Reef-scale failure of coral settlement following typhoon disturbance and macroalgal bloom in Palau, Western Pacific

Doropoulos, Christopher; Roff, George; Zupan, Mirta; Nestor, Victor; Isechal, Adelle L.; Mumby, Peter J.

doi:10.1007/s00338-014-1149-y

Cited by 46 publications

(41 citation statements)

References 64 publications

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“…Perhaps the major difference between reefs in Moorea and those in more speciose locations is the relative paucity of recruits of Acropora (Penin and Adjeroud ). Yet studies from Fiji and Palau, both areas where Acropora dominate coral recruitment, have found relatively high sensitivity of Acropora to macroalgae (Rasher et al ) and a virtual cessation of settlement where macroalgae bloom (Dixson et al , Doropoulos et al ). In short, available data suggest that coral recruitment could be even more sensitive to macroalgal abundance where Acropora dominate recruitment.…”

Section: Discussionmentioning

confidence: 99%

High resilience masks underlying sensitivity to algal phase shifts of Pacific coral reefs

Mumby

Steneck

Adjeroud

et al. 2015

Oikos

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A single ecosystem can exhibit great biogeographic and environmental variability. While a given ecological driver might have a strong impact in one region, it does not necessarily hold that its importance will extend elsewhere. Coral reefs provide a striking example in that coral communities have low resilience in the Atlantic and remarkable resilience in parts of the species‐rich Pacific. Recent experimental evidence from the Atlantic finds that fishing of large herbivorous fish can be a strong driver of coral resilience. Here, we repeat the Atlantic experiment in the highly resilient forereef of Moorea (French Polynesia), which has repeatedly recovered from disturbances. A combination of cages, fish deterrents (FDs), and controls allowed us to simulate the consequences of fishing large herbivores on algal assemblages, coral recruitment, and the demographic rates of coral juveniles. We find that the impacts of removing large herbivorous reef fish vary with early coral ontogeny. Reduced herbivore access led to a modest macroalgal bloom and reduction in coral recruitment. However, larger juvenile corals (> 1 cm diameter) survived better and grew faster under these conditions because of a reduction in corallivory. To determine the net impact of losing larger herbivorous fish, we combined experimental results with estimated demographic parameters in an individual‐based model. Simulating coral recovery trajectories for five years, we find that protecting larger reef fish led to better recovery in 66–99% of simulations, depending on underlying assumptions (with the more credible assumptions being associated with greater likelihood of net positive impacts). While we find that fishing effects are detrimental to corals in both the Atlantic and Pacific systems studied, the nature of the interactions varied markedly. In the identical previously‐published study in the Atlantic, macroalgae exhibited a rapid bloom and caused a sufficiently large reduction in coral recruitment to force a predicted ecosystem shift to an alternative attractor. The commensurate macroalgal bloom in Moorea was weak yet the corals were two orders of magnitude more sensitive to its presence. We do not suggest that a reduction in recruitment in Moorea will lead to alternative attractors but the long‐term risks of a reduction in recovery rate are cause for concern as rates of coral mortality are projected to increase. The emerging picture is that Pacific reefs are less likely to experience macroalgal blooms but are surprisingly sensitive to such blooms if they occur.

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Section: Discussionmentioning

confidence: 99%

High resilience masks underlying sensitivity to algal phase shifts of Pacific coral reefs

Mumby

Steneck

Adjeroud

et al. 2015

Oikos

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“…PERMDISP was used to test for homogeneity of dispersion (equivalent to homogeneity of variances) on raw as well as Log(x + 1), ArcSin, and BoxCox transformed data. Transformation did not improve variances (except for the S. hystrix protein data set) and, thus, a conservative p-value of 0.01 was used3536 on the log-transformed protein or raw F v / F m data for all species. By using a permutation based linear mixed model approach instead of non-parametric statistics we could test for interactive effects between fixed factors (symbiont_treatment; season)363738 and account for sampling separate fragments from individual colonies over time by including ‘individual’ as a random factor.…”

Section: Methodsmentioning

confidence: 99%

“…Transformation did not improve variances (except for the S. hystrix protein data set) and, thus, a conservative p-value of 0.01 was used3536 on the log-transformed protein or raw F v / F m data for all species. By using a permutation based linear mixed model approach instead of non-parametric statistics we could test for interactive effects between fixed factors (symbiont_treatment; season)363738 and account for sampling separate fragments from individual colonies over time by including ‘individual’ as a random factor. In addition, within colony effects were tested using F v / F m data measured for all (pre-treatment) fragments from the same colony at the start of the experiment (not possible for protein content because the sampling method is destructive).…”

