Historical photographs revisited: A case study for dating and characterizing recent loss of coral cover on the inshore 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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Impact evaluation and conservation outcomes in marine protected areas: A case study of the Great Barrier Reef Marine Park

Biological Conservation ◽

10.1016/j.biocon.2019.07.030 ◽

2019 ◽

Vol 238 ◽

pp. 108185 ◽

Cited By ~ 1

Author(s):

Kerrie A. Fraser ◽

Vanessa M. Adams ◽

Robert L. Pressey ◽

John M. Pandolfi

Keyword(s):

Great Barrier Reef ◽

Protected Areas ◽

Marine Protected Areas ◽

Impact Evaluation ◽

Barrier Reef ◽

Marine Park

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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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