Download our ocean - Lake Macquarie City Council

Fact sheet 9a
OUR OCEAN
Where is our ocean?
The body of water off the coast of Lake Macquarie is called the Tasman Sea and is part of the Pacific
Ocean. Lake Macquarie’s ocean ecosystem extends from approximately 1km seaward to the NSW
State Waters boundary, which lies approximately 5km out to sea. This area of approximately 12,766
hectares makes up about 14.2% of the ecosystem area of the City.
Why do we need the ocean?
Our ocean is a seamless ecosystem in which many sediments, nutrients and organisms travel freely.
The ocean is home to marine algae that supply us with two-thirds of the oxygen we breathe. Ocean
ecosystems also provide food for many forms of life, from seaweed to whales, as well as humans.
A combination of wind drift, ocean temperatures and sea water density circulates nutrients and
pollutants. The ocean off Lake Macquarie is part of the Eastern Warm Temperate Zone and is
influenced by the East Australian Current (EAC), which carries warm water from the north to south.
The EAC often brings some interesting and colourful tropical ‘hitchhikers’ to Lake Macquarie, species
that are able to survive here for a short time before the temperature get too cold.
The web of life in the ocean
Oceans, like any other ecosystem, are important for sustaining life. The links in the ocean food
webs are intricate and complicated as you can see in this diagram.
Example of an ocean food web: K Bilham
In a real ecosystem these webs would be much more complicated, with thousands of species and
relationships. It could include seabirds, rock platform animals and plants and seaweed (marine
algae).
There would also be other factors such as temperature, chemicals, tide cycles, and wind patterns, all
of which affect the way the web of life in the ocean operates.
Physical connections to the ocean
The ocean is directly connected to our beaches and can change the look of the beach on a daily
basis, depending on the tides and intensity of waves. The channel at Swansea also opens and
connects our ocean to the lake estuary and waterways.
Source: www.ozcoasts.gov.au/conceptual_mods/stressors/connectivity_model.jsp
Threats to our ocean
Many of our coastal, lake and ocean ecosystems are affected by
‘marine debris’ or rubbish. Most of this is litter washed down
drains and streams, or blown by the wind. Human waste,
especially plastics, can detrimentally affect many of the plants and
animals, including juvenile fish, such as the Eastern Blue Groper.
Increasing ocean temperatures caused by climate change have a
devastating effect on microscopic and planktonic animals and
plants. With increasing ocean temperatures there is an increase in
ocean acidity that has an equally if not more potent effect on fish,
shells, corals, and crustaceans in their larval stages, because they
can’t lay down calcium, which is essential for development early in
their lifecycle.
Photo: William Owyong
What is Council doing to protect our ocean?
Council plays an active role in environmental education throughout the city. Council’s Sustainable
Neighbourhoods Program aims to empower our community to protect the surrounding environment,
including our ocean.
Council facilitates and supports a community ecosystem monitoring program. Community members
can volunteer to become involved in the program.
Council is also involved in reviewing and commenting on federal and state oceans policy, as well as
activities that impact our ocean, such as offshore mining operations. Because of jurisdictional
responsibilities, however, final decisions regarding the use of our oceans do not reside with local
government.
Flagship species
Council has worked with the community to identify nine iconic species that represent each of the
nine ecosystems in Lake Macquarie. These ‘flagship’ species are used to promote the natural
heritage of our city and are incorporated into our citywide ecosystem monitoring program.
The Eastern Blue Groper is the flagship species for our ocean ecosystem.
As adults, eastern blue gropers like to live around rocky coastal reefs in depths up to 40m. They
are handsome fish, with females a reddish brown, or somewhat orange, and the males a vivid blue.
The larger males can grow up to 1.2m and 50kg, however, most are less than 15kg. Eastern blue
gropers are very long-lived fish, not maturing until about 15 years old. After the juvenile stage, all
eastern blue gropers become females. Interestingly, if the male disappears, one of the females in
the ‘harem’ will change sex and colour to become a male.
The adults spawn from July through October, with the larval fish mostly growing up in estuarine sea
grass beds, like many other ocean fish species.
Photo: Tim Hochgrebe
What can I do?
The top ten tips to help care for our ocean are:
1. If you carried it in, carry it out. Rubbish and the marine environment don’t mix. Plastics
especially can kill wildlife such as fish, marine mammals, birds, and reptiles
2. Prevent oil leaks into the lake or ocean by cleaning boat bilges and sumps out regularly on land
3. Use a holding tank on your boat for sewerage, and dispose of waste properly
4. Place anchors correctly and securely and obey anchorage
signs. Shifting anchors damage reefs and seagrass beds,
so use moorings where available
5. Plants hold sand dunes together. Avoid damaging sand
dune plants by walking on formal access ways when going
to and from the beach. Only drive and park vehicles in
designated areas
6. Many seabirds and waders nest on and around the ocean.
They will abandon their nests if disturbed. Avoid bird
colonies during their nesting season.
Keep domestic
animals under control at all times
7. Do you know your limits? Follow bag limits when collecting
animals including fish, abalone, crayfish, pippies, and other
shellfish. In some areas, collecting or fishing is not allowed
8. Only keep what you need. Quickly and carefully return
undersized or unwanted fish to the water. Handle fish with
wet hands to avoid rubbing the protective coating off their
scales
9. Rock platforms containing pools of water and loose rocks
provide habitat for many plants and animals. Leave rockpool
animals and plants in the water. Return overturned rocks to
their original position
10. ‘Only rain down the drain’. Don’t pour oil, paint, chemicals or other nasties down the drain.
Drains discharge to our waterways and eventually into the oceans.
How can I find out more?
For information on the Eastern Blue Groper see:
http://australianmuseum.net.au/Eastern-Blue-Groper-Achoerodus-viridis
For fisheries protection and general requirements see http://www.dpi.nsw.gov.au/fisheries
For marine and aquatic threatened species information see
http://www.dpi.nsw.gov.au/fisheries/species-protection
Information about maintaining fish habitat and recreational fishing can be found on
http://www.fishhabitatnetwork.com.au/
This project has been assisted by the New South Wales Government through its Environmental Trust.