Global warming is commonly associated with the melting polar ice caps and algal blooms in oceans with increasing greenhouse gas emissions and decreasing levels of oxygen. However, lack of oxygen levels also highly affected fish populations, as witnessed by residents from Biscayne Bay, Florida, when thousands of fish were found dead.
Experts also fear that coral bleaching may soon follow. Corals are known to be very sensitive to environmental conditions such as temperature, pollution, light, fishing, and human contact. Stressful conditions force corals to expel algae that live within them while becoming more vulnerable to disease and pollution.
Chris Langdon of the Coral Reefs and Climate Change Laboratory at the University of Miami described the double threat that corals are facing. "Heat is breaking records, and there are more nutrients flowing into the bay, so we are watching closely for signs of stress on the corals."
Florida's coral reefs also face other stressors such as acidification, boat traffic, and dredging. The recent incident with the dead fish is just further proof that water conditions are getting worse.
Thousands of Dead Fish
On August 10, thousands of dead fish were scattered all over the northern side of the bay where temperatures reached 90 degrees Fahrenheit and oxygen levels were depleted. Since then, the government and environmentalists have used massive pumps to mix seawater with air to increase oxygen levels.
Todd Crowl of the Institute of Environment at Florida International University explained, "In principle, taking low-oxygen water from the water column and spraying into there should greatly increase the oxygen molecules that bind." In Miami, they have also set up ground-level water pumps to help make more oxygenated water.
Researchers from the FIU CREST Center for Aquatic Chemistry and Environment have tested the waters for toxic nutrients such as nitrogen or phosphorus but found no traces of toxic algal blooms. Scientists believe that chronic pollution, they dying population of seagrass, and nutrient discharges from canals all contributed to the damage.
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Coral Bleaching
In early July, Brian McNoldy of Rosenstiel School of Marine and Atmospheric Science shared that the Virginia Key recorded its warmest temperature at 92.5 degrees Fahrenheit. NOAA's Coral Reef Watch said that summer temperatures usually peak much later in August, where Biscayne Bay temperatures went from 88 degrees to 90 degrees.
Experts are anticipating that they bay temperatures will get warmer still. "If the temperatures continue to rise as they're forecast to, we're likely to see coral bleaching increase across South Florida," shared Mark Eakin from NOAA. Up to 10 percent of the coral might begin to bleach.
They have already put the keys under level one alert of bleaching, which may soon become level two if large amounts of coral die under the present conditions. Weaker coral species have already died due to pollution, global warming, and other human activities while the more resilient species remain. Other threats include tropical storms and hurricanes.
"It's possible we could see a mass bleaching event if these temperatures don't drop," shared Cory Walter, a biologist from Mote Marine Lab. "If it's really bad, it almost looks like it snows on the reef because everything turns white."
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