Low oxygen levels likely killed fish that washed into Moorings Bay in Naples

Low levels of oxygen likely killed thousands of fish in Naples over the weekend, according to a city official.

A drove of rotting fish carcasses washed into Moorings Bay on Sunday. Dead fish also washed up on several beaches, including Barefoot Beach. 

Naples Natural Resources Manager Stephanie Molloy said water samples of Moorings Bay show low oxygen levels but no traces of red tide or a diatom bloom that has been detected in local waters and that also causes low levels of oxygen.

Previously:Thousands of dead fish litter Naples' Moorings Bay; cause of death unknown

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"It does appear likely that the fish kill is due to low levels of dissolved oxygen," she said, "but we don’t know if that happened in Moorings Bay or out in the Gulf and then the fish washed into the bay."

Crews collected 17 garbage bags of fish carcasses Tuesday, Malloy said, but there will likely be many more as they continue their work throughout the week. She also said most of the fish are bait fish.

The city does not have plans to test the oxygen levels of the Gulf, Malloy said, especially since the levels will likely increase due to Hurricane Michael churning the water.

Meanwhile, scientists found no traces of Karenia brevis, the microorganism that causes red tide, at any Collier beaches earlier this week.

According to the Florida Fish and Wildlife Conservation Commission, the beaches are clear up to Sarasota, where the levels start to increase.

The highest concentration of red tide on the west coast is in the Tampa Bay area, where there are more than 1 million Karenia brevis cells per liter.