The area represents a meeting point of three major climatic regions and forms a change-over between two major groups of plant species – the South West and Eremaean provinces. The number of species that reach the end of their range is a major feature of the region’s flora. Twenty-five per cent (283 species) of the area’s vascular plants are at the limits of their range in Shark Bay. Many vegetation associations and plant species are found only in the areas between different biological zones. The area south of Freycinet Estuary contains the unique type of vegetation known as tree heath. There are also at least 51 species endemic to the region and others that are considered new to science. The Shark Bay region is an area of major zoological importance, primarily due to habitats on peninsulas and islands being isolated from the disturbance that has occurred elsewhere. Of the 26 species of endangered Australian mammals, five are found on Bernier and Dorre Islands. These are the boodie or burrowing bettong, rufous hare wallaby, banded hare wallaby, the Shark Bay mouse and the western barred bandicoot. The Shark Bay region has a rich avifauna, and over 230 species or 35 per cent of Australia’s bird species have been recorded. A number of birds attain their northern limit at Shark Bay including the regent parrot, western yellow robin, blue-breasted fairy wren and striated pardalote. The region is noted for the diversity of its amphibians and reptiles, supporting nearly 100 species. Again, many species are at the northern or southern limit of their range. The area is also significant for the variety of burrowing species, such as the sandhill frog, which apparently needs no surface water. Shark Bay is home to three endemic sand swimming skinks, and 10 of the 30 dragon lizard species found in Australia. The 12 species of seagrass found in Shark Bay make it one of the most diverse seagrass assemblages in the world. Seagrass covers over 4,000 square kilometres of the bay, and the 1,030 square kilometres Wooramel Seagrass Bank is the largest structure of its type in the world. Seagrass has contributed significantly to the evolution of Shark Bay. It has modified the physical, chemical and biological environment as well as the geology and has led to the development of major marine features such as Faure Sill. Faure Island is an emergent portion of the ‘Faure Sill’, a sandbar overlaying sandstone that crosses the eastern gulf of Shark Bay from Peron Peninsula to the mainland. Interestingly, it is this sandbar that has created the vast areas of sandy hypersaline shallows that support the famous Stromatolites of Shark Bay. The barrier banks associated with the growth of seagrass over the last 5,000 years – and the low rainfall, high evaporation and low tidal flushing – have produced the hypersaline Hamelin Pool and L’haridon Bight. This hypersaline condition is conducive to the growth of cyanobacteria which trap and bind sediment to produce a variety of mats and structures including Stromatolites. Stromatolites represent the oldest form of life on earth. They are representative of life-forms which lived some 3,500 million years ago. Hamelin Pool contains the most diverse and abundant examples of Stromatolite forms in the world. Shark Bay is renowned for its marine fauna. The population of about 10,000 dugong, for example, is one of the largest in the world, and dolphins abound, particularly at Monkey Mia. Humpback whales use the Bay as a staging post in their migration along the coast. This species was reduced by past exploitation from an estimated population of 20,000 to around 800 whales in 1962. The population is recovering and is now estimated at up to 3,000. Green and loggerhead turtles are found in Shark Bay near their southern limits, with loggerhead turtles nesting on the beaches of Dirk Hartog Island and Peron Peninsula. Dirk Hartog Island is the most important nesting site for loggerhead turtles in Western Australia. Shark Bay is also an important nursery ground for larval stages of crustaceans, fishes and medusae.
Shark Bay
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Government evidence of impact of climate change:
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Australian Government Department of Agriculture, Water and the Environment, World Heritage Places - Shark Bay
Climate change could also impact on the complex marine ecosystem.
Since then; climate change has emerged as an additional potential threat to the World Heritage values.
Fire also represents a threat to species that are highly restricted in their distribution; particularly populations which only survive on islands which could be severely affected by a single large fire.
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IUCN World Heritage Outlook, Shark Bay, Western Australia, 2014
Outstanding examples of processes of biological and geomorphic evolution taking place in a largely unmodified environment Good Trend Stable The site’s internationally and nationally important biodiversity values; which are more sensitive to anthropogenic impacts; are affected mainly by very low threats (9); with the possible exception of the interacting threats of sheep and goat grazing and climate change (6).
Rising temperatures and a drying climate will affect both terrestrial and marine ecosystems that form part of the initial listing for Shark Bay; as well as increasing risks of fires damaging terrestrial ecosystems and rare and endangered animals.
