Recurrent Mass-Bleaching and the Potential for Ecosystem Collapse on Australia’s Great Barrier Reef

Pratchett, Morgan S.; Heron, Scott F.; Mellin, Camille; Cumming, Graeme S.

doi:10.1007/978-3-030-71330-0_10

Cited by 30 publications

(22 citation statements)

References 147 publications

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“…The 2019 bleaching event had widespread effects on coral reefs across the Hawaiian Archipelago and underscored the rising frequency of thermal stress events not only in the central Pacific, but also around the world. Following the third mass global bleaching event (2014–2017), which resulted in severe mortality, bleaching events have continued to affect reefs globally over the past 5 years including regions such as French Polynesia [ 90 ], Bonaire [ 91 ], and the Great Barrier Reef [ 92 ]. While the 2019 bleaching event in the Hawaiian Islands was not as severe as initially forecasted, future marine heatwaves still harbor the potential for catastrophic impacts.…”

Section: Discussionmentioning

confidence: 99%

Coral taxonomy and local stressors drive bleaching prevalence across the Hawaiian Archipelago in 2019

et al. 2022

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The Hawaiian Archipelago experienced a moderate bleaching event in 2019—the third major bleaching event over a 6-year period to impact the islands. In response, the Hawai‘i Coral Bleaching Collaborative (HCBC) conducted 2,177 coral bleaching surveys across the Hawaiian Archipelago. The HCBC was established to coordinate bleaching monitoring efforts across the state between academic institutions, non-governmental organizations, and governmental agencies to facilitate data sharing and provide management recommendations. In 2019, the goals of this unique partnership were to: 1) assess the spatial and temporal patterns of thermal stress; 2) examine taxa-level patterns in bleaching susceptibility; 3) quantify spatial variation in bleaching extent; 4) compare 2019 patterns to those of prior bleaching events; 5) identify predictors of bleaching in 2019; and 6) explore site-specific management strategies to mitigate future bleaching events. Both acute thermal stress and bleaching in 2019 were less severe overall compared to the last major marine heatwave events in 2014 and 2015. Bleaching observed was highly site- and taxon-specific, driven by the susceptibility of remaining coral assemblages whose structure was likely shaped by previous bleaching and subsequent mortality. A suite of environmental and anthropogenic predictors was significantly correlated with observed bleaching in 2019. Acute environmental stressors, such as temperature and surface light, were equally important as previous conditions (e.g. historical thermal stress and historical bleaching) in accounting for variation in bleaching during the 2019 event. We found little evidence for acclimation by reefs to thermal stress in the main Hawaiian Islands. Moreover, our findings illustrate how detrimental effects of local anthropogenic stressors, such as tourism and urban run-off, may be exacerbated under high thermal stress. In light of the forecasted increase in severity and frequency of bleaching events, future mitigation of both local and global stressors is a high priority for the future of corals in Hawai‘i.

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Section: Discussionmentioning

confidence: 99%

Coral taxonomy and local stressors drive bleaching prevalence across the Hawaiian Archipelago in 2019

et al. 2022

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“…by the 2016 global mass bleaching event (Hughes et al, 2018), which may explain this lack of a positive reserve effect on coral health. Unfortunately, the 2020 bleaching event (Pratchett et al, 2021) seems to have had a bigger impact upon DIMRS (K. Ledesma Trebol, pers. comm.…”

Section: Discussionmentioning

confidence: 99%

Small no‐take areas benefit hard corals more than regulation through fishing permits

