Darwin Harbour biodiversity monitoring

The health of marine biodiversity in Darwin Harbour is monitored by mapping and characterising underwater habitats, and monitoring seagrass habitats and dolphins. 

Mapping seafloor habitats

Mapping seafloor habitats helps understand the range of estuarine and marine habitats, including coral reefs, seagrass meadows and mudflats. 

Bathymetric (depth) mapping uses a multi-beam echo sounder system and has mapped all subtidal areas of the Darwin Harbour area.

Then the seafloor is biologically surveyed using grab samples, trawls and remote video cameras. 

This helps describe the type of sediment and the animals and plants living there. 

The different layers of information are then combined to identify and map the habitats of the harbour.

Read more on marine habitat mapping.

Dolphin monitoring

Three species of coastal dolphin live in NT waters, these are all of the following:

• Australian snubfin
• Indo-Pacific humpback
• Indo-Pacific bottlenose.

All three dolphins live in Darwin Harbour and have been monitored since 2008 to understand how each uses the harbour. This program has expanded to include Bynoe Harbour and Shoal Bay.

Individual animals can be identified through photographing their dorsal fin, which have unique markings and scars. This helps assess the health of these individuals.

Seagrass monitoring

Seagrass meadows play an important role supporting coastal marine communities and diverse flora and fauna. 

Seagrass also maintains coastal water quality and clarity.

Seagrass meadows support coastal fisheries as they are nurseries for many commercially and recreationally important species. 

Seagrass is the favourite food for dugongs and an important habitat for many marine species. 

Seagrass health is linked with dugong population numbers and health, and often shows the overall ecosystem health. 

Important local seagrass meadows in Darwin Harbour are found at Casuarina Coastal Reserve, Mindil Beach, Fannie Bay and West Arm. 

A seagrass watch program started in 2011, working with local schools to survey seagrass at Mindil, Vesteys and Casuarina beaches.