Nearly anyone who lives within close proximity to a coastline is familiar with the term “red tide.” It bodes possible crisis for recreational and commercial fishing, and piques the curiosity of tourists and travelers who have never beheld such an event. But what is a “red tide” event, and what causes it? Is it dangerous to human and animal life? Is a “red tide” always necessarily red?
A “red tide” is the term that is used to describe an event in which algae, whether it be marine, estuarine, or freshwater, accumulate rapidly in the water column due to a couple of main factors. One is entirely biological, where the algae reproduce based on the upwelling of ocean currents, which is a natural occurrence in the cycle of ocean seasons. Another purported cause is due to the runoff from chemical fertilizers and other man-made products, which introduce superfluous nitrates and phosphates into seawater, which encourages the flourishing of phytoplankton that make up the algae bloom. While the “red tide” has been a natural event throughout time based on ecological factors, attention is being focused on how much human activity actually contributes to the severity and length of a “red tide” event.
The reason “red tide” keeps appearing in quotation marks is because the scientific community is estranging itself from that one term that describes many types of algae events. The term “red tide” instills a sense of dread and fear in the populous, while not accurately describing a variety of algal events. In reality, a “red tide” is not always necessarily red, or dangerous. Instead, it is being re-branded as an “algal bloom”, which more fully encompasses the various types of algal events, and makes it less apocalyptic in the sense that it does not necessarily spell disaster.
Algal blooms can certainly cause loss and damage in certain areas, depending on the type of algae that is proliferating the area. For instance, karenia brevis, commonly found in the Gulf of Mexico, is found naturally in this area. However, a high content of the microscopic algae can result in toxins that paralyze local marine life’s central nervous system so they cannot breathe, resulting in the beaching of hundreds to thousands of fish and other aquatic species. Commercial fisheries suffer losses when an algal bloom of this magnitude takes place, and coastal communities are inundated with an ecological hazard. In places where red tides are commonplace, there are status updates to inform the public of what to expect.
While algal blooms are accused of infusing toxins into seawater and stifling oxygen in the water columns, there are some that need to be taken seriously in terms of the threat they pose to humans. The aforementioned karenia brevis is not only toxic to fish, but can cause toxicity in humans if filter-feeding shellfish from an algal bloom area are consumed. For the most part, algal blooms can be considered a natural part of the earth’s many cycles, and are not necessarily an event to be feared. Algal blooms are actually even more of an incentive to keep the balance in our oceans as far as apex predators are concerned, as they contribute heavily to the reduction of phytoplankton such as these overwhelming an ecosystem.
Have you ever seen an algal bloom? Where and when were you when it occurred?
