Rates of decline and recovery of coral cover on reefs impacted by, recovering from and unaffected by crown-of-thorns starfish Acanthaster planci:a regional perspective of the Great Barrier Reef

AbstractCan genetic adaptation in reef-building corals keep pace with the current rate of sea surface warming? Here we combine population genomic, biophysical modeling, and evolutionary simulations to predict future adaptation of the common coralAcropora milleporaon the Great Barrier Reef. Loss of coral cover in recent decades did not yet have detectable effect on genetic diversity in our species. Genomic analysis of migration patterns closely matched the biophysical model of larval dispersal in favoring the spread of existing heat-tolerant alleles from lower to higher latitudes. Given these conditions we find that standing genetic variation could be sufficient to fuel rapid adaptation ofA. milleporato warming for the next 100-200 years, although random thermal anomalies would drive increasingly severe mortality episodes. However, this adaptation will inevitably cease unless the warming is slowed down, since no realistic mutation rate could replenish adaptive genetic variation fast enough.

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Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.1432 ◽

2020 ◽

Vol 287 (1936) ◽

pp. 20201432

Author(s):

Andreas Dietzel ◽

Michael Bode ◽

Sean R. Connolly ◽

Terry P. Hughes

Keyword(s):

Great Barrier Reef ◽

Colony Size ◽

Size Structure ◽

Coral Cover ◽

Spatial Scales ◽

Reproductive Capacity ◽

Barrier Reef ◽

Size Frequency Distribution ◽

Coral Colony ◽

Recovery Potential

The age or size structure of a population has a marked influence on its demography and reproductive capacity. While declines in coral cover are well documented, concomitant shifts in the size-frequency distribution of coral colonies are rarely measured at large spatial scales. Here, we document major shifts in the colony size structure of coral populations along the 2300 km length of the Great Barrier Reef relative to historical baselines (1995/1996). Coral colony abundances on reef crests and slopes have declined sharply across all colony size classes and in all coral taxa compared to historical baselines. Declines were particularly pronounced in the northern and central regions of the Great Barrier Reef, following mass coral bleaching in 2016 and 2017. The relative abundances of large colonies remained relatively stable, but this apparent stability masks steep declines in absolute abundance. The potential for recovery of older fecund corals is uncertain given the increasing frequency and intensity of disturbance events. The systematic decline in smaller colonies across regions, habitats and taxa, suggests that a decline in recruitment has further eroded the recovery potential and resilience of coral populations.

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Cross-Shelf Variation Among Juvenile and Adult Coral Assemblages on Australia’s Great Barrier Reef

Diversity ◽

10.3390/d11060085 ◽

2019 ◽

Vol 11 (6) ◽

pp. 85 ◽

Cited By ~ 1

Author(s):

Michelle J. Jonker ◽

Angus A. Thompson ◽

Patricia Menéndez ◽

Kate Osborne

Keyword(s):

Great Barrier Reef ◽

Coral Cover ◽

Synergistic Effects ◽

Outer Shelf ◽

Lower Latitude ◽

Barrier Reef ◽

Hard Coral ◽

Coral Abundance ◽

The Status ◽

Community Types

Coral reefs are under increasing pressure from a variety of stressors, highlighting the need for information about the status of coral reef communities including the distribution, abundance and composition of juvenile and adult coral assemblages. This information is currently limited for the Great Barrier Reef (GBR) and is necessary for understanding the impacts of disturbances and the system’s potential for recovery. This study reports juvenile and adult hard coral abundance and composition from 122 reefs on the GBR during a period of limited acute disturbance. The data represent baseline observations for juvenile hard coral assemblages spanning the longitudinal cross-shelf gradient of the GBR and 12 degrees of latitude and augment reported distribution of adult coral assemblages over the same scale with inclusion of additional reefs. Juvenile and adult coral assemblages reflected broad differences imposed by the gradient of environmental conditions across the GBR. The mean density of juvenile hard corals was lower in the inshore reefs (5.51 m2) than at either the mid-shelf (11.8 m2) or outer shelf reefs (11.2 m2). The composition of juvenile and adult coral assemblages covaried overall, although there were different relationships between these two life stages across the continental shelf and among community types. Dissimilarity between juvenile and adult coral assemblages was greater on inshore and outer shelf reefs than on reefs in the mid-shelf, although, there were differences in community types both within these shelf positions and those that spanned mid- and outer shelf reefs. Dissimilarity was greatest for Inshore branching Acropora and high for Southern Acropora communities, although very high coral cover and very low juvenile densities at these reefs precluded interpretation beyond the clear competitive dominance of Acropora on those reefs. Dissimilarity was also high between juvenile and adult coral assemblages of Turbid inshore communities suggesting water quality pressures, along with synergistic effects of other stressors, pose ongoing selective pressures beyond the juvenile stage. Conversely, relatively low dissimilarity between juvenile and adult coral assemblages on mid-shelf and lower latitude outer shelf reefs suggests pressures beyond those influencing settlement and early post-settlement survival were having less influence on the composition of adult coral assemblages.

