Taking care of Mareela Reef – the “coral” reef of the Hawkesbury
Mareela Reef is in country cared for over millennia by the Guringai and Darkinjung peoples.
Mareela was chosen as the official name of the reef in 1985 as it is thought to be an aboriginal word for mullet. The mullet connection is through the well-known visit to the island in 1788 by Governor Phillip's expedition who managed to net a good haul of mullet off Bradleys Beach. So the name seems an appropriate one – indeed the island was known as Mullet Island for many years.
Satellite view showing the location of Mareela Reef on the eastern end of Bradleys Beach on Dangar Island
The reef is ecologically important for filtering the water, acting as a buffer for the shoreline to erosion from waves and has developed into a significant waterbird habitat for a diverse range of resident and migratory species. It is part of a network of habitats along the Hawkesbury River estuary where waterbirds feed and rest. They move between these habitats during the day and night in response to changing tides and habitat conditions.
A rich community of benthic invertebrates such as worms, mollusks and barnacles inhabit the reef. These play a major role in the food chain. Not only do they serve as food for fish and birds but they also break down organic matter that falls to the bottom of the reef. The waters adjacent to the reef support feeding marine turtles.
Migratory shorebirds such as the Bar-tailed Godwit feed on worms, molluscs, crabs and oysters which live on the reef and the beach.
White-faced Heron on Mareela Reef, watching for crustaceans, insects, crabs, fish and worms. Image: Bill Lynn-Robinson
A Pied Oyster Catcher probing the mud for worms, molluscs, or crabs. Image: Bill Lynn-Robinson
Migratory shorebirds are protected under international agreements and may fly up to 24000 km annually in an epic journey from their breeding habitats in Japan, Siberia and Alaska to the southern hemisphere and back again.
Mareela Reef provides important habitat for these birds along the East Asian-Australasian Flyway, either as a stopover on the way to wetlands/reef further south or as a longer stay throughout the summer. In recent years their numbers have reduced dramatically due to the destruction of their habitat along their flyways in Eastern Asia. Species recorded include Eastern Curlew, Bar-tailed Godwit, Whimbrel, Common Sandpiper, Sharp-tailed Sandpiper, Grey-tailed Tattler, Red Necked Avocet, Pied Stilt. Little Curlew, White faced and Mangrove herons and Pied Oyster Catcher.
The key threats to shorebirds arise from loss of habitat through urban coastal development, and disturbance of the roost and feeding sites through human activities and interactions with marine debris at key sites. Migratory shorebirds are particularly susceptible to disturbance from human and dog presence in the few months before their migration. Increased tourism activity on the island has resulted in high numbers of visitors walking on and around the Mareela reef, disturbing shorebirds feeding time that can delay their arrival on wintering grounds or force the birds to depart without sufficient fat loads.
Please respect this special place by not walking on the reef with or without your dog. The birds will thank you by returning each year.