Everything You Need to Know About Harmful Algal Blooms

Plastic pollution takes over the majority of our conversations regarding the onslaught of ocean-related issues. Photographs of plastic strewn shores are plastered across our social media and news pages nearly every day but let’s take a look at one of the other threats that lingers amongst the waves. As it turns out, not all the ocean’s worries are due to our doing, with nature itself causing mayhem in the form of microalgal blooms, something frequently experienced in some parts of the world but remain almost a complete mystery to those on other coastlines. The presence of harmful algal blooms (HABs) is increasing under climate change and therefore we should all know what to expect and how to protect ourselves.

HABs are produced by microorganisms in the water, with an estimated 60-80 different algae releasing these toxins. Whilst blooms are a totally natural phenomenon, their abundance in the ocean can pose a significant danger to underwater ecosystems, wildlife and even us. Algal blooms consist of various toxins which we can be exposed to in several different ways; from skin contact to ingestion via a contaminated food chain and even the crashing of waves can turn these bothersome aquatic particles into harmful aerosols ready to enter our lungs on every inhale. Once in our systems, these toxins can produce six different types of poisonings with common symptoms including numbness, drowsiness, rashes, flu-like symptoms, asthma or vomiting. In the natural world, HABs have been associated with memory loss in sea lions and the loss of 80% of the breeding shag population in 1968 as these toxins strip the waterproofing from bird’s feathers. Blue-green algae called Cyanobacteria has also decimated some areas of seagrass forest, an essential store of our carbon dioxide.

One of the most well-known algal blooms occurs frequently in the Gulf of Mexico and is commonly referred to as a red tide due to the discolouration of water as algae takes over our crystal blue seas. The toxin which is the culprit for these sometimes year-long blooms in Florida is Brevotoxin which has been seen to impact fish, dolphins and manatees. Studies in the region showed that the usually popular surf breaks filled with a line up of tanned water lovers turn into empty, almost ghostly, areas in the midst of a red tide as the barrelling waves break apart pieces of the toxin, sending them tumbling through the air and provoking asthma like symptoms in people up to one mile inland. However, in areas where algal blooms are a common occurrence, you can keep yourself safe by following signage found on the beach and by checking online updates from organisations such as NOAA and Surfrider Foundation who keep up to date information on all the U.S. states while The Environment Agency is the port of call in the UK. As frustrating as these blooms sound, ruining both the beautiful underwater world and taking away your beach time, they have recently been found to have one potential good use as part of the Brevotoxin particle is believed not only to be the antidote to the illness it causes but is also a way of fixing the abnormal mucus blanket in the lungs which occurs in those who suffer from cystic fibrosis.

For those in remote tropical regions such as Polynesia, their dietary staple of reef fish carry other dangerous toxins during blooms. Due to lacking management systems in these isolated islands, local people often steer clear of the water and fish to avoid contracting this poisoning which occurs in species such as barracuda and snapper, however this means they also miss out on essential protein and the simple enjoyment of being in the water even when there is no bloom sprouting offshore. Therefore, it is important we understand when to stay away from the water and when to run in with childlike excitement.

Many parts of the world do not experience algal blooms very often, however it seems HABs are yet another consequence in the long list of climate change side effects. As waters warm, different species of algae migrate north with a more recent bloom occurring in the Mediterranean over the last few summers, whilst increased carbon dioxide drives an almost firework-like explosion in the size of colourful blooming algae. Therefore, the chance of a bloom occurring where you live may only increase in the coming years while your holiday locations could already be suffering. For many developed nations, monitoring is in place as part of consumer protection laws so when a bloom is detected, shellfish farms are shut down until the waters have been declared clear for two weeks, ensuring that any seafood you buy will be safe. While the changing colour of the water’s surface is one indication of a bloom, some remain invisible and can be detected instead by the smell of rotting plant life, foam or scum on the surface and dead fish washed up onto the sand. Authorities often put up large information signs during a bloom to warn against contact with the water and if you’re still in doubt, it’s best that both you and your pets stay out. Blooms don’t just occur in the sea either as freshwater lakes and reservoirs are also susceptible.

One large contributing factor to the formation of HABs is the level of nutrients in the water. A high level of nutrients, often deriving from human chemicals, can cause rapid growth in marine plant life such as algae, similar to the way weeds can quickly take over neglected land. These nutrients can make blooms not only larger but also longer lasting. To reduce the leaching of chemicals into our watercourses, we can use smaller amounts of fertiliser on our land or switch to organic alternatives instead. This method is already used in parts of Florida as part of a ‘fertiliser blackout’ where fertilisers are banned between June and September and are never allowed to be used in large quantities or near waterbodies. We can also wash our cars on grass instead of on impenetrable gravel or tarmac to prevent soapy suds running down drains and out to sea, mixing with other agricultural or industrial chemicals as it goes. Even simply picking up after your pet helps and these actions not only alleviate HABs but also increase general water quality.

So while many of the ocean’s issues seem far out of our reach, in reality it was the sum of our small actions that exacerbated many natural issues or even caused the problem in the first place. It is therefore our small actions that are the only way to get us out, or in this case, at least improve our water quality, leaving both us and local wildlife to bathe in peace, floating in a clean and sparkling sea.

By Neve McCracken-Heywood