Impacts of Climate Change on Loggerhead Turtles

by chelseamarie689 (student)

The Impact of Climate Change on Loggerhead Sea Turtles on the Atlantic Coast of Florida

Lauren DeGeorge, Kristin Spiess, Chelsea Linman, Jake Fitzgerald, Kate Forsmark , & El Lorenz

Introduction

Loggerhead sea turtles are an iconic beach reptile. In the face of climate change there is a possibility that this species could be lost without proper mitigation techniques. Loggerheads rely on temperature of both water and air and the availability of beaches in order to properly reproduce, nest, provide nutrients to costal ecosystems, and continue life in the ocean functioning as an important species in sea grass, coral reef, and beach ecosystems (Hawkes, L. A., Broderick, A. C., Godfrey, M. H., & Godley, J., 2007, Wilson, E. G., Miller, K. L., Allison, D., & Magliocca, M., 2003). Climate change threatens Loggerhead sea turtles reproduction processes because of changes in sea temperature, increased storm activity and sea level rise. This can be prevented, however; with proper mitigation measures which include educating the public, continued practice of current conservation methods and increasing the amount of protected shorelines.

The purpose of this study is to provide an overview and analysis of the current literature and to present an estimate of the future populations Loggerhead sea turtles in a changing climate without mitigation. We will also provide a suggestion of the proper mitigation technique to reduce the harmful impacts of climate change and save Loggerhead sea turtle populations on the Atlantic coast of Florida. To do this we used various database and internet sources to gather information on Loggerheads, climate change, and previous studies done on this topic. We then synthesized this data to come to our conclusion.

Loggerhead sea turtles

The Loggerhead turtle is abundant on the Atlantic Coast of Florida with about 80% percent of all nesting takes place in six Florida counties. They are currently listed as threatened under the U.S. Fish and Wildlife Service Endangered Species List (NOAA). These areas are one of the greatest tourist attractions of Florida and tourism is a large part of Florida’s economy. They are also a large source of pride for Florida locals and are an important part of their culture. The viability of Loggerheads is important to our ocean ecosystems and the sandy beaches of south Florida. The loss of this species would have negative impacts (discussed below) on the maintenance of the waters, beaches, and Florida’s economy and culture.

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The Loggerhead sea turtle (Caretta caretta) plays an important role in ocean ecosystems by maintaining and providing key habitats for other marine life and balancing marine food webs. The process of facilitating nutrient cycling maintains healthy sea grass beds and coral reefs, which maintains habitat for countless microorganisms and other marine life. Their powerful jaws allow them to feed on crustaceans and fragment their hard shells which are discarded to the ocean bottom (Wilson et al., 2003). This increases disintegration and the rate at which shells provide nutrients to the benthic ecosystem. In search for food, Loggerheads forage across the sandy sea floor, naturally altering the nutrient distribution of the sediment and benefiting the underwater community (Preen, 1996). Loggerheads also play host to the largest and most diverse communities of epibionts, which attach to their shell to form a commentualist relationship. Loggerhead eggs also contribute to the health of their nesting beaches (Wilson et al., 2003). Nutrients are provided by un-hatched eggs to the sand which aids in the growth of vegetation and thus the stability of beach dunes. The eggs can also provide food to scavengers such as raccoons and ghost crab (Antworth et al., 2006).

Loggerhead nesting typically takes place May through August, peaking in June. Females make their way to the beaches, dig a nest, and lay their eggs (Antworth, R. L., Pike, D. A., & Stiner, J. C., 2006). The average clutch size is about 98.5 plus or minus 1.7 eggs which incubate for about 60 days. Each female will lay two or three nests during the nesting period (Species Fact Sheet : Loggerhead Sea Turtle). In Florida the main risk to Loggerheads are nets from fishing, but with climate change becoming increasingly noticeable it is important to research and prepare for the problems that this species will face.

