Download The South East marine environment

The South East marine environment
Background
The South East marine environment consists of some of the most fertile
waters along southern Australia’s coastline, supporting an amazing
array of animal and plant communities.
There are two distinct marine environmentsin the South East. These
areas are known as the Otway (southern) and Coorong bioregions,
each containing distinct,recognisable biodiversity. The Coorong
bioregion is a complex stretch of coastline which consists of a diversity
of habitats including algal dominated reef interspersed with sandy
habitats. The Otway bioregion also contains a variety of unique
environments with semi-enclosed bays containing seagrass, kelp
beds, calcareous reefs and soft sediment environments.
Ecological characteristics
The amazing marine biodiversity in the region is due to the
presence of aunique current called the Bonney Upwelling which
occurs between December and May each year. South-easterly
winds force shallow water out to sea and allow cold, nutrient rich
water from the deep to move close to the shore. These nutrients
are the foundation of a complex food chain and ecosystem.
corridor and an inner stranded dune barrier, ecosystems include
dunes, sandy beaches, lakes and springs, limestone cliffs and
rocky shores.
The marine environment also consists of a wide diversity of
habitats including reefs, seagrass meadows, kelp forests and
sandy floors. All of which provide shelter and food for many
species of commercial, recreational and conservation significance.
This complexity can be seen in the reef environment where octopus,
molluscs (mussels and abalone), algae, squid, fish, crustaceans (e.g.
crabs, rock lobster), invertebrates such as sponges, soft coral, star fish
and urchins call home. Even South Australia’s own marine emblem,
the Leafy Sea Dragon, can be found hiding behind kelp stands.
These attributes are what makes the South East such a popular
spot for diving, boating and fishing. This environment is extremely
important to the region’s tourism and commercial fishing industries.
Did You Know?
• The largest single seagrass meadow in the South East
(25,062 ha) is located in Lacepede Bay opposite the
township of Kingston. Seagrass communities are very
important as they provide key nursery, breeding, feeding
and shelter environments for species such as King George
whiting, garfish, and snapper.
• Piccaninnie Ponds is now a RAMSAR listed site. This means it is
a wetland of international importance and protected.
• Female Leafy Sea Dragons lay 100 to 250 eggs onto a special
brood patch under the males tale where they are fertilised
and incubated for 4 to 6 weeks. Baby sea dragons are
independent from the day they hatch.
2 | The South East marine environment
Photo credit: Sharon Bruhn
Issues and threats
•
Marine debris and wastes such as plastics, fishing lines and
fish offal generated from fishing activities and general beach
litter from the public can have a severe impact on marine
species. Seabirds can become entangled in discarded tackle
and marine mammals can mistake floating plastics for food.
•
Introduced marine species threaten the regions local
biodiversity but also the social and economic benefits
received from the environment. Some pest species include
the European Shore Crab, Asian Date Mussel and the Pacific
Oyster.
•
Recreational activities such as boating (anchoring on reefs),
harvesting for food and bait, walking and trampling, turning
boulders over, spear fishing, collecting and netting in the
intertidal zones also has a detrimental affect to this
environment.
•
Climate change is a challenge the whole world faces. An
increase in water temperature will change breeding cycles (i.e.
timing, success rate and gender) of marine organisms. This
will affect the survival of species and therefore shape the
future of the fishing industry in the South East.
•
Discharge and industrial runoff release excess nutrients and
pollutants into the marine environment. There is significant
evidence of this where seagrass loss has been recorded
opposite Drain M which flows into Rivoli Bay, at Southend.
•
Physical changes such as coastal development i.e. housing
and marinas, breakwaters, boat ramps and other
constructions which are positioned incorrectly can cause
habitat degradation by disrupting the natural flows of sand
and water.
Critically Endangered Yarra Pygmy Perch. A small fish but significantly
important to the region. Photo credit: Daryl Panther
Critically Endangered Glenecg Spiny Cray
More information
Natural Resources Centre Mount Gambier
11 Helen St, Mount Gambier
T: (08) 87351177
E: [email protected]
www.naturalresources.sa.gov.au/southeast