurred. This hydrilla was fed to both adult mallards and domestic chickens for four weeks. In the second trial, adult mallards were fed hydrilla containing the suspect cyanobacteria collected from the same region of JSTL, as well as a farm pond located 7 km from JSTL, collected weekly for four weeks starting in mid-November. In both trials, control birds were fed hydrilla collected from Lake Marion, SC, that did not contain the suspect Stigonematales species. No birds in the first feeding trial contracted AVM. Ten out of twelve treatment ducks in the second trial contracted AVM, and all control birds were AVM negative. This study provides further evidence that the Stigonematales species may be involved in AVM induction.

Key words: cyanobacteria, wildlife, bald eagles, invasive species

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