Modelling connectivity for resilient protected area design among areas for further assessment identified by DEWHA for the development of a Commonwealth MPA Network in the South-west Marine Region

CSIRO Marine and Atmospheric Research, 2009

Phillip R. England, Scott Condie, Ming Feng & Dirk Slawinski
CSIRO Marine & Atmospheric Research / CSIRO Wealth from Oceans Flagship
Report for Temperate West Marine Conservation, Marine Division, Department of the Environment, Water, Heritage & the Arts. 30 November 2009

Executive summary

General findings

  • The Leeuwin Current drives strong directional connectivity patterns between all Areas for Further Assessment (AFA) so that dispersal into AFAs or areas between them is most likely to occur from the closest northern or western AFA.
  • Connectivity is stronger in autumn months and la Niña years when Leeuwin Current flow is maximal.
  • Connectivity is greater in the west coast AFAs as a result of their closer proximity and higher energy of Leeuwin Current and associated eddy mixingv.
  • Coastal and upper slope waters (0 to 500m) show much greater connectivity between AFAs than deeper waters.
  • Contrasting dispersal patterns can occur between shallow (0-100m) and upper slope (100-500m) waters.
  • At 100-500m generally reduced connectivity relative to shallower waters was observed, although this contrast was weaker on the west coast.

Findings for individual Areas for Further Assessment

  • The Abrolhos AFA supplies propagules to downstream AFAs as far as the Southwest Corner, especially in winter.
  • The Jurien AFA is strongly connected northwards and southwards in spring due to eddy activity.
  • The Perth AFA potentially supplies long lived propagules to southern AFAs.
  • The Southwest Corner AFA is likely to be an important source of propagules both north and eastwards.
  • Increased seabed area at slope depths between 2000 and 3000 represented in the Southwest Corner AFA make this a potentially important source for slope biota especially on the southern coast AFAs.
  • The Recherche AFA shows almost exclusively eastward connectivity.
  • High connectivity between east and west Recherche AFAs.
  • Highly clustered dispersal tragectories from eastern Recherche AFA onto the broad continental shelf continuous with Great Australian Bight.
  • As with the Recherche AFA, there was highly clustered dispersal onto the broad GAB continental shelf.
  • West Eyre AFA links strongly with Murray Canyon MPA and potentially supplies propagules as far as Bass Strait.
  • Areas of high larval retention potential are found within Abrolhos, South Western Corner and Western Eyre AFAs, suggesting these areas may have important ecological qualities worthy of further investigation and protection.