ANCIENT MAYFLY HOOKS
FISHING PROFESSORS
In Tasmania’s southwest, two of Australia’s most prominent scientists are
coaxing the ecological secrets from Lake Pedder’s tannin-stained waters;
providing evidence that this man-made lake is a haven for undiscovered
species, some even pre-dating the dinosaurs.
Emeritus Professors Andrew Osborn and Nigel Forteath, both retired
from the University of Tasmania, have been researching the ecology of
Lake Pedder for the past 10 years.
Their research was originally sparked by the pair’s mutual interest in trout
fishing, and an unusual catch by Andrew Osborn.
“Some 23 or so years ago we were fly fishing down past Coronation,”
he said. “I snagged an old Banksia and lo and behold, brought in a tiny twig
and on it was a freshwater sponge.”
Years later the pair decided they should have a closer look at the sponge,
along with other invertebrates in Lake Pedder. They hoped to establish
Lake Pedder’s ecological value and to find out whether at least some
of the animals found there might be endemic. That is, species native to
Tasmania and/or Australia as a whole.
The research also provides good information for the lake’s managers.
Hydro Tasmania is supporting the research with a grant of $68,000 over
three years as well as providing field assistance and accommodation.
“We’re interested in the environmental condition of all our assets
and waterways,” said Andrew Scanlon, the Hydro’s Environment and
Sustainability Manager.
“There is a perception out there among some people that man-made
reservoirs aren’t biologically interesting and don’t have diverse life forms.
I think the research that these two guys are doing is looking at that, and
finding lots of interesting things so we are keen to support it.”
Lake Pedder is a very large, cold-water body with a vast shoreline of
330 km, equivalent to around 10% of mainland Tasmania’s coastline.
It also has a narrow operating range and is shallow in comparison with
the nearby Lake Gordon. Professor Osborn believes that these combined
attributes of Lake Pedder provide a very stable and important ecological
environment.
“The new Lake Pedder is a very, very special body of water for many
reasons,” Professor Osborn said. “Australia is as we all know a very arid
country only the continent of Antarctica has a lower precipitation rate
than does Australia. So bodies of fresh water, although they are present in
Australia, are relatively unusual.
“Lake Pedder is managed by legislation within a one and a half
metre limit …what that says is that your aquatic weeds within
Lake Pedder, the weed beds are very stable indeed and all the
invertebrates that feed on those aquatic weeds remain there,
other than on a seasonal basis where they’ll build up and decline
again, so it’s an extremely stable biological system.”
The taxonomy of mayflies has formed a major part of the
Professors’ Lake Pedder research. They have already recorded
a new genus and two new species of mayfly that appear to be
endemic to south-west Tasmania .
“The first thing we started to do was to collect mayflies to see
if we could find out what species they were, and while we were
doing that, we came across a very beautiful yellow-coloured mayfly
which I guess would catch anybody’s eye because it was just an
outstanding colour,” said Nigel Forteath.
We first of all found it in one bay and we’ve now found it over a
much greater area and that would suggest to us that it is doing
very nicely in Lake Pedder.”
While Professor Osborn is convinced that the creature is khaki
not yellow, both scientists are delighted with the discovery of the
new species.With a collaborator they have named it Loamaggolonta
pedderensis, which essentially translates to “the mayfly from the
deep still waters of Lake Pedder”.
Professor Forteath says that there are many other species of
mayfly present in the large body of water created in 1972.
“I think that what we’re seeing now after around 35 years is that
the mayfly population is becoming more and more stable and
spreading throughout the lake,” said Professor Forteath.
“That’s fascinating from our point of view because having found
Loamaggolonta pedderensis we’ve now found another new one and
this is a most beautiful dark coloured mayfly, a magnificent animal.
Within the space of 10 years, we’ve named not only a new genus
but have collected two different animals that are obviously two
new species.”
“From our point of view we’re over the moon and it simply proves
the point that Lake Pedder is a very important body of water for
these very ancient animals. I mean mayflies were flying around
before dinosaurs were even thought of I’d suggest to you, so they
are a very ancient fauna and their nearest relatives are found in
South America so they are very much Gondwanaland animals.”
In addition to the mayflies, Professors Forteath and Osborn have
found a sysirid (or sponge fly) which they suspect is also a new
species, feeding on the unidentified freshwater sponge that first
set their quest in motion. Sysirids are quite rare in Australia and
Andrew Osborn believes that Lake Pedder is a crucial Australian
habitat.
Professors Osborn and Forteath are still attempting to classify the
sponge pulled in on the end of a fishing rod all those years ago.
It is yet to be named.
Andrew Osborn is convinced that there are a huge number of
discoveries remaining in Lake Pedder. He believes that more
research is the only way to end speculation about the lake’s
ecological value.
“There is a lot of scientific debate and it is important to unravel this
and put it on a solid scientific footing,” he said.
Each time they embark on a field trip, Nigel Forteath dreams of the
new species he and his colleague might find.
“Lake Pedder has some amazing secrets and over the years we’ll
find more and more of these animals,” he said.
“It’s just a very mysterious place I suppose. When I was a student
at the University of New England we had a lecturer, a professor
there who talked about Dragonflies. I remember him saying if you
ever get to Tasmania, you’ve got to go down to the southwest and
you’ve got to find the rarest dragonfly in the world and I thought
‘oh that’s a bit of a joke I won’t always remember that’. But I have
always remembered it and there it is, in Lake Pedder … you can
find it in Lake Pedder, the rarest Dragonfly in the world.”
Photos courtesy of Nigel Forteath,
story by Helga Grant