Climate change and freshwater ecosystems in Oceania: an assessment of vulnerability and adaptation opportunities

K.M. JENKINSA, R.T KINGSFORDA, G.P. CLOSSB., B.J.WOLFENDENAC., C.D MATTHAEIB and S.E. HAYA

Human-forced climate change significantly threatens the world’s freshwater ecosystems, through projected changes to rainfall, temperature and sea level. We examined the threats and adaptation opportunities to climate change in a diverse selection of rivers and wetlands from Oceania (Australia, New Zealand and Pacific Islands). We found common themes, but also important regional differences. In regulated floodplain rivers in dry regions (i.e. Australia), reduced flooding projected with climate change is a veneer on current losses, but impacts ramp up by 2070. Increasing drought threatens biota as the time between floods extends. Current measures addressing water allocations and dam management can be extended to adapt to climate change, with water buy-back and environmental flows critical. Freshwater wetlands along coastal Oceania are threatened by elevated salinity as sea level rises, potentially mitigated by levee banks. In mountainous regions of New Zealand, the biodiversity of largely pristine glacial and snow melt rivers is threatened by temperature increases, particularly endemic species. Australian snow melt rivers face similar problems, compounding impacts of hydro-electric schemes. Translocation of species and control of invasive species are the main adaptations. Changes to flow regime and rising water temperatures and sea levels are the main threats of climate change on freshwater ecosystems. Besides lowering emissions, reducing impacts of water consumption and protecting or restoring connectivity and refugia are key adaptations for conservation of freshwater ecosystems. Despite these clear imperatives, policy and management has been slow to respond, even in developed regions with significant resources to tackle such complex issues. Key words: flow regime, floodplain, wetland, river regulation, estuary, snow melt rivers, glaciers, dryland rivers

INTRODUCTION communities (Jones et al. 1995; Keith 2004; Kingsford et al. 2009). The few freshwater UMAN-forced climate change has and will H protected areas are mostly in elevated, nutrient continue to affect the world’s freshwater eco- poor terrestrial landscapes that are not managed systems, with social and ecological consequences for freshwater values (Kingsford et al. 2004), (Smit and Pilifosova 2001; Milly et al. 2005; with little protected land in the Pacific Islands Palmer et al. 2008). Global projections indicate (Kingsford et al. 2009). there will be fewer wetter basins while the proportion of drier basins will rise over time Altered climate change will change the key (Milly et al. 2005). Accelerated climate change drivers of freshwater ecosystems: flow regime is pervasive throughout Oceania (Australia, New (Poff et al. 1997; Bunn and Arthington 2002), Zealand and Pacific Islands), changing rainfall, water temperature (Caissie 2006) and water temperature and increasing sea levels (Table 1), quality (Finlayson et al. 2009). Also, low lying all of which affect freshwater ecosystems (IPCC coastal wetlands will be significantly affected by 2007a). Freshwater ecosystems at low elevations sea level rise. These factors will change on coast lines are vulnerable to sea level rise; regionally and for different types of ecosystems glacial and snow-melt streams are particularly (Aldous et al. 2011; Poff et al. 2002). vulnerable to temperature changes and; In alpine regions, where snow melt drives high wetlands in dry areas will experience increased spring flows, increased temperatures will reduce drying with increasing temperatures and snow and shift the timing of melt (Kingsford sometimes reduced run-off. Anthropogenic 2011). Similarly, increasing temperatures accelerate climate change impacts will compound signifi- glacial retreat, altering the unique character of cant anthropogenic threats in freshwater associated streams (Winterbourn et al. 2008). ecosystems (Vörösmarty et al. 2000; MEA 2005; Rising temperatures affect all freshwater eco- Kingsford et al. 2009; Kingsford 2011), causing systems, reducing the resilience of refugia further biodiversity loss (Lake et al. 2000; Heino during low flow periods (Magalhães et al. 2002) et al. 2009). For example, regulation and water and threatening the survival of species (Pittock abstraction has degraded Australian rivers and and Wratt 2001). wetlands (Kingsford 2000) and Pacific islands (Parrish et al. 1978; Kingsford et al. 2009). Land- Reduced rainfall and runoff and consequent use in New Zealand and temperate Australia has reductions in flow and flooding combined with destroyed many floodplain and wetland biotic increasing temperature will significantly impact aAustralian Wetlands and Rivers Centre, School of Biological, Earth and Environmental Sciences, University of NSW, NSW 2052, Australia bDepartment of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand cSnowy Flow Response Monitoring and Modelling, New South Wales Office of Water, 84 Crown Street, Wollongong, NSW 2500, Australia PACIFIC CONSERVATION BIOLOGY Vol. 17: 201–219. Surrey Beatty & Sons, Sydney. 2011. 202 PACIFIC CONSERVATION BIOLOGY . et al (1999), Lal et al. ata from Arnell (1999), Jones ata from 2030: up to 20% more droughts with projected increases with projected droughts 2030: up to 20% more 2000 to 2046 from severity index drought in the Palmer (defined as the 1-in-10 year droughts 2070: 80% more 1974 to 2003) in south-western deficit from moisture Australia. 20 days per event) flood events (currently Large 2030: -12 or + 10 days per event. 2070: 0 9 per event 2050: snow cover decline of 22-85%, earlier snowmelt to rainfall events is expected of extreme The frequency of 1-3°C increase 7-20%, based on a temperature increase 1 in 20 from to increase is predicted frequency Drought frequency to a 5 10 year return year frequency to cause more events likely intensity of extreme Greater Category 4 and 5 as well more flooding and drought, cyclones n.a. 2030: 14cm (IPCC emission scenario A1B, 95th percentile) 2070: 70cm (high emissions scenario) n.a. 2090: 18 to 59 cm to average sea relative level over 1980-1999 and a potential of 2100- of 50– Plausible increase 100 cm and possibly higher 2100: 8–59 cm . (2007), IPCC (2007b), Ministry for the Environment (2008), BMT-WBM (2010) and (2008), BMT-WBM . (2007), IPCC (2007b), Ministry for the Environment et al . (2006), Hennessy et al 2020: -5 to+5%, 2050: -13 to+13%, 2080: -27 to+27%. in in runoff 2050- A decrease 15-35% the Basin of around 2020: -10 to+5%, 2050: -27 to+13%, 2080: -54 to+27%. 2050:-24% to +2.6 in the 2040: +5% increase west in the 2090: +10% increase west in the east : -5% decrease and north 2050: +4.1 to 5.7% . (2005), Wratt . (2005), Wratt C et al o C C. C C. C C o o o o o o C, C, o o emperature Rainfall/ runoff Sea level Events (2003), Mullan 2020: +0.2-1.5 2080: +0.8 to 8.0 2020: +0.1-1.0 2080: +0.4 to 5.4 2050: +0.6 to 2.9 2100: +0.6 to 3.5 2050: +0.5 to 4.0 2050: +0.3 to 2.7 2040: 1°C to 1980-99 2090: 2°C relative (mid-range IPCC A1B scenario 2050: +0.4 to 1.3 et al. (2002), Hennessey Nicholls (2011). Inland Australia Northern Territory Australia alpine New Zealand Islands Pacific Country/region T Table 1. Climate change projections that will impact freshwater ecosystems in Australia, New Zealand and the Pacific islands. D ecosystems in Australia, New Zealand and the Pacific that will impact freshwater 1. Climate change projections Table JENKINS ET AL.: CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS IN OCEANIA 203 inland rivers and wetlands (e.g., Australia, of carbon and aquatic propagules (Jenkins et al. MDBA 2010). In particular, the timing between 2009). flood events is critical to floodplain wetlands The increasing threat of accelerated climate and extending this period beyond the tolerances change (Prowse and Brook 2011) means that of species and ecosystems reduces resilience of freshwater dependent socio-ecological systems aquatic biota and processes (Jenkins and must either adapt or fail (Palmer et al. 2008). Boulton 2007). Climate change impacts on Adaptations represent changes in processes, freshwater