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Invasions by shell-boring polychaetes such as Polydora websteri Hartman have resulted in the collapse of oyster aquaculture industries in Australia, New Zealand, and Hawaii. These worms burrow into bivalve shells, creating unsightly mud blisters that are unappealing to consumers and, when nicked during shucking, release mud and detritus that can foul oyster meats. Recent findings of mud blisters on the shells of Pacific oysters (Crassostrea gigas Thunberg) in Washington State suggest a new spionid polychaete outbreak. To determine the identity of the polychaete causing these blisters, we obtained Pacific oysters from two locations in Puget Sound and examined them for blisters and burrows caused by polychaete worms. Specimens were also obtained from eastern oysters (Crassostrea virginica Gmelin) collected in New York for morphological and molecular comparison. We compared polychaete morphology to original descriptions, extracted DNA and sequenced mitochondrial (cytochrome c oxidase I [mtCOI]) and nuclear (small subunit 18S rRNA [18S rRNA]) genes to determine a species-level molecular identification for these worms. Our data show that Polydora websteri are present in the mud blisters from oysters grown in Puget Sound, constituting the first confirmed record of this species in Washington State. The presence of this notorious invader could threaten the sustainability of oyster aquaculture in Washington, which currently produces more farmed bivalves than any other US state.

The frequency and severity of marine heatwaves causing mass mortality events in tropical and temperate coral species increases every year, with serious consequences on the stability and resilience of coral populations. Although recovery and persistence of coral populations after stress events is closely related to adult fitness, as well as larval survival and settlement, much remains unknown about the effects of thermal stress on early life-history stages of temperate coral species. In the present study, the reproductive phenology and the effect of increased water temperature (+4°C and +6°C above ambient, 20°C) on larval survival and settlement was evaluated for two of the most representative Mediterranean octocoral species (Eunicella singularis and Corallium rubrum). Our study shows that reproductive behavior is more variable than previously reported and breeding period occurs over a longer period in both species. Thermal stress did not affect the survival of symbiotic E. singularis larvae but drastically reduced the survival of the non-symbiotic C. rubrum larvae. Results on larval biomass and caloric consumption suggest that higher mortality rates of C. rubrum exposed to increased temperature were not related to depletion of endogenous energy in larvae. The results also show that settlement rates of E. singularis did not change in response to elevated temperature after 20 days of exposure, but larvae may settle fast and close to their native population at 26°C (+6°C). Although previous experimental studies found that adult colonies of both octocoral species are mostly resistant to thermal stress, our results on early life-history stages suggest that the persistence and inter-connectivity of local populations may be severely compromised under continued trends in ocean warming.

Warming ocean temperatures are severely compromising the health and resilience of coral reefs worldwide. Coral bleaching can affect coral physiology and the energy available for corals to reproduce. Mechanisms associated with reproductive allocation in corals are poorly understood, especially after a bleaching event occurs. Using isotopic labeling techniques, we traced the acquisition and allocation of carbon from adults to gametes by autotrophy and heterotrophy in previously bleached and non-bleached Montipora capitata and Porites compressa corals. Experiments revealed that both species: (1) relied only on autotrophy to allocate carbon to gametes, while heterotrophy was less relied upon as a carbon source; (2) experienced a trade-off with less carbon available for adult tissues when provisioning gametes, especially when previously bleached; and (3) used different strategies for allocating carbon to gametes. Over time, M. capitata allocated 10% more carbon to gametes despite bleaching by limiting the allocation of carbon to adult tissues, with 50–80% less carbon allocated to bleached compared to non-bleached colonies. Over the same time period, P. compressa maintained carbon allocation to adult tissues, before allocating carbon to gametes. Our study highlights the importance of autotrophy for carbon allocation from adult corals to gametes, and species-specific differences in carbon allocation depending on bleaching susceptibility.

