Severe climatic events affect all species, but there is little quantitative knowledge of how sympatric species react to such
situations. We compared the reproductive seasonality of sea turtles that nest sympatrically with their vulnerability to tropical
cyclones (in this study, “tropical cyclone” refers to tropical storms and hurricanes), which are increasing in severity due
to changes in global climate. Storm surges significantly decreased reproductive output by lowering the number of nests that
hatched and the number of hatchlings that emerged from nests, but the severity of this effect varied by species. Leatherback
turtles (
Dermochelys coriacea) began nesting earliest and most offspring hatched before the tropical cyclone season arrived, resulting in little negative
effect. Loggerhead turtles (
Caretta caretta) nested intermediately, and only nests laid late in the season were inundated with seawater during storm surges. Green turtles
(
Chelonia mydas) nested last, and their entire nesting season occurred during the tropical cyclone season; this resulted in a majority (79%)
of green turtle nests incubating in September, when tropical cyclones are most likely to occur. Since this timing overlaps
considerably with the tropical cyclone season, the developing eggs and nests are extremely vulnerable to storm surges. Increases
in the severity of tropical cyclones may cause green turtle nesting success to worsen in the future. However, published literature
suggests that loggerhead turtles are nesting earlier in the season and shortening their nesting seasons in response to increasing
sea surface temperatures caused by global climate change. This may cause loggerhead reproductive success to improve in the
future because more nests will hatch before the onset of tropical cyclones. Our data clearly indicate that sympatric species
using the same resources are affected differently by tropical cyclones due to slight variations in the seasonal timing of
nesting, a key life history process.
Keywords
Caretta
caretta
-
Chelonia mydas
- Climate change -
Dermochelys coriacea
- Erosion
Communicated by Anssii Laurila.