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If you're a salt water organism like those on the reef at the Flower Garden Banks National Marine Sanctuary an influx of freshwater, and the resulting drop in salinity, can kill you.
Scientists noticed a mass deaths among sea life at the Flower Garden Banks after freshwater runoff from flooding on the Gulf Coast hit the reef in 2016. So far, runoff from Hurricane Harvey has not caused the same devastation, although some of the reef has shown signs of stress, researchers said.
“Coral reefs like ocean water, they’re very sensitive ecosystems and they like stable conditions,” said Kathryn Shamberger, a researcher at Texas A&M University. Runoff can introduce pollutants to the reef and also affect salinity, pH and light levels.
"The reef is basically a city where the corals are apartment buildings and there are all sorts of diverse animals and plants living in those apartments," said Adrienne Correa, a researcher Rice University. When one part of the reef, or apartment, is stressed, so too are others. High stress on the reef can lead to mass die-offs like the one in 2016.
Correa said that in 2016 the water was hazy and green, the reef turned pale with pieces its organisms floating around. Right now, there are just small signs of stress. But Correa said researchers are still keeping an eye on the reef.
“We might understand as we have more frequent and intense storms, given climate change, how at risk our coral reef ecosystems are going to be when there's all this freshwater input," Correa said.
Correa said her team will be visiting the reef again in April to observe Harvey's long term effects on the ecosystem.