Global climate change is causing ocean acidification (OA), warming, and decreased dissolved oxygen (DO) in coastal areas, which can cause physiological stress and compromise the health of marine organisms. While there is increased focus on how these stressors will affect marine species, there is little known regarding how changes in water chemistry will impact the bioaccumulation of trace metals. This study compared trace metal concentrations in tissue of Mediterranean mussels (Mytilus galloprovincialis) and Olympia oysters (Ostrea lurida) in Puget Sound, Washington, a region that experiences naturally low pH, seasonal hypoxia, and is surrounded by urbanized and industrialized areas. Shellfish were held at three sites (Carr Inlet, Point Wells, and Dabob Bay) where oceanographic data was continuously collected using mooring buoys. Using inductively coupled plasma mass-spectrometry (ICP-MS) to measure trace metals in the tissue, we found differences in accumulation of trace metals based on species, location, and shellfish size. Our study found differences between sites in both the mean metal concentrations and variability around the mean of those concentrations in bivalves. However, high metal concentrations in bivalves were not associated with high concentrations of metals in seawater. Metal concentrations in shellfish were associated with size: smaller shellfish had higher concentrations of metals. Carr Inlet at 20 m depth had the smallest shellfish and the highest metal concentrations. While we could not eliminate possible confounding factors, we also found higher metal concentrations in shellfish associated with lower pH, lower temperature, and lower dissolved oxygen (conditions seen at Carr Inlet at 20 m and to a lesser extent at Point Wells at 5 m depth). There were also significant differences in accumulation of metals between oysters and mussels, most notably copper and zinc, which were found in higher concentrations in oysters. These findings increase our understanding of spatial differences in trace metal bioaccumulation in shellfish from Puget Sound. Our results can help inform the Puget Sound aquaculture industry how shellfish may be impacted at different sites as climate change progresses and coastal pollution increases.

The genomes of mitochondria and chloroplasts contain ribosomal RNA (rRNA) genes, reflecting their evolutionary ancestry as free-living bacteria prior to endosymbiosis. In microbiome studies of animals, plants, or other eukaryotic hosts, these organellar rRNAs are often amplified. If identified, they can be discarded, merely reducing sequencing depth. However, incorrectly annotated mitochondrial reads may compromise statistical analysis by distorting relative abundances of free-living microbes. We quantified this by reanalyzing 7,459 samples from seven 16S rRNA sequencing studies, including the microbiomes of 927 unique animal genera. We find that under-annotation of cryptic mitochondrial reads affects multiple of these large-scale cross-species microbiome comparisons, and can be severe in some samples. It also varies between host species, potentially biasing cross-species microbiome comparisons. We propose a straightforward solution: by supplementing existing taxonomies with diverse mitochondrial rRNA sequences, we resolve up to 97% of unique unclassified sequences in some entire studies as mitochondrial (14% averaged across all studies), without increasing false positive annotations in mitochondria-free mock communities. Overall, improved annotation decreases the proportion of unknown sequences by ≥10-fold in 2,262 of 7,459 samples (30%), including representatives from 5 of 7 studies examined. While standard DADA2 analyses are severely affected, the default positive filter in Deblur run through QIIME2 discards many divergent mitochondrial sequences, preventing bias in analysis, but also making analysis of these sequences more difficult. We recommend leveraging mitochondrial sequence diversity to better identify, remove and analyze mitochondrial rRNA gene sequences in microbiome studies.

