Long-term decline in survival and reproduction of dolphins following a marine heatwave

Extreme Effects of Extreme Disturbances: A Simulation Approach to Assess Population Specific Responses

“…Our results suggest that extreme climate change scenarios have the third largest influence on both abundance and fecundity, after high intensity epizootic events, for both gulfs. The model results are comparable to the reported changes in survival following an extreme heatwave event in Western Australia that resulted in a 5.9-12.2% decline in the abundance of bottlenose dolphins (Wild et al, 2019). The reduction in food availability modeled as part of these scenarios likely drives these results, with increased metabolic need, especially for lactating females, leading to reduced reproductive success, something seen in the natural population post-heatwave in Western Australia (Wild et al, 2019).…”

“…Climate change was considered the disturbance most likely to impact the bottlenose dolphins within the gulfs and was assumed to include issues such as changes to temperature, frequency of storm activity, ocean acidification and warming, as well as increases in salinity. These shifts in climate can lead to changes in dolphin dispersal based upon thermal tolerances and fluctuations in survival and reproduction in extreme heatwave events, as well as variation in prey distribution and availability (Schumann et al, 2013;Wild et al, 2019). Four climate change scenarios were considered for each population and were based upon historic sea surface temperature (SST) anomalies for the region from 1998 to 2018, SST data was sourced from the Integrated Marine Observing System (IMOS, 2019), which is a national collaborative research infrastructure, supported by the Australian Government.…”

A Systematic Review of How Multiple Stressors From an Extreme Event Drove Ecosystem-Wide Loss of Resilience in an Iconic Seagrass Community

“…Indeed, green turtles in poor body condition in Shark Bay spend more time in the middle of shallow seagrass habitats, which offers higher quality food resources but also reduces the potential for escape from tiger shark encounters (Heithaus et al, 2007). Long-term demographic data on Shark Bay's resident Indo-Pacific bottlenose dolphin (Tursiops aduncus) population revealed a significant decline in female reproductive rates following the MHW, with capture-recapture analyses indicated 5.9 and 12.2% post-MHW declines in the survival of dolphins that use tools to forage relative to those that do not (Wild et al, 2019). Lower survival has persisted, suggesting that habitat loss following extreme weather events may have prolonged, negative impacts on even behaviourally flexible, higher-trophic level predators, but that the tool-using dolphins may be somewhat buffered against the cascading effects of habitat loss following the MHW (Wild et al, 2019).…”

“…Long-term demographic data on Shark Bay's resident Indo-Pacific bottlenose dolphin (Tursiops aduncus) population revealed a significant decline in female reproductive rates following the MHW, with capture-recapture analyses indicated 5.9 and 12.2% post-MHW declines in the survival of dolphins that use tools to forage relative to those that do not (Wild et al, 2019). Lower survival has persisted, suggesting that habitat loss following extreme weather events may have prolonged, negative impacts on even behaviourally flexible, higher-trophic level predators, but that the tool-using dolphins may be somewhat buffered against the cascading effects of habitat loss following the MHW (Wild et al, 2019). The Indo-Pacific bottlenose dolphins altered their habitat use patterns similarly following seagrass loss, increasing their use of profitable but dangerous shallow banks during periods of high tiger shark abundance, suggesting a need to increase foraging in these habitats despite predation risk (Nowicki et al, 2019).…”

Cultural change in animals: a flexible behavioural adaptation to human disturbance

“…If such climate-change-led adaptations fit the cultural criteria, this will constitute strong evidence that humans alter animal cultures indirectly. However, because there is currently limited evidence of the connection between climate change and animal cultures (but see Wild et al (2019) who report that culture may alleviate the effects of climate variation in bottlenose dolphins (Tursiops aduncus)) and specifically NHP cultures, our focus will be on behavioural adaptations in response to direct encounters with humans or human activities. Habitat loss and fragmentation have been shown to reduce movements in numerous mammal species worldwide (Tucker et al, 2018), with many mammals (e.g., elephants, (Loxodonta africana, Bates et al, 2007)) or chimpanzees (Pan troglodytes, Hicks et al, 2013)) modifying their behaviour to avoid contact with humans.…”