The influence of avian biovectors on mercury speciation iin a coastal wetland
LE3 .A278 2018
2018
O'Driscoll, Nelson Mallory, Mark
Acadia University
Master of Science
Masters
Biology
Mercury is a persistent and bioaccumulative chemical that is present in many remote environments due to its ability to be transported long distances in the atmosphere and to be deposited far from the original source. Wetland ecosystems are important hot spots for mercury in eastern Canada, providing anoxic environmental conditions which promote the bacterial methylation of mercury. Methylmercury is the most biologically available form of mercury and the form which biomagnifies in food webs. Seabird guano is a well-documented biovector for metals –including mercury –and nutrients, which may indirectly affect metal speciation. The site for this study, Big Meadow Bog (Brier Island, Nova Scotia, Canada) has a history of ditching in the 1950s, which changed hydrology significantly, resulting in colonization by ~3000 pairs of Herring gulls (Larus argentatus) and Great Black-Backed gulls (Larus marinus) in the 1980s. To quantify changes in mercury mobilization and speciation in response to this biovector, groundwater and surface water samples were collected over two years (2015 and 2016) from this site and a reference bog site with similar geological and hydrological characteristics, as well as another reference bog site in 2016. The filtered samples were analyzed for total mercury, methylmercury, and water chemistry (pH, conductivity, anions, cations, and dissolved organic and inorganic carbon). Results from 2015 indicated that the gulls significantly impacted water chemistry in Big Meadow Bog compared to the reference bog and MeHg hotspots were co-located with the densest area of Herring and Great Black-Backed gull inputs. Further analyses in 2016 also suggested trends of greater variation in water chemistry parameters in the avian disturbed area.
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https://scholar.acadiau.ca/islandora/object/theses:2716