Mangrove coasts

'Mangroves are the rainforests by the sea' (Quarto 2000), and they are highly productive, dynamic and unique 'edge' ecosystems which link land and sea environments. The term 'mangrove' can refer to a particular species of mangrove (of which there are approximately 69 species worldwide), but can also refer to the overall habitat associated with this vegetation, including the estuarine region, the waterways, the forests, and the fauna within. Within Australia, mangroves cover an area of 11 600 square kilometres, with an estimated 39 species present, most of which occupy the tropical areas of Australia (Kelleher et al. 2000). Although previously believed to be 'wastelands', their importance to maintaining healthy coastal ecosystems is now recognised, but nonetheless mangroves are 'one of the most threatened' habitats in the world (Quarto 2000).

Approximately 70% of mangroves in Australia are located within estuaries (Kelleher et al. 2000), but mangrove species composition and distribution vary because of several factors, including climate/rainfall, water temperature, estuary size, sediment availability, river run-off, tidal patterns, degree of shelter from wave energy, salinity, local sea levels, coastal geomorphology, and geology. Broad differences in distribution and species composition are pronounced in terms of location and climate/rainfall. The greatest species diversity occurs within tropical regions, and the least diversity is evident within temperate regions (e.g. see Ball 1998, Duke et al. 1998). The mangroves around Hinchinbrook Island, Queensland, provide an excellent example of the former, while the mangroves within the Port River Estuary in South Australia provide an excellent example of temperate mangroves within Australia.