Temp increases could decimate loggerheads

Temp increases could decimate loggerheads



Feb 2007 - Climate change is 
further imperiling loggerhead turtles that nest on Florida 
beaches, according to a new study by British researchers. The 
study warns that predicted temperature increases could 
decimate male North American loggerhead populations, with 
global ramifications for the species. 
The researchers analyzed 26 years of loggerhead turtle nesting 
and climate data and compared the findings with models for 
future temperatures. 
Temperature during plays a major role in the health and sex of 
baby turtles, with warmer temperatures during incubation 
producing females and cooler conditions producing males. 
An increase of just one degree Celsius could completely 
eliminate the birth of male turtles from some beaches, the 
research team said, and a rise of three degrees Celsius would 
lead to extreme levels of infant mortality and declines in 
nesting beaches across the United States. 
Loggerheads are considered endangered by The World 
Conservation Union and protected internationally by the 
Convention on International Trade in Endangered Species. 

"We are stunned by these results and what they could mean for 
the species in the future," said Dr Brendan Godley of the 
University of Exeter's School of Biosciences. "In particular, 
we are concerned that populations that are already 
predominantly female could become 100 percent female if 
temperatures increase by just one degree. This is a major 
issue for nesting populations further south, in Florida, for 
example, where males are already in short supply." 
In Florida, which accounts for more than 90 percent of 
loggerhead nesting in the United States, 90 percent of 
hatchlings are female. By contrast, in North Carolina, 42 
percent are male. Scientists believe some of these males 
currently travel south, bolstering southern populations, but 
fear there are not enough male turtles to overcome a further 
shortage in Florida beaches. 
Conservation efforts for the species, listed as threatened on 
the U.S. Endangered Species Act, should focus on protecting 
northern breeding grounds, the researchers said. 
"In the face of climate change, it's essential that we 
prioritize the protection of sites that produce males not only 
for local breeding success, but to help support potentially 
vulnerable populations further south," Godley said. 
The study is "an important step in identifying essential 
thermal habitat for marine turtles," said study co-author Dr. 
Matthew Godfrey, of the North Carolina Wildlife Resources 
Commission. "It highlights the need to establish measures to 
specifically protect male-producing beaches." 
Published in the journal "Global Change Biology," the research 
was conducted in partnership with the Bald Head Island 
Conservancy and the North Carolina Wildlife Resources. 
The study adds to growing concern about the future of 
loggerhead turtles, which primarily nest on beaches in Oman 
and Florida and take 20 to 30 years to reach maturity. 
Last year scientists found continued evidence of decline on 
Florida beaches, where nest counts have slumped 22.3 percent 
from 1989 to 2005. 
That report suggested that loggerheads are dying before they 
reach the nesting beaches - drowning in fishing trawls or 
taken as bycatch by the long line commercial fishing industry 
in the open Atlantic Ocean. 
Loggerheads can weigh up to 400 pounds and are among the 
world's largest marine turtles. 
Longline fishing is a major threat to all marine turtles, as 
is habitat loss and the poaching of turtle eggs, which some 
cultures regard as a delicacy. 
But there are some encouraging signs regarding the species, 
particularly in South Africa. Conservationists say loggerhead 
nestings have reached record levels along the South African 
coastline, with more than 2,000 nestings found over the 
2005-2006 season. 
"This is the highest number recorded in 43 years," said 
Richard Penn Sawers, head of the WWF/Green Trust Turtle 
Monitoring and Community Development Project. 
The conservation group contends that a major factor 
contributing to the stability of South Africa's marine turtle 
populations is that they breed almost entirely within the 
Greater St Lucia Wetland Park, which is a designated marine 
protected area and World Heritage site. 

---