Heat-wave triggers multi-trophic shocks permeating marine-terrestrial ecoregion

Background/Question/Methods

While drought is recognized in most recent climate change assessments as a critical type of extreme event impacting ecosystems, heat waves are generally not.  Heat waves can co-occur with drought, as typically seen in terrestrial systems or alone, as in marine systems, yet ecological impacts of heat waves have not been widely documented despite the well-recognized consequences of heat waves on human health.  Here we document a suite of synchronous, abrupt mortality events and demographic shifts permeating multiple trophic levels at a regional scale adjoining marine and terrestrial ecosystems in response to a heat wave.

Results/Conclusions

Documented multi-trophic marine and terrestrial impacts of a 2011 heatwave in Western Australia include: algal mortality and kelp epibiosis, widespread woodland and forest tree mortality, failure of post-mine re-vegetation, coral bleaching and altered branching, commercial abalone collapse, substantial fish mortality, greatly reduced penguin breeding success, endangered bird population collapse, range extensions of tropical fish and megafauna species and establishment of invasive mussels. This multi-trophic ecoregional shockwave underscores ecological vulnerability to heat waves, mirroring previously documented impacts of heat waves on human health. These findings highlight the capacity of heat waves, alone or compounded with drought, to trigger synchronous, multi-trophic ecological responses, necessitating their explicit consideration in future risk assessments.