Sanibel wildlife, especially aquatic wildlife, has had its share of challenges over the last two years with three major storms resulting in large storm surge events.

Hurricane Ian, the most severe of these storms, decimated the freshwater wetlands across the island. Salinities went from 0-4 parts per thousand (ppt) to 14-28 ppt on most of the island and freshwater wetlands were converted to highly brackish or seawater overnight, resulting in die-off and high stress on many aquatic species.

“Over the last two years, many areas have recovered, especially shallow areas, where the very active wet season of 2024 either created new temporary waterbodies or diluted the salt concentration of others,” said SCCF Wildlife & Habitat Management Director Chris Lechowicz.

Although some aquatic freshwater species were severely reduced from freshwater body loss, there was promise of a slow comeback due to heavy amounts of rainfall.

“Within a two-week period, the storm surges from Hurricane Helene and Hurricane Milton inundated many of our recovered or recovering wetlands with salt water again,” said Lechowicz.

Many of these wetlands, especially shallow wetlands, had returned to a mostly freshwater state or 4 ppt or less which has been tolerable to most of the species found on the island.

Now, some of these wetlands are showing salinities as high as 28 ppt again.

Freshwater gamefish that were introduced in 1960 by the J.N. “Ding” Darling National Wildlife Refuge have not been documented since Ian.

“This last event with Hurricane Milton reduces the chances of them existing without reintroduction,” said Lechowicz.

The small live-bearing fish such as sailfin mollies (Poecilia latipinna), mosquitofish (Gambusia holbrooki), and the egg-laying marsh killifish (Fundulus confluentus) were present in good numbers this past year and we expect that they will survive.

Amphibians, frogs, and toads, were beginning to recover across the island as many ephemeral waterbodies filled across the island with the very active rainy season to allow frogs to reproduce and repopulate areas.

“The added saltwater will set this back as frogs will wait to seek out low salinity pools to lay their eggs,” he added.

Barrier islands have ever-changing habitats that can allow certain species to thrive for a period and then change with a storm or two to allow other species to thrive for a finite amount of time.

“Over the ~6000 years of Sanibel’s existence, it is certain that species have come and gone, and even repopulated due to environmental changes to the island,” said Lechowicz.