Current understanding of the resilience of Australia’s marine environment is limited because it is difficult to monitor the environment across timescales relevant for assessing resilience. This difficulty is a result of the vast spatial extent of Australia’s marine ecosystems, their complexity, and the many and varied sources of pressures exerted on them.
Ecosystems that have relatively high diversity tend to be more resilient to external pressures, largely because of high variability in their population densities and their ability to maintain properties, such as nutrient cycling or food web functioning (Hughes et al. 2005, Levin & Lubchenco 2008). Studies of shallow-water marine reserves around Australia have shown an increased stability in fish populations compared with outside the reserve (Babcock et al. 2010). However, determining direct effects on populations takes at least 5 years, and identifying indirect effects on other species takes more than 10 years (Babcock et al. 2010).
Within Australian marine ecosystems, ecosystem modelling approaches are used to investigate anthropogenic impacts on ecosystems, including increased nutrient input, climate change and fishing, and to test management strategies (e.g. Fulton et al. 2005, 2011). It is accepted that even well-managed systems such as the Great Barrier Reef are unlikely to resist human-caused pressures originating outside the management area, making their prognosis poor (GBRMPA 2014a, Hughes et al. 2015).
Evaluation frameworks are also being developed to assess management approaches to particular sectors. Evaluation models have been used to:
- assist in the restructuring of management frameworks for fisheries managed by the Australian Government in the South-east Marine Region (Fulton et al. 2011, 2014)
- evaluate biosecurity measures to reduce the risk of the northern Pacific starfish spreading further (Dunstan & Bax 2009)
- evaluate multiple-use management strategies in the Pilbara and Gascoyne regions of the North-west Marine Region (Gray et al. 2006)
- evaluate management options for prawn trawl fishing and differing levels of spatial zoning in the Great Barrier Reef Marine Park (Gribble 2007, 2009), and within the North Marine Region (Dichmont et al. 2013).
Management frameworks that include adaptive capabilities have been, or are being, implemented for commercial fisheries across Australian Government, state and territory jurisdictions (e.g. Kolody et al. 2010, Hillary et al. 2016). The Harvest Strategy Policy includes management actions for monitoring, assessing and responding to the biological and economic conditions of individual fisheries, with the aim of achieving defined biological and economic objectives.
For most sectors, however, management plans in place for the marine environment are reactive rather than proactive, and are not coordinated across sectors. As a result, management plans fail to address the cumulative nature of multiple impacts and do not support improved understanding of how to build resilience within coupled socio-ecological marine ecosystems.
The National Representative System of Marine Protected Areas is one exception to this reactive approach, and provides an experimental framework that could improve our knowledge of marine resilience. The review process incorporated into this system also allows adaptive management of the marine environment. Sustained ecological monitoring will be required to understand the role that marine protected areas have in building long-term resilience at local and broader scales.