macroinvertebrates in floodplain practices, or structures in response to expected wetlands may be considerable, given limited or actual climate change (Smit et al. 2000). They dispersal routes, changes in water quality can be either autonomous (ecological and (temperature and availability), and the human) or planned, and may or may not be considerable anthropogenic impacts already beneficial (Smit et al. 2000, Barnett and O’Neill affecting freshwater systems (Woodward et al. 2010). Planned adaptations may buffer 2010). As the driest inhabited continent, ecosystems, although such efforts may be Australia is particularly affected by changing challenging. Due to the complexity of social- climate and impacts on water resources. Since ecological systems, adaptation measures must be 1950, Australian average annual and seasonal incorporated into management and policy. Due temperatures have increased, leading to more to the difficulty in predicting impacts and severe droughts (Nicholls and Collins 2006), consequences (Poff et al. 2002), an adaptive increasing fire risk (Driscoll et al. 2010) and management framework can address the impacts reducing flooding (Steffen et al. 2009). Water of climate change on freshwater ecosystems resource competition is predicted to rise with (Kingsford et al. 2011a). reductions in rainfall in south-west and inland Australia (Pittock and Wratt 2001, Hennessy et We review the vulnerability of freshwater al. 2007). Conversely an increased frequency of ecosystems and options for adaptation to these high-intensity rainfall in northwestern Australia changes in climate in six different case studies may increase flooding (CSIRO 2007), from Oceania with the aim of identifying benefitting wetlands but damaging human common threats, adaptations and management communities. Most models predict an increase and policy options. We also examine the effects in extreme events, such as flooding and drought of current pervasive threats and how these (Bates et al. 2008; Prowse and Brook 2011). interact with climate change (Kingsford et al. 2009). The six case studies were chosen to be Projected sea level rise is a significant threat representative of freshwater ecosystems in to coastal wetlands throughout Oceania Oceania. First, we assess the challenges for the (Kingsford et al. 2009). On Pacific Islands, sea Macquarie Marshes with its long history of level is projected to rise by 28–43 cm by 2100 environmental flow management to reduce (Legra et al. 2008) and in the Northern impacts of regulation (Kingsford et al. 2011a). Territory freshwater swamps are already Second, we examine snow melt rivers in impacted by saltwater intrusion (Mulrennan and Australia, where climate change is projected to Woodroffe 1998). Estuarine wetlands in coastal significantly alter flow by reducing snowfall and New Zealand will also suffer severe impacts of melt (Hennessy et al. 2007), amplifying impacts climate change (Schallenberg et al. 2010). The of hydro-electric schemes. We contrast these structure and composition of communities will Australian alpine systems with snow melt and change as species disperse or disappear glacial fed streams from New Zealand, where (Kingsford et al. 2009). adaptation opportunities are limited to the As a result of these changes, novel and gradual loss of glaciers and warming of streams unpredictable ecosystems will be created, with (Winterbourn et al. 2008). Then, we review how different species assemblages and dominant sea level rise will affect estuarine wetlands in processes (Poff et al. 2002). For example, the coastal New Zealand and freshwater wetlands in timing of breeding and migration of birds is the Northern Territory of Australia; altering the changing (Beaumont et al. 2006) and waterbird extent of tidal influence and salinity and flow distributions (Chambers et al. 2005), potentially regimes (Mulrennan and Woodroffe 1998; reflecting alterations in their foraging and Schallenberg et al. 2010). Our final case study breeding habitat (Larson 1994; Kingsford and is from the Pacific Islands (Melanesia, Micronesia and small, developing island states Norman 2002). Interactions between CO2, water supply, grazing and fire regimes will also be of Polynesia) where sea level rise will influential (Hughes 2003). By 2070, climate significantly constrain adaptation opportunities change and increased water demand in rivers (Legra et al. 2008). (237 examined globally) is predicted to result in a loss of 75% of freshwater fish fauna from Macquarie Marshes, Australia rivers with reduced discharge (Xenopoulos et al. The Macquarie Marshes is a forested arid- 2005). Increased drying may cause severe loss zone (sensu Boulton 2000) wetland on the lower 204 PACIFIC CONSERVATION BIOLOGY

Macquarie River, New South Wales, Australia in (operational in 1967) and Windamere Dams the highly regulated Murray-Darling Basin (operational in 1984) with weirs (Dubbo, (Kingsford 2000). It is representative of Narromine, Gin Gin, Warren and Marebone) floodplain wetlands located on other rivers in providing further flow control in downstream the Murray-Darling Basin including the Gwydir, reaches (Kingsford and Auld 2005). Flows are Lachlan, Murrumbidgee and Murray Rivers also affected by structures that redirect and (Kingsford 2000; Kingsford et al. 2004). The capture flooding on the floodplain (Steinfeld Murray-Darling Basin is one of Australia’s and Kingsford 2011). Flows to the Macquarie largest and economically vital catchments Marshes now depend on an environmental flow (MDBA 2010). Many parts of the Basin are arid allocation, local flooding, flows from unregulated or semi-arid, typified by isolated ephemeral tributaries and dam spills (Kingsford et al. wetland ecosystems that connect during times of 2011a). Regulation and water abstraction for flooding. The healthy functioning of floodplain irrigated agriculture has significantly impacted wetlands, such as the Macquarie Marshes, the flow regime; the median annual modelled underpins their ecology and ecosystem services flow is currently only 43% of the natural flow, they provide. In particular, many are managed and only 59% of the natural floodplain is for free-range livestock production (sheep and inundated (Ren et al. 2010). Floodplain cattle); landholders depend on the regular inundated with high frequency (i.e., annually) flooding for their livelihoods (Kingsford 1999). now covers only 5184 ha, less than a quarter of The Macquarie Marshes and its flooding regime pre-regulation levels (Thomas et al. 2011), is integral for the survival of colonial waterbirds reducing soil carbon levels, invertebrate and other waterbirds, resulting in listing under biodiversity (Jenkins et al. 2009), waterbird the Ramsar convention as a wetland of communities (Kingsford and Thomas 1995) and international significance (Kingsford 2000). vegetation communities, particularly river red gum (Thomas et al 2011; Steinfeld and The Macquarie Marshes supports up to 74 Kingsford 2011). Although biota are adapted to species of waterbirds (Kingsford and Thomas a boom and bust regime, regulation has already 1995; Thomas et al. 2011), including 44 exceeded tolerance thresholds in many parts of breeding species (Kingsford and Auld 2005). the system, substantially reducing the extent of About 10% of the Macquarie Marshes are the Marshes and shifting the mosaic of flood legislated as a protected area Nature Reserve histories and associated biodiversity and with parts of this Nature Reserve and a private processes (Thomas et al. 2011). property “Wilgara” recognized as a significant wetland under the Ramsar convention since Perhaps the most dramatic example of the 1986 (Thomas et al. 2011). Most other parts of impact of regulation on biotic thresholds and the Marshes are privately owned and used for resilience occurred in the recent decade-long livestock production. The Macquarie River drought, the “Big Dry” (Prowse and Brook system contributes about five percent of flows to 2011), the first since the current levels of the Barwon-Darling River system that eventually abstraction. During the period from 2001-2009, flows through to the River Murray mouth in the Marshes experienced unusually long dry South Australia. Renowned as one of