degradation of coastal ecosystems and direct use. While avoiding disturbance to estuaries should always be the first consideration, where it cannot be avoided, environmental offsets should be required and applied to reduce other threats to estuaries. In response to the emerging threat of accelerating sea level rise, developers should consider the potential for shoreline retreat and the need for the subsequent movement of estuarine habitat landward. This should be factored into all planning schemes to ensure the long-term viability of these habitats. Understanding status and trends and requirements for ecosystem health It is important to ensure management of estuaries is based on good science and underpinned by an effective research and monitoring program. Almost all the current estuarine monitoring is in close proximity to ports. Despite this focus, the limits and tolerance of estuarine ecosystems to various threats, such as increased nutrients and changes to hydrology, are still not well understood. Very little is known about the population status, ecological roles and/or pressures and impact thresholds for estuarine flora and fauna, nor their reliance on adjacent ecosystems. Information is required at regional (basin) scales on key connectivity and hydrological mechanisms (especially groundwater recharge, discharge and extraction). There is also a need to use such knowledge to better manage cumulative impacts on estuaries. Climate change Broad national and global initiatives required to address climate change are not considered here. Information on cumulative impacts can be found in the Great Barrier Reef Marine Park Authority’s Climate Change and the Great Barrier Reef – A Vulnerability Assessment. 19 Efforts by the Great Barrier Reef Marine Park Authority are primarily aimed at understanding the vulnerability of the Reef’s ecosystems, including estuaries. These efforts focus on maintaining them in a healthy state, which builds resilience to climate change in the broader Reef ecosystem and the communities and industries that depend on it. There should be continued focus on actions that protect or improve the existing condition and function of estuaries, and hence the resilience of high-risk habitats and species to climate change threats. Specific adaptive management measures that will facilitate species and habitat adaption to new environmental conditions, particularly those associated with elevated sea levels and altered catchment run-off are also critical.
Lockhart 75 75 100 Stewart 10 10 100 Normanby 97 96 99 Jeanie 85 85 100 Endeavour 26 25 98 Wet Tropics natural resource management region 364 340 93.5 Daintree 33 32 98 Mossman 15 14 93 Barron 12 9 72 Mulgrave–Russell 52 44 86 Johnstone 38 34 90 Tully 19 19 99 Murray 79 78 100 Herbert 116 109 94 Burdekin Dry Tropics natural resource management region 277 269 97.2 Black 8 8 98.5 Ross 40 38 93.3 Haughton 146 146 99.4 Burdekin 2 1 63.3 Don 80 77 96.0 Mackay–Whitsunday natural resource management region 323 316 97.6 Proserpine 93 92 99.4 O'Connell 104 102 98.6 Pioneer 9 7 71.9 Plane 118 115 97.4 Fitzroy natural resource management region 534 524 98.3 Styx 57 56 99.9 Shoalwater 129 129 99.9 Waterpark 199 199 99.9 Fitzroy 94 92 97.7 Calliope 43 40 93.1 Boyne 11 8 69.0 Burnett–Mary natural resource management region 144 140 97.2 Baffle 82 81 99.6 Burnett 11 10 86.7 Kolan 14 12 90.6 Burrum 15 15 98.0 Mary 23 22 97.3 Figure 6: Estuary types and their relative susceptibility to change (from National Land and Water Resources Audit 20022)
Vulnerability assessment matrix summary for estuaries Pressure Exposed to source of pressure Degree of exposure to source of pressure Sensitivity to source of pressure Adaptive capacity — natural Adaptive capacity — management Residual vulnerability Level of confidence in supporting evidence Commercial tourism Yes — locally Low Low Good Good Low Good Defence activities Yes — locally Low Low Good Good Low Good Traditional use Yes — Great Barrier Reef catchment wide, localised higher pressure Low Low — can be higher where other pressures exist Good — can be poorer where other pressures exist Good Low Moderate Climate change Yes — entire region, multiple expressions of pressure such as sea level rise, extreme climate/ storms, elevated temperatures, ocean acidification, altered ocean currents Very high — without effective emissions mitigation that avoids dangerous climate change High to very high — for species and habitats on terrestrial margin, at limits of tolerance ranges, and estuaries with narrow tidal range, low gradient coastal plain, landward development constraints, highly developed catchment, poor tidal flushing, higher rates of sea level rise, and other pressures. Poor — if climate change/sea level rise is rapid, estuary condition and function is poor, catchment is highly developed, estuary is vulnerable type, subject to frequent storm disturbances, low gradient coastal plain, highly seasonal climate with biotic community at tolerance margins Poor — if effective global emissions control not achieved, and if estuary has poor natural adaptive capacity High to very high Poor High uncertainty surrounds predictions of sea level rise, temperature and ocean acidity rates of change and end points. Specific community tolerance thresholds for parameters that are predicted to change are not well understood. Analysis of potential shoreline retreat and subsequent movement of estuarine habitat inland has not been done. High — with best case emission mitigation Moderate — for estuaries with greater tidal range, tidal flushing, water mixing, lower sediment retention, limited catchment, landward development, steeper coastal plain, species-broad tolerances, lower rates of sea-level rise Moderate — if pressure mitigated by emissions control, estuary/ catchment condition/function good, resilient estuary type, storm disturbances infrequent, higher gradient coastal plain, less seasonal climate, biota tolerant Moderate — where natural adaptive capacity is moderate and legislative and planning frameworks can enable shoreline retreat/landward migration of estuary High
