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asking local communities to help restore endangered Posidonia seagrass meadows
by collecting shoots that naturally become detached after large storms.
A team led by
the Sydney Institute of Marine Science and UNSW have launched ‘Operation
Posidonia’ to encourage local coastal communities to help restore ecologically
and economically important seagrass meadows. Project leader,
Associate Professor Adriana Vergés from UNSW’s School Biological, Earth and
Environmental Sciences said while seagrass meadows may not be the most striking
of marine habitats, “they are one of the most productive ecosystems on Earth”.
provide critical habitat for conservation icons like seahorses, as well as many
fish species that we like to catch recreationally like snapper, luderick or
leatherjackets”, she added.
These marine plants,
however, have become severely threatened by human activities like coastal
development and pollution, and this has led to their decline at alarming rates
worldwide. On average, seagrasses are disappearing at the same rate as coral
reefs, ie. one soccer field every half hour.
The aim of Operation Posidonia is to
restore meadows of Posidonia australis,
a beautiful and slow-growing seagrass that makes extensive underwater meadows
all over the southern half of Australia.
Posidonia project is funded by the NSW Government’s Restoration and
Rehabilitation Grant Program, which encourages and enables organisations to
protect, conserve and restore the state’s environment. The team includes
seagrass restoration experts from the NSW Department of Primary Industries and
the University of Western Australia.
Co-investigator Dr Elizabeth Sinclair from
the University of Western Australia said the declines of Posidonia meadows in the central
parts of NSW (where most people live) have been so severe that six meadows have
been formally listed as ‘endangered’ by both the
Australian Commonwealth Government (EPBC Act) and the NSW government.
“There’s a very real risk that Posidonia may become locally extinct
from some of these NSW estuaries within the next 15 years unless
new conservation actions reverse current trends,” she said.
In recent years, boating activities
have emerged as an important threat to Posidonia meadows
in eastern Australia. This is because the sheltered bays where this seagrass
naturally thrives are also ideal locations for boat moorings.
block and chain boat moorings scour the seafloor, remove seagrass and create
bare patches that fragment the meadow and destabilise sediments, which can
accelerate further declines”, project co-investigator Dr John Statton from the
University of Western Australia said.
Mapping has shown that boat mooring
scars can be very large, form quickly and take decades to recover fully once a
mooring is removed. Individual mooring scars as large of 700 m2 have
been mapped among Posidonia in
For Posidonia to recolonise old boat mooring scars,
traditional swing moorings need to be replaced with environmentally friendly
moorings that do not have heavy chains or other elements dragging along the
seafloor. Although environmentally friendly designs are replacing swing
moorings in many coastlines world-wide, they are still not widely used in NSW.
New mooring designs are,
however, not enough, according to Dr Sinclair. “Even when mooring chains are removed,
the natural recolonisation of bare patches by Posidonia can take decades”, she said. “This is why we want to intervene and
give nature a helping hand by restoring lost Posidonia in old mooring scars where swing moorings
have been either removed or replaced by environmentally friendly moorings.”
Associate Professor Vergés said that
because Posidonia is
a protected species, “one of the greatest challenges for restoration in the
east coast is finding seagrass shoots to revegetate the bare patches”.
And this is
where local citizen scientists can play a role in helping out, as UNSW PhD
student Lana Kailich explained. “We are asking local beach goers to
help us with the restoration by collecting live, green Posidonia shoots that often wash
ashore after storms”, she said.
The team will
then transplant these shoots into old mooring scars. The project has
already featured some restoration trials in Port Stephens using detached
seagrass shoots, with very promising results: survival of 70 per cent
of planted shoots after 5 months.