Wright

2022

Aquatic Conservation

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Situated in the coral triangle, the Philippines hosts some of the world's most diverse coral reefs. Yet there are few national marine protected areas (MPAs) in place that coincide with these reefs. Municipal MPAs partially alleviate this issue but a controlled comparison of the effects of different small‐scale management strategies on coral reefs is lacking. Danjugan Island Marine Reserve and Sanctuaries (DIMRS) is one of these community‐based MPAs that encompasses a collection of small (0.3–0.34 km2) marine reserves situated in a larger MPA where fishing is regulated through permits. The unique juxtaposition of different management strategies within DIMRS was used as a model system to test whether reserves are better for corals than limited fishing permits by comparing ecosystem indicators (coral cover, bleaching, disease, and morphological diversity). Total and live hard corals were 169% and 204% more abundant inside than outside no‐take zones in 2016. This distinction increased between 2002 and 2016 as a result of a more marked decrease in coral cover over time in the partially protected zones. A 70% higher coral community evenness outside the reserves further suggests that scleractinian coral communities on fished reefs are more disturbed. Live coral cover within the MPAs of DIMRS in 2016 (39 ± 4%) is above the current mean for Philippine reefs (23%) and is comparable with the long‐term average for reefs situated within Philippine MPAs (36%). This study suggests that exceptionally small reserves may benefit hard corals more than regulation via fishing permits.

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“…Loss of reef habitat complexity and structure directly impacts the diversity and abundance of reef-associated organisms. On the Great Barrier Reef alone, major episodes of bleaching were reported in 2016, 2017(Pratchett et al 2021. During the 2016 event, high temperatures led to the catastrophic die-off of fast-growing staghorn and tabular corals, leading to a shift in ecological functioning and reduction in three-dimensionality that impacted approximately one-third of the reef (Hughes et al 2018).…”

Section: Coral Reefsmentioning

confidence: 99%

“…The term marine heatwave (MHW)-referring to a discrete period of unusually high seawater temperatures-was coined following an unprecedented warming event off the west coast of Australia in the austral summer of 2011, which led to a rapid dieback of kelp forests and associated ecosystem shifts along hundreds of kilometers of coastline (Pearce & Feng 2013. Since then, a number of high-intensity events have occurred (Sen Gupta et al 2020) (Figure 1; Supplemental Table 1), including low-latitude MHWs linked to the El Niño of 2015-2016 in the central/eastern tropical Pacific and multiple MHWs in the Coral Sea (in 2016, 2017, and 2020), all of which led to widespread coral bleaching and mortality (Pears et al 2017, Pratchett et al 2021. The longest (non-El Niño) MHW on record, the Blob, covered much of the northeastern Pacific from 2014 to 2016 and has been linked to major ecosystem impacts-including extreme low productivity (Hart et al 2020), mass mortality events for mammals and seabirds (Cavole et al 2016), and harmful algal blooms (McCabe et al 2016)-that in turn affected the delivery of ecological goods and services for human society (Smith et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Biological Impacts of Marine Heatwaves

Smith

Burrows

Hobday

et al. 2023

Annu. Rev. Mar. Sci.

194

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Climatic extremes are becoming increasingly common against a background trend of global warming. In the oceans, marine heatwaves (MHWs)—discrete periods of anomalously warm water—have intensified and become more frequent over the past century, impacting the integrity of marine ecosystems globally. We review and synthesize current understanding of MHW impacts at the individual, population, and community levels. We then examine how these impacts affect broader ecosystem services and discuss the current state of research on biological impacts of MHWs. Finally, we explore current and emergent approaches to predicting the occurrence and impacts of future events, along with adaptation and management approaches. With further increases in intensity and frequency projected for coming decades, MHWs are emerging as pervasive stressors to marine ecosystems globally. A deeper mechanistic understanding of their biological impacts is needed to better predict and adapt to increased MHW activity in the Anthropocene. Expected final online publication date for the Annual Review of Marine Science, Volume 15 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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Recurrent Mass-Bleaching and the Potential for Ecosystem Collapse on Australia’s Great Barrier Reef

Cited by 30 publications

References 147 publications

Coral taxonomy and local stressors drive bleaching prevalence across the Hawaiian Archipelago in 2019

Coral taxonomy and local stressors drive bleaching prevalence across the Hawaiian Archipelago in 2019

Small no‐take areas benefit hard corals more than regulation through fishing permits

Biological Impacts of Marine Heatwaves

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