State of the Environment

2001

Coasts and Oceans Theme Report

Australia State of the Environment Report 2001 (Theme Report)
Australian State of the Environment Committee, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06751 5

Habitats and species (continued)

Intertidal mudflats

Much of Australia's shore comprises mudflats that are subject to tidal inundation. They are rich in species and frequently are the homes to migratory shorebirds.

Large areas of intertidal mudflats are located in Port Phillip Bay in Victoria, Botany Bay in Sydney, Moreton Bay in Queensland and Roebuck Bay in Western Australia.

Intertidal mudflats are ecologically important, particularly in areas where there are high tidal ranges. Research on intertidal mudflats has been neglected in Australia in favour of studies on coral reefs, rocky seashores and vegetated habitats within estuaries (Fairweather and Quin 1995).

One of the most extensive studies has been conducted in Roebuck Bay in northern Western Australia. This study confirmed the importance of the intertidal mudflats as habitat for migratory shorebirds, and as a diverse habitat in its own right (Pearson et al. 1999). About 200 taxa (species, families or larger groupings) were recognised. This was possibly one of the first detailed studies of benthic biodiversity on tropical intertidal mudflats.

This vast expanse of intertidal sand and mudflat is the first Australian landfall for tens of thousands of migratory shorebirds from August to April. The benthic animals provide food on both inward and outward legs of their migration.

Detailed studies of the benthic fauna were part of this study in Roebuck Bay. They show that the most abundant animals are polychaete worms (about 70%) followed by bivalves (13%) and crustacea (10%) (Pepping 1999). These are distributed quite unevenly both in their proportions and in total density.

The authors concluded there was an urgent need to standardise the methodology of intertidal studies world-wide, as few studies have so far been conducted that are comparable. A better understanding of intertidal ecosystems is needed before these coastal habitats are affected by human impacts.