New Publication on Leatherback turtles

Tomillo, P., Saba, V. S., Lombard, C. D., Valiulis, J. M., Robinson, N. J., Paladino, F.V., Spotila, J. R., Fernández, C., Rivas, M.L., Tucek, J., Nel, R. nd Oro, D. 2015. Global analysis of the effect of local climate on the hatchling output of leatherback turtles. Scientific Report, DOI: 10.1038/srep16789

Photo from www.seeturtles.org

Summary: The most recent climate change projections show a global increase in temperatures along with precipitation changes throughout the 21st century. However, regional projections do not always match global projections and species with global distributions may exhibit varying regional susceptibility to climate change. Here we show the effect of local climatic conditions on the hatchling output of leatherback turtles (Dermochelys coriacea) at four nesting sites encompassing the Pacific, Atlantic and Indian Oceans. We found a heterogeneous effect of climate. Hatchling output increased with long-term precipitation in areas with dry climatic conditions (Playa Grande, Pacific Ocean and Sandy Point, Caribbean Sea), but the effect varied in areas where precipitation was high (Pacuare, Caribbean Sea) and was not detected at the temperate site (Maputaland, Indian Ocean). High air temperature reduced hatchling output only at the area experiencing seasonal droughts (Playa Grande). Climatic projections showed a drastic increase in air temperature and a mild decrease in precipitation at all sites by 2100. The most unfavorable conditions were projected for Sandy Point where hatching success has already declined over time along with precipitation levels. The heterogeneous effect of climate may lead to local extinctions of leatherback turtles in some areas but survival in others by 2100.

New Book !!!!! Edited by R. Spotila and P. Santidrián Tomillo: The Leatherback Turtle - Biology and Conservation

New book out now!! 
The leatherback Turtle, Biology and Conservation. 
 Edited by J. R. Spotila and P. Santidrián Tomillo. Johns Hopkins University Press.

Weighing as much as 2,000 pounds and reaching lengths of over seven feet, leatherback turtles are the world’s largest reptile. These unusual sea turtles have a thick, pliable shell that helps them to withstand great depths—they can swim more than one thousand meters below the surface in search of food. And what food source sustains these goliaths? Their diet consists almost exclusively of jellyfish, a meal they crisscross the oceans to find.Leatherbacks have been declining in recent decades, and some predict they will be gone by the end of this century. Why? Because of two primary factors: human redevelopment of nesting beaches and commercial fishing. There are only twenty-nine index beaches in the world where these turtles nest, and there is immense pressure to develop most of them into homes or resorts. At the same time, longline and gill net fisheries continue to overwhelm waters frequented by leatherbacks.
In The Leatherback Turtle, James R. Spotila and Pilar Santidrián Tomillo bring together the world’s leading experts to produce a volume that reveals the biology of the leatherback while putting a spotlight on the conservation problems and solutions related to the species. The book leaves us with options: embark on the conservation strategy laid out within its pages and save one of nature’s most splendid creations, or watch yet another magnificent species disappear.

James R. Spotila is the L. Drew Betz Chair Professor of Environmental Science at Drexel University and director of the Center for Biodiversity and Conservation. The founding president of the International Sea Turtle Society and chairman of the board of The Leatherback Trust, he is the author of Sea Turtles: A Complete Guide to Their Biology, Behavior, and Conservation and Saving Sea Turtles: Extraordinary Stories from the Battle against Extinction.  

Pilar Santidrián Tomillo is a Marie Curie Fellow at the Mediterranean Institute for Advanced Studies and the research director of The Leatherback Trust.

 
(have a look inside here)
 

New publication on seaturtles and global change!

Santidrian Tomillo, P., Genovart, M., Paladino, F. V., Spotila, J. R. and Oro, D. Climate change overruns resilience conferred by temperature-dependent sex determination in sea turtlesand threatens their survival. Global Change Biology doi: 10.1111/gcb.12918

Abstract: Temperature-dependent sex determination (TSD) is the predominant form of environmental sex determination (ESD) in reptiles, but the adaptive significance of TSD in this group remains unclear. Additionally, the viability of species with TSD may be compromised as climate gets warmer. We simulated population responses in a turtle with TSD to increasing nest temperatures and compared the results to those of a virtual population with genotypic sex determination (GSD) and fixed sex ratios.