Australia’s periods when the Water Sharing Plan failed to more significant waterbird breeding sites balance water use in the catchment and was (Kingsford and Johnson 1998; Kingsford and ultimately suspended (NWC 2009). Following Auld 2005) and supporting between 10 000 and decades of reduced flooding, waterbird 300 000 waterbirds after floods, the area of the populations plummeted (Kingsford et al. 2011b), Marshes was estimated at 200 000 ha in the more than half the wetland vegetation was lost, 1990s (Kingsford and Thomas 1995). At this and what remains is in decline (DECCW 2010; time, there was 72 000 ha of semi-permanent Thomas et al. 2011). Responding to the wetland vegetation including lignum Muehlenbeckii widespread degradation of wetlands last decade florulenta, common reed Phragmites australis, the State and Commonwealth Governments cumbungi Typha orientalis, water couch Paspalum invested in water buy-back for wetlands in the paspaloides, and extensive floodplain eucalypts Basin, increasing the environmental water (river red gum, Eucalyptus camaldulensis, allocation from 125 000 ML for the Marshes coolibah, E. coolabah and blackbox, E. largiflorens) (Kingsford and Auld 2005) to about 300 000 (Paijmans 1981). The Marshes is a biodiversity ML. hotspot with records of 130 species of birds In the Murray-Darling Basin, runoff has other than waterbirds, 15 species of fish, four reduced as rising air temperatures increase species of turtle, 30 species of lizards, 14 species evapotranspiration, compounding impacts of of snakes and 15 species of amphibians (NPWS many interception structures (e.g., Steinfeld and 1993; DECCW 2010). Kingsford 2011) and land use (i.e., clearing) The Macquarie River is heavily regulated (70% (CSIRO 2007). A 15% reduction of inflows has of the flows in the river) by Burrendong occurred with a 1°C rise in average temperature, JENKINS ET AL.: CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS IN OCEANIA 205 and these are predicted to fall by 55% if and potentially competing objectives, there is a temperatures rises by 2°C by 2060 (Cai and need for an explicit adaptive management Cowan 2008). By 2030, climate change is process. This is currently under development predicted to increase the time between floods by allowing incorporation of climate adaptation 10–24% with floods declining in size by 5–38% options (Kingsford et al. 2011a). (Table 1) (CSIRO 2008). Within the Murray- Darling Basin annual streamflow is likely to fall Snow melt rivers in Australia 10–25% by 2050 and 16–48% by 2100 (CSIRO Snow melt creates seasonally variable thermal 2008). These predictions are in the range of and hydrological regimes that promote a unique those for inflows to the Macquarie Marshes diversity of specialist aquatic fauna adapted to which are projected to decline by 0–15% in 2030 cues provided by thawing in spring (sensu etc.). and 0–35% in 2070 (Jones and Page 2001). These include thermal and hydrological cues for Plantations will also affect flows (Herron et al. spawning, migration, and metamorphosis, coin- 2002), but not to the same extent (CSIRO ciding with increased availability of resources 2008). from high flows (Yarnell et al. 2010). Globally, Reduced rainfall, runoff and subsequently climate change is expected to alter the timing decreased flooding with climate change has and volume of snow melt flows through earlier affected inland wetlands but still only represent snow melt, reduced snow depth and cover, and a veneer on top of the impacts already increased evapotranspiration (Adam et al. 2009). experienced due to river regulation (Jenkins et There is a relatively small area of land affected al. 2011). Although the biota of arid-zone by snow cover in Australia (Pickering and wetlands are adapted to a boom and bust Armstrong 2003). Associated Australian snow ecology (Kingsford et al. 1999), regulation has melt rivers are mostly in the steep and rugged already exceeded the limits for many taxa and Snowy Mountains region of New South Wales, climate change will exacerbate these impacts. and North Eastern Victoria. The upper parts of Projections for 2070 are more severe, and with the mountains have a relatively high annual river regulation, may irreversibly alter the rainfall (1400–1800mm; Morton et al. 2010), character of the Macquarie Marshes. The mostly stored as snow during winter. During projected increase in drought intensity is a spring and early summer, accumulated snow significant threat (Prowse and Brook 2011), above ~1500m asl melts into streams and drains given the sensitivity of wetland biota to either south into the Snowy River or north and increased time since flooding and current west to the Murray and Murrumbidgee Rivers. impacts of regulation (Kingsford and Thomas Perhaps due to their remote and rugged 1995; Jenkins and Boulton 2007; CSIRO 2008, location, the ecology of Australian snow melt Thomas et al. 2011). These changes to flow will systems is poorly known (Bevitt et al. 1999), restrict natural overbank flows leaving many particularly the dependence of endemic biota on wetlands reliant on targeted environmental flow flow and temperature. Mountain galaxias allocations (Aldous et al. 2011). The combination Galaxias olidus are widely distributed throughout of the arid climate and high water demands Australia and are the only fish found above the (Poff et al. 2002) will make these freshwater snowline during winter (Lintermans 2009). ecosystems particularly vulnerable to the effects Although this species was once common across of climate change. Despite this, existing south-eastern Victoria, they are now restricted to management infrastructure means there is also the upper reaches, not yet invaded by brown a broad scope of adaptation strategies (i.e., dam Salmo trutta and rainbow trout Oncorhynchus re-operation, re-licensing) that can be adapted mykiss (Raadik and Kuiter 2002). The two-spined to mitigate climate impacts (Pittock and blackfish Gadopsis bispinosus lives only in cool Hartman 2011; Watts et al. 2011). upland or montane streams that drain to the In the Macquarie Marshes, environmental upper Murray River (Lintermans 2009). Several flows are the key mechanism to adapt to climate frog species are endemic to alpine and change and strong institutional arrangements subalpine regions including the alpine tree frog exist via the Environmental Flows Reference Litoria verreauxialpina, the southern corroboree Group established under the Water Sharing Plan frog Pseudophryne corroboree, northern corroboree and water buy-back (Kingsford et al. 2011a). The frog Pseudophryne pengelleyi and baw baw frog challenge is to develop flow rules that consider Philoria frosti; (Osborne et al. 1999). Many future climate change to enable carry-over and macroinvertebrate species are also highly release of larger volumes of environmental endemic in the Australian alps. Two mayfly water. There is an opportunity to develop clear nymphs Coloburiscoides spp. have only been objectives that assist in transparent decision- recorded in upland streams about Mt. making for environmental flows aimed at Kosciuszko and the Bogong High Plains (Suter achieving conservation of ecosystems. Given the and McGuffie 2007). Several stoneflies Leptoperla complexity and scale of the Macquarie Marshes curvata and L. cacuminis and mayflies 206 PACIFIC CONSERVATION BIOLOGY

