By
LSCISSM Rachel Irving
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This 40mm Mytilus sp. mussel was found inside Anzac’s
seawater systems
Photos courtesy Anzac SPO.
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A
close up of the mussel flesh inside of it’s shell.
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When HMAS ships Anzac and Darwin berthed in Fremantle after returning
from The Gulf earlier this year, it was feared they had an unwelcome
visitor onboard.
HMAS Anzac reported mussels in her internal sea water pipework
and systems in a signal sent prior to her arrival. The presence
of mussels in Darwin was unknown at this stage.
With early digital images provided by Anzac’s MEO, it was
feared the mussels might be an indigenous species from The Gulf.
The mussels were immediately deemed to be potential marine pests
posing a significant threat environmentally and economically for
Australia.
Anzac identified through her urgent defect signal mussels in her
internal seawater systems blocking the flow of water. This in
turn caused issues with machinery and weapons systems as the mussels
caused problems in the respective cooling systems.
Mr John Polglaze, an environmental scientist from URS Australia,
spoke with Navy News.
“The concern was not only the ship’s diminished capability
but also if the mussels originated in The Gulf, then they had
the potential to become a marine pest in Australia,” Mr Polglaze
said.
On that basis, the Navy sought help from AFFA - Agriculture Forestry
and Fisheries Australia who run the Australian Quarantine Inspection
service, as well as the HMAS Stirling Environmental officer and
DSTO for assistance.
“When Anzac and Darwin arrived home after their respective
deployments to The Gulf, URS were tasked to inspect the ships
for fouling.
“When we conduct these surveys what we are looking for is
fouling organisms, particularly those that have the potential
to develop and establish in Australian ports, for example Careening
Bay in the West.”
Fouling organisms are the growth that develops on ships. This
can take the form of weed, hard animals such as mussels, oysters
and barnacles, or mobile animals which ‘catch a lift’
on ships.
“These organisms can then become an ecological pest where
they can out-compete or predate on native marine species. They
can also become an economic pest by destroying local industries,
or encrust themselves so thickly into the intakes or outlets for
industrial facilities,” Mr Polglaze said.
Photographs taken onboard Anzac while she was at sea were sent
to Australia for identification and early evidence suggested the
mussels might have been a species known as Perna picta, or the
painted mussel, native to The Gulf region. If the mussels proved
to indeed be Perna picta then they represented a considerable
risk.
On that basis there was a response plan put in place for Anzac
and Darwin including hull inspections and dosing of areas such
as the sonar dome. In fact divers were in the water almost immediately
on completion of the welcome home ceremony.
Mr Polglaze said, “When we got the specimens from the ship
we sent them for more detailed classification and inspection,
and it was determined that the species were in fact a local Cockburn
Sound species, Mytilus. They were probably settled in the ship
before they left for their respective deployments but rather extraordinarily
they survived and multiplied.”
There were hundreds of mussels found throughout Anzac, up to about
50-60mm long, all throughout her internal systems.
As for future prevention, Mr Polglaze said a meeting in Canberra
this month will examine what is required to both protect Australia’s
environment, as well as the capabilities of our Naval force, and
to ensure we do not infect regions and ports we sail into.
The Anzac SPO are investigating methods to stop reoccurrences
of this problem.
