New giant clam species offers window into ...( as a new variety. Analysis of those...)

Analysis of those apparent differences in morphology confirmed that the species was in fact clearly distinct. To further resolve the relationship of this new variety to the other giant clams, Marc Kochzius at the University of Bremen led the molecular genetic analysis, which confirmed T. costata as a new species.

The new giant clam differs from others in the Red Sea in an early and brief reproductive period each spring, coinciding with the seasonal plankton bloom, they report. Underwater surveys carried out in the Gulf of Aqaba and northern Red Sea revealed that the long-overlooked clam must be considered critically endangered. Only six out of a thousand live specimens the researchers observed belonged to the new species.

Early shellfishing evidence in other areas has led to speculation that the dispersal of modern humans out of Africa into the Red Sea and adjacent regions 110,000 to 90,000 years ago was driven largely by competition for marine resources, the researchers said.

" Our discovery that T. costata was already on a trajectory of decline prior to this period corroborates this hypothesis, by providing the first circumstantial evidence that humans were not only using but also depleting reef resources, making T. costata the likely earliest victim of anthropogenic degradation of coral reefs," they wrote. "Declining marine and terrestrial resources, by human and climatic factors, respectively, may have acted in concert to thwart the precocious but short-lived colonization of the Near East by anatomically modern but technologically primitive humans at the end of the last interglacial."

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