Section: Methodsmentioning

confidence: 99%

Coral symbioses under prolonged environmental change: living near tolerance range limits

Sampayo

Ridgway

Franceschinis

et al. 2016

Sci Rep

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As climate change progresses, understanding the long-term response of corals and their endosymbionts (Symbiodinium) to prolonged environmental change is of immediate importance. Here, a total of 1152 fragments from 72 colonies of three common coral species (Stylophora pistillata, Pocillopora damicornis, Seriatopora hystrix) underwent a 32-month reciprocal depth transplantation. Genetic analysis showed that while S. hystrix maintained its generalist symbiont, some S. pistillata and P. damicornis underwent temporary changes in resident symbionts immediately after stress (transplantation; natural bleaching). These temporary changes were phylogenetically constrained to ‘host-compatible’ symbionts only and reversion to original symbionts occurred within 7 to 12 months, indicating long-term fidelity and stability of adult symbioses. Measurements of symbiont photo-physiology (dark adapted yield, pressure over photosystem II) and coral health (host protein, bleaching status, mortality) indicated a broad acclimatory capacity. However, this came at an apparent energetic expense as disproportionate mortality amongst symbioses that persisted outside their distribution range was observed following a natural bleaching event. As environmental changes due to climate change become more continuous in nature, sub-lethal effects linked to the existence near tolerance range limits coupled with the inability of adult coral colonies to change resident symbionts makes corals particularly susceptible to additional environmental fluctuations or stress events and reduces the resilience of coral populations.

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“…Algae blooms can also occur under additional conditions of eutrophication, iron enrichment, or herbivore depletion, affecting coral growth and recruitment (Mumby et al, ; Hughes et al, ; Steneck et al, ). Coral recruitment can be inhibited by two major categories of algae: (1) algal turfs (Birrell et al ., ), and (2) fleshy macroalgae – particularly carpeting Lobophora spp., and erect Sargassum spp., which both reduce coral larval settlement and increase post‐settlement mortality (Doropoulos et al, ; Webster et al, ). Coral recruitment is essential for reef recovery after disturbances, highlighting the critical need for key functional herbivores to facilitate coral settlement.…”

Section: Biology Ecology and Life‐history Characteristicsmentioning

confidence: 99%

Linking the biology and ecology of key herbivorous unicornfish to fisheries management in the Pacific

Ford

Bejarano

Marshell

et al. 2016

Aquatic Conservation

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Naso lituratus (orangespine unicornfish) and Naso unicornis (bluespine unicornfish) are widespread species that are heavily targeted in many nearshore fisheries of Pacific Island countries. In addition to providing a critical food and income source, both species fulfil critical ecological functions in the top‐down control of coral reef macroalgae; particularly fleshy brown algae (i.e. Sargassum spp.) which can out‐compete and smother corals. Despite heavy long‐term harvesting, there are currently very limited species‐specific management measures. This review assesses the biology and ecology of both species, and combines this with the current status of the fisheries in the Pacific, and proposes realistic ecosystem‐based species‐specific fisheries policies. Although unicornfish populations have displayed continuing resilience to heavy fishing pressure, reports of declining stocks combined with a range of life‐history traits (i.e. longevity, habitat‐specificity, easily targeted aggregations), indicate that both species are vulnerable to overexploitation. Modern day common fishing practices such as scuba and night‐time spearfishing are intensifying their exploitation. The most effective management measure would be fishing effort constraints, including banning modern and unsustainable methods. However, owing to enforcement limitations in Pacific Islands, the most practical approach to management would include a combination of management tools, including periodic sales bans around identified spawning times (i.e. Hawaii; May–June), and size/catch limits. Furthermore, home range data suggest that even with limited knowledge, small MPAs (<1 km2) in structurally complex areas using natural boundaries should accommodate the movement patterns of both species and provide sufficient protection; although MPAs of > 10 km linear distance are recommended for N. lituratus. This comprehensive review confirms the pressing need for implementation of the aforementioned management practices to protect these species in regions where they are heavily targeted, and prevent the impairment of their critical ecological function and importance as a food and income source. Copyright © 2016 John Wiley & Sons, Ltd.

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Reef-scale failure of coral settlement following typhoon disturbance and macroalgal bloom in Palau, Western Pacific

Cited by 46 publications

References 64 publications

High resilience masks underlying sensitivity to algal phase shifts of Pacific coral reefs

High resilience masks underlying sensitivity to algal phase shifts of Pacific coral reefs

Coral symbioses under prolonged environmental change: living near tolerance range limits

Linking the biology and ecology of key herbivorous unicornfish to fisheries management in the Pacific

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