HABS and the "red tide"

Imagine standing on the ocean shore of Florida, the Gulf of Maine, or the Bering Sea and watching the ocean slowly turning red. It might look beautiful at first, but this "red tide" is actually a harmful algal bloom of the species Alexandrium catenella.

Impacts of Alexandrium catenella

Alexandrium catenella is a dinoflagellate that produces saxitoxins that poison nearby shellfish. If consumed by humans, these toxic shellfish can cause Paralytic Shellfish Poisoning with symptoms of muscle weakness, respiratory issues, and difficulty swallowing or speaking. Neurological complications may also develop. This harmful algal bloom (HAB) is not only injurious to health but can also lead to the decline of shellfisheries that are critical industries and food sources for coastal communities.

Why Are Blooms Increasing?

Over the past few years, Alexandrium catenella blooms have become more and more common. There are a few main reasons for this increase. Firstly, rising ocean temperatures can lead to a more habitable environment for this algae. Secondly, nutrient pollution of nitrogen and phosphorus from fertilizer runoff can lead to larger blooms. In fact, in 2005, there was an especially large bloom of Alexandrium catenella in the Gulf of Maine because of a spike in ammonium levels.

Future

As nutrient inconsistencies and increases in temperature continue, these blooms will likely keep developing. To prevent this from happening, we need to reduce CO2 emissions that fuel the ocean temperature rise and turn to organic fertilizers to decrease nutrient pollution.

Research poster on Alexandrium catenella blooms that I presented at the SEA Ocean Sciences Program