Photo from the web

Then, we assessed the effectiveness of TSD as a mechanism to maintain populations under climate change scenarios. TSD populations were more resilient to increased nest temperatures and  mitigated the negative effects of high temperatures by increasing production of female offspring and therefore, future fecundity. That buffered the negative effect of temperature on the population growth. TSD provides an evolutionary advantage to sea turtles. However, this mechanism was only effective over a range of temperatures and will become inefficient as temperatures rise to levels projected by current climate change models. Projected global warming threatens survival of sea turtles, and the IPCC high gas concentration scenario may result in extirpation of the studied population in 50 years.

New Publications !!

Rivas, M., Santidrián Tomillo, P., Diéguez Uribeondo, J. and Marco, A. Leatherback hatchling sea-finding in response to artificial lighting: Interaction between wavelength and moonlight.

© Dawn Witherington | DrawnbyDawn.com

Over the last decades, growing human populations have led to the rising occupation of coastal areas over the globe causing light pollution. For this reason, it is important to assess how this impact threatens endangered wildlife. Leatherback turtles (Dermochelys coriacea) face many threats of anthropogenic origin including light pollution on nesting beaches. However, little is known about the specific effects. In this study we studied the effect of different light wavelengths (orange, red, blue, green, yellow and white lights) on hatchling orientation under the presence and absence of moonlight by analyzing: (i) the mean angle of orientation, (ii) crawling duration, and (iii) track patterns. Hatchling orientation towards the sea was always better under controlled conditions. In the absence of moonlight, leatherback hatchlings were phototaxically attracted to the experimental focus of light (misoriented) for the colours blue, green, yellow and white lights. Orange and red lights caused a lower misorientation than other colors, and orange lights produced the lowest disrupted orientation (disorientation). On nights when moonlight was present, hatchlings were misorientated under blue and white artificial lights. Crawling duration was low for misoriented hatchlings and high for the disoriented individuals. Our conclusion to this is that hatchlings can detect and be impacted by a wide range of the light spectrum and we recommend avoiding the presence of artificial lights on nesting beaches. Additionally, actions to control and mitigate artificial lighting are especially important during dark nights when moonlight is absent

Journal of Experimental Marine Biology and Ecology 463 (2015) 143–149

Dornfeld, T, Robinson, N. J, Santidrián Tomillo, P., Paladino,  · Frank V. Ecology of solitary nesting olive ridley sea turtles at Playa Grande, Costa Rica

© Dawn Witherington | DrawnbyDawn.com

Olive ridley turtles (Lepidochelys olivacea) have two distinct mating systems: independent (solitary) and synchronized and mass assemblages (arribadas). Arribada nesting beaches have been the focus of most research, even though solitary nesting is the most common behavior. The purpose of this study was to assess the contribution of solitary nesting turtles to the olive ridley turtle population. We studied the nesting ecology of solitary nesting olive ridley turtles within the national park Parque Nacional Marino Las Baulas (PNMB) in Playa Grande, Costa Rica (10°20′N, 85°51′W) and compared these turtles to nearby arribada turtles. Between 2009/2010 and 2013/2014, an estimated 933 nesting activities occurred within PNMB. This number of turtles has not changed significantly since 1995. During this study, 285 females were tagged; of these, 30 females were encountered nesting on more than one occasion. Significantly, more females emerged (31.1 % of tracks) during the third-quarter moon, often a predictor. of arribada events, than any other moon phase. However, there was no significant change in nesting activity at PNMB during nearby arribada events. Mean hatching success (78.5 ± 23.4 % SD) was higher, and incubation temperatures were lower (ranging from 28.3 to 33.4 °C) than at nearby arribada beaches. Thus, clutches are relatively successful and may produce males. These data suggest that solitary olive ridley turtles are important. Currently, PNMB protects turtles from October to March; however, hatching success was highest and 40 % of nesting activity occurred during the rainy season (August–November). More turtles could be protected by increasing the temporal scope of park protection.

Marine Biology: DOI 10.1007/s00227-014-2583-7