Fish and Macroinvertebrates

Waterways such as Narrabeen Lagoon and the creeks that feed into it provide habitat and food for a great diversity of aquatic macroinvertebrates, small animals, and fish.

Some macroinvertebrates (small animals that commonly support other animals higher up the food chain) are permanent residents of creeks, such as freshwater shrimps, yabbies and snails, while others reside there only as juveniles, completing their lifecycle on land, such as caddisfly larva, dragonfly and mayfly nymphs.

Monitoring waterways for macroinvertebrates assists land managers in determining the health of the water. If a creek is polluted, the biodiversity or number of different animals found in the water will be low, however, if the creek is in good condition then the number of different animals will be greater.

Also, certain species of animals can only live in nearly ‘pristine’ water , such as mayfly and stonefly nymphs, crayfish and yabbies, while others, such as flatworms, freshwater snails and blood worms can exist in polluted and healthy waters.

 

Fish

Several native fish live in Narrabeen Lagoon, including freshwater, estuarine and marine species. This diversity adds to the overall uniqueness of the catchment area. Some of the fish found in the lagoon include:

Striped Gudgeon (Gobiomorhis australis)

This fish is found naturally only in Australia and lives in a variety of conditions ranging from clear, fast-flowing streams to muddy waterholes. The adults feed on feral Eastern Gambusia (Exotic Mosquito Fish) and aquatic insects.

Sea Mullet (Mugil cephalus)

Sea Mullet are the largest Australian mullet, growing to at least 79cm  and weighing 8kg. They are found in the ocean, estuaries and rivers. They feed by sucking up the mud from the bottom of waterways and digesting the edible bits of food found there.

Dusky Flathead (Platycephalus fuscus)

This marine species can also be found in estuaries and lagoons. The colour of this fish is different depending on where it lives. It is brown when it lives in sandy areas and green and brown when living in seagrass beds.

 

Luderick (Girella tricuspidata)

This species is found in marine and estuarine waters and can be found off the eastern shores of Australia and the north island of New Zealand. Luderick feed mainly on algae which they graze off rocks or floating material.

Sand Whiting (Sillago ciliata)

Sand Whiting are found in bays, estuaries and lagoons. The juvenile fish live in seagrass beds, like those found in Narrabeen Lagoon.