The melanistic form of the turtle-headed sea snake (Emydocephalus annulatus)IMAGE: CLAIRE GOIRAN / CURRENT BIOLOGYIn another illustration of the “industrial melanism,” populations of a sea snake species in the South Pacific are becoming increasingly dark as a result of pollution, researchers claim in a new study. The poster child of the phenomenon has been the peppered moth, whose populations vacillated between dark and light color morphs because of 19th century England’s soot-covered landscapes.
The study, published in Current Biology yesterday (August 10), provides evidence that some populations of the turtle-headed sea snake (Emydocephalus annulatus) are becoming dominated by more-uniformly dark-pigmented individuals, whereas other populations contain more-familiar color morphs that have alternating dark and light patches or stripes. The key to this apparent melanistic adaptation, the authors of the study suggest, is pollution, such as nickel, from mining runoff close to the shore of the Pacific Island of New Caledonia. Snakes in these urban populations, they write, “accumulate trace elements, which are expelled when the skin is sloughed.”
By measuring levels of trace elements in the evenly colored populations compared to populations with lower toxic exposures, the researchers found that more algae accumulated on darker patches of skin, and ...
