Intertidal Habitats of the Gorgon Gas Development EIS/ERMP-Technical appendix C9

Brief description

RPS Bowman Bishaw Gorham has conducted a number of studies of intertidal habitats around Barrow Island prior to the present proposal. Le Provost Environmental Consultants (1991) surveyed intertidal habitats around the Island in 1990. Further studies of the areas expected to be affected by the proposed development have been undertaken to assist formal environmental assessment of the proposal (Bowman Bishaw Gorham 2003). This report describes the results of the current field surveys and relates the findings to existing information for similar areas within the region. The Montebello/Lowendal/Barrow Islands region is characterised by limestone islands, running along the western edge of the Rowley Shelf, exposed to open ocean swells on their west coasts and sheltered on their east coasts. The Leeuwin Current connects the Montebello/Lowendal/Barrow Island regions with areas further north and provides the area with an ongoing source of recruits for reestablishment of new biotic habitats or recovery of disturbed ones. Wave energy plays a major role in the physical structure of intertidal habitats, and exposure to salinity and the desiccating effects of the sun play major roles in shaping biotic intertidal habitats. The local distribution of intertidal habitats is affected by the regular passage of tropical cyclones that shape sandy beaches, redistribute boulders and sand sheets over intertidal platforms and, in extreme cases, cause widespread destruction of biotic habitats. The ongoing effects of exposure to wave energy have led to the development of different intertidal habitats on the west and east coasts of the regions islands. The predominant habitats on the exposed west coasts of islands in the Montebello/Lowendal/Barrow Island region are sandy beaches, rocky shores and cliffs. The predominant physical habitats on the sheltered east coasts and the adjacent mainland coast are sand flats, mud flats, rocky pavements and platforms. Mangroves have developed on sheltered coasts of the islands and along the mainland coast. Tidal inundation plays a major role in shaping the distribution of the essentially marine assemblages of intertidal habitats. Biotic habitats in the intertidal zone are generally represented by stunted and resilient ecomorphs of marine macrophytes, due to the physiological stress imposed by the environment.

Lineage

Maintenance and Update Frequency: unknown

Statement: Original record compiled for the Gorgon Gas Development EIS/ERMP.

Notes

Credit
Jeremy Fitzpatrick: RPS Environment