Improving the predictability of harmful algal blooms around Shetland, for Scottish aquaculture

Harmful algal blooms (HABs) are often high biomass blooms, which can cause the water column to become eutrophic and undersea sediments to turn anoxic. HABs can also be of relatively low biomass, but composed of species which produce toxins. Toxins can then accumulate inside organism eaten by humans, such as mussels, scallops and oysters. When these shellfish are eaten by humans, illnesses like diarrhoea, paralysis, amnesia and death can result.

During the summer of 2013, there was an exceptionally large bloom of Dinophysis species. Although preliminary reports suggested this bloom could become harmful, shellfish in the area were still below the limit which EU regulations prohibit they be sold to consumers. A change in the prevalent wind direction on Shetland caused a large bloom of toxin forming Dinophysis spp. cells to be blown into the West coast of Shetland (Whyte et al., 2014). Some mussels were sold to prestigious restaurants in London and approximately 50 people because ill, experiencing the unpleasant symptoms of diarrhetic shellfish poisoning.

This episode demonstrates that while routine monitoring of phytoplankton and toxin concentrations within shellfish is important, sometimes HABs can grow very rapidly. It is in this context that my PhD topic will be of use.

I will be looking through past data collected by routine phytoplankton and toxin monitoring sites on Shetland to find occurrences of blooms, and data collected by continuous plankton recorder (CPR). I will attempt to link this to weather conditions around the time of the bloom. Offshore data from the CPR is important, as it will elucidate whether blooms in the ocean around Shetland are always seen around farms. 

My practical work will focus on measuring the water column structure around Shetland. Some preliminary work suggests that the 100m isobath west of Shetland may be an important area where HABs can initiate. I will be using CTDs and taking water samples to allow analysis of nutrients and chlorophyll in the water at various depths.

Supervisors

Professor Keith Davidson, SAMS

Dr Callum Whyte, SAMS

Dr Andrew Dale, SAMS

Dr Beth Mouat, NAFC

Dr Andrew Turner, CEFAS

Funder

European Social Fund (ESF)

University of the Highlands and Islands

University

University of the Highlands and Islands

Publications

Paul Dees, Eileen Bresnan, Andrew C Dale, Martin Edwards, David Johns, Beth Mouat, Callum Whyte, and Keith Davidson (2017) Harmful algal blooms in the Eastern North Atlantic ocean. Proceedings of the National Academy of Sciences. www.pnas.org/cgi/doi/10.1073/pnas.1715499114