USGS Columbia Environmental Research Center Project: An Assessment of the Occurrence, Fate, and Effects of Cyanotoxins in the Upper Klamath Lake, OR: Are Endangered Lost River Sucker Populations at Risk?


Statement of Problem: Upper Klamath Lake is a large hyper-eutrophic lake (270 km2 surface area; 2 m mean depth) that receives runoff from a 9,758 km2 watershed located on the eastern slope of the Cascade Mountains in Southern Oregon (Walker 2001). Wetland drainage and subsequent conversion of wetlands to agricultural production have resulted in significant inputs of nitrogen and phosphorus to the Lake. High nutrient levels result in cyclical phytoplankton blooms resulting in chlorophyll levels as high as 200 ug/L (Kann and Smith 1999). Severe decreases in dissolved oxygen, increases in pH, and increases in ammonia commonly occur following periods of algal die-offs. Degraded water quality conditions can indirectly facilitate numerous fish parasites and diseases which can also result in mortality of fishes including the endangered Lost River sucker (Deltistes luxatus) and the short-nosed sucker (Chasmistes brevirostris). Numbers of these two species have declined over the past 50 years in parallel with the documented declines in water quality. Shively and Lynch (2005) developed an Integrated Science Plan for the Upper Klamath Basin and outlined a series of research and information needs that were identified in a February 2004 Upper Klamath Basin Science Workshop. Five areas of research were identified: 1) sucker biology and ecology; 2) fish health and disease; 3) water quality dynamics; 4) riparian and wetland habitat restoration; and 5) hydrology of the Basin. Each of these science needs were identified due to their relationship to the primary problem: degraded water quality. Martin and Saiki (1999) studied water quality conditions of Upper Klamath Lake and concluded that low dissolved oxygen levels were the most important determinant of mortality of Lost River sucker. Low dissolved oxygen levels primarily occur following die-offs of large blooms of blue-green algae (cyanobacteria) including Aphanizomenon flos-aquae and Microcysis aeruginos as decay processes occur. These two species of blue-green algae are both capable of producing toxins that are released in water upon the death of the algal cells. The major class of these natural toxins is the microcystins, liver toxins that are cyclic peptides composed of seven amino acids. Reports of animal deaths resulting from drinking water with microcystin toxins have been made periodically (Chorus 1999, Carmichael 1997). Studies indicate effects on humans, such as dermatitis, gastrointestinal disorders and evidence suggesting higher incidence of liver cancers in rural populations in China exposed to microcystins in drinking water from chronic low level exposure (Chorus 1999). Microcystin has been found and studied in blue-green algae dietary supplements (Gilroy et al 2000) derived from UKL AFA. Two other classes of natural toxins have also been found in Aphanizomenon sp.¿anatoxin-a and cylindrospermopsin¿but have not been studied in UKL AFA. Anatoxin-a is an alkaloid neurotoxin with an LD50 of 200-250 ug/kg body weight (Chorus 1999). Cylindrospermopsin is an alkaloid hepatotoxin that also may damage other organs, such as kidney, spleen, heart and thymus (Chorus 1999). While AFA dominates UKL M. aeruginosa has also been found and has been found to be dominant in downstream reservoirs. These potent bio-toxins, produced under environmental conditions that are poorly understood, can be lethal to humans, mammals, birds, and fish. However, to date, there is insufficient information regarding the possible role of algal toxins in the observed declined of endangered fishes in the Upper Klamath region.

Objectives: 1. Determine the seasonal and spatial dynamics of cyanobacteria blooms in Upper Klamath Lake in relation to water quality conditions; 2. Determine seasonal and spatial levels of cyanotoxins in water, phytoplankton, and zooplankton during algal blooms in Upper Klamath Lake; and 3. Determine the toxicity of documented cyanotoxins in Upper Klamath Lake to Lost River sucker and short-nosed sucker.
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