Yabbies untangle food web science
Yabbies are helping ANSTO scientists find out who
eats what in the Murray-Darling basin and other
wetland ecosystems.
Dr Debashish Mazumder and his team are using
yabbies to find out how naturally-occurring
radioisotopes in an animal’s food, are incorporated
into its body.
Animals eat a combination of different prey items,
and identifying all the components of an animal’s diet
can be especially difficult in the murky waters of
wetland environments.
Instead, scientists can identify predator-prey relationships by analysing the isotopic signature of
different organisms in the ecosystem. The ratio of these isotopes can reveal an organism’s position
in the food web and the different components of its diet.
Scientists can use isotope analysis to monitor how wetland food webs change in different
environmental conditions. Understanding how food webs in the Murray-Darling basin change during
periods of drought and flooding will be crucial for the future management of this threatened river
system.
Isotope analysis
Different plants and animals contain unique ratios of carbon and nitrogen isotopes. When an organism
eats another, some of the radioisotopes in the prey are incorporated into the body tissues of the
predator.
Dr Mazumder feeds his laboratory yabbies artificial diets with known isotope ratios, including mixtures
of kangaroo and lamb meat. By measuring how the isotope signature of the yabbies changes in
response to their diet in the laboratory, scientists can better identify the components of an animal’s diet
in the wild.
δ15N
Organisms at higher levels of the food
web contain larger proportions of
carbon-13 and nitrogen-15 than primary
producers.
Image credit: Carol Kendall, US
Geological Survey
δ13C