LOCAL AND REGIONAL DRIVERS OF OXYGEN VARIABILITY IN COASTAL EMBAYMENTS ON THE SOUTHWEST SCOTIAN SHELF: IMPLICATIONS FOR NOVA SCOTIA ATLANTIC SALMON (SALMO SALAR) FARMING

• Main Author: Burke, Meredith
• Other Authors: Department of Oceanography, Doctor of Philosophy, Karen Wild-Allen, David Barclay, Jinyu Sheng, Douglas Wallace, Jonathan Grant, Ramon Filgueira, Not Applicable, Yes
• Language: English
• Published: 2022
• Subjects: Dissolved Oxygen; Aquaculture; Scotian Shelf; Temperature; Atlantic Salmon; Atlantic salmon; Salmo salar
• Online Access: http://hdl.handle.net/10222/81927

Globally, the coastal ocean is increasingly threatened by climate change-related stressors, such as ocean warming and deoxygenation. As a result, anthropogenic activities such as sea cage aquaculture, which often occurs in these ecosystems, are left vulnerable. Additionally, coastal oxygen deficits are intensified due to eutrophication as there is increased nutrient input from coastal development, which then affect cultured fish directly through stress, vulnerability to diseases and ultimately, increased mortality. Therefore, it is important to effectively monitor aquaculture farms and the adjacent coastal zone to ensure optimal fish welfare and marine management. This thesis explores the local and regional drivers of dissolved oxygen and temperature dynamics in coastal embayments within southwest Nova Scotia. Novel real-time oxygen and temperature sensors were used to understand local dynamics. First, a dense array of 63 sensors was deployed through an aquaculture farm to explore the drivers of oxygen variability. Tidal driven currents were determined to have the most significant impact on oxygen, with the influence varying depending on the position of the cage within the farm (Chapter 2). Second, the sensors were used to determine how an oxygen supplementation system affects oxygen distribution within 3 sea cages. Overall, oxygenation likely resulted in the upwelling of cool waters to the surface, increasing oxygen solubility and lowering fish metabolism, subsequently increasing oxygen concentrations (Chapter 3). To explore regional along-shore and cross-shore oxygen distribution and variability, a Slocum glider was deployed in a zigzagging pattern along the inner southwest Scotian Shelf. Wind direction had a significant affect, with strong cross-shore winds advecting water masses of differing properties to the coast, and persistent southwesterly winds causing upwelling of high DO from the subsurface. This data was then compared to a sensor within a bay to examine the offshore-inshore interaction, which has ...