There is little information about the specific effects of climate change on marine wildlife. Changes in water temperatures, ocean chemistry, ocean processes and weather patterns associated with climate change may have both direct physiological impacts on marine wildlife and indirect effects through impacts on their habitats. However, some impacts can be predicted by examining the biology and ecology of species such as marine turtles:

• The sex of marine turtle hatchlings is determined by the incubation temperature of the eggs, with warmer incubation temperatures giving rise to higher numbers of female hatchlings
• Climate change may alter beach sand temperatures and thus, cause changes in the male/female sex ratio in marine turtle populations
• Once hatched, changing sea temperatures may affect the growth rate of hatchlings and juvenile turtles
• Climate change may also affect critical turtle habitats. Rising sea levels and an increase in the frequency and intensity of severe storms may erode critical nesting beaches and reduce the availability of suitable nesting sites
• Climate change may also alter ocean circulation patterns and disrupt marine food webs, both of which would have significant impacts on turtles during pelagic phases of their lifecycle. For example, the El Niño Southern Oscillation is thought to have a significant impact on the numbers of green turtles nesting in the Great Barrier Reef. Higher than normal sea temperatures have resulted in major coral bleaching episodes in 1998 and 2002, as well as seagrass burning
• Continued increases in sea temperatures may lead to an increasing frequency and intensity of coral bleaching and seagrass burning events, reducing the amount and/or quality of both shelter and food for marine turtles
• The long life span and generation times of marine turtles reduces the ability of these animals to cope with rapidly changing climatic conditions.

Actions

Climate change is a global issue. The Great Barrier Reef Marine Park Authority (GBRMPA) is committed to addressing climate change issues as they relate to the Great Barrier Reef. Maintaining the Great Barrier Reef ecosystem’s resilience to climate change is the focal point of the GBRMPA’s response to climate change. Maintaining the resilience of key habitats will be vital to help animals, such as dugongs and turtles, cope with pressure from climate change.

• The GBRMPA has developed a Climate Change Response Programme to investigate the potential impacts of climate change on the animals, plants and habitats of the Great Barrier Reef, and to identify strategies to mitigate these impacts
• A revised Great Barrier Reef Marine Park Zoning Plan was introduced on 1 July 2004 to ensure there is adequate protection for all of the habitat types in the Great Barrier Reef ecosystem. By preserving an adequate portion of each habitat type in a network of protected areas, the new Zoning Plan will help maintain the biodiversity, ecological functions and biological connections between habitats of the Great Barrier Reef
• As described in ‘Habitat degradation and disturbance’, the GBRMPA is also working to reduce pressure from declining water quality through the Reef Water Quality Protection Plan and to improve fisheries management
• Other efforts to reduce direct pressures on dugongs and turtles by reducing by-catch in fisheries, boat strike and improving water quality will help to maintain the resilience of dugong and marine turtle populations to cope with effects of climate change.