Coral diseases have increased in frequency and intensity around the tropics worldwide. However, in many cases, little is known about their etiology. Montipora white syndrome (MWS) is a common disease affecting the coral Montipora capitata, a major reef builder in Hawai'i. Chronic Montipora white syndrome (cMWS) is a slow-moving form of the disease that affects M. capitata throughout the year. The effects of this chronic disease on coral immunology and microbiology are currently unknown. In this study, we use prophenoloxidase immune assays and 16S rRNA gene amplicon sequencing to characterize the microbiome and immunological response associated with cMWS. Our results show that immunological and microbiological responses are highly localized. Relative to diseased samples, apparently healthy portions of cMWS corals differed in immune activity and in the relative abundance of microbial taxa. Coral tissues with cMWS showed decreased tyrosinase-type catecholase and tyrosinase-type cresolase activity and increased laccase-type activity. Catecholase and cresolase activity were negatively correlated across all tissue types with microbiome richness. The localized effect of cMWS on coral microbiology and immunology is probably an important reason for the slow progression of the disease. This local confinement may facilitate interventions that focus on localized treatments on tissue types. This study provides an important baseline to understand the interplay between the microbiome and immune system and the mechanisms used by corals to manage chronic microbial perturbations associated with white syndrome.

Coral bleaching is the single largest global threat to coral reefs worldwide. Integrating the diverse body of work on coral bleaching is critical to understanding and combating this global problem. Yet investigating the drivers, patterns, and processes of coral bleaching poses a major challenge. A recent review of published experiments revealed a wide range of experimental variables used across studies. Such a wide range of approaches enhances discovery, but without full transparency in the experimental and analytical methods used, can also make comparisons among studies challenging. To increase comparability but not stifle innovation, we propose a common framework for coral bleaching experiments that includes consideration of coral provenance, experimental conditions, and husbandry. For example, reporting the number of genets used, collection site conditions, the experimental temperature offset(s) from the maximum monthly mean (MMM) of the collection site, experimental light conditions, flow, and the feeding regime will greatly facilitate comparability across studies. Similarly, quantifying common response variables of endosymbiont (Symbiodiniaceae) and holobiont phenotypes (i.e., color, chlorophyll, endosymbiont cell density, mortality, and skeletal growth) could further facilitate cross-study comparisons. While no single bleaching experiment can provide the data necessary to determine global coral responses of all corals to current and future ocean warming, linking studies through a common framework as outlined here, would help increase comparability among experiments, facilitate synthetic insights into the causes and underlying mechanisms of coral bleaching, and reveal unique bleaching responses among genets, species, and regions. Such a collaborative framework that fosters transparency in methods used would strengthen comparisons among studies that can help inform coral reef management and facilitate conservation strategies to mitigate coral bleaching worldwide. published

Recent warnings from scientists suggest there is limited time to enact policies to avert wide‐ranging ecological and social damage from climate change. In the United States, discussions about comprehensive national policies to avert climate change have begun, with “Green New Deal” proposals and climate plans put forth by members of Congress and presidential candidates. Oceans are largely absent or separate from these nascent policy proposals. Here, we highlight a policy framework to develop terrestrial and ocean‐integrated policies that can complement and enhance terrestrial‐focused initiatives focused on four specific sectors: 1) energy; 2) transportation; 3) food security; and 4) habitat restoration. Given political friction and constrained budgets, an integrated policy framework offers greater potential to achieve a portfolio of mitigation and adaptation goals in a cost‐effective manner, beyond what could be realized with marine or terrestrial policy solutions alone.

Ocean acidification and increased ocean temperature from elevated atmospheric carbon dioxide can significantly influence the physiology, growth and survival of marine organisms. Despite increasing research efforts, there are still many gaps in our knowledge of how these stressors interact to affect economically and ecologically important species. This project is the first to explore the physiological effects of high pCO2 and temperature on the acclimation potential of the purple-hinge rock scallop (Crassadoma gigantea), a widely distributed marine bivalve, important reef builder, and potential aquaculture product. Scallops were exposed to two pCO2 (365 and 1050 μatm) and temperature (14 and 21.5 °C) conditions in a two-factor experimental design. Simultaneous exposure to high temperature and high pCO2 reduced shell strength, decreased outer shell density and increased total lipid content. Despite identical diets, scallops exposed to high pCO2 had higher content of saturated fatty acids, and lower content of polyunsaturated fatty acids suggesting reorganization of fatty acid chains to sustain basic metabolic functions under high pCO2. Metagenomic sequencing of prokaryotes in scallop tissue revealed treatment differences in community composition between treatments and in the presence of genes associated with microbial cell regulation, signaling, and pigmentation. Results from this research highlight the complexity of physiological responses for calcifying species under global change related stress and provide the first insights for understanding the response of a bivalve's microbiome under multiple stressors.

