Cryptic coral recruits as dormant “seed banks”: An unrecognized mechanism of rapid reef recovery

Doropoulos, Christopher; Bozec, Yves‐Marie; Gouezo, Marine; Priest, Mark A.; Thomson, Damian P.; Mumby, Peter J.; Roff, George

doi:10.1002/ecy.3621

Cited by 6 publications

(5 citation statements)

References 20 publications

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“…This method allows the sampling of the same plots through time to quantify the succession of facilitative and competitive organisms following a large disturbance, when space becomes available and ecological succession occurs. On coral reefs, applying this method in areas that have shown extremely rapid recovery (<6 years) would help to elucidate the key facilitative drivers that enable successful recruitment and rapid growth of juvenile corals, topics which are still debated (Doropoulos et al, 2022; Edmunds, 2018; Gilmour et al, 2013). This method could also be applied during coral larval restoration (dela Cruz & Harrison, 2017; Harrison et al, 2021) to investigate larval supply density‐dependence effects on early stages of survival and growth of settled corals, previously done using tiles (e.g.…”

Section: Discussionmentioning

confidence: 99%

Underwater macrophotogrammetry to monitor in situ benthic communities at submillimetre scale

et al. 2023

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Larval settlement and recruitment of sessile organisms are key ecological processes for population recovery and maintenance that occur at scales invisible to the human eye. Accordingly, proxies of recruitment have commonly been quantified using artificial substrata such as settlement tiles made of diverse materials and shapes, which are typically transported to the laboratory for examination. However, it is unknown how much bias is introduced with this sampling strategy and how recruitment quantified on tiles relates to recruitment on nearby natural substrata. Here, we applied techniques that combine macrophotography with photogrammetry (macrophotogrammetry) underwater to monitor benthic communities at submillimetre scale. This application allows the investigation of recruitment and community succession of the earliest life‐history stages in situ and on natural substrata. We tested the use of four different imaging systems, varying in costs from US$ 1400 to US$ 5440. While the most expensive SONY αRiv system provided the best visual output and ground resolution (up to 5 μm/pixel with a + 4 close‐up lens); regardless of systems, 3D models always had a ground resolution ≤23 μm/pixel and errors in planar measurements of submillimetre features were similar among systems. This level of resolution compares well with stereomicroscopy in the range of 5:1 to 10:1 magnification, while providing detailed 3D digital records through time. Using a coral reef example, we apply this approach to demonstrate how it can be used to monitor small reef areas (~300–600 cm2) through time, including the quantification of biophysical metrics such as cover of small facilitative and competitive organisms and microhabitat complexity. We further show that organisms as small 0.5 mm in size, such as 2‐month‐old coral settlers, can be located accurately within the 3D models and measured with a good level of confidence. This method can be readily applied to other benthic environments to elucidate drivers of early recruitment and recovery of benthic organisms following disturbance impacts at very fine scales, directly on natural substrata, to avoid biases inherent with laboratory‐based analyses of artificial surfaces.

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Section: Discussionmentioning

confidence: 99%

Underwater macrophotogrammetry to monitor in situ benthic communities at submillimetre scale

et al. 2023

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“…However, the relatively large size of these corals (mean diameter = 2.6 cm; SD = 0.95 cm) suggests that most juvenile corals had probably settled to cryptic surfaces (cracks, crevices, etc.) in our plots prior to our manipulation and only became visible to us as they grew out of these locations (see Doropoulos et al, 2022;Mumby et al, 2016). Finally, to test whether fish consumers had an overall impact on the size structure of juvenile corals we used a linear mixed-effects model to test whether the mean size of these juvenile corals varied among the four herbivory treatments.…”

Section: Discussionmentioning

confidence: 99%

“…In fact, when uncontrolled by herbivores, macroalgae can become abundant on newly available substrate in a matter of months (Adam et al, 2011 ; Roff & Mumby, 2012 ; Vieira, 2019 ). By contrast, it takes years to decades for corals to dominate substrate following a disturbance even in systems with high rates of coral recruitment (Colgan, 1987 ; Doropoulos et al, 2022 ; Gilmour et al, 2013 ; Holbrook et al, 2018 ). Such a large disparity in the ability of macroalgae to colonize and subsequently dominate new substrate compared with corals suggests that priority effects between corals and macroalgae will often favor macroalgae.…”

Section: Discussionmentioning

confidence: 99%

Priority effects in coral–macroalgae interactions can drive alternate community paths in the absence of top‐down control

