Stay in the know about wildlife, water quality, and ecosystems on Sanibel and Captiva Islands and in Southwest Florida

Sea Turtle Nest Found, Beach Impacts Discussed

October 27, 2022

Seventeen sea turtle nests remained on Sanibel and Captiva beaches before Hurricane Ian (out of 787 total during the 2022 season). After the storm, the SCCF sea turtle team used a Trimble GPS device to check on the remaining nests and were able to find one total — a green sea turtle nest. The others likely washed away from wave action and storm surge.

“Unfortunately, the nest we located is not likely to hatch due to the severe and prolonged inundation it experienced,” said SCCF Coastal Wildlife Director and Sea Turtle Program Coordinator Kelly Sloan. “It’s worth noting that sea turtles have a nesting strategy that accommodates for storms — they lay multiple nests per season so as to not put all their eggs in one basket, so to speak.”

SCCF staff member Jacob Wozny looks for a sea turtle nest on Sanibel after Hurricane Ian

It’s likely that the turtles who laid the nests lost during the hurricane successfully produced other offspring during the season, Sloan said, adding that over 35,800 sea turtle hatchlings have emerged on the islands this year. Adult sea turtles likely fared fine during the hurricane — satellite telemetry data from previous studies shows that they change their movement and dive behaviors during large storms, presumably to stay out of harm’s way.

“Sea turtles are very resilient and have adapted to living in habitats that experience hurricanes regularly,” Sloan said.

The team also found an intact water logger on west Sanibel and was able to extract data on water levels during the storm. The maximum depth recorded was 11.6 feet at 2:05 p.m. on Sept. 28, and there was over 8 feet of water from 12-3:30 p.m.

image of graph of water levels

Beach elevation relative to mean sea level decreased across Sanibel and Captiva after the storm, with Captiva experiencing the most significant change. Prior to the storm, Captiva’s sea turtle nest sites averaged 7.2 feet in elevation. That number is now 3.6 feet. Sanibel sea turtle nest elevation experienced an average loss of 1.64 feet on the west end and 1.3 feet on the east end.

“Beach elevation has effects on sea turtle nest conditions including groundwater exposure and ambient nest temperature, which can affect hatchling sex ratios and hatch success,” Sloan said. “The erosion could have been much worse, but there are still certainly areas of the beach that have been heavily impacted. However, we’re optimistic that the beach will continue to provide suitable habitat for nesting wildlife, including sea turtles and shorebirds.”

Other observations include substantial loss of dunes and dune vegetation in many places, as well as the formation of pools of water called runnels and washed-up garbage and debris across the beaches. The team also collected data on beach slope and width, which will be analyzed in the coming weeks.

“Beaches are naturally dynamic and experience accretion and erosion, and they can recover,” Sloan said. “We still have to worry about other factors such as development and coastal squeeze, but for now we are hopeful that the beaches and vegetation will recover to pre-Ian conditions in time for the upcoming nesting season.”


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