Friday, August 21, 2009

Females threaten to overtake turtle species

From: ABC News – The World Today with Eleanor Hall 20/08/09

ELEANOR HALL: Australia is home to the world's largest population of green sea turtles but females are threatening to overtake the species.
Scientists say climate change is threatening the turtle population's gender balance and could also see the ocean rising to inundate nesting sites.
But there is some optimism that the turtles will adapt.
Annie Guest spoke to Townsville based scientist Mariana Fuentes.
MARIANA FUENTES: The northern Great Barrier Reef green turtle population is actually the largest green turtle population in the world.
There is basically 50,000 turtles nesting during a high nesting year and this population of sea turtles nests is on the northern Great Barrier Reef region and Torres Strait region.
So this population of sea turtles has a very important ecological role but also a social and cultural importance because Torres Strait Islanders rely on the sea turtle population as food sources and also as a symbol during social gatherings and ceremonies.
ANNIE GUEST: And what have you found about the future for the northern Australian green sea turtle population?
MARIANA FUENTES: I found that by 2070 under an extreme scenario climate change, there will be more female turtles being produced into this population as well as a reduction in the hatchlings� success.
ANNIE GUEST: Why will there be more female turtles produced?
MARIANA FUENTES: Sea turtles have temperature dependent sex determination and this means that the sex of the hatchlings is determined by the same temperature, with warmer temperature producing more females and cooler temperature producing more males.
ANNIE GUEST: So if there are more females in the green sea turtle population is that then dire for this community to survive?
MARIANA FUENTES: We think they can adapt but it would take a long time for them to adapt so in the process of adapting the population might reduce in numbers.
ANNIE GUEST: How have sea turtles adapted over the centuries to climate change? You say that they are an example of a species that has done this well.
MARIANA FUENTES: Millions of years ago the areas that are land now used to be ocean and that is where they went to lay their eggs so they have changed where they nested to different areas that are now available.
ANNIE GUEST: And they have done this successfully? Well they are now a threatened species?
MARIANA FUENTES: Yes they have done it successfully. The reason why they are threatened now is because of anthropogenic activities, human impact.
ANNIE GUEST: Your research has also made other forecasts that are quite negative for this green sea turtle population. Can you tell us about those?
MARIANA FUENTES: We also found that sea level rise will impact this population and by this I mean that we found that about 34 per cent of the nesting area available for this population will be lost or inundated as a result of sea level rise by 2070. So there will be more density dependent issues and diseases in those nesting grounds.
ANNIE GUEST: We started this interview by talking about the significance of this green sea turtle population to the Torres Strait Islanders for a food source and cultural reasons.
If this green sea turtle is affected by these two issues of more females in the population and nesting sites going underwater, what could that mean for Torres Strait Islanders?
MARIANA FUENTES: Torres Strait Islanders won't see the impacts from climate change until a few years because sea turtles take about 30 years to mature but what will happen is there will be less number of turtles available for islanders to rely on and to take as a food source.
ANNIE GUEST: And that could be at the turn of the next century then?
MARIANA FUENTES: Yes.
ELEANOR HALL: That�s ecologist Mariana Fuentes speaking to Annie Guest at a conference on Ecology in a Changing Climate in Brisbane.

No comments: