A "Sea"ccess!

Chaloupka, M., K.A. Bjorndal, G.H. Balazs, A.B. Bolten, L.M. Ehrhart, C.J. Limpus, H. Suganuma, S. Troeng, and M. Yamaguchi. 2008. Encouraging outlook for recovery of a once severaly exploited marine megaherbivore. Global Ecology and Biogeography 17: 297–304. http://accstr.ufl.edu/publications/Chaloupka_etal_GEB_2008.pdf

Mortimer, J.A., R.G. von Brandis, A. Liljevik, R. Chapman, and J. Collie. 2011. Fall and rise of nesting green turtles (Chelonia mydas) at Aldabra Atoll, Seychelles: Positive response to four decades of protection (1968–2008). Chelonian Conservation and Biology 10: 165–176. http://www.swetswise.com.ezproxy.tru.ca/FullTextProxy/swproxy?url=http%3A%2F%2Fwww.chelonianjournals.org%2Fdoi%2Fpdf%2F10.2744%252FCCB-0872.1&ts=1328759412200&cs=3094114707&userName=5786541.ipdirect&emCondId=5786541&articleID=163757158&yevoID=3454990&titleID=39926&referer=4&remoteAddr=192.146.156.172&hostType=PRO&swsSessionId=dgs4vW4-33ycBXdp2TmMhw__.pasc1

Standora, E.A., and J. Spotila. 1985. Temperature dependent sex determination in sea turtles. Copeia 3: 711-722. http://www.jstor.org/pss/1444765

Troeng, S., and E. Rankin. 2004. Long term conservation efforts contribute to positive green turtle Chelonia mydas nesting trend at Tortuguero, Costa Rica. Biological Conservation 121: 111–116. http://www.conserveturtles.org/pdf/scientific/Troeng_Rankin_2005BiologicalConservation.pdf

After a somewhat depressing start to the semester of conservation biology, we are in need of a few success stories to lighten our mood. A prime example of animals that are significantly benefiting from our conservation efforts are the sea turtles (I will focus on the green turtle, Chelonia mydas). Sadly, for the last 141 years, green turtle populations have declined by 37-61%; and as a result, the species is listed as endangered by the IUCN (Troeng et al., 2004). There have been many causes contributing to their decline: (1) exploitation by humans for eggs and meat; (2) conflicts with commercial fishing; and (3) coastal development (Troeng et al., 2004; Chaloupka et al., 2008). Sea turtles are especially sensitive to coastal development, as they are very specific as to what beaches they will nest on, and they tend to return to the same beach year after year. They also have temperature dependent sex determination, where lower incubation temperatures for the eggs result in males, and higher temperatures produce females; therefore, buildings along the coast provide shade that could drastically alter the normal offspring sex ratios of the sea turtles (Standora and Spotila, 1985). The loss of green turtles is of particular concern because they contribute greatly to the health of seagrass and coral reef ecosystems (Chaloupka et al., 2008). In response to these threats, countless sea turtle conservation organizations have been established to try to save these beautiful creatures from extinction.

Monitoring and conservation of the green turtle population began in 1955 (Troeng et al., 2004); yet, sea turtles are a species with late maturity and low population growth rates, so it can take decades to see results (Troeng et al., 2004; Chaloupka et al., 2008).  Multiple studies have shown significant increases in nesting in several different populations over their study periods: 417% increase in Tortuguero, Costa Rica over 32 years (Troeng et al., 2004); 500-800% increase in Aldabra Atoll, Seychelles over 40 years (Mortimer et al., 2011); and up to a 14% increase per year in Florida over 25 years (Chaloupka et al., 2008). Nonetheless, other populations have still been seriously depleted, and numbers for all populations are still below historical abundance levels (Chaloupka et al., 2008). However, these trends reveal the positive effects that worldwide conservation efforts have had on the recuperation of the endangered green turtle populations. Although, there is still a long way to go, the outlook for green sea turtles looks promising!

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