Subcontinental heat wave triggers terrestrial and marine, multi-taxa responses

Katinka X Ruthrof,Jatin Kala,Neal J Enright,Thomas Wernberg,Giles E St J Hardy,David D Breshears,Ben P Miller,Joseph B Fontaine,Shaun K Wilson,George Matusick,Ray H Froend,Mike Van Keulen,Darin J Law,Patrick J Mitchell

doi:10.1038/s41598-018-31236-5

Abstract

Heat waves have profoundly impacted biota globally over the past decade, especially where their ecological impacts are rapid, diverse, and broad-scale. Although usually considered in isolation for either terrestrial or marine ecosystems, heat waves can straddle ecosystems of both types at subcontinental scales, potentially impacting larger areas and taxonomic breadth than previously envisioned. Using climatic and multi-species demographic data collected in Western Australia, we show that a massive heat wave event straddling terrestrial and maritime ecosystems triggered abrupt, synchronous, and multi-trophic ecological disruptions, including mortality, demographic shifts and altered species distributions. Tree die-off and coral bleaching occurred concurrently in response to the heat wave, and were accompanied by terrestrial plant mortality, seagrass and kelp loss, population crash of an endangered terrestrial bird species, plummeting breeding success in marine penguins, and outbreaks of terrestrial wood-boring insects. These multiple taxa and trophic-level impacts spanned >300,000 km2—comparable to the size of California—encompassing one terrestrial Global Biodiversity Hotspot and two marine World Heritage Areas. The subcontinental multi-taxa context documented here reveals that terrestrial and marine biotic responses to heat waves do not occur in isolation, implying that the extent of ecological vulnerability to projected increases in heat waves is underestimated.

Highlights

Recent dramatic ecological shifts in response to climate extremes have had profound societal impacts[1] and have galvanized recognition of extreme climate events, rather than gradual, mean change, as the most conspicuous hand of climate change[1,2]
The terrestrial maximum temperatures extending from 25°S at Shark Bay to 34°S at Cape
The results of our meta-analytic approach illustrate a broad range of diverse and pervasive biotic disruptions caused by a heat wave, reflecting strong spatial coherence between climate signal and ecological response

Summary

Introduction

Recent dramatic ecological shifts in response to climate extremes have had profound societal impacts[1] and have galvanized recognition of extreme climate events, rather than gradual, mean change, as the most conspicuous hand of climate change[1,2]. Heat waves are explicitly discussed in terms of impacts on human populations in the most recent climate assessment reports, their full and detailed effects on ecosystems is lacking[1,12]. Given these gaps in reporting and knowledge, the full extent of ecological vulnerability to projected heat waves may be underestimated. Following a heat wave event in early 2011, which straddled both the marine and terrestrial ecosystems of Western Australia, we aimed to document, using a meta-analytic framework, the pervasive ecological effect of a climate change-induced extreme event, highlight the breadth of taxa affected, and quantify demographic change in the abundance and mortality rates. Organisms present prior to the event (sessile species, long-lived vagile taxa) were assumed a priori to be negatively impacted, whereas vagile consumers that were not present or rare pre-heat wave were presumed to be neutral or increasing following a heat wave event

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Conclusion