Tolerance of American eel to acidification
MSc project, Craig Reynolds
The American eel (Anguilla rostrata) has declined over much of its range. Although a variety of causes, including overfishing, dams, pollution and various other forms of habitat degradation are likely to have contributed to the decline, in south-western Nova Scotia, acidification of rivers and lakes has been suggested as a factor. My MSc study examines the tolerance of various life history stages of eel to low pH water. I am also examining genetic variation among arrival waves and year classes of eels.
The general problem
American eel (Anguilla rostrata) has experienced a substantial decline in numbers within specific regions during the last few decades, and has recently been designated as a species of special concern by the Committee on the Status of Wildlife in Canada (COSEWIC). The population health (status) of the American eel depends ultimately on the abundance of arriving eels from the Sargasso Sea and on their subsequent survival throughout each life stage, elver, yellow and silver eel). Therefore, conservation efforts should be centered on maximizing survival at all stages of the life-cycle. Although the leading causes of eel mortality have not yet been defined, potential key threats have been identified. In some watersheds, particularly in Nova Scotia, these potential threats include high levels of acidity (low pH) . My project examines the effect of low pH on eel survival using both laboratory and field based trials. This research will be incorporated into conservation and management decisions regarding the Atlantic elver fishery and American eel stocks.
Population structure
Evidence from population genetic studies suggests that the American eel is comprised of single, randomly mating, panmictic population exhibiting complete genetic homogeneity across its geographical range (Avise et al. 1986, Wirth and Bernatchez 2003). Using AFLP markers I will examine the degree of temporal genetic differentiation that may exist among year classes and between arrival waves of American eel.
For more information on the American eel follow this link.
References
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Avise J.C, G.S.Helfman N.C. Saunders, L.S. Hales. 1986. Mitochondrial DNA differentiation in North Atlantic eels: population genetic consequences of an unusual life history pattern. Proc. Natl Acad. Sci. USA. 83:4350-4354.
Wirth T. & L. Bernatchez.2001. Genetic evidence against panmixia in the European eel. Nature. 409:1037-1040.