Adaptive management of the Great Barrier Reef: a globally significant demonstration of the benefits of networks of marine reserves

Abstract

The Great Barrier Reef (GBR) provides a globally significant demonstration of the effectiveness of large-scale networks of marine reserves in contributing to integrated, adaptive management. Comprehensive review of available evidence shows major, rapid benefits of no-take areas for targeted fish and sharks, in both reef and nonreef habitats, with potential benefits for fisheries as well as biodiversity conservation. Large, mobile species like sharks benefit less than smaller, site-attached fish. Critically, reserves also appear to benefit overall ecosystem health and resilience: outbreaks of coral-eating, crown-of-thorns starfish appear less frequent on no-take reefs, which consequently have higher abundance of coral, the very foundation of reef ecosystems. Effective marine reserves require regular review of compliance: fish abundances in no-entry zones suggest that even no-take zones may be significantly depleted due to poaching. Spatial analyses comparing zoning with seabed biodiversity or dugong distributions illustrate significant benefits from application of best-practice conservation principles in data-poor situations. Increases in the marine reserve network in 2004 affected fishers, but preliminary economic analysis suggests considerable net benefits, in terms of protecting environmental and tourism values. Relative to the revenue generated by reef tourism, current expenditure on protection is minor. Recent implementation of an Outlook Report provides regular, formal review of environmental condition and management and links to policy responses, key aspects of adaptive management. Given the major threat posed by climate change, the expanded network of marine reserves provides a critical and cost-effective contribution to enhancing the resilience of the Great Barrier Reef.

Fig. 1.

Abundance and biomass of coral trout on fished and no-take reefs spread across ≈1,000 km of the Great Barrier Reef (see map in Fig. S1). Solid lines are no-take zones; dashed lines are fished reefs. Data are means ±SEM from scuba-based, visual transects of reefs zoned in 2004, updated from ref. . Data for inshore reefs (A) include data from before zoning implementation. Note different vertical axes and periods (dates) for A and B.

Fig. 2.

Abundance of reef sharks in different zones in the northern and central GBR. Abundance of sharks based on scuba-based, visual transects for A (from ref. 20) and for B (from ref. 21). (C) Catch rates of sharks using commercial line fishing, disaggregated from ref. . All data are means ±SEM.

Fig. 3.

Effects of zoning on coral-eating starfish and hence on coral populations. (A) Frequency of outbreaks of crown-of-thorns starfish on no-take and fished midshelf reefs in regions with active outbreaks present. Data are for 1994–2004, redrawn from ref. ; note low numbers of no-take reefs were available pre-2004; further background in SI Section 4. (B) Abundance of hard corals on midshelf reefs after crown-of-thorns starfish outbreaks. Data, previously unpublished, are means ±SEM of percent cover; details of methods in SI Section 4.

Fig. 4.

Economic costs and benefits for the Great Barrier Reef. (A) Economic value of the GBR to the Australian economy (–52), compared to expenditure on management of the Great Barrier Reef Marine Park (–67). Tourism provides the vast majority of economic benefits (numbers indicate ratio of tourism to commercial fishery estimates). Percentages above costs give expenditure as percentage of revenue, respectively, for overall expenditure on management of the Marine Park and for field management. (B) Costs of field management (including enforcement) and other management of the GBR (–69). All values in Australian dollars.