Jonny Stark — benthic ecologist
There’s three main objectives to the Environmental Impact Assessment. The first is to look at the nature and extent of impacts, if there are any, associated with the outfall. The second is to look at the dispersing characteristics around the outfall site, so how the sewage plume is being dispersed and whether it’s a good dispersing environment. The third part of the EIA is to look at ecotoxicology of sewage, so to assess how sensitive some of the local animals and plants are to sewage, and also to come up with some dilution factors so that we know roughly how much the sewage needs to be diluted to not have an impact on the local environment.
The main research tool we use is diving. Diving is a fantastic method for getting really detailed marine science done. You can do so much more when you’re in the water than you can from floating above it. So we operate a dive program. We’ve been running one for about 10 years now at Casey, but this will be the first time we’ve operated it at Davis. We use surface-supplied diving, otherwise known as Hookah. So we have a bank of air on the surface and that’s pumped down an umbilical to the divers. The divers wear specially designed dry suits for use in cold water — a thick vulcanised rubber. Underneath that, we have several layers of insulating clothing, so we’re actually very comfortable and warm when we’re diving. We also use a full face mask, which the air comes into, and we have two-way communication, so we can talk to the dive supervisor on the surface; we can talk to each other.
In terms of the types of impacts we’re expecting to see, it would depend on the type of habitat that is around the outfall site itself. If there’s a lot of rocky habitats, we expect to see a large amount of algae, so a large amount of seaweed. We might expect to see some changes of the types of communities that we use in those sediments. Marine sediments are a very rich and diverse habitats — hundreds of thousands of animals per metres squared; a whole range of crustaceans and worms. So we might expect to see, if there is an impact at the outfall, a shift in this community that we find in sediments, whereby there might be a loss of biodiversity, there might be dominance of one or two species which can tolerate extra nutrients or extra organic material that you find in sewage.
So there’s a whole series of different projects that sort of cover a broad scope of research, and in fact, this is probably the most comprehensive Environmental Impact Survey of a sewage outfall that’s ever been done in Antarctica.
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Benthic ecologist, Dr Jonny Stark, will don his diving suit this summer but not for a tropical holiday, he’ll be taking a dip in the icy waters around Australia’s Davis station.
Dr Stark is leading a major Environmental Impact Assessment study of the sewage outfall at the station.
The Antarctic Division is planning to upgrade the wastewater treatment at Davis and wants to determine the impact of the current system.