News of the Wild: Bats, Loggerhead Sea Turtles and King Crabs
From the August/September 2011 issue of National Wildlife
Roger Di Silvestro
Threats to Bats Could Cost Agriculture Billions
“People often ask why we should care about bats,” says Paul Cryan, a U.S. Geological Survey research scientist. He is one of the authors of a new study, published recently in the journal Science, that answers the question: Pest-control services provided by insect-eating bats likely save the U.S. agricultural industry as much as $53 billion a year, according to the analysis, which also warned that noticeable economic losses to North American agriculture could occur in the next four to five years as a result of emerging threats to bat populations.
“Bats eat tremendous quantities of flying pest insects, so the loss of bats is likely to have long-term effects on agricultural and ecological systems,” says Justin Boyles, a researcher with the University of Pretoria and the lead author of the study.
Bat populations are at risk in some parts of the nation from a life-threatening fungal disease called white-nose syndrome, which infects bats while they hibernate. Declines in the Northeast, the most severely affected U.S. region, have exceeded 70 percent, and the disease probably has killed more than a million bats.
Pollution Threatens Loggerhead Sea Turtles
A study published recently in the journal Environmental Toxicology and Chemistry provides some of the first measurements ever made of persistent organic pollutants (POPs) in adult male loggerhead sea turtles, says Jennifer Keller, a researcher at the National Institute of Standards and Technology who participated in the study.
Biologists from the Hollings Marine Laboratory and the South Carolina Department of Natural Resources tracked 19 of the threatened sea turtles that had been tagged off Florida and sampled their blood for POPs, a large group of toxic chemicals that includes DDT and PCBs. They found that POP levels were higher in 10 turtles that traveled along the Atlantic coast as far north as New Jersey. Nine turtles that stayed in Florida waters had lower levels, presumably because foods eaten by the more nomadic turtles were foraged in areas with higher pollution levels.
Another study from the lab found that female loggerheads nesting in western and eastern Florida had lower concentrations of POPs in their eggs than did females from North Carolina. The chemicals can be hazardous to the turtles, and knowing geographic variations can help wildlife managers to refine measures taken to recover the beleaguered species.
A New Antarctic Invader
A team of U.S. and Swedish marine biologists has discovered that king crabs are beginning to move out of the sea depths off Antarctica and toward the shallower waters of the continental shelf, where no fishes capable of crushing shelled creatures have lived for millions of years.
Consequently, the shellfish, starfish and sea urchins that live in the region have not developed heavy shells and are vulnerable to the crabs’ powerful claws.
“If you look at the warming trends on the [Antarctic] peninsula, you would expect that the crabs would come back in 40 or 50 years,” one of the researchers, Richard Aronson, told a Discovery News reporter, “but, boom, they’re already here.”
Since the 1950s, average ocean temperature in the region has increased 1.8 degrees F. Some biologists fear that the crabs could rapidly diminish the defenseless prey populations, including sea squirts being studied for a chemical that fights skin cancer.