Could Global Warming Be Crushing Blow to Crocodiles?

With global temperatures generally on the rise, crocodiles may have a harder time finding mates. For crocodiles, gender is not determined genetically, but rather by embryo temperature during incubation, notes Earthwatch-supported scientist Dr. Alison Leslie, of South Africa’s University of Stellenbosch.

In an interview with three teenagers on a mission to find out about their planet, the subject of the new film A Year on Earth, Leslie explained how global warming could affect crocodile populations worldwide.

“A difference of 0.5 - 1ºC in incubation temperature results in markedly different sex ratios,” says Leslie, principal investigator of Earthwatch’s Crocodiles of the Okavango Delta project. Research shows that nest temperatures of about 32-33 degrees Celsius result in males, while temperatures higher and lower result in females. Temperatures within a nest can vary from the top to the bottom of the nest, and can result in mixed-gender hatchlings.

“More female hatchlings due to the cooler or hotter incubation temperatures could lead to eventual extirpation of the species from an area,” says Leslie.

The three teens, Jamie (18), Arsen (17), and Tyler (16), visited Leslie at her camp in the Okavango Delta, Botswana, where they acted as field research assistants on Leslie’s Earthwatch-supported research expedition. Their participation was part of a feature-length documentary, A Year on Earth, that will air on the Discovery Kids Channel in December.

The teens helped Leslie trap and examine Nile crocodiles big and small to monitor their diet, health, movements, and reproductive biology. Crocodile populations have dwindled dramatically in Botswana, due to overexploitation by hide hunters and conflicts with nearby communities.

“Even though crocodilians have been around for millions of years, and as important as these creatures may be in the systems they occupy, they are a much understudied species,” says Leslie. For more than eight years, in both Botswana and South Africa, Leslie has been working with the support of Earthwatch Institute to change that.

In 2007, Leslie will leave behind her Okavango research camp (in the capable hands of staff member Sven Bourquin), and will embark on a new study of the crocodiles along Zambia’s Zambezi River. Earthwatch volunteers will continue to assist her as she assesses the conservation needs of this population and surveys local villagers about crocodile impacts.

Earthwatch Institute is a global volunteer organization that supports scientific field research by offering members of the public unique opportunities to work alongside leading field scientists and researchers. Earthwatch's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment. The year 2006 marks Earthwatch's 35th anniversary.

See Dr. Alison Leslie in A Year on Earth, a two-part special to debut on Discovery Kids Channel on December 3 and 10. A Year on Earth chronicles the work of three American teens who join Leslie in the Okavango Delta and several other Earthwatch research projects around the world. Together, they discover how ordinary people can make a difference in the most pressing environmental issues of our time.

Source: Earthwatch Institute

Related stories:

Phoenix Returns Treasure Trove for Science
NASA's Phoenix Mars Lander performed its first wet chemistry experiment on Martian soil flawlessly yesterday, returning a wealth of data that for Phoenix scientists was like winning the lottery.
Embryonic Star Captured With Jets Flaring
A developing star wrapped in a black cocoon of dust is seen sprouting giant jets in a new image from NASA's Spitzer Space Telescope.

Research reveals secret to interaction between Earth's core and mantle
Leslie Hayden’s research into deep Earth interactions has led to some important findings, particularly for someone so new to the field, and the scientific world is paying attention. Hayden, a graduate student at Rensselaer Polytechnic Institute, is first author on a paper to be published in the scientific journal Nature. The findings will be published in the Nov 29, 2007 edition of the journal.
Can meteorites carry primitive life from one planet to another?
An academic from the University of Aberdeen will be one of more than 60 scientists and technicians preparing for the European Space Agency’s Foton M3 mission next month.
Engineers Devise New Method of Chemical Vapor Deposition for Smaller Nanostructures
Engineers at the California Institute of Technology have invented an ingenious new method for depositing tiny amounts of materials on surfaces. The researchers say that the technique, known as plasmon-assisted chemical vapor deposition, will add a powerful new tool to the existing battery of techniques used to construct microdevices.
The Living Worlds Hypothesis
Saturn's moon Titan is enveloped in a thick orange haze, and the organic particles that make up that smog have been raining out of the atmosphere and down onto the surface for millennia. This rich chemical brew is thought to be ripe for life's origin, similar in some aspects to Earth in its earliest days.
In lean times, flies can't survive without their sense of smell
It's not just bomb-sniffing dogs; animals everywhere rely on their sense of smell. Now, Howard Hughes Medical Institute and Rockefeller University researchers show just how important olfaction is, proving that fruit flies with a normal sense of smell have a survival advantage over those that don't. The findings, to appear in the July 31 advance online issue of Current Biology, may be useful in controlling insect populations and reducing insect-borne disease.
Hip Bone Density Helps Predict Breast Cancer Risk
Measuring a woman’s bone mineral density can provide additional information that may help more accurately determine a woman’s risk of developing breast cancer. That is the conclusion of a new study published in the September 1, 2008 issue of Cancer, a peer-reviewed journal of the American Cancer Society. The study’s results suggest that incorporating bone mineral density tests with current risk assessments might significantly improve physicians’ ability to predict breast cancer risk in older, postmenopausal women.

News discussion:

Space & Earth science news