In lieu of an abstract, here is a brief excerpt of the content:

Sediment Quality Assessment and Management: Insight and Progress Edited by M. Munawar© 2003 Ecovision World Monograph Series Aquatic Ecosystem Health & Management Society Spatial and temporal trends in chlorophyll a, nutrients, and sediment in relation to avian mortality, Whitewater Lake, Manitoba, Canada K.N. Irvine1*, T.P. Murphy2, T. Tang3, L.M. Greer3, D. Walters3 1Department of Geography/Planning, State University of New York, College at Buffalo, 1300 Elmwood Ave., Buffalo, NY 14222, U.S.A. * 2National Water Research Institute, 867 Lakeshore Rd., Burlington, Ontario L7R 4A6, Canada. 3Department of Geography/Planning, State University of New York, College at Buffalo, 1300 Elmwood Ave., Buffalo, NY 14222, U.S.A. Keywords: prairie lakes, avian botulism, nutrient cycling, sediment resuspension Introduction Whitewater Lake, Manitoba, is an important nesting and molting ground for migratory waterfowl, but the lake also experiences frequent, large scale avian mortality. The principal cause of mortality is Type C botulism and, in fact, this type of botulism has been observed to affect waterfowl throughout the world, with significant annual losses in North America (Rocke, 1993; Rocke et al., 1999). Botulism outbreaks are common not just in Whitewater Lake, but in lakes and wetlands throughout the Canadian prairies. In response to growing concerns about large scale mortality, the Working Group onAvian Botulism was formed to look at all aspects of the botulism problem, from initiation, to propagation, to appropriate management strategies (Working Group on Avian Botulism, 1998; Pybus, 2000). Botulism essentially paralyzes the bird when it absorbs the neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum is an anaerobe that forms dormant spores in aerobic or other adverse environmental conditions. These dormant spores commonly are found in wetland sediment, particularly in those areas that 270 previously had experienced an outbreak, as well as in the tissue of wetland invertebrates and even healthy waterfowl (Wobeser et al., 1987; Rocke, 1993). The ecological factors that initiate the vegetative growth of dormant spores are not well understood, but appear to include anaerobic conditions, temperatures greater than 10 oC, and a protein-rich substrate, such as animal carcasses. The pH of the water, as well as benthic organism biomass, and sediment oxygen-reduction potential also may be related to botulism outbreaks (Rocke et al., 1999). The requirement of a protein-rich substrate involves the “microenvironment concept”, in which animal tissue acts as the substrate and toxin production can occur within the carcass (Bell et al., 1955; Reed and Rocke, 1992; Working Group on Avian Botulism, 1998). Maggots involved in the carcass decay process ingest and concentrate the botulism toxin and other birds subsequently feed on the maggots. This cycle, then, propagates the botulism outbreak. It has been observed that duck mortality on lakes in Finland and Thailand occurred when blue-green Microcystis blooms and associated toxic microcystins were present (e.g. Ericksson and Lindholm, 1988; Mahakhant et al., 1999). It is possible that during storm events, for example, lysis of toxic algal cells occurs, thereby releasing the toxins to the water column.Alternatively, birds could directly ingest the algae containing the toxins. Regardless of the pathway, Murphy et al. (2000) hypothesized that ingestion of algal toxins could produce an initial source of carcasses that acts as a trigger for the botulism outbreak. Whitewater Lake, Manitoba, can be hypertrophic and the presence of various microcystins (microcystin-LR, anatoxin-a) has been detected in the algae from the lake (Murphy et al., 2000). Accordingly, an interesting question arises – can potentially toxic algae blooms be controlled as a tool to reduce avian mortality and the initiation of avian botulism? Blue-green algae control can be done through manipulation of the nutrient budget for a waterbody or through methods including algae settling using a flocculant or in situ sediment treatment (e.g. Murphy et al., 1988; Babin et al., 1989; Hall et al., 1994; Murphy et al., 1996; 1999). The frequency of direct treatment of the lake must be estimated before any engineering efforts such as in situ sediment treatment is considered, particularly if control of external nutrient sources cannot be effectively implemented. Furthermore, if the algae blooms are always located in the same small parts of the lake, treatment of these hotspots is more amenable. However, if these hotspots appear randomly (e.g. due to wind movement), in situ treatment would be more difficult. Nutrient sources and cycling are not well understood for Whitewater Lake. Wind on shallow lakes such as Whitewater Lake also potentially can move algae blooms as well as resuspend...


Additional Information

Related ISBN
MARC Record
Launched on MUSE
Open Access
Back To Top

This website uses cookies to ensure you get the best experience on our website. Without cookies your experience may not be seamless.