Around the world, harmful algal blooms are thought to be on the increase. About 4000 known marine species of phytoplankton –also known as microalgae– live in our oceans, harvesting sunlight for energy through photosynthesis. Though delicate under a microscope, phytoplankton form the foundations of the food chain in our world’s oceans.
Some species of microalgae have sporadic explosions of dense growth or “blooms”, and a number of those species are harmful.
Harmful algal blooms (HABs) are a natural part of marine ecosystem processes, and at SAMS a team of researchers study a handful of the 40 species of marine microalgae known to naturally produce bio-toxins that are harmful to people and the environment.
Dinoflagellates, such as Alexandrium tamarense, are not dependent on sunlight and can gain energy from nutrients in the surrounding waters.
“Both toxic (group I) and non-toxic (group III) strains of A.tamarense can be found in UK waters,” said Professor Keith Davidson, head of the microbial and molecular biology department at SAMS.
“The group I strain is more prevalent in waters around Shetland and Orkney, and can be found around coastal regions of Scotland. Group III prefers warmer waters further south. However, with warming sea surface temperatures in the north, this non-toxic group is pushing into higher latitudes,” Professor Davidson explained.
Commercially farmed bivalve molluscs, such as mussels and oysters, filter feed on drifting phytoplankton. Although bio-toxins are relatively harmless in low doses, the toxins can build up in the edible flesh of shellfish and although there is no apparent effect to the animal, human consumers can suffer far more significant consequences. In Scotland, shellfish farming is worth around £8.9 million at first sale, and so the presence of harmful algae in the area can have detrimental effects on the economy.
EU legislation requires all member states to have an “official control” monitoring system. SAMS is part of the UK-wide, official HABs team that monitors all active classified shellfish production and relaying areas. The team analyses more than 100 shellfish samples every week, and 100 water samples every month, as part of the programme to stop the harvesting or sale of products containing biotoxins above prescribed EU limits.
Keith, who is a lecturer on the undergraduate course at SAMS, was awarded a professorship by the University of Highlands and Islands in 2013 and has generated a great deal of research into HABs.
“I don’t spend much time in the lab anymore,” he said, but he is always willing dive in to help his PhD students who continue to investigate HABs.
Keith is currently supervising six PhD students: Grigorios (Greg) Moschonas, Silje-Kristin Jensen, Caroline Sharpes, Rebecca Weeks, Iona Campbell and Ruth Paterson.
Ruth is trying to find out how dinoflagellate Azadinium spinosum operates and the conditions it thrives in, because it produces biotoxins that lead to Azaspiracid Shellfish Poisoning (AZP). Although its effects are similar to diuretic shellfish poisoning, the toxins “appear more severe, with long term effects spanning weeks rather than days and is a major issue in aquaculture,” Ruth explained.
Azadinium spinosum unusually produces toxins during autumn and winter when “you wouldn’t expect there to be many phytoplankton around,” said Ruth who often works in the field.
“Most research has been conducted under laboratory conditions, which aren’t very representative of coastal and environmental conditions. Temperature, salinity and wind can have an effect on algal growth,” she added.
Keith’s work, supported by a vast network of loyal and hard-working colleagues is well on its way to saving the world one harmful algal bloom at a time. As a natural part of ecosystem processes the aim is not to ‘get rid’ of the problem, but to work around it by knowing how to “think like phytoplankton” and avoid the potential impacts by evolving technologies and minds to better mitigate the effects of harmful algal blooms.
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