American Oceans

Red Tides in Tampa Bay: What’s the Deal?

Red tides can be deadly to some and downright unpleasant to others. Here’s what you need to know about red tides and what’s happening in Tampa Bay right now.

What is a Red Tide?

For starters, we need to understand what exactly a red tide is. In short, a red tide is a type of harmful algal bloom (or HAB) — this occurs when colonies of algae grow out of control in any given area. An oversaturation of algae — especially toxic algae — can easily diffuse into the food chain, rendering things like fish and shellfish dangerous to eat. True to its namesake, these HABs often turn the water red due to their unique coloration. 

red tide phenomenon in tampa bar, florida

Not all algal blooms are harmful. Most blooms, in fact, are actually beneficial as these small plant organisms are food for many animals in the ocean. They are a keystone species in the ocean — most ocean life would not exist without algae to eat. That being said, when the algae does, on rare occasions, become toxic, it is hard to avoid local wildlife that hasn’t been affected by the bloom. 

Even non-toxic blooms, when unchecked, can harm ecosystems — when masses of algae decompose after death, the specific process of decaying can lower oxygen levels in the surrounding area, forcing wildlife around the bloom to either leave the area or risk death. 

What’s Happening in Tampa?

The particular bloom that’s overtaken Tampa Bay is almost assuredly the result of a manmade disaster: more than 200 million gallons of polluted water was dumped into the bay between late March and early April by a fertilizer plant in Manatee County, Florida. 

The state of Florida allowed this to happen because professional regulators feared the nearby reservoir was on the verge of collapse, putting dozens of neighborhoods and businesses at risk of a severe flood. Instead of pushing the limits of the reservoir, it was emptied into the nearby bay, along with all the nitrogen an algal bloom would ever need to feed. 

dead fish affected by red tide in tampa bay
Dead fish washed up on Tampa Bay

Florida’s wildlife agency notes that red tides have been spotted in the gulf and recorded as far back as the 1700s and are even mentioned in the records of Spanish explorers. Nobody knows quite what causes (or determines the end of) a red tide, only that the occurrence and duration of these kinds of algal blooms depend on certain factors like sunlight, nutrients, salinity, and the direction and speed of the wind and water currents. 

Researchers believe that recent southerly winds likely blew in the tides north, where they eventually hit Tampa Bay. Scientists believe drought conditions and a lack of freshwater have left the estuary with high salinity levels that are conducive to the algae that cause a red tide.

Tides can last as little as a week or up to a year. In addition to this, they tend to ease up a little and reoccur, making them unpredictable. 

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