Fire represents a significant threat to species that are highly restricted in their distribution; particularly populations which only survive on islands; where they could be severely affected or totally destroyed by a single large fire; especially from lightning strikes. (6) Vegetation structure in the site has been modified through grazing on current and ex pastoral leases.
Similarly; the site’s biodiversity values; which are more sensitive to anthropogenic impacts; are affected mainly by low threats; with the possible exception of ocean acidification and increasing temperatures in the marine environment.
Ocean acidification has risks for Shark Bay’s calcareous environments and the essential processes driving the ecosystem.
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IUCN World Heritage Outlook, Shark Bay, Western Australia, 2017
Climate change poses the largest threat to the site’s World Heritage values and it is expected to significantly increase.
Habitat Shifting Alteration; Ocean acidification; Temperature extremes; Storms Flooding High Threat Inside site; throughout( 50 ) Outside site Effects of climate change will likely result in impacts on the property’ habitats; and ecosystems; as well as changes in salinity and nutrient levels which will directly affect Hamelin Pool and the stromatolites.
Stromatolites are also becoming increasingly threatened as stomatolite growth is vulnerable to rising sea level and extreme climate events (Suosaari et al.; 2016).
Risks of increasing frequency of such events with changes in global climate are still unknown (6).
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IUCN World Heritage Outlook, Shark Bay, Western Australia, 2020
The Shark Bay World Heritage Advisory Committee (SBWHAC) has identified the vulnerability of the site in response to future climate change as being a major issue (NESP; 2018 Fraser et al.; 2019).
Climate change poses the largest threat to the site’s World Heritage values and it is expected to significantly increase.
Low Threat Fire Fire Suppression (Wild fires) Inside site; extent of threat not known Outside site The extent of the threat of fires is understood and whilst more hot days and warm spells predicted through climate change will make fire more likely; they are generally retarded by the high salt content in the local vegetation.
A 2018 workshop convened by the Shark Bay World Heritage Advisory Committee classified Shark Bay as being in the highest category of vulnerability to future climate change (NESP; 2018 Fraser et al.; 2019).
Habitat Shifting Alteration; Temperature extremes; Very High Threat Storms Flooding Inside site; throughout( 50 ) Outside site (Climate change) Effects of climate change will likely result in impacts on the site’s habitats; and ecosystems; as well as changes in salinity and nutrient levels which will directly affect Hamelin Pool and the stromatolites.
Stromatolites are also becoming increasingly threatened as stromatolite growth is vulnerable to rising sea levels and me climate events (Suosaari et 2016).
The following implications of climate change in Shark Bay that can be predicted with a degree of confidence are Increased average air temperatures in all seasons (very high confidence) More hot days and warm spells with a substantial increase in the temperature reached on hot days; the frequency of hot days and the duration of warm spells (very high confidence) Decreasing winter and spring rainfall (high confidence) More intense extreme short duration rainfall (high confidence) with the wettest day of the year being wetter; and Rising mean sea level and increased height of extreme sea level events (very high confidence) (NESP; 2018).
The exception however; are the threats relating to climate change (Arias Ortiz et al; 2018 NESP; 2019); particularly extreme heat wave events in the marine environment; such that which had a ‘catastrophic’ impact in 2010 11 (Fraser et al; 2014; 2019) which have a flow on effect to biodiversity; especially seagrasses and associated fauna such marine turtles (Fraser et al; 2019).
Climate change is recognised as a significant major potential threat to the site; and is the focus of recent and ongoing work by the Shark Bay World Heritage Advisory Committee (NESP; 2018).
It has been noted that despite Shark Bay being declared as being in the highest category of vulnerability to future climate change relatively little media attention and research funding has been paid to this World Heritage Site that is on the precipice (Fraser et al.; 2019).
However; the Shark Bay World Heritage Advisory Committee (SBWHAC) has identified the vulnerability of the site in response to future climate change as being a major issue (NESP; 2018 Fraser et al.; 2019).
Risks of increasing frequency of such events with changes in global climate are projected for the future.
Potential impacts of climate change on the site’s values are of concern; and the site’s vulnerability to future climate change has been identified as being a major issue (NESP; 2018 Fraser et al.; 2019).
Factors negatively affecting provision of this benefit Climate change Impact level High; Trend Increasing The seagrass banks suffered a large scale dieback and defoliation during the summer of 2010 11 as a result of a marine heatwave event.
