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1. A physiological crisis drives the coral recruitment bottleneck

   https://doi.org/10.1098/rsbl.2025.0103  

   Edmunds, Peter; Cheh, Adrian; Burgess, Scott (June 2025, Biology Letters)

   Recruitment failure is an important factor contributing to population declines of tropical corals. Because the causes of death for juvenile corals are unclear, it is challenging to predict how recruitment bottlenecks will change in the future. We tested the hypothesis that depletion of metabolic reserves increases mortality of juvenile corals under thermal stress. Metabolic reserves of juvenile colonies (<30 mm diameter) of broadcast spawningPocilloporafrom Moorea, French Polynesia, were manipulated using elevated temperature to increase respiration, and reduced day length to decrease photosynthesis, and estimated as biomass. Corals with high or low biomass were incubated at 28°C and 31°C for 15 days. JuvenileP. meandrinawith high biomass were six times more likely to die at 31°C versus 28°C, but corals with low biomass were 48 times more likely to die at 31°C versus 28°C. When juvenilePocilloporawere grown in seawater augmented with bicarbonate to reduce the cost of skeletogenesis in support of growth, growth was not affected, but energy expenditure was reduced by 20% to reduce reliance on metabolic reserves. Resource limitation of juvenile corals can affect their response to elevated temperatures, supporting the hypothesis that a physiological crisis initiated by resource limitation mediates the stringency of recruitment bottlenecks. 

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2. The potential for self-seeding by the coral Pocillopora spp. in Moorea, French Polynesia

   https://doi.org/10.7717/peerj.2544  

   Tsounis, Georgios; Edmunds, Peter J. (January 2016, PeerJ)

   Coral reefs in Moorea, French Polynesia, suffered catastrophic coral mortality through predation by Acanthaster planci from 2006 to 2010, and Cyclone Oli in 2010, yet by 2015 some coral populations were approaching pre-disturbance sizes. Using long-term study plots, we quantified population dynamics of spawning Pocillopora spp. along the north shore of Moorea between 2010 and 2014, and considered evidence that population recovery could be supported by self-seeding. Results scaled up from study plots and settlement tiles suggest that the number of Pocillopora spp. colonies on the outer reef increased 1,890-fold between 2010 and 2014/2015, and in the back reef, 8-fold between 2010 and 2014/2015. Assuming that spawning Pocillopora spp. in Moorea release similar numbers of eggs as con-generics in Hawaii, and fertilization success is similar to other spawning corals, the capacity of Pocillopora spp. to produce larvae was estimated. These estimates suggest that Pocillopora spp. in Moorea produced a large excess of larvae in 2010 and 2014 relative to the number required to produce the recruits found in the back reef and outer reef in 2010 and 2014, even assuming that ∼99.9% of the larvae do not recruit in Moorea. Less than a third of the recruits in one year would have to survive to produce the juvenile Pocillopora spp. found in the back and outer reefs in 2010 and 2014/2015. Our first order approximations reveal the potential for Pocillopora spp. on the north shore of Moorea to produce enough larvae to support local recruitment and population recovery following a catastrophic disturbance. 

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3. Hypoxia disrupts metabolism in coral and sea anemone larvae

   https://doi.org/10.1242/jeb.250372  

   Glass, Benjamin H; Barott, Katie L (June 2025, Journal of Experimental Biology)

