Intertidal Health

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The mangroves of Port Curtis are also monitored under the PCIMP Intertidal Monitoring program. Monitoring the health of the mangroves and the intertidal areas in which they live, is also very important in assessing the overall ecological health of Port Curtis.

The intertidal zone includes the area between the high and low tide marks and is an area of high biodiversity. Intertidal areas are ecologically important areas which provide breeding grounds and nurseries for many fish, prawn and crab species. However, these areas can also act as a sink, or a place where contaminants from the harbour may deposit.

The Intertidal Monitoring program commenced in 2006 and examined over 62 sites across the harbour. The mangrove themselves, the sediments and invertebrate communities (crabs, worms, bivalves, etc) have been examined. The health of mangroves is monitored by measuring tree height, biomass and density as well as the number of new seedlings and saplings appearing at each site. Sediments are collected and assessed for levels of contaminants, including metals and organic pollutants (polycyclic aromatic hydrocarbons, or PAHs). The numbers and types of invertebrates, or small fauna, living within the sediments are also counted, which indicates the biodiversity within the site. Crabholes in each area are also counted, as a large crab population tends to result in more crabholes.

The results from the Intertidal Monitoring program have shown that diverse mangrove communities exist throughout the whole of Port Curtis, with at least five mangrove species found commonly throughout the harbour. Sediment contaminant concentrations are below the Low Australian Sediment Quality Guidelines in the majority of sites and PAH concentrations were mostly below laboratory limits of detection. Diverse invertebrate communities are also found throughout the harbour, with numerous crustacean, mollusc, bivalve and polychaete species found in a variety of locations.