News

Global warning on global warming: a turtle's story


6 June 2007

What is striking about the findings is that slight variations in the seasonal timing of nesting made a huge difference in breeding success rates, and increased storm severity due to changes in global climate could have a huge impact
What is striking about the findings is that slight variations in the seasonal timing of nesting made a huge difference in breeding success rates, and increased storm severity due to changes in global climate could have a huge impact

The impact of global warming on plant and animal life is gradually becoming apparent; an unfortunate reality of this is that many of our most fragile species will have to bear the full force of the consequences of climate change.

A recent project undertaken by an international team of researchers to measure the destructive impact of tropical cyclones on the breeding success if sea turtles, has shed light on one such case.

The team, led by PhD student David Pike from University of Sydney School of Biological Sciences, compared the reproductive seasonality of three sea turtle species in remote nesting areas along the Atlantic coast of Florida in the United States.

'From 1995 to 2005 we conducted nightly beach surveys of more than 40,000 nesting leatherback (Dermochelys coriacea), loggerhead (Caretta caretta) and green (Chelonia mydas) turtles beginning in April and ending in late September,' said David. .

'When comparing breeding success with severe storm data we found that frequent or intense storms were particularly devastating because they reduced the number of nests hatching and the number of hatchlings emerging from each nest,' said David. 'Reptile eggs are particularly vulnerable to moist (and saline) conditions, which can cause nest failure or low hatching rates.'

Each of the species that were surveyed nest at different times. Leatherbacks begin nesting earliest and most of their offspring hatched before the tropical cyclone season arrived, resulting in little negative effect. Loggerheads nest later, however only the nests laid last in the season were damaged by seawater.

'We found that the green turtles' nesting season occurred during the tropical cyclone season making their developing eggs and nests extremely vulnerable to cyclone surges,' said David. The team actually found that storm surges affected virtually all (95 per cent) of the green turtle nests.

'For example, in 2004 and 2005 tropical cyclones occurred sporadically from June to September, which encompasses the entire green turtle nesting season. As a result we saw only 2 per cent of all green turtle nests hatching,' said David.

'What is striking about our findings is that slight variations in the seasonal timing of nesting made a huge difference in breeding success rates, and increased storm severity due to changes in global climate could have a huge impact,' he said.

'Australian turtles also face problems from cyclones, but the effects are currently unknown. However, studying the effects of cyclones on flatback turtles (Natator depressus) is of importance because they only occur in the offshore waters of northern Australia.'


Contact: Jake O'Shaughnessy

Phone: +61 2 9351 4312 or 0421 617 861

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