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Females threaten to overtake turtle species -

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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

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'

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?


ELEANOR HALL: That's ecologist Mariana Fuentes speaking to Annie Guest at a conference on Ecology
in a Changing Climate in Brisbane.