A NEW METHOD FOR PRIORITIZING CATCHMENTS FOR TERRESTRIAL LIMING IN NOVA SCOTIA
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Freshwater acidification is a chronic issue in South Western Nova Scotia (SWNS). Despite reductions in emissions causing acid deposition in SWNS, water quality in the region is not predicted to improve for another 60 years (Clair et al., 2004). Acidification is the primary factor limiting the Southern Upland (SU) Atlantic salmon (Salmo salar) designatable unit which was evaluated as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2010. The SU salmon have declined from 88-99% since the 1980’s and have a high probability of extirpation in the next 50 years if habitat quality is not improved (DFO, 2013). Liming, the addition of base cations to an acidified system, is the only mitigation method for acidification. Terrestrial liming is the addition of buffering material to the catchment of an acidified river and is a promising mitigation method for rivers in SWNS as it is sustainable and requires no maintenance (Olem, 1991). The effectiveness of terrestrial liming varies by location therefore an assessment of potential liming catchments is necessary to identify the top priority sites for terrestrial liming. The federal government and community groups are interested in terrestrial liming in SWNS to improve water quality and help support the SU salmon population but unfortunately a method for identifying and prioritizing catchments for terrestrial liming does not exist. I have developed a comprehensive and quantitative GIS decision model to prioritize catchments for terrestrial liming in Nova Scotia. The model identifies catchments that best support effective liming and the SU population; these catchments are the primary units of SU conservation when using terrestrial liming mitigation methods. Additionally this research identifies key information needs required for improved terrestrial liming catchment selection.