Processes Impacting on Lake Macquarie

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What role do seagrasses play in the Lake’s ecosystem?
They may not always be aesthetically pleasing, but seagrasess are a vital component of Lake Macquarie’s ecosystem.

I am often asked why seagrasses are so important to the Lake’s health and this week I will address this common question.

In areas where seagrasses are lost, marine life is lost too. Seagrass meadows form the foundations of the Lake’s food chain and are the nursery grounds for many of Lake Macquarie’s fish and crustacean species as they provide food and protection from predators.

A number of epiphytes attach themselves to the leaves of seagrasses such as small worms called spirorbide and minute colonial animals known as bryzoans. These epiphytes are a vital food source for small fish and other marine life that live in the Lake.

Seagrass meadows also act as a natural filter in the water. The strap-like leaves of seagrass plants slow the movement of the water above, allowing any sediment that is suspended in the water to fall down into the seagrass meadow where is can be contained. This natural process helps to protect the Lake’s water quality.

Typically, seagrass beds fringe the shorelines of the Lake and the roots assist in reducing sand erosion in the bed.

When seagrass leaves break off and wash up on the shoreline it is known as seagrass wrack. It often accumulates on shorelines to the dismay of some locals. Although the seagrass wrack may not be visually pleasing to everyone, an important part of the Lake’s food chain is destroyed when seagrass wrack is removed from shorelines.

Seagrass wrack is a source of nutrients for marine life and salt marsh areas and is an essential part the food chain for the Lake’s ecosystem, whether it is in or out of the water.

Local Council staff will occasionally remove seagrass wrack from public reserve areas when it is absolutely necessary if excessive amounts cover the shoreline. Removal of seagrass wrack is controlled and regulated by New South Wales Fisheries.

The Lake is a dynamic and living thing that is constantly changing. People often comment that some areas of the Lake previously had sandy bottoms, but are now covered in seagrass. The size and location of seagrass beds constantly changes over time and is in fact a positive sign for the health of the Lake. This change reflects the evolving nature of the living Lake.

Through working together and protecting the Lake’s natural processes, the future of Lake Macquarie will be bright.


Channel Challenges
Channel & Water Quality
Constant Change
Threats to the Lake
Vegetated Swales
Water Sensitive Urban Design
Wrack & Ruin