Researchers report the discovery of the first new living species of giant clam in two decades, according to a report to be published online on August 28th in Current Biology, a Cell Press publication. While fossil evidence reveals that the new species, called Tridacna costata, once accounted for more than 80 percent of giant clams in the Red Sea, it now represents less than one percent of giant clams living there.
The researchers said they cannot say for sure which factors contributed to the loss of this giant clam species in favor of others, but the overall decline in giant clam stocks and the striking loss of large specimens is a "smoking gun" for overharvesting by humans many thousands of years ago, said Claudio Richter of the Alfred-Wegener-Institute for Polar and Marine Research in Germany. The new species appears to live only in the shallowest waters, making it particularly vulnerable to overfishing.
" These are all strong indications that T. costata may be the earliest example of marine overexploitation," he said.
Modern humans are believed to have coasted out of Africa during the last interglacial, some 125,000 years ago, Richter said. The Red Sea, a saltwater inlet between Africa and Asia, may have acted as a bottleneck, and its overall aridity may have driven the early hunter-gatherers to rely on shallow-water marine resources. Giant clams would have been a prime target, because of their sedentary nature, conspicuousness, and large size, he added.
The research team, including scientists from the Center of Tropical Marine Ecology in Germany and the University of Jordan, discovered the new species while attempting to develop a breeding program for another prized giant clam species. Study coauthor Hilly Roa-Quiaoit of Xavier University in the Philippines, known as the "mother of clams," recognized the new species, which can measure up to a foot long and has a shell with a distinctive zig-zag outline
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