Baseline surveys of subtidal reefs in the South West National Park Marine Nature Reserve 2004-2005.

Abstract

Surveys of subtidal rocky reefs were conducted in Port Davey/Bathurst Channel as part of a broader study into the effectiveness of marine protected areas (MPAs) in Australian temperate waters. Surveys were undertaken with an identical methodology to that applied in corresponding studies in Western Australia, South Australia, Tasmania and Victoria. Surveys assessed fish size, diversity and abundance, as well as macro invertebrate and algae abundance. Baseline surveys of Tasmania’s South West National Park Marine Nature Reserve were conducted in March/April 2004 (15 replicates), and April 2005 (21 replicates). Zoning was implemented in the marine park in February 2005. Surveys at Port Davey have recorded a relatively low diversity of fish fauna, dominated by Notolabrus fucicola (Purple wrasse) and Notolabrus tetricus (Blue-throat wrasse). Mobile invertebrate assemblages were dominated by Haliotis rubra (blacklip abalone) and Jasus edwardsii (southern rock lobster) with other mobile invertebrate species only being found at low densities. A very diverse algal community was recorded with no species consistently dominating assemblages throughout the area. The acidic, tannin-stained water from Bathurst Channel is concentrated around the eastern shores of Port Davey. Survey results display geographical separation between eastern and western coasts for algal assemblages. Mobile invertebrate assemblages show a similar pattern but with more overlap between east and west, while a consistent fish fauna occurs at all sites in Port Davey, with no clear separation of sites by geographic region. The survey methodology is designed to detect changes at all levels of species interaction and the response of each zone (sanctuary and restricted take) to protection. Ideally surveys will continue to be repeated each year, producing a time-series of data documenting changes in the abundance and size distribution of species of interest. This will allow clear trends through time in protected zones to be differentiated from chance divergence, providing an indication of MPA performance and a reference role for assessing the extent of fishing related system and species changes in SW Tasmanian waters.