Keys Weekly, January 29, 2024
In Florida Bay, the flow of fresh water from Lake Okeechobee in the north through the Everglades nourishes the Keys ecosystems and economies. Anything disrupting this natural process poses a serious threat.
Enter salt – and a lot of it.
“Salinity refers to the salt content in a coastal water body,” explained Steve Davis, the chief science officer at the Everglades Foundation. “Ocean salinity is roughly 35 parts per thousand (ppt). If you’ve ever swam in the ocean and tasted it, you know what that is. When salt content gets higher than that of the ocean, we call it hypersalinity.”
Basically, Florida Bay is becoming hypersaline more often and in greater severity than ever before. We’re to blame.
Davis said, “It’s all driven by water balance. If you don’t have fresh water coming in from the Everglades, it leads to hypersalinity and events like the 2015 mass die off of seagrass.”
Lake Okeechobee is made up of fresh water, with a salinity of zero. The water in Florida Bay is naturally both fresh and salty because it’s composed of the outflow from the lake mixed with ocean water from the Gulf of Mexico and the Atlantic Ocean. However, “there have been recent increases in salt concentration because of no fresh water coming in from the Everglades to flush the system.”
On top of that, the water in Florida Bay gets trapped. As the sun evaporates it, salt is left behind. So, the salinity of the bay begins to increase and becomes greater than the salinity of the surrounding ocean. In years with less than average rainfall such as drought years, effects are exacerbated.
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