New Publication on sea turtles!

Santidrián Tomillo, P., Pujol, F., Félix, G., Núñez-Reyes, V., Saba, V., Tomas, J., Marco, A., 2023 Colonization of new nesting areas could provide climate refuge to loggerhead turtles under climate change. Biological Conservation, 284. https://doi.org/10.1016/j.biocon.2023.110146

Abstract: Climate change can impact regional and global biodiversity for multiple reasons. In sea turtles, changes in local climate at nesting beaches can affect egg and hatchling survival and primary sex ratios. Sea turtles could respond to climate change by occupying new nesting areas. The recent increase in sporadic nesting in the western Mediterranean may indicate colonization of new nesting beaches. We assessed the suitability of a western area, the Balearic Islands (∼1500 km from current nesting grounds) as climate refuge for loggerhead turtles (Caretta caretta) under current (2015–2017) and climate change scenarios to the mid (+40 years) and end (+80 years) of the 21st century. Using a correlative approach based on air and sand temperatures, we predicted nest temperatures and sex ratios for 19 beaches. Most beaches could provide viable temperatures and predominantly produce male hatchlings under all scenarios. 

Photo: wikipedia.com

 Sex ratio projections were male-biased but with an increasing female ratio throughout time. Although mean sex ratio under the +80 years scenario was still male-biased, the warmest beaches could provide female-biased ratios, which are similar to those estimated for current nesting sites. The Balearic Islands could function as climate refuge for loggerhead turtles in the Mediterranean because temperatures could favor embryo viability and a male sex ratio. However, a nesting population may not be established until the percentage of female hatchlings increases and turtles return to nest as adults. Conditions at sea should also favor survival of hatchlings and juveniles. Because western Mediterranean beaches are popular tourist destinations, active management may be needed to protect nesting populations.

New Publication on Sea Turtles range expansion!

Santidrián Tomillo, P., Tomás, J., Marcos, A., Panagopoulou,A. and Tavecchia,G. 2022 Enviornmental changes in the Mediterranean Sea could facilitate the western expansion of loggerhead turtles. MEPS DOI: https://doi.org/10.3354/meps14149

ABSTRACT: Climate change may affect life on Earth in multiple ways. Whereas some populations may encounter detrimental conditions that cause extirpations, those occupying cooler thermal limits of a range may benefit by expanding. For sea turtles, egg maturation in the female oviduct and nest incubation are temperature-dependent and vulnerable to climate change. 

Mediterranean loggerhead turtles Caretta caretta nest in the eastern basin although sporadic nesting occurs on the western side. To assess the likelihood of a climate-related expansion, we compared historical air and sea surface (SST) temperatures between locations near established eastern nesting areas and western areas where sporadic nesting is increasing (Palinuro, Italy) or just started (Balearic Islands, Spain). Our results suggest that summer air and water temperatures in western sites were suitable for nesting over the last 40-50 yr, at least in July-August, having (1) SSTs above suboptimal threshold temperature (22°C) and (2) similar air temperatures to those of Greece, but among the lowest in the Mediterranean. There was a decreasing east-to-west gradient in SST. However, SSTs were similar around beaches of Zakynthos (Greece), Palinuro and Ibiza (Balearic Islands), where SST was above 22°C for at least 60 d, potentially allowing turtles to lay multiple clutches. A warming trend was detected in air temperature and SST since the 1970s-1980s. Although conditions in the western Mediterranean currently seem suitable for nesting, lower air temperatures in May-June and higher precipitation in September could shrink the nesting window. If warming continues, conditions in the western basin could progressively become more favorable for nesting.