Climate Change in Florida

It is difficult to accurately predict the impacts that climate change will have on areas like Florida because experts are not able to create accurate reconstructions of past climate due to lack of proxies, like ice cores. Past climate data allows scientists to more accurately create models that account for more changing factors. Scientists have estimated that the air temperature will rise slightly due to urbanization and wetland drainage but not as much as climates further north (Lazarus, 2009). The main impacts of climate change on the Florida coast will be sea level rise and increasing storm frequency and intensity. As the air warms due to increased levels of greenhouse gases in the atmosphere water molecules in the ocean expand and take up more space (Scheinder, S. H., Rosencranz, A., Mastrandrea, M. D., & Kuntz-Duriseti, K., 2009). This phenomenon is already having a visible effect on many coast lines around the world and the sea level on Florida coasts is rising at a faster rate than any in the last 5,000 years (Lazarus, 2009). Research on storms in a changing climate is still very speculative. Tropical storms require warm water in order to form, so the theory is that since surface waters will more frequently be at the temperature required to form a tropical storm they will be able to occur more frequently and maintain greater force throughout their life (Van Houtan, K.S.,& Bass, O.L., 2006). Other potential changes to the Florida climate include drought causing increased wildfire potential, intense rainy season and flooding, and coastal erosion (Lazarus, 2009). The survival of the Loggerhead sea turtle depends on the successful nesting, incubation, and hatching of eggs; both of which are threatened by the impacts of climate change.

Impacts of Climate Change on Loggerhead Sea Turtles

The most significant impact climate change will have on the loggerhead turtles is how it will affect their nesting and reproductive habits. With a warming climate the female’s phenology is altered; they tend to nest earlier in the season which reduces the nutrients available to them and therefore reduces clutch sizes (Antworth et al., 2006). Earlier nesting could also lead to changes in incubation periods. Also, sexual determination is temperature dependent in Loggerhead hatchlings, therefore warmer temperatures favor more females developing. In choosing a mate females are courted by males and are extremely selective. A reduction in the number of males in the Loggerhead population could make in much more difficult for individuals to find a mate as a single female will be courted by multiple males before choosing a mate (Edwards, 1995).

Mitigation

In an effort to protect the nests of Loggerhead hatchlings, it is most important to educate the public, both locals and tourists, on visiting beaches safely. Beaches should be monitored and discovered nest sites should be flagged and marked with informational signs. Local cities on nesting beachfronts should agree to reduce their lighting output during specific night hours within the summer months to avoid unsuccessful hatching. Shorelines need to be protected by banning the use of motorized vehicle use and by limiting development beyond the dunes, in an attempt to prepare for potential sea level rise, due to a change in climate.

Works Cited

Antworth, R. L., Pike, D. A., & Stiner, J. C. (2006). Nesting ecology, current status, and conservation of sea turtles on an uninhabited beach in Florida, USA. Biological Conservation, 130, 10-15. Retrieved from Science Direct.

Edwards, S. (1995). Turtles of Palm Beach [Electronic version]. South Florida Dive Journal.

Hawkes, L. A., Broderick, A. C., Godfrey, M. H., & Godley, J. (2007). Investigating the potential impacts of climate change on a marine turtle population [Electronic version]. Global Change Biology, 13, 923-932.

Lazarus, S. M. (2009). Florida's Climate: Past, Present, and Future. American Institute of Physics. Retrieved from Academic Search Premier.

Loggerhead Turtle (Caretta caretta) (n.d.). In NOAA Office of Protected Resources. Retrieved November 14, 2012

Preen, A. R. 1996. Infaunal mining: A novel foraging method of loggerhead turtles. Journal of Herpetology 30(1): 94-96.

Species Fact Sheet : Loggerhead Sea Turtle (n.d.). In Sea Turtle Conservancy. Retrieved November 16, 2012.

Scheinder, S. H., Rosencranz, A., Mastrandrea, M. D., & Kuntz-Duriseti, K. (2009). Climate Change Science and Policy. Washington D.C.: Island Press.

Van Houtan, K. S., & Bass, O. L. (2006). Stormy oceans are associated with declines in sea turtle hatching. Current Biology,17(15). Retrieved from Academic Search Premier.

Wilson, E. G., Miller, K. L., Allison, D., & Magliocca, M. (2003). Why Healthy Oceans Need Sea Turtles: The Importance of Sea Turtles to Marine Ecosystems [Electronic version]. Oceana.