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Marine Turtle Newsletter 28:1-2, © 1984

Marine Turtle Newsletter-Online

Editorial

N. Mrosovsky

Every conservationist has a favourite threat. There are many immediate threats to sea turtles: excessive slaughter, incidental catch, habitat destruction. Whether turtles are classified as endangered or vulnerable, there are urgent tasks for conservationists. There is also a danger of becoming so absorbed in putting out brush fires that the conflagration gathering on the horizon goes unnoticed. Fires, conflagration? Isn't that overdramatizing? But the idea of destruction through heat is not altogether far fetched. Two recent reports estimate that global temperatures could rise by about 2OC, maybe more, in the course of the next century (1983, Environmental Protection Agency, USA; 1983, National Research Council, USA). That may not seem much, but it would be enough to result in a massive feminizing bias in species whose sex is determined by the temperature prevailing during incubation (see Figure). What would the sea turtles do--in this greenhouse? Assuming that there were sandy beaches left, would their physiologies evolve so that they produced a reasonable number of males as well as females at the new higher temperatures? Would they move? Would loggerheads haul out of the sea for nesting in New England and Tasmania, in Hokkaido and the Bay of Biscay? Would turtles nest at different times of year? Or would a rigidity of behaviour and body doom them to stick to their old ways till the last unrequited female crawled ashore to lay its last unfertilized eggs? We cannot predict, partly because we do not really know what the turtles are doing now. If the world is to warm up, then such topics as the heritability of pivotal temperature (the temperature at which 50% of each sex is produced) and the factors underlying nest-site fixity (the tendency to return to the same place for renesting) become of more than academic interest. And the possibilities of sperm storage and artificial insemination of unmated females become of more than commercial consequence. The cry for immediacy, for 'conservation content' by the relevant granting agencies is all very well, but we also need more--much more--of what is erroneously labelled pure research.

Sand Temperatures (60 cm) in Suriname and Pivotal Temperature
(those producing 50% of each sex) for Turtles Nesting in the Gulanas

Based on data from:

  1. Mrosovsky, Dutton & Whitmore (ms)
  2. Rimblot , Fretey, Yrosovsky, Lescure & Pieau (ms)