Climate and its repercussions on reproduction and survival of Dermochelys Coriacea (leatherback sea turtles)

Global warming is a well-known phenomenon, which is directly related to the decay of the Dermochelys Coriacea population. Throughout the investigation, different harmful factors, all sparked by the climate change, will be regarded more closely, such is the case of the effects of the loss of the ice caps, changes in precipitation and coastline erosion.

IMAGE 1. Winter multi-year ice cover and sea volume in the Arctic Ocean between 2004 and 2008

Effects of the loss of the ice caps

Apart from rising oceanic levels, the melting of the polar ice caps releases more greenhouse gases into the atmosphere (gases that were trapped within the ice), as well as varying the heat movement across the globe. As the poles melt, and freshwater mixes with salt water, dissolving it, a fall in density occurs, which in turn alters the sea’s heat carrying capacities, and affects ocean currents. The loss of density and further damages to water quality could lead to the harm of reproductive and feeding habits of species like the leatherback ocean turtle.

IMAGE 2. Near-surface currents and vertical thermal structure in the eastern tropical and South Pacific, based on climatological annual data

Coastline ErosionWhen the concentration of gases in the atmosphere increases, the loss of ozone allows for the sun’s rays to penetrate more strongly. As a consequence, seawater levels increase at a very rapid rate. If sea levels swell, the overall movement of masses of water decreases, implying that not only the deposition of sediments will not happen, but also the location designated for the turtle eggs will be deteriorated, limiting the amount and quality of the offspring. After spawning occurs, and in order for the recently born turtles to walk safely into the sea, a quality beach is required, meaning that eroded coasts are unsuitable for the proper spawning of the turtles.

IMAGE 3. Aqua monthly climatology composites between 2002 and 2009

PrecipitationPrecipitation is directly related to reproductive patterns of leatherback sea turtles. It has been found that during the rainy season (La Niña), the laying of eggs decreases, contrary to the behaviour observed during the phenomenon of El Niño (dry season). While under “El Niño”, and due to the light surge it brings, photosynthesis rate increases, leading to an ascent in the food availability, which eventually generates an increase on the birth rate.

BibliographyImage 1. Author: Icesat, NASA, title: Trend in winter sea ice volume , internet: http://static.betazeta.com/www.fayerwayer.com/up/2009/07/365871main_earth3-20090707-full.jpgImage 2. Author: 10.1371/journal.pbio.0060171.sg001 Title: Schematic representation of near-surface currents and vertical thermal structure in the eastern tropical and South Pacific, based on climatological annual data. ; internet http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0060171Image 3. Author: S Cerdeira–Estrada, G López–Saldaña Title: MODIS/ Aqua monthly mean climatology composites for 2002-2009, internet: http://www.scielo.org.mx/img/revistas/ciemar/v37n2/a10f2.jpg Publication: Copeia 1998(2) internet http://science.nationalgeographic.com/science

Threats of the turtlesOften, human interaction has a negative effect on the turtle population, affecting it’s homeostatic abilities with chemical pollutants such as phthalates, moreover it is common for the turtles to confuse plastic bags with food leading to malnutrition, suffocation, or even poisoning. Furthermore and although their hunting is forbidden, they are frequently caught by fishermen accidentally , and used as bait, diminishing their numbers.

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Relevance of the Leatherback Sea Turtle

If this turtle species were to become extinct, the whole of the natural balance of the sea ecosystem would be affected, as the turtles serve as a natural regulator of species such as jellyfish and several other species of cephalopods. This would in turn result in over preying of these animal’s food sources, which are organisms such as fish and the vital zooplankton, this unbalance would severely harm the entire sea food web and biosphere. The disappearance of the Leatherbacks would also mean one less food source for animals like Monitor Lizards, and Sea Gulls, (who prey on the newborn turtles) expanding the damage even beyond the sea.

TABLE 1.Variables affecting seaturtles

Maria Paula Aguilera, Luis Alejandro Bravo, Mario Dániel, Daniela Gómez, Daniela Infante, Melizza Mosquera, Juliana Penagos 11A