A dynamic understanding of coral reef health informs resilience-based management of the Great Barrier Reef

Coral reefs are among the most sensitive ecosystems to climate change. Managing coral reefs at a time when changing sea temperatures, levels and chemistry are already negatively affecting the capacity of hard corals to settle, grow, calcify and persist, presents a unique set of challenges. In many reef areas, increasingly frequent environmental disturbances combined with anthropogenic stressors are challenging the natural resilience of reef systems. Adaptively managing coral reefs to support their resilience requires a dynamic understanding of their health and condition. The journey towards the goal of ensuring managers of the Great Barrier Reef (GBR) have a dynamic understanding of reef health and condition forms the focus of this thesis. Dynamic information on reef health will only become available to managers at the scale of the GBR by building capacity among regular reef visitors to assess and monitor reef condition and impacts. A key issue is that many impacts on coral reef health are cryptic, ephemeral and readily confused with other impacts. Chapter 2 describes the development and production of a field guide that enables observers to recognise characteristic signs of compromised coral health on Indo-Pacific Reefs. The guide's structure is based on a colour-coded decision tree that serves as a visual index to help users navigate the content. The decision tree aids the differential diagnosis of diseases and other reef health impacts using characteristic macroscopic signs. The layout of the content was developed in consultation with coral health experts, managers, rangers and tourism operators. The final guide, published in 2008, takes the form of a spiral bound book of underwater cards made to fit the pockets found in dive equipment. In the year following publication of the guide, it was used to enable managers, rangers and tourism staff working within the GBR Marine Park (GBRMP) to distinguish among coral diseases and other reef health impacts. Since 2009, this enhanced capacity among non-specialist observers has provided an early warning system for disease outbreaks. The value of this early warning system is described in the strategic framework for responding to disease presented in Chapter 3. The strategic framework enables managers to use remote sensing and field observations to produce a near real-time estimate of outbreak likelihood and impact severity. Automated coral disease outbreak alerts are now created at the Great Barrier Reef Marine Park Authority (GBRMPA) based upon outbreak thresholds developed while writing the response framework. The development and implementation of the framework helped to focus the views of my GBRMPA colleagues on the increasing need for holistic evaluation of coral reef health. Until 2009, GBRMP managers had limited access to detailed information on reef condition and impacts, primarily from only 48 sites surveyed once every two years by the AIMS Long Term Monitoring Program. In Chapter 4, I describe how from 2009-2014, I led the process of developing the revised 'Eye on the Reef' program, which integrates previous participatory monitoring programs and includes: a Reef Health and Impact Survey (RHIS) method tailored to the time constraints of rangers and tourism operators, an online and field-based training system, a web-enabled database and data entry interface, and automated reporting through Google Earth™. The integrated Eye on the Reef program has now become the primary mechanism by which the GBRMPA gathers up-to-date information on coral reef health and impacts in the Marine Park. Previously, the GBRMPA had access to less than 10% of the information on reef condition and impacts that is available now. Importantly, the scene is now set to use the information extensively to inform adaptive resilience-based management. A severe tropical cyclone in 2011 provided an opportunity to test the RHIS protocol and evaluate the effectiveness of a management action. TC Yasi was a category 5 cyclone when it crossed the Park and was unique among the storms that have crossed the Park since 1985, in that it was both severe and had a large circulation size. In the weeks that followed TC Yasi crossing the Reef, dozens of managers, rangers and research scientists conducted 882 RHIS at 76 reef locations. In Chapter 5, I present the results of this study, which revealed cross-shelf variation in the severity of mechanical damage caused by the storm, as well as patterns in impact severity with respect to direction (north and south) and distance from the cyclone eye. A key conclusion from this work is that more coral was lost in the 24-hour period in which TC Yasi crossed the Park than in any other 24-hour period in at least the last 30 years. Understanding spatial patterns in the severity of impacts following TC Yasi helped the GBRMPA to communicate key information about the event and to target local-scale actions to support recovery. After such actions are implemented, the integrated Eye on the Reef network can help managers evaluate the effectiveness of the actions. Chapter 6 reviews a recent example of such an evaluation from the southern Great Barrier Reef, where the RHIS protocol was used to assess the effectiveness of no-anchoring areas (NAAs) established in 2008. I led teams of managers from GBRMPA and rangers from Queensland Parks and Wildlife that completed RHIS protocols within the NAAs and at control sites from 2008-2012. Declines in anchor damage were immediately apparent in 2010 and virtually no anchor damage was seen within the NAAs by 2012. The Keppel Bay case study is an example of how the effectiveness of a management action can be evaluated by having non-specialist observers undertake RHIS. A significant outcome of the Keppel Bay study is a precedent for using the observer network and survey protocol to assess management effectiveness and that can guide the use of the network/protocol in this way in future years. The ability to target local-scale, short-term actions to support recovery of the GBR has been greatly enhanced as a result of the work presented in this thesis. The Keppel Bay study within Chapter 6 highlights that there are multiple benefits for managers (and management of the Reef) as a result of involving community members in monitoring coral reef condition and impacts. The Keppel Bay study encapsulates the primary message of my thesis and the story of how adaptive management is meant to work. Actions to support reef resilience and recovery (Chapter 6), can now be targeted, evaluated and refined as a consequence of building capacity among non-specialists to monitor reef condition and impacts (Chapters 2-5). The network of observers participating in Eye on the Reef monitoring is now providing information on reef condition and impacts from hundreds of reefs every year. The consequence is that we are starting to dynamically understand reef health, condition and environmental exposure. Importantly, this enables the GBR to be managed adaptively by responding to impacts and by increasingly targeting and trialling actions to support reef resilience.