Adam

Holbrook

Burkepile

et al. 2022

Ecology

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The outcomes of species interactions can vary greatly in time and space with the outcomes of some interactions determined by priority effects. On coral reefs, benthic algae rapidly colonize disturbed substrate. In the absence of top‐down control from herbivorous fishes, these algae can inhibit the recruitment of reef‐building corals, leading to a persistent phase shift to a macroalgae‐dominated state. Yet, corals may also inhibit colonization by macroalgae, and therefore the effects of herbivores on algal communities may be strongest following disturbances that reduce coral cover. Here, we report the results from experiments conducted on the fore reef of Moorea, French Polynesia, where we: (1) tested the ability of macroalgae to invade coral‐dominated and coral‐depauperate communities under different levels of herbivory, (2) explored the ability of juvenile corals (Pocillopora spp.) to suppress macroalgae, and (3) quantified the direct and indirect effects of fish herbivores and corallivores on juvenile corals. We found that macroalgae proliferated when herbivory was low but only in recently disturbed communities where coral cover was also low. When coral cover was <10%, macroalgae increased 20‐fold within 1 year under reduced herbivory conditions relative to high herbivory controls. Yet, when coral cover was high (50%), macroalgae were suppressed irrespective of the level of herbivory despite ample space for algal colonization. Once established in communities with low herbivory and low coral cover, macroalgae suppressed recruitment of coral larvae, reducing the capacity for coral replenishment. However, when we experimentally established small juvenile corals (2 cm diameter) following a disturbance, juvenile corals inhibited macroalgae from invading local neighborhoods, even in the absence of herbivores, indicating a strong priority effect in macroalgae–coral interactions. Surprisingly, fishes that initially facilitated coral recruitment by controlling algae had a net negative effect on juvenile corals via predation. Corallivores reduced the growth rates of corals exposed to fishes by ~30% relative to fish exclosures, despite increased competition with macroalgae within the exclosures. These results highlight that different processes are important for structuring coral reef ecosystems at different successional stages and underscore the need to consider multiple ecological processes and historical contingencies to predict coral community dynamics.

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“…In addition to understanding larval dispersal and ensuring population connectivity (Greiner et al ., 2022), there is a continual need to explore other mechanisms that facilitate rapid reef recovery. For example, Doropoulos et al . (2022) hypothesised that coral cryptic seed banks play an important role in reef recovery after cyclone disturbances.…”

Section: Discussionmentioning

confidence: 99%

High-latitude marginal reefs support fewer but bigger corals than their tropical counterparts

Chong

Sommer

Stant

et al. 2022

Preprint

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AimDespite the awareness that climate change impacts are typically detrimental to tropical coral reefs, the effect of increasing environmental stress and variability on the population size structure of coral species remains poorly understood. This gap in knowledge limits our ability to effectively conserve coral reef ecosystems because size specific dynamics are rarely incorporated. Our aim is to quantify variation in the size structure of coral populations along a tropical-to-subtropical environmental gradient.Location20 coral populations along a latitudinal gradient on the east coast of Australia (∼23°S to 30°S).Time PeriodBetween 2010 and 2018.Major taxa studiedScleractinian corals.MethodsWe apply two methods to quantify the relationship between environmental covariates and coral population size structure along a latitudinal environmental gradient. First, we use linear regression with summary statistics, such as median size as response variables; a method frequently favoured by ecologists. The second method is compositional functional regression, a novel method using entire size-frequency distributions as response variables. We then predict coral population size structure with increasing environmental stress and variability.ResultsCompared to tropical reefs, we find fewer but larger coral colonies in marginal reefs, where environmental conditions are more variable and stressful for corals in the former. Our model predicts that coral populations may become gradually dominated by larger colonies (> 148 cm2) with increasing environmental stress.Main conclusionsWith increasing environmental stress and variability, we can expect shifts in coral population size structure towards more larger colonies. Fewer but bigger corals suggest low survival, slow growth, and poor recruitment. This finding is concerning for the future of coral reefs as it implies populations may have low recovery potential from disturbances. We highlight the importance and usefulness of continuously monitoring changes to population structure over large spatial scales.Data availabilityData is supplied in the supplementary information, or upon request. Once accepted for publication it will be made openly available on Dryad.

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Cryptic coral recruits as dormant “seed banks”: An unrecognized mechanism of rapid reef recovery

Cited by 6 publications

References 20 publications

Underwater macrophotogrammetry to monitor in situ benthic communities at submillimetre scale

Underwater macrophotogrammetry to monitor in situ benthic communities at submillimetre scale

Priority effects in coral–macroalgae interactions can drive alternate community paths in the absence of top‐down control

High-latitude marginal reefs support fewer but bigger corals than their tropical counterparts

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