Validation and Verification Field Trials of Air Diffuser Systems for Upwelling Applications

Abstract As a consequence of climate change, the ocean surface temperature is rising. Warmer water has low dissolved oxygen, which can adversely affect the health of fish and their survival rates in aquaculture operations. Upwelling is a process in which deeper, colder water is lifted to the surface providing thermal mixing and circulation of oxygen-rich water. This paper discusses the design and execution of field trials to validate the performance of CanadianPond air diffuser upwelling systems for use in the aquaculture industry. Field trials were carried out at The Launch, an ocean innovation hub owned by the Marine Institute, in Holyrood Bay, NL, Canada. The upwelling systems were deployed at 20 m water depth and tested with 10 to 100 Standard Cubic Feet per Minute (SCFM) air flow rates. An electromagnetic current meter was used to measure the vertical and horizontal velocities generated by the upwelling systems at various locations underwater. Water depth-temperature profiles and dissolved oxygen levels were also measured prior to and during the trials. A Computational Fluid Dynamics (CFD) model was developed in parallel to assess the upwelling performance in different conditions and scales. The study concluded that localized upwelling was possible using the air diffusers tested, with effectiveness varying based on the applied air flow rate.