Grant: 21-001R
Project Title: Investigating loggerhead sea turtle embryonic tolerance to wave exposure and groundwater inundation
Project Manager: Mariana Fuentes
Organization: Florida State University (Research and Educational Institute)
Grant Amount: $22,902.00
Completion Date: 2022-06-27

Summary: Exposure of sea turtle eggs to tides, groundwater, and waves may result in impacts to nest productivity and hatchling fitness. As sea levels rise and coastal development increases, strategies to assess and manage risks of wash-over, inundation, and erosion to nesting beaches are likely to become increasingly urgent. However, there are still important gaps in our understanding of 1) embryonic tolerance to wave exposure and inundation under natural conditions, and 2) when or how this threat may be addressed to limit unintended consequences. Both gaps restrict the decision-making process for the ongoing conservation of protected sea turtle species. The goal of the project is to describe embryonic tolerance to wave exposure and groundwater inundation in the Florida portion of the northern Gulf of Mexico loggerhead recovery unit. Morning patrols will be used to collect information related to the frequency, duration, and timing of wave exposure across the study area during the nesting season. A subset of nesting locations will receive HOBO water level loggers to provide high temporal resolution (? 1 h) data on inundation frequency, duration, severity, and timing. The wave exposure and inundation datasets will be combined with nest excavation data to evaluate hatching and emergence success as a function of exposure frequency, duration, severity, and/or timing. The outputs of this project will help fill critical knowledge gaps in our understanding of sea turtle biology and further inform our discussions of appropriate management actions, particularly in the face of growing climate threats.

Results: All 16 HOBO loggers were deployed between 16-28 June 2021. Of these, 7 were lost to erosion during TS Fred (16 August 2021), 2 were eroded away by TS Fred but subsequently recovered, and 7 yielded viable inundation data for further analysis. A total of 252 nests were laid on St George Island in 2021 – 230 loggerhead (91.3%) and 22 green turtle (8.7%). 177 (77%) loggerhead nests reported any degree of wave wash-over. TS Fred significantly impacted St George Island – 157 nests (85.3% of nests incubating at the time) reported any degree of wave wash-over, while 94 of these nests (51.1%) completely washed out. 93 loggerhead nests were 1) not washed away, 2) were not predated or otherwise disturbed, and 3) have excavation data available. Hatchling productivity (i.e., hatching and/or emergence success) was not affected by the timing of wave exposure relative to the date the nest was laid. Due to rates of wash-out during TS Fred, HOBO inundation data was only available from 7 nests. This dataset was combined with similar monitoring data from past seasons from the Fort Morgan Peninsula of Alabama, boosting sample size to 28 nests. Hatching and emergence success declined in a similar pattern to wave wash-over and declined to 0 after approximately 20 hours of cumulative inundation. These data were presented virtually at the 40th International Sea Turtle Symposium and a copy of the presentation can be found at https://youtu.be/Vu0djdFqoEg. Additional data from multiple years is currently being accumulated and analyzed for manuscript publication.