The rising threat of peyssonnelioid algal crusts on coral reefs

Edmunds, Peter J.; Schils, Tom; Wilson, Bryan

doi:10.1016/j.cub.2023.08.097

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…Proportionally large increases in the average cover of Porifera and green macroalgae, Halimeda species in particular, were also observed. Interestingly, the average cover of encrusting red algae of the order Peyssonneliales, some of which are known to outcompete and overgrow corals and other invertebrates on disturbed reefs [ 35 , 110 – 113 ], remained largely constant throughout the three surveys. Prior to the disturbance events in 2013, hard corals determined benthic cover at Lafac Bay [ 82 , 114 ].…”

Section: Discussionmentioning

confidence: 99%

“…The cumulative impact of disturbance events have caused rapid and pronounced changes on coral reefs, many of which do not completely recover and instead undergo a transition (phase shift) to an alternative stable state [ 31 – 33 ]. The best-known phase shifts on coral reefs are transitions from scleractinian-dominated communities to a dominance of fleshy macroalgae [ 33 ], though other transitions to communities dominated by coralline or peyssonnelioid algae [ 34 , 35 ], sponges [ 36 , 37 ], corallimorphs [ 38 ], or other zoantharians [ 39 , 40 ] have also been reported. Shifts in community composition and overall reef degradation could drive local or regional extinctions of reef-associated species, emphasizing the need to examine reef dynamics at a local scale [ 41 ].…”

Section: Introductionmentioning

confidence: 99%

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Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Mills,

Ungermann,

Rigot

et al. 2024

PLoS ONE

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The island of Guam in the west Pacific has seen a significant decrease in coral cover since 2013. Lafac Bay, a marine protected area in northeast Guam, served as a reference site for benthic communities typical of forereefs on the windward side of the island. The staghorn coral Acropora abrotanoides is a dominant and characteristic ecosystem engineer of forereef communities on exposed shorelines. Photoquadrat surveys were conducted in 2015, 2017, and 2019, and a diver-operated hyperspectral imager (i.e., DiveRay) was used to survey the same transects in 2019. Machine learning algorithms were used to develop an automated pipeline to assess the benthic cover of 10 biotic and abiotic categories in 2019 based on hyperspectral imagery. The cover of scleractinian corals did not differ between 2015 and 2017 despite being subjected to a series of environmental disturbances in these years. Surveys in 2019 documented the almost complete decline of the habitat-defining staghorn coral Acropora abrotanoides (a practically complete disappearance from about 10% cover), a significant decrease (~75%) in the cover of other scleractinian corals, and a significant increase (~55%) in the combined cover of bare substrate, turf algae, and cyanobacteria. The drastic change in community composition suggests that the reef at Lafac Bay is transitioning to a turf algae-dominated community. However, the capacity of this reef to recover from previous disturbances suggests that this transition could be reversed, making Lafac Bay an excellent candidate for long-term monitoring. Community analyses showed no significant difference between automatically classified benthic cover estimates derived from the hyperspectral scans in 2019 and those derived from photoquadrats. These findings suggest that underwater hyperspectral imagers can be efficient and effective tools for fast, frequent, and accurate monitoring of dynamic reef communities.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Mills,

Ungermann,

Rigot

et al. 2024

PLoS ONE

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“…This trend has accelerated since 2013 following a succession of severe environmental disturbances, including extreme low tides from 2014-2015 triggered by an El Niño Southern Oscillation (ENSO) event, as well as severe island-wide bleaching events in 2013, 2014, 2016, and 2017 [61,62]. This sequence of events resulted in a 34-37% decline in island-wide coral cover [61,62] and notable changes in benthic community composition [63,64]. The declining health of Guam's reefs has made the need for monitoring more pressing than ever.…”

Section: Introductionmentioning

confidence: 99%

Structural Complexity of Coral Reefs in Guam, Mariana Islands

Mills,

Schils,

Olds

et al. 2023

Remote Sensing

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The complexity of tropical reef habitats affects the occurrence and diversity of the organisms residing in these ecosystems. Quantifying this complexity is important to better understand and monitor reef community assemblages and their roles in providing ecological services. This study employed structure-from-motion photogrammetry to produce accurate 3D reconstructions of eight reefs in Guam and quantified the structural complexity of these sites using seven terrain metrics: rugosity, slope, vector ruggedness measure (VRM), multiscale roughness (magnitude and scale), plan curvature, and profile curvature. The relationships between terrain complexity, benthic community diversity, and coral cover were investigated with generalized linear models. While the average structural complexity metrics did not differ between most sites, there was significant variation within sites. All surveyed transects exhibited high structural complexity, with an average rugosity of 2.28 and an average slope of 43 degrees. Benthic diversity was significantly correlated with the roughness magnitude. Coral cover was significantly correlated with slope, roughness magnitude, and VRM. This study is among the first to employ this methodology in Guam and provides additional insight into the structural complexity of Guam’s reefs, which can become an important component of holistic reef assessments in the future.

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Attached and free-living crustose coralline algae and their functional traits in the geological record and today

Teichert

2024

Facies

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Crustose coralline algae (CCA) are important ecosystem engineers and carbonate producers today and in the geological past. While there is an increasing number of publications on CCA every year, it is evident that there are many misunderstandings and inconsistencies in the assignment of CCA to taxonomic and functional groups. This is partly because CCA are treated by biologists, ecologists and palaeontologists as well as covered by studies published in journals ranging from geo- to biosciences, so that there is often a mixture of terminology used and differing scientific focus. In this review, a comprehensive overview is given on what is known about CCA, their functional traits and their roles in environments from the present and the past. In this context, some bridges are built between the commonly different viewpoints of ecologists and palaeontologists, including suggesting a common and straightforward terminology, highlighting and partially merging different taxonomic viewpoints as well as summarizing the most important functional traits of CCA. Ideally, future studies should seek to quantitatively analyse potential implications for CCA and their associated organisms under ongoing global change.

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The rising threat of peyssonnelioid algal crusts on coral reefs

Cited by 5 publications

References 10 publications

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Structural Complexity of Coral Reefs in Guam, Mariana Islands

Attached and free-living crustose coralline algae and their functional traits in the geological record and today

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