Salt water consumption levels remain high in the Sanibel Lakes

LEE COUNTY, Florida. The Sanibel Captiva Conservation Foundation has been monitoring 30 lakes and assessing water quality in Sanibel Slough every month since Hurricane Yan changed the habitat.

Prior to Hurricane Yan, the lakes on Sanibel were mostly populated
freshwater plants and fish. After the storm surge hit, most of the freshwater fish died because they couldn’t handle the increase in salt brought in by the storm.

Prior to Yan, SCCF monitored about 80 lakes, collecting significant data.

In October, the range of water salinity was 20-33 practical units of salinity. The target level for fresh water is a salt intake in the range of 0–1.5 PSU.

SCCF scientist Mark Thompson said that the more rain there is, the more salt will gradually decrease. However, Florida is currently in the dry season, and during this period, the supply of fresh water to the lakes is reduced.

Replenishment of the lakes with local freshwater fish is not possible in the current state of the water due to animal intolerance to salt.

“When we looked at the rate of salinity decline after the storm surge, we estimated that this could happen at least next summer until the salinity is low enough for local freshwater fish to survive again,” Thompson said.

However, this may take longer.

Some fish species can survive a wider range of salt intake while others cannot. The lakes will begin to naturally replenish with species that can tolerate salt over the next few months.

Salt inflow into the Sanibel lakes remains at the sea water level and will not decrease until groundwater is replenished with fresh water.