by Kaelin Ferland '23 on March 16, 2023
In October, a harmful algal bloom was detected in Florida. However, the red tide has recently become significantly more dangerous. Since then, the red tide has dispersed its red waters to the entire southwest coast of Florida, spanning 5,000 miles and devastating marine ecosystems. Since Dec. 12, 2022, 20 tons of fish have been found beached along the coast. It’s estimated that 104 sea turtles and seven manatees have also died. Human health is similarly at risk with some Florida residents reporting coughs, difficulty breathing, and burning of the eyes. The red tide is not expected to end in the near future, with conditions expected to worsen before they improve.
Harmful algal blooms are formed when algal growth increases exponentially. Usually, algal blooms aren’t harmful, serving as a food source for animals that rely on them. However, harmful algal blooms, as the name implies, produce toxins that threaten both wildlife survival and human health. If humans inhale these toxins, they will enter the body and cause a variety of health issues including coughing, difficulty breathing, and eye and skin irritation. If contaminated fish are consumed, however, the human health effects can be much more severe, leading to multiple forms of shellfish and fish poisoning illnesses including paralytic shellfish poisoning and neurotoxic shellfish poisoning.
The animal health effects are very similar to those experienced by humans. Harmful algal blooms affect not only fish but also marine mammals and seabirds. Fish and shellfish are part of the diets of many marine species, including dolphins and seabirds. This means that, like humans, these organisms are ingesting toxins by eating contaminated fish. Marine mammals, specifically ones like dolphins and manatees that require oxygen, can also inhale toxins when they visit the surface to breathe, leading to respiratory problems.
A main factor that leads to harmful algal blooms is climate change. Blooms begin to form when there are more nutrients in the water. Nutrients usually enter water via runoff following periods of precipitation. As climate change increases the severity and frequency of weather events, precipitation and runoff will become more common, fueling more harmful algal blooms. Increases in carbon dioxide in our atmosphere also promote algal growth as algae are a plant species that relies on photosynthesis. Increased temperatures are also optimal for algal growth which will become more common due to global warming. Usually, the winter weather moves algal blooms away from the coast. However, as climate change makes our winters milder, this allows harmful algal blooms to persist and cause further damage.
Climate change continues to have a relationship with the most devastating environmental issues we are witnessing today. Actions need to be taken to mitigate climate change and prevent subsequent environmental catastrophes.