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Assessing loss of coral cover on the Great Barrier Reef: A response to Hughes et al. (2011)

Coral Reefs ◽

10.1007/s00338-011-0794-7 ◽

2011 ◽

Vol 30 (3) ◽

Cited By ~ 23

Author(s):

H. Sweatman ◽

C. Syms

Keyword(s):

Great Barrier Reef ◽

Coral Cover ◽

Barrier Reef

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High survival following bleaching highlights the resilience of a highly disturbed region of the Great Barrier Reef

10.1101/2021.10.18.464880 ◽

2021 ◽

Author(s):

Cathie A Page ◽

Christine Giuliano ◽

Line K Bay ◽

Carly J Randall

Keyword(s):

Great Barrier Reef ◽

Coral Cover ◽

Heat Exposure ◽

High Survival ◽

Barrier Reef ◽

Recovery Potential ◽

Coral Communities ◽

Degree Heating Weeks ◽

High Turbidity ◽

Exposure Metrics

Natural bleaching events provide an opportunity to examine how local scale environmental variation influences bleaching severity and recovery. During the 2020 marine heatwave, we documented widespread and severe coral bleaching (75 – 98% of coral cover) throughout the Keppel Islands in the Southern inshore Great Barrier Reef. Acropora, Pocillopora and Porites were the most severely affected genera, while Montipora was comparatively less susceptible. Site-specific heat-exposure metrics were not correlated with Acropora bleaching severity, but recovery was faster at sites that experienced lower heat exposure. Despite severe bleaching and exposure to accumulated heat that often results in coral mortality (degree heating weeks ~ 4 – 8), cover remained stable. Approximately 94% of fate-tracked Acropora millepora colonies survived, perhaps owing to reduced irradiance stress from high turbidity, heterotrophic feeding, and large tidal flows that can increase mass transfer. Severe bleaching followed by rapid recovery, and the continuing dominance of Acropora populations in the Keppel Islands is indicative of high resilience. These coral communities have survived an 0.8 °C increase in average temperatures over the last 150 years. However, recovery following the 2020 bleaching was driven by the easing of thermal stress, which may challenge their recovery potential under further warming.

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Great Barrier Reef Degradation, Sea Surface Temperatures, and Atmospheric CO2 Levels Collectively Exhibit a Stochastic Process with Memory

10.21203/rs.3.rs-299051/v1 ◽

2021 ◽

Author(s):

Allan Elnar ◽

Christianlly Cena ◽

Christopher Casenas Bernido ◽

M. Victoria Carpio-Bernido

Keyword(s):

Stochastic Process ◽

Great Barrier Reef ◽

Coral Cover ◽

Sea Surface ◽

Atmospheric Co2 ◽

Sea Surface Temperatures ◽

Barrier Reef ◽

Hard Coral ◽

Co2 Levels ◽

Hard Coral Cover

Abstract Quantifying ecological memory could be done at several levels from the rate of physiological changes in an ecosystem all the way down to responses at the genetic level. One way of unlocking the information encoded in a collective environmental memory is to examine the recorded time-series data generated by different components of an ecosystem. In this paper, we probe into the case of the Great Barrier Reef (GBR) which is threatened by elevated sea surface temperatures (SST) and ocean acidification attributed to rising atmospheric CO 2 levels. Specifically, we investigate the interrelated dynamics between the degradation of the GBR, SST, and rising atmospheric CO 2 levels, by considering three datasets: (a) the mean percentage hard coral cover of the GBR from the archives of the Australian Institute of Marine Science; (b) SST close to the GBR from the National Oceanic and Atmospheric Administration; and (c) the Keeling curve for atmospheric CO 2 levels measured by the Mauna Loa Observatory. We show that fluctuating observables in these datasets have the same memory behavior described by a non-Markovian stochastic process. All three datasets show a good match between empirical and analytical mean square deviation. An explicit analytical form for the corresponding probability density function is obtained which obeys a modified diffusion equation with a time dependent diffusion coefficient. This study provides a new perspective on the similarities of and interaction between the GBR’s declining hard coral cover, SST, and rising atmospheric CO2 levels by putting all three systems into one unified framework indexed by a memory parameter μ and a characteristic frequency ν . The short-time dynamics of CO2 levels and SST fall in the superdiffusive regime, while the GBR exhibits hyperballistic fluctuation in percent coral cover with the highest values for μ and ν .