Tasmanophlebia lacuscoerlei and Ameletoides distribution with climate change (Chessman lacusalbinae are also only found in the Snowy 2009). These effects mostly occur through Mountains region (Campbell et al. 1986). changes in temperature which governs species’ distributions by lethal effects, such as extreme Flows from many of these alpine systems were heat or cold, or sub-lethal effects such as significantly altered by river regulation. The impaired growth or reproduction (e.g., Briers et Snowy Mountains Hydroelectric Scheme (SMHS) al. 2004). The driving importance of the completed in the 1950s and 1960s diverted 99% thermal regime (Caissie 2006) may shift the of flows (~1 000 GL) from the southern flowing viable range of distribution of stenotherms Snowy River to the western flowing rivers, upward, increasing the vulnerability of species generating hydroelectricity and providing water already facing extinction. Increases in ambient to the inland irrigation industry (Ghassemi and temperature and reduced rainfall are predicted White 2007). The SMHS is an extensive network to increase frequency and intensity of bushfires of large and small impoundments and diversion (Hennessey et al. 2007), affecting sedimentation structures that enables water to be shunted and erosion (Suter and McGuffie 2007). For among reservoirs, passing through various example, in 2002-2003, wildfires throughout the hydropower stations before eventually flowing Snowy Mountains increased inputs of sediment west via the Murray and Murrumbidgee valleys and ash to the Snowy River (Russell et al. 2008), (NoW 2010). The resulting altered hydrology and the Alpine rivers of the Snowy Mountains, and lost longitudinal connectivity has severely markedly changing aquatic invertebrate impacted on aquatic communities in rivers communities and threatening the extinction of affected by the SMHS (Pendlebury et al. 1996; endemic species (Suter and McGuffie 2007). Erskine et al. 1999). Some environmental flows are returning to the Snowy and some of the The potential for Australian snow melt streams montane rivers within the Scheme (NoW 2010). and their biota to adapt to long-term climate change is impeded by inaccessibility and few The river system and its dependent biota, viable options for managing water temperature upstream of impoundments, remains largely and/or flow. Below reservoirs, regulation unaffected but will be affected by climate structures like the SMHS offer opportunities to change, particularly biota dependent on timing manage climate impacts (Pittock 2009). Flows and quantity of snow melt. Endemic biota in from reservoirs could be managed to mimic the snow melt systems are particularly vulnerable to natural flow regime, protecting rivers against climate change (Brown et al. 2007). Climate drought and regulation (Poff et al. 1997), and modelling predicts precipitation rates will unnatural thermal regimes (Olden and Naiman change by between +2.6 and -24% by 2050 2010). However, existing impacts on rivers due while air temperature is predicted to increase by to regulation (e.g., Bevitt et al. 1999) and o between 0.6 and 2.9 C (values relative to 1990; aggressive invasive species (e.g., trout, Raadik Table 1; Hennessey et al. 2007). These changes and Kuiter 2002) probably outweigh the will increase water temperature and reduce flow comparatively minor short term impacts from but also change the timing of flows through climate change. Moreover, flows from reservoirs reduced area and duration of snow cover. Snow are usually already of low water quality depth has already decreased by 40% in the (Sherman 2000). Already, ski resort operators Snowy Mountains since 1962 (Nicholls 2005) use snow-making technology as an adaptation to with further declines of 22-85%, predicted for reductions in snow cover but these are relatively 2050 (Table 1; Hennessey et al. 2003). Snow small scale and temporarily effective (Hennessey melt across four rivers in the Snowy Mountains et al. 2008), with a minor effect on the now occurs a month earlier than in the 1950s hydrology of streams. Any adaptation options (Reinfelds, I, unpubl. data). This pattern is for snowmelt ecosystems in Australia are limited consistent with observation in the mid altitude by current lack of knowledge of the relationship snow melts rivers of Northern Western USA of temperature and flow with aquatic organisms. (Stewart 2009). The duration of snow cover is further predicted to reduce by 15–100 days and Glacial and alpine river systems in New snow depth by 10–99% by 2050 (Hennessey et Zealand al. 2007). Climate change affects the distribution A substantial part of the South Island of New and phenology of alpine aquatic fauna elsewhere Zealand is covered by the mountain chain of the (e.g., Briers et al. 2004; Harper and Peckarsky Southern Alps, extending about 700 km north- 2006) but little information exists for Australian south (40–47ºS) and 100 km east-west. Much of species, particularly in alpine regions (Williams this area is steep, with gradients of 0.4 or more, and Russell 2009). and located above the tree line (~1400 m at the Australian macroinvertebrate species that northern end of the chain and ~1000 m at its favour cold, fast flowing water are most likely to southern end). Above the tree line, subalpine decline in abundance and contract in shrubs, tussock grasses and bare scree slopes JENKINS ET AL.: CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS IN OCEANIA 207 extend to permanent snow and ice. Annual species (Winterbourn et al. 2008; Hitchings precipitation in this sub-alpine and alpine zone 2009). is high, ranging from 1500–2000 mm in the A similar concern is held for specialist stonefly relatively dry eastern foothills to 5000–12000 populations. Their larval stages inhabit high- mm in the western part of the mountain chain, altitude streams where there is a high degree of where the weather patterns are dominated by endemism in the Fiordland region of the wet westerly winds from the nearby Tasman Sea. Southern Alps (Peat and Patrick 1996), with The summertime snowline descends to1600 m eleven endemic species, four occurring in the west and 2200 m in the east (Mark and predominantly above the tree line. Because of Dickinson 1997). As a consequence of the high the generally high degree of endemism in New precipitation and the steep terrain, the alpine Zealand, further aquatic invertebrate groups and sub-alpine zone contains numerous cold common in subalpine and alpine streams such fast-flowing streams and small rivers, which as Trichoptera (see Peat and Patrick 1996) and possess a high water quality based on their net-winged midges (Blephariceridae) probably physicochemistry and ecology (Winterbourn also contain several more endemic species 1997). Because the Southern Alps also contain adapted to cold water temperatures. The net- over 3 000 glaciers ranging in area from about winged midges are particularly well known for 1 to 10 000 ha (2001 data; Chinn, 2001; 2004), their preference of cold, fast-flowing and highly many sub-alpine and alpine streams are glacier- turbulent streams (see e.g., Frutiger 2002; fed, and snow melt during spring and summer Frutiger and Buergisser 2002), and their larvae contributes a considerable part of the annual can be highly abundant in alpine streams of the discharge in the non-glacier-fed streams. Southern Alps, such as in Arthur’s Pass National Park (C.D. Matthaei, unpubl. data). Such Due to its long isolation from other land endemism in the Southern Alps of New Zealand masses, New Zealand possesses a high (Hitchings 2009) may have resulted from percentage of endemic animals and plant repeated periods of glacial advance and retreats species, compared to most other parts of the which has similarly produced high endemism world (see e.g., Daugherty et al. 1993; Wallis and rates in the cold-adapted aquatic fauna from Trewick 2009). This high degree of endemism Western Europe (Ward 1994). Most of these has been well-documented for large animals endemic aquatic species are vulnerable to such as birds (Lee et al. 2010) or fish (Hickey et extinction due to climate-change induced loss of al. 2009), and also for plants including many extreme cold-water habitats (Winterbourn et al. alpine species (Dawson and Lucas 1996; Peat 2008; Hitchings 2009) even though it is likely and Patrick 1996). By comparison, the aquatic that many are yet to be formally identified by fauna of high-altitude streams, especially its science. taxonomy and degree of endemism, is far less It is thought that taxa may adapt to flow and well known. A few studies exist that allow temperature changes in snow melt streams by projections regarding the potential effects of migrating to high altitudes, but this option is climate change (Table 1) on sub-alpine and short-term and the steep gradients will give rise alpine stream communities. For example, four to waterfalls, rather than a shift in similar species of the mayfly genus Deleatidium are habitats upwards, as temperatures rise. This confined to the upper limits of lotic freshwaters option will not be possible in glacial systems, on the altitudinal zone