Sea turtle eggs are heavily influenced by the environment in which they incubate, including effects on hatching success and hatchling viability (hatchling production). It is crucial to understand how the hatchling production of sea turtles is influenced by local climate and how potential changes in climate may impact future hatchling production. Generalized Additive Models were used to determine the relationship of six climatic variables at different temporal scales on loggerhead turtle ( Caretta caretta ) hatchling production at seventeen nesting beaches in Bahia, Espirito Santo, and Rio de Janeiro, Brazil. Using extreme and conservative climate change scenarios throughout the 21 st century, potential impacts on future hatching success (the number of hatched eggs in a nest) were predicted using the climatic variable(s) that best described hatchling production at each nesting beach. Air temperature and precipitation were found to be the main drivers of hatchling production throughout Brazil. CMIP5 climate projections are for a warming of air temperature at all sites throughout the 21 st century, while projections for precipitation vary regionally. The more tropical nesting beaches in Brazil, such as those in Bahia, are projected to experience declines in hatchling production, while the more temperate nesting beaches, such as those in Rio de Janeiro, are projected to experience increases in hatchling production by the end of the 21 st century.

Climate change is expected to impact animals that are heavily reliant on environmental factors, such as sea turtles, since the incubation of their eggs, hatching success and sex ratio are influenced by the environment in which eggs incubate. As climate change progresses it is therefore important to understand how climatic conditions influence their reproductive output and the ramifications to population stability. Here, we examined the influences of five climatic variables (air temperature, accumulated and average precipitation, humidity, solar radiation, and wind speed) at different temporal scales on hawksbill sea turtle (Eretmochelys imbricata) hatchling production at ten nesting beaches within two regions of Brazil (five nesting beaches in Rio Grande do Norte and five in Bahia). Air temperature and accumulated precipitation were the main climatic drivers of hawksbill hatching success (number of eggs hatched within a nest) across Brazil and in Rio Grande do Norte, while air temperature and average precipitation were the main climatic drivers of hatching success at Bahia. Solar radiation was the main climatic driver of emergence success (number of hatchlings that emerged from total hatched eggs within a nest) at both regions. Warmer temperatures and higher solar radiation had negative effects on hatchling production, while wetter conditions had a positive effect. Conservative and extreme climate scenarios show air temperatures are projected to increase at this site, while precipitation projections vary between scenarios and regions throughout the 21st century. We predicted hatching success of undisturbed nests (no recorded depredation or storm-related impacts) will decrease in Brazil by 2100 as a result of how this population is influenced by local climate. This study shows the determining effects of different climate variables and their combinations on an important and critically endangered marine species.

The environment and climate in which sea turtle eggs incubate affects how successful and viable hatchlings are. Therefore, it is crucial to understand how local climate impacts sea turtle hatchling production as well as how potential changes in climate may impact future hatchling production. In this study, we investigated the effects of five climate variables at different temporal scales on loggerhead sea turtle (Caretta caretta) hatchling production from North Florida, USA. Humidity, air temperature, and accumulated precipitation were the main climatic drivers of hatchling production, while sea surface temperature and wind speed did not demonstrate to have strong effects. Climate projections show air temperatures increasing at the nesting beaches throughout the 21st century, while precipitation and humidity projections vary between sites and projection scenarios. Due to the temperate nature of these nesting beaches, increases in hatching success for nests that incubate undisturbed (not affected by depredation and storm-related impacts) are projected for this region by 2100. This study demonstrates how different climate variables and their interactions can have a determining effect on an important marine species.

Florida's rich biodiversity is the product of climatic conditions Key Messages Climate Change Impacts on Biodiversity and Ecology• Climate change has differential impacts on: coastal ecosystems, freshwater wetlands, and upland ecosystems. Coastal ecosystems, in particular, are subject to the "squeeze" of human impacts, changing climate, and rising sea levels.• The Florida Keys and the Everglades are particularly vulnerable to sea level rise over the next 50 to 100 years due to their low elevation (typically less than 1 m).• Out of 1,200 species tracked by the Florida Natural Areas Inventory, 25% are likely to lose at least half of their current habitat due to sea level rise alone.• Florida's species have migrated and adapted to climate change in the past, but that ability is severely compromised now due largely to human modification of the landscape. Up to 76% of 236 surveyed species were deemed unlikely to be able to relocate inland in response to rising sea level.• Several keystone species are particularly vulnerable to the impacts of climate change and the loss of these species can have cascading impacts on natural communities.• Sea turtles are likely to respond to climate change through altered sex ratios of hatchlings, northward movements of rookeries, decreased reproductive output due to storm events, and potential shifts in foraging ground locations. • BETH STYS ET AL.• Phenology, or the timing of life history events, are likely to change in response to climate shifts, both as the climate becomes warmer but also as it becomes more variable. This is particularly true for plants and can cause major disruptions to co-evolutionary relationships, such as those between pollinators and the plants they pollinate. Existing Stressors and Climate Change• Habitat loss and degradation are the leading causes of extinctions in Florida and globally.The impacts of climate change on species and natural communities are greatly magnified by decreased adaptive capacity due to habitat loss and degradation.• Many invasive species are projected to have enhanced fitness under future climate change scenarios, potentially causing greater disruption to natural communities.• Climate change is projected to increase the vulnerability of native species to foreign and domestic pathogens and parasites.• Overexploited species have diminished capacity to adapt to climate change, making them especially vulnerable. Preserving Biodiversity for the Future• Planning for climate change involves impact assessments, adaptation scenario planning, and research and monitoring.• While many of the ways in which species and natural communities respond to climate change are gradual, other changes can be abrupt and non-linear. These so-called thresholds, trigger points, or paradigm shifts are harder to predict, but are often more consequential than linear patterns of change through time.

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