The Hawaiian Archipelago is one of the largest and most isolated island chains in the world, and its marine ecosystems are well-studied. Research on Hawaiian mesophotic coral ecosystems (MCEs) began in the 1960s and has intensified during the past decade. In Hawai‘i, rich communities of macroalgae, corals and other invertebrates, and fishes inhabit MCEs and are associated with increased water clarity and decreasing average current strength with depth. Extensive calcified and fleshy macroalgal beds are found both in discrete patches, dense beds, and meadows over both hard and soft substrates. Several species of corals typical of shallow reefs extend to depths of ~60 m. The dominant corals below 60 m are in the genus Leptoseris, which can form extensive coral reefs spanning tens of km2. Few octocoral species inhabit shallow reefs and upper MCEs (30–70 m) but are diverse at the deepest range of MCEs (>130 m). Sponges do not represent a major structural component of MCEs. Many species of fishes occur on both shallow reefs and MCEs, but MCEs harbor more endemic species (up to 100% endemism). Several new species of macroalgae, corals and other invertebrates, and fishes have recently been documented. Over 60% of the territorial waters surrounding the archipelago are protected as the Papahānaumokuākea Marine National Monument; however, no specific protections exist for MCEs. Generally, threats affecting Hawai‘i’s shallow reefs also affect MCEs to varying degrees. MCEs may be more insulated from some threats but more vulnerable than shallow reefs to others (e.g., water clarity).

Despite widespread climate-driven reductions of coral cover on tropical reefs, little attention has been paid to the possibility that changes in the geographic distribution of coral recruitment could facilitate beneficial responses to the changing climate through latitudinal range shifts. To address this possibility, we compiled a global database of normalized densities of coral recruits on settlement tiles (corals m^) deployed from 1974 to 2012, and used the data therein to test for latitudinal range shifts in the distribution of coral recruits. In total, 92 studies provided 1253 records of coral recruitment, with 77% originating from settlement tiles immersed for 3-24 mo, herein defined as long-immersion tiles (LITs); the limited temporal and geographic coverage of data from short-immersion tiles (SITs; deployed for 20° latitude). These trends indicate that a global decline in coral recruitment has occurred since 1974, and the persistent reduction in the densities of recruits in equatorial latitudes, coupled with increased densities in sub-tropical latitudes, suggests that coral recruitment may be shifting poleward., 論文

To project how ocean acidification will impact biological communities in the future, it is critical to understand the potential for local adaptation and the physiological plasticity of marine organisms throughout their entire life cycle, as some stages may be more vulnerable than others. Coralline algae are ecosystem engineers that play significant functional roles in oceans worldwide and are considered vulnerable to ocean acidification. Using different stages of coralline algae, we tested the hypothesis that populations living in environments with higher environmental variability and exposed to higher levels of pCO 2 would be less affected by high pCO 2 than populations from a more stable environment experiencing lower levels of pCO 2. Our results show that spores are less sensitive to elevated pCO 2 than adults. Spore growth and mortality were not affected by pCO 2 level; however, elevated pCO 2 negatively impacted the physiology and growth rates of adults, with stronger effects in populations that experienced both lower levels of pCO 2 and lower variability in carbonate chemistry, suggesting local adaptation. Differences in physiological plasticity and the potential for adaptation could have important implications for the ecological and evolutionary responses of coralline algae to future environmental changes.