from the tree line to the which will continue to retreat and vanish as the snow line in the Southern Alps and their climate warms as they have in the last 100 years neighbouring ranges (Hitchings 2009). All four (Chinn 2004). Adaptation options seem limited, species are adapted to cold, fast-flowing streams apart from establishing captive colonies which and rivers and the frequently severe conditions are sustained under controlled conditions. imposed by an unstable terrain and high winds. Translocation is also suggested for taxa unable There is also a fifth cold-water specialist mayfly to migrate in systems where connectivity is lost species, in the same genus, found at five stream (Turak et al. 2011). However, in the case of sites in Mt Aspiring National Park, including glacial, and to a lesser extent snow melt streams, three glacier-fed sites (Winterbourn et al. 2008). these habitats are vanishing, leaving limited A rise in water temperatures associated with places to colonize. Clearly, even if these options global warming would likely result in a were possible, they could only be implemented southward retreat of these alpine specialists with for a few species. climate change (Winterbourn et al. 2008; Hitchings 2009). A projected 3ºC warming Coastal wetland systems in New Zealand (Ryan and Ryan 2006) would displace the Estuaries are the interface between freshwater regression of annual degree days on latitude and marine environments, and are therefore southward by 670 km, correspondingly reducing highly sensitive to climate-related changes in glaciation and warming of alpine streams and either environment (Winder et al. 2011). The resulting in extinction of the five alpine mayfly dynamics of opening regimes, patterns of 208 PACIFIC CONSERVATION BIOLOGY saltwater influx and mixing, and other aspects (Schallenberg and Burns 2003; Schallenberg et of water chemistry are influenced by a complex al. 2010). Increasing the frequency of even interaction between the quantity and quality of minor saline intrusions into these systems freshwater entering the estuary from upstream, reduces their biodiversity (Schallenberg et al. and tidal sea water intrusion through the estuary 2003b), and threatens the viability of inanga berm (Schallenberg et al. 2003a; Schallenberg et fisheries, given the low salinity required for egg al. 2010). These clearly interact to produce fertilisation during spawning (Hicks et al. 2010). habitats and ecosystem processes that support The impacts of climate change (Table 1) on aquatic biodiversity. The Otago coastline forms small, intermittently open estuaries are likely to the southeast corner of the South Island of New be more complex, given these systems are more Zealand with a rich diversity of estuarine numerous and diverse (Lill et al. 2011). They habitats, including permanently open estuaries exist along a continuum, from ones rarely closed and many small, intermittently open systems to rarely open (Lill et al. 2011). The biodiversity (Lill et al. 2011). Tidally influenced freshwater of communities that live within them reflect this wetlands and shallow lakes are also a feature of gradient of exposure to the marine environ- the continuously open estuaries, such as the ment, with invertebrates and fish more Waihola/Waipori wetlands in the lower Taieri characteristic of freshwater habitats dominating River catchment (Schallenberg et al. 2003a; estuaries that rarely open to the sea (Lill et al. Hunt 2007). Collectively, these ecosystems 2011). Rising sea levels and changing patterns support a rich biodiversity, with significant of rainfall and evaporation (Table 1) will interact populations of native fish including inanga to alter patterns of saline intrusion and Galaxias maculatus, giant kokopu G. argenteus, freshwater discharge into estuaries in unpredictable and native birds including fernbird Bowdleria ways (Laurance et al. 2011). Increased punctata, Australasian bittern Botaurus poiciloptilus) temperatures and evaporation will increase rates and New Zealand scaup Aythyanovae seelandiae of upstream water abstraction for irrigation, (David et al. 2002; Hunt 2007; Kattel and Closs reducing freshwater inputs to estuaries that 2007). dilute discharge of nutrients and other The impacts of climate change on these pollutants (Schallenberg et al. 2010; Laurance et estuarine systems and the species they support al. 2011; Winder et al. 2011). Eutrophication of will vary depending on their different intermittently open estuaries due to characteristics and dependencies (i.e., open accumulation of diffuse inputs of nutrients and estuaries and associated tidal freshwater lakes other pollutants is already significant in many and wetlands or intermittently open estuarine New Zealand estuaries (Schallenberg et al. 2010), systems) (Schallenberg et al. 2010; Lill et al. including those along the Otago coastline (Lill 2011) and the increasing effects of sea level rise et al. 2011). in particular. Continuous high freshwater discharge from large rivers, such as the Taieri Estuarine systems, subject to the influence of and Clutha, maintains a permanently open river and sea, are dynamic and resilient (Lill et channel to the sea (Schallenberg et al. 2003a). al. 2011). Indeed, within the past 10,000 years Such estuaries usually have predictable patterns sea levels have been lower and higher than of tidal variation and seawater intrusion, today, and estuarine systems have adapted interspersed by brief periods of extreme rainfall (Hunt 2007). The extensive cockle beds buried and drought (Schallenberg et al. 2003a). In these in the sediments of Lake Waihola (now systems, biological communities exhibit longitu- effectively a freshwater system) indicate that this dinal zonation, reflecting prevailing patterns of shallow lake functioned as a marine system seawater dilution and mixing at various points within the past 4000 years (Hunt 2007). along the estuary (Sutherland and Closs 2001). However, present-day patterns of diversity have The influence of the tides extends upstream into developed in response to the relatively freshwater wetlands that are only occasionally predictable environmental conditions prevailing subjected to saline intrusion during periods in the recent past. Increasing the frequency of of exceptionally low freshwater discharge extreme events (IPCC 2007a) within these (Schallenberg et al. 2003a). These freshwater present-day systems will reduce their within- wetlands support diverse invertebrate com- system diversity and threatens their ecological munities and are critical spawning habitat for stability and function (Schallenberg et al. 2010; inanga, the juveniles of which support Winder et al. 2011), at least over temporal scales significant recreational fisheries (Sutherland and relevant to human societies (i.e. 2-3 generations, Closs 2001; Kattel and Closs 2007). The wet- 100 years). The critical challenge for managing lands are only marginally above sea level the impacts of climate change on large open (Schallenberg et al. 2003a), and particularly estuaries is determining whether tidally vulnerable to sea level rise which will alter their structured communities can migrate up rivers. hydrology, generating unpredictable changes in Whether this can occur will be dependent on freshwater wetland distribution and structure system-specific features such as local hydrology JENKINS ET AL.: CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS IN OCEANIA 209 and geomorphology (e.g., the proximity of high al. 2006). Tidal influence can extend up to 105 gradient landforms or large areas of human km up the river with a range of 5-6m at the settlement upstream of existing estuarine river mouth (Woodroffe et al. 1989). reaches), the speed of climate-related changes, Kakadu National Park (19,800 km2) is part of and the scope and options for human-assisted the region with particularly high biodiversity, habitat restoration and creation (Hickford et al. some of which is highly dependent on the 2010; Hickford and Schiel 2011). The aquatic ecosystem; it has a quarter of Australia’s management of intermittently open estuarine land mammals (77 species), more than a third systems must focus on maintaining a diversity of Australia’s birds (271 species), 