In this era of increased environmental awareness and concern, the term “red tide” appears all too frequently in news all over the world. Native to no particular place and yet equally as unwelcomed as an invasive species, red tide can occur in almost every kind of coastal marine environment. The damage incurred from red tide varies according to the economic stability of a developed area, the ecological sensitivity of the region, and how plentiful the resources are to deal with the invasion.
In order to understand how red tide affects coastal marine ecosystems, it’s important to understand what red tide is. To find this out, the Catalyst interviewed New College professor of political science Frank Alcock.
“It is a dinoflagellate, a plant-like algal species,” Alcock said. Alcock, who remains involved in environmental causes, led a commission that issued the first policy report on red tide in Sarasota.
“It’s ancient!” he said. “Its DNA is more complicated than ours. It tends to thrive under conditions that are relatively low-nutrient and evolved to the point where [researchers] are pretty sure it initiates off-shore and grows very slowly. If you had a few Karenia brevis [the species currently affecting Sarasota] cells out there with a few other forms of algae and critters and throw a bunch of nutrients in the water, you won’t see much in terms of red tide bloom because the other critters will outdo it.”
This at least indicates that red tide species are very hardy and able to survive. However, they tend to be kept in check by more nutrient-consumptive species. So why is it such a threat, if it gets outcompeted so often?
“It reaches a point where it takes over and dominates and then uses anything to keep itself going,” Alcock said. According to researchers, red tide can reproduce and sustain themselves to the point of stability if they are able to find a patch of water with very little biomass. Once it is established as a vibrant colony, its true potential damage can be caused due to its high levels of motility. Each K. brevis cell produces a toxin called “brevitoxin,” which has been proven to be highly toxic to many species of marine organisms and has directly contributed to fish, dolphin, and manatee kills (to name a few examples). Furthermore, the toxin doesn’t break down as quickly as other solutes (i.e., sea salt) in water and accumulates in the guts of prey species, which are in turn consumed by bigger species such as dolphins, which in turn accumulate the toxin exponentially. This type of cross-species contamination is called “bioaccumulation” and is seen in a wide variety of real-life examples, notably mercury and hard metal accumulation in tuna fat.
Since K. brevis is such an environmentally-dynamic species, what does this mean for public health, the environment, and the local economy?
“[For] anybody who’s at the beach, if the wind blows on their face, it can cause irritation of the respiratory tract and their sinuses will burn a little and they’ll get a cough, which is called a ‘red tide cough,’” Alcock warned. “But once they get about a mile away from the shore, they’ll feel better. Now, with vulnerable populations like those with asthma and the elderly, impacts can be more longer-lasting. The research shows that people will show signs of respiratory problems a few days later. More rare and more acute problems are shellfish poisoning.
“Economically, when there’s a bunch of dead fish laying on the beach, people don’t want to come to the beach and they don’t want to eat in the restaurants right on the water with a bunch of smelly dead fish or an irritating sting from breathing the air, so red tides can inundate an area for a period of time and have severe economic impacts,” he continued.
“For a little tiny species of algae, it’s remarkable and complex,” Alcock noted aloud.
He would not be alone in his coupled feelings of dread and admiration for the potentially destructive organisms.