Harmful algal blooms, otherwise known as HABs, are caused by the unprecedented proliferation of microscopic algae colonies. These events create vivid masses of color in the waters that they plague, all the while threatening oceanic ecosystems, marine life, human health, and coastal economies. HABs are a serious hazard to the world’s oceans (and even freshwater bodies).
But how are microscopic algae so deadly? Aren’t they the base of the oceanic food web?
While algae is certainly crucial to marine communities, too much of these important organisms can become a terrible reality. As the masses of algae in a HAB die and decay, oxygen is severely depleted from the water. This lack of oxygen, or hypoxia, effectively suffocates fish and other marine life, just as air without oxygen would effectively suffocate us and any other lung-bearing creature. HABs can also physically suffocate marine life too, as the shear number of algae in the water can smother gills and bodies. Certain types of HABs are even composed of toxin-producing algae that poison and kill anything that enters or ingests their waters, including humans.
While HABs do occur naturally, many studies have shown that human activities are worsening these already dangerous phenomena. Pollution, agricultural runoff, introduction of non-native species, overfishing, and climate change have all been shown to affect the frequency, scope, and lethality of HABs. Though it’s difficult to fully understand just how deeply any one of these factors impacts HABs, the cumulative effect of our various environmental irresponsibilities is astonishing.
Many scientists dedicate their careers to studying HABs in an effort to better predict them, mitigate their impact, and even prevent them. As citizens, we can do our part by always practicing good stewardship and never using too much fertilizer, reducing our dependence on fossil fuels, eating only sustainable seafood, and so much more.