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AQUACULTURE Q


iEye


n the sky


Satellite technology can help aquaculture sectors such as the shellfish industry to accurately monitor and forecast water quality events such as harmful algal blooms


24 Words: Kelly-Marie Davidson


In spite of their beautiful appearance, algal blooms hide a darker, more destructive side. Harmful algal blooms (HABs) can, as the name suggests, harm or result in the death of other organisms through the production of toxins or rapid oxygen depletion of their surrounding waters. Algal blooms occur when environ- mental conditions are favourable for the algae to thrive. Necessary conditions include a good supply of sunlight, comfortable temperatures and high levels of nutrients such as agricul- tural run-off or sewage. Not all blooms are harmful and the development of a HAB very much depends on its intensity and the species forming it. Subsequently, they can be hard to detect and occur with very little warning, while having a significant impact on many industries that rely on good water quality.


Vulnerable business


The farming or cultivation of seafood is an important source of protein around the world. As global population continues to grow at 1.13% annually, the expansion of aquaculture is considered a key factor in ensuring food security for future generations. In the UK shellfish farming generates a turnover of £20-25 million each year, while worldwide


demand for shellfish is anticipated to increase by 5% a year. This expected growth provides a clear business opportunity for UK shellfish farming. However, without effective strate- gies in place to deal with damaging environ- mental events such as HABs, it will be an uphill struggle. Aquaculture industries are vulnerable to


these kinds of biological events and, in particular, the shellfish farming is especially susceptible to HABs as many species intended for our plates are filter feeders and can accumulate HAB toxins in their tissues. In the US, HABs are considered to be a major environmental problem in all 50 states, occurring in both fresh water and sea water.


Climatic impact


Research suggests that climate change is having an impact on bloom frequency, intensity and species composition.


Observations indicate that there is an expansion of HAB distribution across the globe, as waters warm and species move to higher latitudes, and seasonal windows are widening. This is a recipe for earlier, longer and unexpected HAB events. In fact, this year California bore witness to the largest bloom in recorded history, seemingly fuelled by ‘The Blob’ of warm water in the Pacific, that stretched for an estimated 40 miles and went 650 feet deep. Atmospheric CO2


emissions, produced by


the burning of fossil fuels and industrial activities, also play a part in the process. As microscopic plants, algae use dissolved CO2 grow. As CO2 levels continue to increase in the


to


atmosphere, half of this is absorbed by the ocean, which will spur algal growth. The North Pacific Marine Science Organization (PICES), the Global Ecology and Oceanography of Harmful Algal Blooms


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