132 reptile of estuary opening regimes across a regional species, 27 frog species, about 1600 plant scale (Lill et al. 2011). To some degree, opening species and more than 10,000 species of regimes can be managed artificially by invertebrates (SEWPaC 2011). This outstanding mechanical breeching of the estuary berm (Lill biodiversity resulted in listing of the area on the et al. 2011), however protection of freshwater IUCN World Heritage Register (1981) and discharge from excessive abstraction is also a listing as a wetland of international importance critical element in ensuring the sustainability of under the Ramsar Convention. The system of these systems (Schallenberg et al. 2010). wetlands is particularly significant for the high The recently promulgated National Coastal concentrations of waterbirds (Morton et al. 1990; Policy Statement 2010 and National Policy Morton et al. 1993a,b,c) which undoubtedly Statement for Freshwater Management 2011 reflect their considerable productivity. Most of provide the overarching legislative framework these birds collect on the large freshwater for management of estuarine systems in New wetlands on the floodplains of the rivers, where Zealand (DOC 2010, New Zealand Government more than one million magpie geese Anseranas 2011). While both policies clearly state semipalmata may be found during the dry season sustainable management of ecosystems is a core (Morton et al. 1993a). Given the region’s government priority, the failure to set clear proximity to the sea, some of the wetlands are minimum environmental standards and limits highly vulnerable to long-term sea level change, within either policy means both statements are exacerbated by invasive species (Bayliss et al. open to a broad interpretation of what 1997; Finlayson et al. 1997; Brook and minimum environmental standards may be Whitehead 2006). About 20cm sea level rise acceptable. Climate change is mentioned in five occurred during the 20th century and projected of the 29 coastal policies in the coastal levels may rise up to one metre by 2100 (Table statement, in relation to impacts of rising sea 1, Brook and Whitehead 2006). level on coastlines, property and residents. The The coastal floodplains of Kakadu are only 3- single policy that addresses biodiversity does not 4 m above sea level (Finlayson et al. 1997). refer to rising sea level nor provide any Globally, average sea level has risen by 21 cm adaptations to protect coastal wetlands (DOC since 1880 (Church and White 2011) with 2010). Similarly the freshwater management projections of potentially more than one metre statement makes brief mention of climate over the next century (Prowse and Brook 2011). change and none of adaptation, requiring The river valleys were probably inundated by regional council’s to set objectives for freshwater the sea about 8 000 years ago with swamps including quality, levels and environmental flows establishing about 6 000 years ago and some for “all bodies of fresh water in its region plant associations only 2 000 years ago (except ponds and naturally ephemeral water (Chappell and Woodroffe 1985; Woodroffe et al. bodies)”, having regard to the “reasonable 1993). Freshwater wetlands are separated from foreseeable impacts of climate change” (New dendritic saltwater channels by low levee banks Zealand Government 2011). (Finlayson et al. 1997) which may be overtopped with saltwater surges or linked by intruding tidal Wetlands in the Kakadu region, northern channels (Winn et al. 2006), allowing salt water Australia to flow into freshwater wetlands, changing their The wetlands of the Kakadu Region of the physico-chemical composition. This may also be Northern Territory are among the more exacerbated by reductions in run-off and biodiverse and well known in Australia (Morton cyclonic activity which have altered geo- et al. 1993a; Finlayson et al. 1997) and the world morphology (Winn et al. 2006). Salinisation has (Junk et al. 2006). A series of rivers flow north already changed the state of some freshwater to the sea, the Wildman, East Alligator, South wetlands: freshwater plants have died and salt Alligator and West Alligator Rivers, particularly tolerant ones have invaded the wetlands during the monsoon season, and they have (Finlayson et al. 2009). For example, the tidal created a range of different wetlands: inter-tidal part of East Alligator River has invaded inland mudflats, mangroves, hyper saline flats and by four kilometres since the 1950s, increasing freshwater floodplains and streams (Finlayson et the amount of saline mudflats by nine times and 210 PACIFIC CONSERVATION BIOLOGY killing more than half the paperbark preferred condition, given that many of the Melaleucaleuca dendra forest (Winn et al. 2006). wetlands were once saline more than 6,000 years In addition, water buffalo Bubalus bubalis, ago. introduced in the 1980s, broke through some of the levee banks, allowing salt water intrusion Wetlands of the Pacific Islands and changing ecosystem states from freshwater Freshwater resources of the Pacific Islands (see to estuarine (Steffen et al. 2009). Magpie geese Kingsford et al. 2009; Kingsford and Watson rely predominantly on the wild rice Oryza spp. 2011) are characterized by coastal wetlands, and Eleocharis spp., sustained by fresh water flow. predominantly estuarine mangrove wetlands and Saltwater intrusion is exacerbated in dry salt marshes. Only Papua New Guinea, Fiji, monsoonal periods, low-frequency and intensity Vanuatu and Samoa have significant inland cyclonic storm cells which are not counteracted freshwater reserves, particularly Papua New by wet season flows (Winn et al. 2006). Guinea with several million hectares of wetlands Subsidence of freshwater wetlands, as well as (Osborne 1993). While most Pacific Island changes to wind direction and strength and nations have some coastal wetlands, the small rainfall variability may contribute further to the size of islands and often low-lying coral and problem. limestone-based nature of the land masses of There are predicted to be increased saltwater many Pacific Islands limits freshwater resources intrusions on Kakadu wetlands in the dry season and aquatic ecosystems. Only six of the nearly in the South Alligator River catchment in 2030 2 000 areas designated under the Ramsar con- and 2070, associated with respective sea level vention as wetlands of international importance rise increases of about 14cm and 70cm are on Pacific Islands. corresponding to IPCC emission scenario A1B, While island ecosystems are, by nature, 95th percentile and a high emissions scenario respectively (BMT-WBM 2010). This would be vulnerable to disturbances, many coastal wet- through increased tide height and velocity lands, including estuaries, have been heavily extending tidal channels into the floodplain and modified and intensively developed over the increasing overtopping of levees (BMT-WBM past few decades (Kingsford et al. 2009), 2010). There may be a threshold effect where significantly increasing their vulnerability to there is widespread inundation of the coastal climate change. With the exception of Papua plains by tidal flows, resulting from exponential New Guinea, most Pacific Islanders live in the expansion of creek networks (Woodroffe 2007). coastal zone, and population growth is generally This is expected to be detrimental to freshwater high (UNEP 1999; Kingsford et al. 2009). biodiversity (e.g., magpie geese, pig-nosed turtle Extensive coastal development is supported by Carettochelys insculpta, potadramous fish and tourism, which accounts for up to half of gross freshwater crocodiles Crocodylus johnstoni). Such domestic product for some Pacific Island nations impacts are likely to also affect cultural values (Jiang et al. 2010). Development pressures in and tourism, dependent on freshwater bio- many Pacific Island countries have led to diversity. Such major changes would certainly exploitation of mangrove wetlands in particular. substantially change the ecological character of As in other regions, Pacific Island watersheds the Kakadu wetlands and possibly its status as have substantially changed with development, a hotspot of biodiversity. This vulnerability may including deforestation, agricultural practices be