An algae bloom – or algal bloom – has closed beaches in Mississippi and Louisiana in recent weeks. Harmful algae blooms (HABs) can occur in any coastal or Great Lakes state, and can shut down beaches, fishing, and other recreational activities focused on water. The particular blue-green algae in the Gulf releases toxins that can be harmful to our health, potentially causing rash, stomach cramps, nausea, diarrhea and vomiting.
So, how did this happen in the Gulf? The events that set the bloom into motion started back in the winter and spring.
Flooding across the Plains and the Midwest sent a excessive amount of freshwater into the Mississippi River and then into the Gulf of Mexico near Louisiana. Freshwater can contribute to algae blooms by delivering more nutrients and lowering the salinity (salt level) of coastal waters. The consistent input of freshwater, plus the warming sea surface temperatures that naturally occurs in the summer, the algae has been able to grow significantly.
A tropical disturbance could bring some changes to Gulf waters later this week, but unfortunately they might not be good changes. Tropical systems bring a ‘mixed bag’ of effects to algae blooms. The rainfall can cool temperatures enough to threaten further growth, but it can also worsen flooding and add even more freshwater for the algae to grow on. The freshwater being added to the Gulf is likely to be the biggest factor in determining how the algae responds. That means, the tropical cyclone is likely to just help the algae continue growing.
It’s hard to predict when algae blooms will die-off or dissipate, since they’ll last as long as conditions are favorable for the algae. That could last weeks or even months. In this case, the bloom could last through the remainder of the summer season. You should continue to monitor beach conditions and check WHNT.com for the latest on the bloom’s impact(s).