Factors negatively affecting provision of this benefit Climate change Impact level High; Trend Increasing There is evidence of some fisheries (scallop) having been seriously impacted by the 2010 heatwave (Mueller et al.; 2018).
Fire can have a detrimental impact particularly on species highly restricted in their distribution (IUCN Consultation; 2020).
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Western Australian Government Department of Environment and Conservation and Australian Government Department of the Environment, Water, Heritage and the Arts, Shark Bay World Heritage Property Strategic Plan 2008-2020
There is one threatened ecological community and several other ecological communities at risk in the Shark Bay area (May and McKenzie 2003) Table 5 Threatened Ecological Communities and Other Ecosystems at Risk in the Shark Bay Area Community Status3 Threatening Processes Threatened Ecological Community Hypersaline microbial community V; P4 Recreation; climate change leading to changed (Hamelin stromatolite) sea levels; nutrient enrichment Other ecosystems at risk Reptile assemblages of islands; gulfs and Feral animals (cats; foxes; goats); grazing; peninsulas changed fire regimes Coastal heath communities at Steep Point V Grazing; feral animals (goats); clearances for proposed developments Eucalyptus mallee sp. and Acacia scrub Increasing fragmentation; loss of habitat and with scattered E. loxophleba lack of recruitment; grazing feral animals (rabbits) changed fire regimes Acacia rostellifera low forest Increasing fragmentation; loss of habitat and lack of recruitment; grazing feral animals (rabbits) changed fire regimes V V V The conservation of these ecological communities is essential in maintaining biological diversity and Shark Bay’s World Heritage values.
Potential sources of pollution include atmospheric pollution; for example; industrial and vehicle emissions; carbon dioxide levels (see section 4.3.15 Climate Change) or bushfires marine pollution; for example; fuel and oil spills; littering (especially plastics and fishing line); bilge and ballast discharge from ships; sewage; dredging; discharge of bitterns Shark Bay World Heritage Property Strategic Plan Conservation chemical; nutrient; or exotic biota pollution from existing industries; such as salt mining and aquaculture; and associated shipping activities land pollution; for example; littering and urban; industrial and agricultural pollution groundwater pollution; for example; seepage from septics; and nutrients and chemicals from agricultural activities dust associated with mining and agricultural practices and noise pollution.
The Western Australian Greenhouse Taskforce (2004) listed the following changes evident in the Western Australian climate during the last 90 years rising daily average temperatures and consistent regional trends in rainfall changes with the trend in the northern regions being to wetter conditions.
Climate modelling and analysis by CSIRO (2001b) suggests continued warming and changes in rainfall patterns in Australia including an increase in the average annual temperature of 0.4 2 C over most of Australia by (relative to 1990); with slightly more warming in north western Australia an increase in the average annual temperature of between 1.0 6.0 C over most of Australia by 2070; with spatial variations similar to those for 2030; and the highest potential increases projected for the northwest of Western Australia and a likely decrease in rainfall in the south west with rainfall projections for other parts of Western Australia less certain.
There are also indications that weather events may generally be more extreme; with increases in floods; droughts and lightning; and that tropical cyclones may have greater peak wind intensity and more intense rainfall (Western Australian Greenhouse Taskforce 2004).
At a national level climate change resulting from emissions of greenhouse gases has been identified as a key threatening process under the EPBC Act.
Climate change presents an additional pressure for native species and ecosystems as well as exacerbating existing pressures such as habitat fragmentation modification; competition by introduced species and altered fire regimes.
The IPCC consider natural systems especially vulnerable to climate change because of limited adaptive capacity; and suggest that whilst some species may increase in abundance or range; climate change will increase existing risks of extinction of some more vulnerable species and increase loss of biodiversity (IPCC 2001; cited in Western Australian Greenhouse Taskforce 2004).
Climate change also is likely to bring increases in acidity of oceans leading to bleaching events; increases in storm surges and consequent damage to infrastructure.
The National Biodiversity and Climate Change Action Plan 2004 2007 (DEH 2004) details other species and communities that may be more vulnerable to climate change including those with very limited or restricted climatic ranges limited dispersal ability very specialised habitat requirements and small populations and or low genetic diversity Within the Shark Bay World Heritage Property there are a number of species and communities that are endemic or at or near the limits of their range (see sections 4.3.3 Conservation of Native Flora and Fauna and 4.3.4 Conservation of Ecological Communities) and which are likely to be particularly vulnerable to climate change.
Disturbance by events such as cyclones and fire can have significant environmental impacts.
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