   Anthropogenic pollution is driving an increase in the frequency and severity of seawater hypoxic events in coastal marine ecosystems. Although hypoxia decreases physiological performance in coral and sea anemone (phylum Cnidaria) larvae, the underlying cellular mechanisms remain unexplored. Here, larvae of the reef-building corals Galaxea fascicularis and Porites astreoides and the estuarine sea anemone Nematostella vectensis were exposed to normoxia or a simulated hypoxic event (6 h at <2 mg dissolved O2 l−1), and their metabolomic response was quantified at the end of the exposure period using targeted liquid chromatography-mass spectrometry. Baseline metabolite profiles (81 amino acids, acylcarnitines, organic acids and nucleotides) were broadly divergent between the three species, with the corals displaying a reliance on nitrogen cycling through amino acid metabolism, whereas N. vectensis relied on nucleotide metabolism. By contrast, several changes in metabolite abundances under hypoxia were shared (e.g. increases in lactate) and suggest the upregulation of glycolysis, lactic acid fermentation and fatty acid β-oxidation as conserved mechanisms for energy production under hypoxia. Changes in these pathways were correlated with adverse physiological outcomes, including conserved declines in swimming behavior and growth. Importantly, life history traits affecting metabolism influenced hypoxia responses. For example, P. astreoides larvae, which possess algal endosymbionts, displayed the least severe metabolic response to hypoxia among these species, possibly owing to symbiont resources. Overall, these findings demonstrate that hypoxia disrupts metabolic performance in coral and sea anemone larvae through conserved and divergent pathways, emphasizing the need to limit drivers of ocean deoxygenation. 

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4. Environmental and biological determinants of the size, shape, and orientation of coral bommies in the back reef of Moorea, French Polynesia

   https://doi.org/10.5343/bms.2023.0099  

   Dahl, Adelaide; Edmunds, Peter J (January 2025, Bulletin of Marine Science)

   On shallow coral reefs, coral bommies create patchy communities where interactions among patches are likely to affect a variety of ecological features. Here, we describe bommies in the back reef of Moorea, French Polynesia, and evaluate the role of select factors in determining their size, shape, and distribution. We tested the hypothesis that the distribution and growth of corals varies across the surface of bommies (i.e., north, south, east, and west sides), and therefore might play a role in determining bommie shape and their propensity for fission and fusion. Bommies were elliptical in planar shape, with their long axes parallel to ambient flow and perpendicular to the direction of offshore waves.Poritesspp. andPocilloporaspp. were the most abundant corals, and they were uniformly distributed over the surface of bommies. During April 2022, small colonies (≤ 4 cm height) ofPocilloporaspp. grew at similar rates on the north, south, east, and west sides of the bommies, among which integrated seawater flow during the experiment was similar. These results suggest that the contemporary growth and distribution of corals is unlikely to play a strong role in determining the features of present-day bommies. Evaluating how environmental conditions mediate the structure of coral bommies in shallow habitats will help to understand whether habitat mosaics can mediate coral reef resilience in the Anthropocene. 

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5. The Pace of Life: Metabolic Energy, Biological Time, and Life History

   https://doi.org/10.1093/icb/icac058  

   Brown, James H; Burger, Joseph R; Hou, Chen; Hall, Charles A (July 2022, Integrative and Comparative Biology)

   Synopsis New biophysical theory and electronic databases raise the prospect of deriving fundamental rules of life, a conceptual framework for how the structures and functions of molecules, cells, and individual organisms give rise to emergent patterns and processes of ecology, evolution, and biodiversity. This framework is very general, applying across taxa of animals from 10–10 g protists to 108 g whales, and across environments from deserts and abyssal depths to rain forests and coral reefs. It has several hallmarks: (1) Energy is the ultimate limiting resource for organisms and the currency of biological fitness. (2) Most organisms are nearly equally fit, because in each generation at steady state they transfer an equal quantity of energy (˜22.4 kJ/g) and biomass (˜1 g/g) to surviving offspring. This is the equal fitness paradigm (EFP). (3) The enormous diversity of life histories is due largely to variation in metabolic rates (e.g., energy uptake and expenditure via assimilation, respiration, and production) and biological times (e.g., generation time). As in standard allometric and metabolic theory, most physiological and life history traits scale approximately as quarter-power functions of body mass, m (rates as ∼m–1/4 and times as ∼m1/4), and as exponential functions of temperature. (4) Time is the fourth dimension of life. Generation time is the pace of life. (5) There is, however, considerable variation not accounted for by the above scalings and existing theories. Much of this “unexplained” variation is due to natural selection on life history traits to adapt the biological times of generations to the clock times of geochronological environmental cycles. (6) Most work on biological scaling and metabolic ecology has focused on respiration rate. The emerging synthesis applies conceptual foundations of energetics and the EFP to shift the focus to production rate and generation time. 

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