Micronutrient Distribution in Relation to Waste Emission from Aquaculture Activities: A field study in Trondheimsfjorden

Abstract

Bioactive trace metals, or micronutrients, are crucial as cofactors in enzymes used in various macronutrient cycles in marine systems. Aquaculture releases large quantities of macronutrients, which may lead to a shift in the distribution of micronutrient. At the coast of Norway there are several areas with aquaculture activity, but there are no historical data on the metal concentrations in the Norwegian coastal system.In this thesis, the distribution of micronutrients close to fish farms, has been compared to a location whiteout any known aquaculture activity. To do this, samples of seawater was collected in the Trondheimsfjord in two cruises, one in February and one in April. The samples were analysed with an HR-ICP-MS with the techniques of direct sampling, chelex-100 and DGT units. The following metals were focused on: Fe, Mo, Mn, Cu, Co, Zn and Cd. There was a general seasonal trend of decrease from the first to the second cruise, but not a clear trend between the different locations and it did not seem like the distribution of micronutrients was significantly affected by aquaculture activities. The lack of background value of the micronutrients makes it difficult to decide whether the current values are natural or due to aquaculture activities. However, the data obtained in this thesis can be used as a baseline for both the rest of the CINTERA project and more importantly for the future.