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Historical photographs revisited: A case study for dating and characterizing recent loss of coral cover on the inshore Great Barrier Reef

Scientific Reports ◽

10.1038/srep19285 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 8

Author(s):

Tara R. Clark ◽

Nicole D. Leonard ◽

Jian-xin Zhao ◽

Jon Brodie ◽

Laurence J. McCook ◽

...

Keyword(s):

Great Barrier Reef ◽

Coral Cover ◽

Barrier Reef ◽

Historical Photographs ◽

Inshore Great Barrier Reef

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Genetically Engineering Coral for Conservation: Psychological Correlates of Public Acceptability

Frontiers in Marine Science ◽

10.3389/fmars.2021.710641 ◽

2021 ◽

Vol 8 ◽

Author(s):

Aditi Mankad ◽

Elizabeth V. Hobman ◽

Lucy Carter

Keyword(s):

Synthetic Biology ◽

Great Barrier Reef ◽

Technology Development ◽

Coral Cover ◽

Public Support ◽

Genetically Engineered ◽

Path Model ◽

World Heritage Site ◽

Relative Advantage ◽

Barrier Reef

Coral bleaching contributes to widespread reef loss globally, including Australia’s World Heritage site, the Great Barrier Reef. Synthetic biology offers the potential to isolate and cultivate strains of coral that can naturally withstand higher sea surface temperatures associated with climate change. A national survey was conducted (N = 1,148 Australians) measuring psychological predictors of support for a synthetic biology conservation solution to coral loss. The analysis showed a partially mediated path model was useful in explaining a significant amount of variance in public support for the development of genetically engineered coral for conservation (R2 = 0.40) and in willingness to visit parts of the Great Barrier Reef where genetically engineered coral had (hypothetically) been introduced (R2 = 0.24). Participants were moderately strongly supportive of technology development and were most keen to implement genetically engineered coral with between 50 and 70% of reef remaining intact; recent estimates of coral cover across the Great Barrier Reef are well below that already. There was a negative association between perceived risks of genetically engineered coral and public support; however, perceived benefit of genetically engineered coral in protecting the reef and relative advantage of a synthetic biology solution over existing protection strategies were the most influential predictors of public support. The findings suggest that the general public are not averse to the development of a synthetic biology solution for restoring the reef, and they may be especially influenced by whether the synthetic biology solution is shown to be efficacious, particularly in comparison to other conservation solutions. However, support for a synthetic biology intervention is conditional and many participants expressed concerns about possible long-term impacts on humans, animals, and the environment as a result of deploying engineered coral.

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Large-scale interventions may delay decline of the Great Barrier Reef

Royal Society Open Science ◽

10.1098/rsos.201296 ◽

2021 ◽

Vol 8 (4) ◽

Author(s):

Scott A. Condie ◽

Kenneth R. N. Anthony ◽

Russ C. Babcock ◽

Mark E. Baird ◽

Roger Beeden ◽

...

Keyword(s):

Solar Radiation ◽

Great Barrier Reef ◽

Tropical Cyclones ◽

Large Scale ◽

Coral Cover ◽

Solar Radiation Management ◽

Successful Implementation ◽

Barrier Reef ◽

Cumulative Impacts ◽

Coral Rubble

On the iconic Great Barrier Reef (GBR), the cumulative impacts of tropical cyclones, marine heatwaves and regular outbreaks of coral-eating crown-of-thorns starfish (CoTS) have severely depleted coral cover. Climate change will further exacerbate this situation over the coming decades unless effective interventions are implemented. Evaluating the efficacy of alternative interventions in a complex system experiencing major cumulative impacts can only be achieved through a systems modelling approach. We have evaluated combinations of interventions using a coral reef meta-community model. The model consisted of a dynamic network of 3753 reefs supporting communities of corals and CoTS connected through ocean larval dispersal, and exposed to changing regimes of tropical cyclones, flood plumes, marine heatwaves and ocean acidification. Interventions included reducing flood plume impacts, expanding control of CoTS populations, stabilizing coral rubble, managing solar radiation and introducing heat-tolerant coral strains. Without intervention, all climate scenarios resulted in precipitous declines in GBR coral cover over the next 50 years. The most effective strategies in delaying decline were combinations that protected coral from both predation (CoTS control) and thermal stress (solar radiation management) deployed at large scale. Successful implementation could expand opportunities for climate action, natural adaptation and socioeconomic adjustment by at least one to two decades.

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The 27-year decline of coral cover on the Great Barrier Reef and its causes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1208909109 ◽

2012 ◽

Vol 109 (44) ◽

pp. 17995-17999 ◽

Cited By ~ 929

Author(s):

G. De'ath ◽

K. E. Fabricius ◽

H. Sweatman ◽

M. Puotinen

Keyword(s):

Great Barrier Reef ◽

Coral Cover ◽

Barrier Reef

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