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

Abstract

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.

Inundation requirements for persistence and recovery of river red gums ( Eucalyptus camaldulensis ) in semi-arid Australia

“…Efficient use of environmental water will increase in importance under anticipated reductions in water availability across the entire region (CSIRO, 2008b), particularly when projected climate change reduces flows (Chiew et al, 2010;Jenkins et al, 2011). Genetic investigations suggest some adaptive capacity in river red gums in dealing with a range of environmental conditions (Dillon et al, 2014) but applicability to trees near threshold conditions of water availability needs to be better understood.…”

The end of the Pacific? Effects of sea level rise on Pacific Island livelihoods

“…Sea level rise has affected coastal food supplies largely by the drowning or salinization of productive land including coastal wetlands (Jenkins et al ., ). Examples have been reported from the island groups of Cook Islands, Fiji, Vanuatu and several atoll nations (FAO, ; Webb, ).…”

Current knowledge and potential impacts of climate change on New Zealand’s biological heritage

“…This process may release habitat for galaxiids that will be free of salmonid competition and predation in warmer waters, but it may have the opposite effect in cooler waters (Boddy & McIntosh 2017). In contrast, many specialised indigenous species are high-altitude coldtolerant species which may be severely affected by increasing temperature (Jenkins et al 2011), while low-altitude systems may be strongly impacted by changes in hydrology and sealevel rise (Schallenberg et al 2003). Similarly, the ability to migrate and disperse will largely affect how species can adapt to changing conditions, and this varies widely between species and systems in New Zealand (McDowall 2006).…”