Science topics
Antarctic food webs - Dr Simon Jarman
The Scientist
Simon is a geneticist who has worked on diverse organisms including
flies, bacteria, tobacco, shrimps and whales. The main theme of
his research has been the study of natural variation in DNA, either
among individuals within a species; determining DNA similarities
between related species; or identifying the diversity of DNA in
predator diets. He has been working on the diet of Southern Ocean
predators such as whales, seals and penguins for eight months. Prior
to this, he developed methods for CSIRO marine research to study
genetic variation in diverse animal species. His doctoral thesis
was on DNA evolution in krill, an abundant group of shrimp-like
crustaceans that are an important component of offshore marine ecosystems.
Simon's collaboration is with artist Dawn
Csutoros.
The Research
DNA methods for studying the Southern Ocean food web.
We are developing new techniques for identifying the prey consumed
by whales, seals and penguins in the Antarctic. Finding out what
these predators eat is vital for understanding how the Southern
Ocean ecosystem functions. These predators are relatively easy to
count, compared to the smaller species that they eat like fish,
krill and squid. Once we know what species a predator eats and how
many of the predators are present in the Southern Ocean, we can
build a more complete picture of the food web.
Discovering which species are consumed by large marine predators
is surprisingly difficult. It is not possible to directly observe
all of their feeding behaviour. Methods for identifying prey from
its appearance in predator stomach contents and faeces fail to identify
many soft-bodied prey items. A further problem with these methods
is that they involve killing the predator or flushing out its stomach
contents. Lethal methods are no longer acceptable for Australian
researchers and the invasiveness of stomach pumping is highly undesirable.
Our idea was to avoid these procedures by collecting predator poo
and using the prey DNA in the poo to identify what the predator
had consumed. Although it seems unpleasant to have to work with
poo, it is far less distressing for both the animals we are studying
and the scientists doing the collection in Antarctica to pick up
a piece of poo than to catch a seal or penguin and flush its stomach.
Whale diet cannot be studied any other way by Australian scientists
and the sampling of stomach contents after killing whales, which
is allowed in other countries, is generally disliked.
This project is in its early stages, but we have had very good
initial success. So far we have concentrated on identifying species
of krill in whale and penguin poo. Krill are small shrimp-like animals
that occur in huge swarms in the Southern Ocean. They are the primary
food source for many whales, penguins and seals. We have successfully
identified krill species from the DNA in poo of blue whales (the
largest animal in the world) and Adelie penguins (the most abundant
penguin in the Antarctic). This success proves that our DNA-based
approach works and we are now developing methods for identifying
other prey items such as fish and squid.
More information can be found at these sites:
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