Wetland senescence and productivity trends in the Cumberland Marsh Region, Atlantic Canada
LE3 .A278 2017
Master of Science
Wetland creation and restoration are important management practices designed to increase biodiversity,and compensate for the global decline in the number and area of natural wetlands. Anecdotal observations indicate that impoundment biodiversity, and waterbird usage and available food supplies can decrease in aging compensatory wetlands (impoundments) along the upper Bay of Fundy–a trend called “senescence” that is not well documented or understood. The purpose of this study was to examine biogeochemistry and productivity in rural impoundments located in the Cumberland Marsh Region (CMR) on the New Brunswick –Nova Scotia border to better understand factors controlling senescence. Surface water chemistry (pH, dissolved oxygen, conductivity, temperature, phosphorus and nitrogen) was examined in newly created and older impoundments to determine how water chemistry varies in relation to impoundment age and landscape position. Sediments were also analyzed from older impoundments using paleolimnological techniques to acquire a spatial and temporal perspective on impoundment productivity, nutrient availability, organic matter supply and accumulation, and erosional processes. I determined that senescence is attributed to the ecological and sedimentological stabilization of impoundments upon aging, and can result in decreased productivity, nutrient loadings and organic matter accumulation. Although nutrient availability was elevated within 1 year of impoundment creation, the data indicate that impoundments in the CMR are influenced strongly by internal nutrient sources, and lack sufficient influxes of sediments, nutrients and plant matter from the altered watershed and surrounding landscape to sustain long-term productivity. Consequently, rural impoundments may be prone to declines in waterbird forage and wildlife usage after creation.
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