Many studies have reported reductions in body size and calcification rates for marine larvae exposed to ocean acidification conditions. However, the physiological mechanisms driving these effects, and mechanisms underlying body size variation in general, are poorly understood. Here, we combine transcriptome sequencing with bulked segregant analysis to assess the physiological response to acidification in larvae of the California mussel, Mytilus californianus, and to explore physiological basis of variation in larval size. We reared three families of M. californianus larvae under ambient (∼350 µatm, pHtotal 8.1) and high (∼1300 µatm, pHtotal 7.6) pCO2 conditions, then passed larvae through a mesh filter, separating each family × pCO2 treatment into fractions of larvae with large vs. small body sizes. We sequenced larval mRNA for each family × treatment × body size combination, and assembled a de novo transcriptome. We then mapped reads from each library to this assembly to identify effects of high pCO2 on gene expression, and to identify transcriptomic differences between small vs. large larvae of the same age class. Although larvae reared under elevated pCO2 were smaller, we observed no consistent effect of elevated pCO2 on gene expression. Nevertheless, 1225 transcripts, primarily related to metabolism, were differentially expressed between large vs. small larvae, regardless of CO2 treatment. We conclude that the observed reduction in larval body size under high CO2 may be driven by a direct effect of the environment on phenotype, unmediated by changes in gene expression. Because M. calfornianus has evolved in the context of seasonal upwelling, exposure to 1300 µatm, pCO2 may not produce the large stress-mediated effects on gene expression that might be expected for an organism exposed to conditions far outside those of its typical environment.

Advances in nucleic acid sequencing technology are removing obstacles that historically prevented use of genomics within ocean change biology. As one of the first marine calcifiers to have its genome sequenced, purple sea urchins (Strongylocentrotus purpuratus) have been the subject of early research exploring genomic responses to ocean acidification, work that points to future experiments and illustrates the value of expanding genomic resources to other marine organisms in this new 'post-genomic' era. This review presents case studies of S. purpuratus demonstrating the ability of genomic experiments to address major knowledge gaps within ocean acidification. Ocean acidification research has focused largely on species vulnerability, and studies exploring mechanistic bases of tolerance toward low pH seawater are comparatively few. Transcriptomic responses to high pCO₂ seawater in a population of urchins already encountering low pH conditions have cast light on traits required for success in future oceans. Secondly, there is relatively little information on whether marine organisms possess the capacity to adapt to oceans progressively decreasing in pH. Genomics offers powerful methods to investigate evolutionary responses to ocean acidification and recent work in S. purpuratus has identified genes under selection in acidified seawater. Finally, relatively few ocean acidification experiments investigate how shifts in seawater pH combine with other environmental factors to influence organism performance. In S. purpuratus, transcriptomics has provided insight into physiological responses of urchins exposed simultaneously to warmer and more acidic seawater. Collectively, these data support that similar breakthroughs will occur as genomic resources are developed for other marine species.

© 2015 International Society for Microbial Ecology All rights reserved. Despite being one of the simplest metazoans, corals harbor some of the most highly diverse and abundant microbial communities. Differentiating core, symbiotic bacteria from this diverse hostassociated consortium is essential for characterizing the functional contributions of bacteria but has not been possible yet. Here we characterize the coral core microbiome and demonstrate clear phylogenetic and functional divisions between the micro-scale, niche habitats within the coral host. In doing so, we discover seven distinct bacterial phylotypes that are universal to the core microbiome of coral species, separated by thousands of kilometres of oceans. The two most abundant phylotypes are co-localized specifically with the corals' endosymbiotic algae and symbiont-containing host cells. These bacterial symbioses likely facilitate the success of the dinoflagellate endosymbiosis with corals in diverse environmental regimes.