Pressure has both contaminant load and altered run-off hydrology components. contaminant loads and changes in flow, is still limited A degree of uncertainty surrounds effectiveness of strategies to minimise run-off from agricultural lands. Moderate — catchments with mixed land use, and regulating ecosystem services, and/or low intensity land use with some land degradation Low — where estuary has good condition/function and/or flushing/ mixing and/or contaminant loads/ hydrological change are within ecosystem health thresholds Good — if pressure only short-term stress, system has good condition/ function, estuary type resilient, changes within thresholds Moderate — actions underway where exposure and sensitivity to run-off pressure is medium and catchment land use, condition, functional process integrity and natural adaptive management capacity good Medium — for basins with a variegated land use pattern, which retain and support catchment ecosystems services that regulate contaminant loads and transport Low — catchments with low intensity land use, little or no land degradation Good — where exposure and sensitivity to pressure is low and estuary has good condition and function Low — for undeveloped basins with low intensity land use and little or no land degradation
Management of estuaries in the Great Barrier Reef Marine Park The Australian Government, along with state and local governments, and landholders and the wider community have responsibility for managing estuaries in the Reef catchment. Responsibilities are formalised in laws and through international obligations. Various government agencies manage estuaries by applying a range of laws, policies and programs. Up-to date information on these laws, policies and programs can be found at WetlandInfo: Figure 9: Coastal mangroves Appendix 1: Vulnerability assessment matrix Commercial marine tourism Exposed to source of pressure (Yes/No) Yes — localised pressure Degree of exposure (low, medium, high) Low: Boat wake, propellers, anchors, mooring chains and rope, vessel waste discharge and small spills are possible impacts. There is high volume visitor access to Reef areas with established infrastructure rather than estuarine habitats, although there is small-scale visitation and operation in and around estuaries generally near urban centres. Associated marina development to moor vessels can have localised impacts, although most use existing port infrastructure. Sensitivity to source of pressure (low, medium, high, very high) Low: Although disturbances from anchoring and boat propellers do occur69,70, it is only likely on a small scale within estuaries. Sensitivity is not attributable to any one source. Adaptive capacity natural (Poor, moderate, good) Good: Estuarine communities have the ability to regrow or recolonise small areas following disturbance.
* Coastal habitats (reefs, foreshores, rivers and estuaries) are under increasing pressure from human activities. More than 85 per cent of Queensland's population lives on the coastal fringe. Predicted strong population growth means the intensity of activity and development in coastal zones is likely to persist or increase. The purpose of this vulnerability assessment process is to provide a mechanism to highlight key concerns and make assessments of the vulnerabilities of species, groups of species or habitats to sources of pressure within the Great Barrier Reef. The purpose of the vulnerability assessment matrix is not to produce a comprehensive ecological risk assessment, but to identify and document key pressures that influence a species, species group or habitat, using a standardised and transparent process. To achieve this objective, it has been necessary to apply a linear relationship (e.g. a=b, or exposure=sensitivity) to comparisons that are sometimes non-linear by nature. For example, when applying the exposure/sensitivity matrix to create a combined score for the two, if a species, group of species or habitat has a very high level of exposure to a pressure but low sensitivity to it (using the Great Barrier Reef Outlook Report 2009 risk assessment process outlined below), it is scored as having a medium–high exposure/sensitivity score. This medium–high score may be the same as determined for another assessment where there may be a low level of exposure but a very high level of sensitivity. This implies a linear relationship between the sensitivity of a species or habitat and a given level of exposure, which may not necessarily be the case. However, it does provide managers with the required level of resolution on these relationships for the purpose of vulnerability assessments and Great Barrier Reef Biodiversity Conservation Strategy 2013. Criteria for determining the degree of exposure or sensitivity against each source of pressure are based on those published in Appendix 4 of the Great Barrier Reef Outlook Report 2009. For each pressure, once the likelihood and consequence of exposure (or sensitivity) has been established using Appendix 4, the risk (or in the context of the pressure assessment matrix, the degree of exposure or degree of sensitivity being assessed), is calculated using the matrix of Figure 8.1 on page 166 of the Outlook Report.5