Marine heatwave proves devastating to Shark Bay and dolphins

Dolphin survival and reproductive rates suffered a significant decline following a 2011 marine heatwave affecting around 1,000km of Western Australia's coastline. The findings, published in Current Biology and representing an international collaboration of researchers and universities, including Zurich and Bristol, have important implications for marine conservation and mitigating the effects of climate change. In early 2011, a marine heatwave produced a mass of warm water increasing coastal sea temperatures in Western Australia up to 4? above average. This event led to the loss of seagrass meadows and fish communities in Shark Bay , a World Heritage area in Western Australia and home to an iconic population of Indo-Pacific bottlenose dolphins. Using long-term demographic data from over 5,000 dolphin encounters in the area between 2007 and 2017, the research team investigated the impact that habitat degradation after this extreme weather event had on dolphin survival and reproduction rates. They discovered a decline of over 12 per cent in survival rates and a reduced number of dolphin calves per female that continued after the event until 2017. The researchers suggest the loss of food availability and habitat has prevented fish stocks from recovering to pre-heatwave levels forcing the dolphins to spend more time searching for food leading to reduced vigilance, and ultimately, more shark predation on calves.