Reef-building corals inhabiting the mesophotic zone (30�150 m) not only survive but thrive in light-limiting environments. Similar to shallow corals, mesophotic corals also exhibit coral fluorescence. Because fluorescent proteins (FPs) absorb high-energy light and emit lower- energy light, FPs could play an important role in mesophotic coral physiology and ecology. For 4 species of the Hawaiian mesophotic reef-building coral Leptoseris (65�125 m), we investigated the abundance of fluorescent morphs, types of FPs, fluorescence emission phenotypes, and the physiological relationship between coral fluorescence and endosymbiotic Symbiodinium (dino - flagellate; Dinophyta). Cyan/green coral fluorescence emission was widespread in mesophotic Leptoseris spp.; more than 70% of corals fluoresced, yet fluorescent and nonfluorescent corals co- occurred at all depths investigated. Coral fluorescence was attributed to 2 proteins, a cyan fluores- cent protein (CFP, λex = 424 nm, λem = 490 nm) and a green fluorescent protein (GFP, λex = 478 nm, λem = 502 nm). The type of FP in Leptoseris colonies was correlated with depth; CFP was dominant in corals from shallower depths (65�85 m), GFP was dominant in corals from deeper depths (96�125 m), and CFP and GFP were present in corals from middle depths (86�95 m). Coral FP emission was primarily localized in the coenosarc and/or the oral disc. Symbiodinium from corals with and without fluorescence emission had similar genotypes, abundances, photosynthetic pigments, photosynthetic efficiencies, photosynthetic rates, and chlorophyll excitation spectra. As such, it is unlikely that these FPs play a significant role in enhancing symbiont photosynthesis. The high abundance of fluorescent morphs (>70%) dominating this energetically limited environ- ment may suggest that FPs play an integral and conserved physiological role in corals.

Environmental conditions can influence the physiology of marine organisms and have important implications for their reproductive performance and capacity to supply new recruits. This study examined the seasonal reproductive patterns of the coral Montipora capitata in habitats exposed to different sedimentation regimes. Although M. capitata is a main reef-building coral in the Hawaiian Archipelago, little is known about the gametogenic cycle and reproductive ecology of this important species. Our results indicate that gamete production in M. capitata is a resilient process; no differences in gamete development or fecundity were observed among sites with very different sedimentation regimes. The gametogenic cycle of M. capitata lasts between 10 and 11 months, with spawning occurring over 3-5 months during warmer months (May-September). Oocytes were found throughout the year, but spermatocysts were only found April-August. The largest increases in oocyte size occurred during February to May, the months when solar radiation increased rapidly. The largest variation in oocyte sizes was found during July and August; during this period individual colonies contained mature oocytes for immediate spawning and new oocytes being formed for spawning the next year. The capacity of M. capitata to reproduce in areas with high sedimentation is an interesting finding highlighting the potential of the species for acclimatization, adaptation, or both. Despite this optimistic finding, the management of terrestrial runoff and the restoration of habitat quality for corals remains a top priority to ensure the renewal and maintenance of coral populations.

Increasing terrestrial runoff due to anthropogenic activities has become a major problem for coral reef ecosystems around the world. Turbidity due to runoff can reduce light availability (via nutrient enrichment and sedimentation) and influence the biology and ecology of coral reefs. In this study, we explored the physiology and acclimatization potential of Porites rus , a morphologically variable reef-building coral that is common in Moorea, French Polynesia, and a species that thrives across turbidity gradients driven by proximity to terrestrial runoff. We compared tissue biomass, Symbiodinium identity, Symbiodinium density, chlorophyll concentrations, and stable isotope ratios in plating and branching areas of colonies sampled in turbid and non-turbid environments. A reciprocal transplant experiment (RTE) was also employed to compare the acclimatization capacity of P.rus from turbid and non-turbid environments. Our results indicate that the physiological differences between plating and branching regions within individual colonies of P. rus are greater than those of colonies from turbid and non-turbid environments. Plating regions of colonies had larger tissue biomasses than branching areas, regardless of environment. Plating regions also had higher chlorophyll concentrations than branching regions at the non-turbid site. The densities and genetic identity of Symbiodinium were the same at both sites. At the turbid site, δ 13 C signatures were lower in plating than branching regions of the colony, suggesting they exhibit different rates of photosynthesis and/or capacity for heterotrophy. δ 15 N were similar across sites and between morphologies, indicating that colonies from both sites were feeding at similar trophic levels and utilizing similar nitrogen sources. The RTE showed that P. rus acclimatizes differently when transplanted to the turbid and non-turbid environments. Corals from the non-turbid site grew less when transplanted to the turbid site, whereas corals from the turbid site showed no change in growth regardless of transplant location. Coral fragments transplanted to the non-turbid site, had lower levels of chlorophyll per tissue area than fragments transplanted to the turbid site, most likely reflecting the higher light levels at this site. Thus, our results demonstrate that there is significant variation in the physiology of P.rus at the colony level (branching vs. plate regions) and at the site level (turbid vs. non-turbid) and that this species can acclimatize to changes in environmental conditions on short time scales (weeks). This acclimatization potential may play an important role in enabling this coral species to diversify strategies for energy acquisition within the colony and facilitate persistence in turbid environments.

