Brown tide to blame for Indian River fish kill

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For the second time since 2012, the Indian River has experienced a massive fish kill due to a bloom of the algae —  Aureoumbra lagunensis.

The algae, which is miniscule in size, blooms in such large numbers that the water it resides in appears brown, giving it the colloquial name “brown tide.”

Brown tide affects the Indian River lagoon system by making the water brown, and not allowing sunlight to pass through it to reach the seagrass beds on the bottom of the lagoon. These seagrass beds form habitats for small, growing fish, crabs, shrimp and oysters. Seagrass is also a staple of a manatee’s diet.

The brown tide algae also decreases the level of dissolved oxygen in the water, causing fish to die from lack of oxygen.

The last time the brown tide bloomed in the Indian River in 2013, more than 120 manatees died in one year.

Brown tide has plagued the Indian River Lagoon system since it first appeared in 2005, with bloom levels appearing in 2013 and 2016. The same brown tide appeared in Texas’ gulf coast in the 1990’s killing off seagrass in the area.

Charles Jacoby, an environmental scientist with the St. John’s Water Management District hopes that low temperatures in the lagoon will cause the brown tide to die out, but if the blooms persist into the spring, the algae will grow better in warmer water temperatures.

The problem that’s perceived now is that the algae that’s killing smaller fish will have a ripple effect that will eventually cause larger predators such as dolphins to be affected. Once fish start to die off, they will then be decomposing in the river and create even more environmental issues.

Jon Shenker, a fish biologist at Florida Tech, voiced his opinion.

“My biggest concern is that it might have also affected all of the juvenile fish,” Shenker said. “We may still see a bunch of big fish around, but in a few years, there aren’t going to be any new fish to replace all of the old fish.”

Across the state, residents are trying to find some sort of legislator or organization to blame. A petition to get Rick Scott to stop Lake Okeechobee discharge into the Indian River gained over 21,000 petitions.

Some believe that the Army Corps of Engineers pumping out high levels of water in Lake Okeechobee has led to the algae bloom in the Indian River and subsequent eutrophication due to the large amount of fertilizer in the agricultural wetlands surrounding Lake Okeechobee. This “back pumping” of polluted waters from Lake Okeechobee, which reached a record high at the end of January, consisted of water coming mainly from sugar farms.

Similar circumstances occurred before the algae bloom in 2013 as Lake Okeechobee rose 16 feet above normal levels after Tropical Storm Isaac.