Scientists Publish Good News for Green Turtles Long-Term Nesting Beach Protection Works

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HONOLULU, HI — This week in Global Ecology and Biogeography, encouraging news has emerged for one of the world's largest marine herbivores, the green turtle (Chelonia mydas). A new study shows that long-term protection of the sea turtles' nesting beaches is successful in achieving increases in the green turtle populations. 

The authors of the article, who research green turtles in Australia, Costa Rica, Japan, and the United States, analyzed nesting data from six of the world's major green turtle rookeries for which there are reliable long-term data of 25 years or more. The analysis shows that green turtle nesting on four beaches in the Pacific (Ogasawara, Japan; French Frigate Shoal, Hawaii, U.S.A.; and Heron and Raine Islands, Australia) and two beaches in the Atlantic (Archie Carr National Wildlife Refuge, Florida, U.S.A.; and Tortuguero, Costa Rica) have increased by an estimated four to fourteen percent each year over the past two to three decades. The increases in nesting varied considerably among the rookeries, most likely because historical and current exploitation of green turtles is different at each site.

"These results should be celebrated," said Milani Chaloupka, lead author of the report and vice chair of the IUCN Marine Turtle Specialist Group (MTSG). "They demonstrate that green turtle populations and presumably the green turtles' ecosystem roles can be recovered in spite of drastic population declines in the past." Sebastian Troëng, co-author, MTSG member, and senior director of regional marine strategies at Conservation International, said, "This analysis shines a light of hope on marine conservation efforts for endangered species and for biological diversity as a whole. Ambitious strategies including long-term protection of habitats and reduction of survival threats are working, and endangered species can be recovered."

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Scientists Publish Good News for Green Turtles Long-Term Nesting Beach Protection Works

Found: The clearest ocean waters on Earth - earth - 29 June 2007 - New Scientist Environment

NewScientist.com news service

Tedetti says the ocean waters, which the researchers sampled using these canisters, were "almost violet" (Image: Joséphine Ras)Enlarge Satellite images reveal the chlorophyll-poor patch of water in the south-east Pacific (in purple) (Image: SeaWiFS Project, NASA/Goddard Space Flight Center, ORBIMAGE)Enlarge
As clear as the clearest lakes on the planet, salty as ocean waters, and roughly the size of the Mediterranean – this, say researchers, is the clearest and most lifeless patch of ocean in the world. And it is in the middle of the Pacific.
"Satellite images that track the amount of chlorophyll in ocean waters suggested that this was one of the most life-poor systems on Earth," explains Patrick Raimbault of the University of the Mediterranean, in Marseille, France (see image, right).
In October 2004, Raimbault and colleagues set out to study the remarkable patch of ocean water on a three month cruise – called BIOSOPE – that left from Tahiti in French Polynesia, passed by Easter Island and ended on the Chilean coast. Along the way, they sampled the water's chemistry, physics and biology.
Marc Tedetti, also from the University of the Mediterranean, was on the expedition to investigate the water's clarity. He was struck by the colour of the water, which he describes as closer to violet than to blue (see image, right).
Found: The clearest ocean waters on Earth - earth - 29 June 2007 - New Scientist Environment

Creature clones itself to avoid becoming fish food

• 18:00 13 March 2008
• NewScientist.com news service
• Catherine Brahic

Bottom-dwelling sand dollars are related to sea urchins and sea stars (Image: GNU licence)

Cloned larvae (right) are smaller than non-cloned larvae (scale bar: 0.2 mm) (Image: Dawn Vaughn)

It's a novel escape route that makes a mockery of the status of the individual: if you run the risk of being eaten, just clone yourself. That is the approach taken by the larvae of sand dollars – marine animals related to sea urchins.

Fish are voracious predators of sand dollar larvae. Dawn Vaughn and Richard Strathmann of the University of Washington, Seattle, found that when they put four-day-old sand dollar larvae in a tank with fish mucus, the larvae cloned themselves.

They did this by either splitting in two or by producing a small bud which detached itself and developed into a new larva. Either way, the clones were smaller than the original larvae. Sand dollars did not clone themselves if there was no fish mucus in the water.

Vaughn and Strathmann believe the larvae sense the mucus, interpret it as a sign that fish are nearby, and respond by producing clones.

Better odds

There is no parental care in this species. "[The mother] is on the seafloor," says Vaughn. "She has no idea what types of risk her offspring are going to meet, so the larvae respond to cues from predators."

Cloning gives the larvae's genes a greater chance of survival in two ways. With two copies around one is statistically more likely to escape predation. Also, the smaller clones are less likely to be detected by predators.

"Studies indicated there is an optimal size below which fish do not detect their prey," says James McClintock, an ecologist at the University of Alabama at Birmingham, US, who studies how "things that can't run away from predators defend themselves".

Cloning does have a cost, however. Vaughn and Strathmann found that cloned larvae developed into smaller sand dollars: just before metamorphosing into adults, the clones were on average one-third the volume of non-cloned individuals.

Unique response

This could make it more difficult for clones to survive as adults, which only reproduce sexually, but suggests that overall, the benefits outweigh the risks.

Cloning has been seen before in echinoderms – a group of marine organisms that have a five-axis symmetry, including brittle stars, sea stars and sea urchins, and sand dollars. But in all cases, it has been in response to conditions that are favourable for growth, such as plentiful food or favourable temperatures.

"This is the first demonstration that cloning can be induced by predation," says McClintock. "What is so unique in Vaughn's study is that this defence becomes a reproductive response – making more of yourself in anticipation of risk."

While this is the first demonstration in nature, cloning as a response to predation is common in science fiction – it's how Cylons in the TV show Battlestar Galactica, for example, cheat death.

Journal reference: Science (vol. 319 p. 1503)