Substrate composition and relationship to bacterial communities during production and fallow periods at hard-bottom aquaculture sites in Newfoundland

Knight, Robyn Michelle (2020) Substrate composition and relationship to bacterial communities during production and fallow periods at hard-bottom aquaculture sites in Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

Newfoundland salmonid aquaculture is established in deep, sheltered bays and above hard-bottom substrates. Over time, organic waste accumulates on the seafloor, changing sediment chemistry and community structure. Visual markers including white bacterial mats are used to monitor organic enrichment but alternative methods may be more informative. I sampled substrates at two aquaculture sites in Newfoundland [experiencing production (active) and fallow (inactive) conditions], characterized abiotic features and bacterial communities, and tested for associations with bacterial mats. Organic enrichment and abiotic markers of aquaculture were prominent during both production and fallow periods, especially near cages. Bacterial mats were associated with elevated concentrations of organic matter, Zn, Cd and Cu. Bacterial community clusters show relationships with organic matter and Zn, and mats were associated with all identified bacterial community clusters. This research highlights the potential use of bacterial and abiotic markers for monitoring organic enrichment and site recovery at aquaculture sites in Newfoundland.

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