countered by projected increased rainfall and and urbanization leading to altered hydrology run-off with climate change (Winn et al. 2006; and sedimentation effects (UNEP 2006). Steffen et al. 2009). Given most Pacific Island wetlands are coastal, Opportunities for adaptation for this low lying climate change is already adversely impacting system are particularly problematic, given how these ecosystems. Sea level rise is the most extensive it is and the force of wet seasons flows. serious problem, contributing to coastal erosion, Conceivably levees could be erected around the saline incursions of ground and surface waters more vulnerable and important freshwater from high sea level. Sea level is projected to rise wetlands. There are extensive earthen barrages 18–59 cm by 2100 (Table 1; IPCC 2007a). Sea already built at the mouth of the Mary River, level rise effects are likely to be exacerbated by further to the east, which also has significant other projected climate changes (Prowse and freshwater wetlands (Steffen et al. 2009). Given Brook 2011), with El Niño climate patterns and the relative absence of built environment, there greater intensity of extreme events likely to may also be a natural migration of freshwater cause more flooding and drought, as well as wetlands upstream although the catchment of more Category 4 and 5 cyclones (Table 1; steep ranges that do not allow for any wetland Nicholls 2011). Small island regions in the development are reasonably close to the sea in Pacific, Indian Oceans and Caribbean Sea are this region. Decisions to build protection of most at risk globally from sea level rise (IPCC these systems will involve value judgments of the 2007a). JENKINS ET AL.: CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS IN OCEANIA 211

Wetland loss presents significant risks to (Kingsford et al. 2009; Duffy 2011). The lack of biodiversity, given the high degree of endemism financial resources in most Pacific Island nations and large proportion of globally threatened means that environmental issues are not as high species found on Pacific Islands. Many Pacific a priority as trade and economic development, Island species are threatened with extinction health and public sector reform, and adaptation (Kingsford et al. 2009). While dependent on to climate has historically been reactive (Hay various factors such as tidal range and sediment and Mimura 2006). Accordingly, environmental supply, some mangrove forests and their priorities with respect to climate change focus associated ecosystems, will be lost on small on provision of clean drinking water and islands with sea level rise (IPCC 2007a). In some protection of homes and food-growing capacity areas, increased vertical accretion and inland from sea-level rise. There is an absence of migration of coastal wetlands could occur as an wetland policies (Ellison 2009, SPREP 2011) and autonomous adaptive response to sea level rise a recent SPREP report referred to swamps as (Nicholls 2011), but the ability of wetlands to “perfect breeding grounds for mosquitoes that adapt naturally to sea level rise is limited in cause malaria and dengue fever” (Wickham et al. areas with extensive coastal infrastructure. 2009). Further constraints come from a lack of Furthermore, adaptive capacity may also be technical skills (Kingsford et al. 2009) and often limited by the lack of sediment inputs on low- ad-hoc funding from foreign aid (UNEP 1999, lying islands, and there is some debate as to Duffy 2011). Systems of governance, and whether this response is likely to be significant therefore forms of environmental policy and (Alongi 2008). There is also uncertainty about uptake of initiatives are highly variable at the complex ecosystem responses (McLeod 2010). national level. This pattern reflects global projections of At a regional level, several multilateral significant decline of coastal wetlands due to sea environmental agreements have been widely level rise over the next century, particularly adopted across Pacific Island countries. The when combined with direct human impacts United Nations Framework Convention on (Gillman et al. 2007; Legra et al. 2008; Nicholls Climate Change has been ratified in many of et al. 1999). For example, native mangrove the Pacific Islands. With the Australian Bureau species are projected to reduce in area by 13% of Meteorology, the South Pacific Sea Level and by 2100, across the 16 Pacific Island territories Climate Monitoring Project collects oceanic, sea- (UNEP 2006). There is potential to ameliorate level and weather data in 11 nations and has effects of climate change on coastal wetlands strengthened technical and scientific capacity particularly, through the management of other (UNEP 1999). Climate change and biodiversity threatening activities, (i.e., harvesting of management are key roles of the intergovern- mangrove forests for timber; Kingsford et al. mental Secretariat of the Pacific Regional 2009). Environment Programme (SPREP). Co-operation Accurate projections of the extent of coastal and representation of Pacific nations in these wetland affected by sea level rise are required ways will continue to be important in building but improved planning of coastal zone develop- the capacity of individual states to develop ment could protect some vulnerable wetlands. climate change adaptation policies to protect Measures to reduce erosion, particularly during coastal wetlands at a more local level. There is extreme events, include preservation of natural also a critical need to manage other threats barriers, such as coral reefs and dunes, or (Kingsford et al. 2009) to build resilience in construction of physical barriers such as sea freshwater ecosystems. walls (Mimura 1999). Protection of coastal wetlands themselves affords protection from Synthesis erosion and inundation to adjacent ecosystems. Although the direct reliance of Pacific Island Climate change significantly threatens fresh- societies on biodiversity is widely recognized, water biodiversity, demonstrated by the six case adaptation measures are more likely to be study freshwater ecosystems in three major ways: implemented if they offer immediate socio- increases in temperatures, changes to rainfall, economic or climate benefits as well as long- run-off and consequent effects on flow and sea level rise (Table 2). Increased temperatures will term climate change adaptation (Nicholls 2011; particularly affect alpine areas where flow Duffy 2011; Grantham et al. 2011). For example, regimes are dictated by temperatures and adaptive measures such as rainwater collection residence time of snow. Snow melt rivers in can preserve groundwater resources to lessen Australia are heavily regulated but impacts of effects of saltwater intrusion, benefiting natural temperature affect dependent biota in their wetlands and crops. unregulated upper catchments (Hennessey et al. Pacific Island nations face substantial barriers 2007). Similarly, alpine and glacial rivers in New to the implementation of policy and manage- Zealand will be affected, impacting on cold- ment options with respect to climate change adapted species as temperatures rise. In arid- 212 PACIFIC CONSERVATION BIOLOGY zone rivers and wetlands, already degraded by system and its size is a critical adaptation option anthropogenic impacts (i.e., the Macquarie but this may be less successful for aquatic Marshes), projected water loss by 2030 is minor ecosystems unless the freshwater inflows are compared to losses already experienced by river protected. Certainly, the establishment of regulation (Jenkins et al. 2011). Projected protected areas on rivers provides a strong increases in severe droughts and consequent policy imperative for governments to actively reductions in run-off will mean less flow for manage river systems. For example the downstream wetlands, compounding dramatic protected area in the Macquarie Marshes has losses in biodiversity already experienced from strongly positioned the conservation agency to river regulation and diversion of flows upstream. support and implement the buy-back of Coastal wetlands throughout Oceania, already environmental flows for the ecosystem to meet impacted by human developments and water their legal