Global Sea Turtle Resilience to Climate Change

            Many people are well aware of the sea turtle conservation efforts that have been implemented in the past decade. Six of the seven marine turtle species are considered threatened or endangered worldwide. The past threats to turtle populations can be attributed primarily to fisheries, illegal markets, and coastal development. However, the future holds an even greater potential threat to marine turtles: climate change. A primary concern is that climate change will compound the threats that sea turtles already face. Turtles are extremely vulnerable to environmental temperature changes because of their rather complex life history. Climate change could detrimentally affect both hatchling and adult turtles in a variety of ways. The most apparent threat involves multiple aspects of their reproduction. Marine turtles exhibit temperature-dependent sex determination. Elevated temperatures could feminize populations and possibly decease reproductive success overall. Other concerns include the loss of nesting beaches and changes in food availability.

            Resilience can be described as a species’ ability to adapt or resist to environmental change. Fuentes and colleagues set out to quantify the resilience of marine turtle species around the world. More specifically, they sought to better understand the factors that are important to genetic diversity, geographic distribution and breeding population size. The researchers consulted with over 200 of the world’s leading marine turtle experts to obtain the resilience criteria to be used in their analysis. The consultants were knowledgeable of 58 marine turtle populations around the world, which are termed Regional Management Units (RMU’s). The goal of the researchers is to determine which RMU’s could be most threatened by climate change and to identify the factors that make these populations susceptible.

            The study assessed two types of traits that affect population characteristics: population trends/threats to genetic diversity and non-climactic threats (fisheries, coastal development, pollution, etc). The most resilient RMU’s consisted of leatherback and green sea turtle populations in the Atlantic and Indian Oceans. Hawksbill and loggerhead RMU’s were found to be the least resilient, witht he Indian Ocean hosting the largest proportion of least resilient RMU’s. According to the results, the expert correspondents agree that rookery vulnerability and nonclimate threats are the most important variables to the resilience of populations facing climate change. A rookery refers to the nesting population of turtles. Thus, maintaining prime nesting areas is vital for the persistence of RMU’s. Development of the coast along the southeast United States in burgeoning and will pose a serious threat to rookery vulnerability in combination with climate change and other variables. The two most influential non climatic threats to marine turtle resilience were found to be fishery bycatch and coastal development. For six of the least resilient RMU’s, expert correspondents reported fishery bycatch as the most common threat.

            Not only are sea turtles captivating animals, but they are also keystone marine species. They cycle nutrients and bolster coral reef diversity by consuming algae, sponges and corals that compete with each other for space. Quantifying resilience is a complicated task, but Fuentes and colleagues’ study is a great step towards understanding the factors that influence individual populations’ adaptability to changing environmental conditions. It is imperative that we devise future conservation strategies that predict the impact of climate change. Such strategies will have to cater to the deficits of individual populations to adapt to changing conditions.

Source: Fuentes, Mariana M. P. B., David A. Pike, Andrew Dimatteo, and Bryan P. Wallace. "Resilience of Marine Turtle Regional Management Units to Climate Change." Global Change Biology 19 (2013): 1399-406. Print.