responsibilities. In arid-zone rivers, use, will also be irrevocably changed by sea level where regulation and climate change both rise and salt water intrusion (Finlayson et al increase drying, water buy-back and environ- 2009; Schallenberg et al. 2010). mental flows provide the main adaptation to both regulation and human-forced climate Clearly, reductions in overall greenhouse gas change. Any success in clawing back the impacts emissions will limit the extent of impacts on of regulation with the purchase of environmental freshwater ecosystems. There are also many flows may be eroded by the projected impacts opportunities to improve resilience of ecosystems of climate change in drying these systems. For to climate change, through broad policy and river systems that are not yet regulated, there specific management. And yet, despite the should be an imperative to protect their flows projected threats and current evidence of (Kingsford et al. 2009; Pittock and Finlayson biodiversity loss due to climate change in 2011), as this will increase their resilience to freshwater ecosystems, the management and climate change. There will also be adaptation policy response is slow. In Australia, the impacts opportunities focused on improvements in the of sea level rise on coastal systems in the management of environmental flows. Many Northern Territory was anticipated in the late rivers are primarily managed for extraction and 1990s (Finlayson et al. 1997) and yet policy to so dam management and release of environ- reduce carbon emissions is yet to be mental flows offers considerable opportunities implemented. Even major policy documents for for improvements (Watts et al. 2011; Kingsford managing freshwater ecosystems pay scant 2011; Pittock and Hartmann 2011). These attention to the long-term impacts of climate include “piggy-backing” environmental flows on change. For example, the Guide to the delivery flows for irrigation as well as mimicking upcoming Murray-Darling Basin plan (MDBA the pulses of flows in rivers when providing 2010) adopted only a 3% reduction in surface water downstream for extractive use. There will water availability by 2012, half the wettest (and also be an increasing focus on the management least likely given rainfall projections) scenario of environmental flows to meet specific modeled by CSIRO (2008) (Schofield 2011). conservation objectives (Kingsford et al. 2011a) The Guide contained only brief reference to and this is likely to drive increasingly innovative climate change as did the Adaptive Environ- ways of maximizing the outcomes in the mental Management Plan for the Macquarie management of environmental flows. This Marshes (DECCW 2010). In New Zealand, the management will need to meet the principle of abundance of water and remoteness of melting maintaining or improving connectivity between glaciers may reduce the political imperatives for aquatic ecosystems. With increasing drying of adaptation policy dealing with climate change, freshwater ecosystems, there is a danger that although at least the government has introduced connectivity will be lost between wetlands or a carbon trading scheme. In the Pacific Islands, refugia. This includes lateral connectivity which lack of resources is the greatest constraint to the is already compromised on many river systems development and implementation of policy in the Murray-Darling Basin (e.g., Macquarie options to protect coastal wetlands from climate Marshes, Steinfeld and Kingsford 2011). change (Morton et al. 2009; Kingsford et al. 2009; Duffy 2011). Temperature increases and effects on dependent alpine freshwater ecosystems will be Specific adaptations to threats of increased difficult to counteract (Table 2). Revegetation of temperatures, altered flow regimes and sea level riparian areas will reduce temperatures and rise for freshwater ecosystems are possible albeit provides a possible adaptation although it may challenging and limited in spatial applicability be difficult to establish in alpine areas. For key (Table 2). A key adaptation will be to increase aquatic species, translocation may be the only the resilience of freshwater aquatic ecosystems option (Turak et al. 2011), but this will be costly to other threats, particularly river regulation and may impact on biota in ecosystems that given its pervasive effect on biodiversity. For receive translocated species. For coastal terrestrial regions, increasing the protected area wetlands, sea level rise will be difficult to combat JENKINS ET AL.: CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS IN OCEANIA 213 All freshwater ecosystems All freshwater Macquarie Marshes and wetlands in dry regions New Zealand coastal wetlands, Island Kakadu wetlands, Pacific wetlands Australian and New Zealand alpine and snow melt streams New Zealand alpine Case studies - Freshwater tems in this review. Revegetate riparian landscapes to shade freshwater Revegetate refugia, ecosystems, focus on low flow management to protect other impacts (i.e. livestock), expand habitats from protect rivers, maintain or free-flowing protect areas, protected connectivity (especially between refugia) improve piggy-back carry over, flows (water buy-back, Environmental dam management, focus on low on irrigation flows), improve free-flowing protect refugia, flow management to protect rivers update water sharing plans to manage during drought, maintain or improve regulation, from threats reduce minimise impacts connectivity (especially between refugia), invasives from communities up Levee banks, migration of tidally structured reduce and creation, rivers assisted by habitat restoration harvesting such as mangrove threats Migration or translocation to higher elevations, minimize when structures invasives, use regulation impacts from maintain or flow/thermal regime, available to improve connectivity (especially between refugia) improve rise gas emissions to slow temperature greenhouse Reduce Species loss as thresholds for tolerance to higher exceeded temperatures Species loss as thresholds for tolerance to drying exceeded Species loss as thresholds for tolerance to salinity exceeded Species loss as flow disrupted and regime increase temperatures Species loss as glacial habitat retreats Higher water temperature, dissolved oxygen reduced flooding, Reduced time between increased floods, Elevated salinity snowfall and melt Reduced Melting glaciers Increased temperatures Increased rainfall, Reduced drought extended Rising sea level temperatures, Increased rainfall reduced Table 2. Climate change drivers, physical impacts, risks, and adaptation opportunities for the six case study freshwater ecosys 2. Climate change drivers, physical impacts, risks, and adaptation opportunities for the six case study freshwater Table Climate change drivers Physical impacts Risks Adaptation opportunities ecosystems impacted 214 PACIFIC CONSERVATION BIOLOGY with relatively few adaptation options that will occur with the increasing loss and reduction in guard against the loss of biodiversity (Table 2). function in freshwater ecosystems. Where coastal freshwater ecosystems are not able to migrate inland because of elevation or human ACKNOWLEDGEMENTS infrastructure, they will be lost. In some places, adaptation to salt intrusion in coastal rivers may We thank Claire Sives for assisting our be achieved by building levees but this will be research on aspects of climate change in the spatially limited and would probably need to Macquarie Marshes and Simon Williams for his coincide with human requirements for comments on snow melt streams in Australia protection. and adaptations in freshwater ecosystems. We also thank two anonymous reviewers and James In addition to these adaptations, there should Watson for insightful comments that improved be a focus on active reduction of other threats our manuscript. The case study on the that affect long term conservation of aquatic Macquarie Marshes was supported financially by biodiversity (e.g., pollution, invasive species). For the Australian Government and the partners in example, removal of introduced trout in some the NCCARF. streams may buffer impacts of increasing temperature on cold adapted freshwater biota. 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