Parental effects have been largely unexplored in marine organisms and may play a significant role in dictating the phenotypic range of traits in coral offspring, influencing their ability to survive environmental challenges. This study explored parental effects and life-stage differences in the Hawaiian reef-building coral Montipora capitata from different environments by examining the biochemical composition of mature coral colonies and their eggs. Our results indicate that there are large biochemical differences between adults and eggs, with the latter containing higher concentration of lipids (mostly wax esters), ubiquitinated proteins (which may indicate high turnover rate of proteins) and antioxidants (e.g., manganese superoxide dismutase). Adults displayed high phenotypic plasticity, with corals from a high-light environment having more wax esters, lighter tissue δ13C signatures and higher Symbiodinium densities than adults from the low-light environment who had higher content of accessory pigments. A green-algal pigment (α-carotene) and powerful antioxidant was present in eggs; it is unclear whether this pigment is acquired from heterotrophic food sources or from endolithic green algae living in the adult coral skeletons. Despite the broad phenotypic plasticity displayed by adults, parental investment in the context of provisioning of energy reserves and antioxidant defense was the same in eggs from the different sites. Such equality in investment maximizes the capacity of all embryos and larvae to cope with challenging conditions associated with floating at the surface and to disperse successfully until an appropriate habitat for settlement is found.

The release of gametes into the water column by broadcast-spawning marine inver- tebrates represents the culmination of several physiological events in the parents and the first step in the supply of new recruits to marine ecosystem. The input of new propagules to coral reefs relies on spawning events that display remarkable synchronicity during limited periods each year. Although the timing of spawning is known for most species, other aspects of coral reproduction (polyp fecundity or spawning synchronicity) are less understood. This largely reflects the sporadic nature of reproductive activities and logistical problems of studying the ephemeral coral spawn- ing events in situ on the reef at night. Here, we address this gap by exploring the spatial and tem- poral spawning dynamics of Montipora capitata, a broadcast-spawning, reef-building coral from the central Pacific Ocean, by using the systematic sampling of gametes in the field. Our results indicate that spawning in this species varies among years, months and lunar days, and that the proportion of colonies spawning and synchrony of spawning do not reflect coral colony morphol- ogy, colony size or the differences in environments between sites within a year. Major differences in reproductive outputs (spawned material) were observed between the 2 yr studied, which most probably reflects variability in temperature between years or shifts in the timing of spawning (phenology). This study highlights the complexity of spawning dynamics in corals and suggests that a more comprehensive understanding of interplay between reproduction and environment is fundamentally important to accurately predict the effects of climate change in these important ecosystems.

The majority of scleractinian corals are hermaphrodites that broadcast spawn their gametes separately or packaged as egg–sperm bundles during spawning events that are timed to the lunar cycle. The egg–sperm bundle is an efficient way of transporting gametes to the ocean surface where fertilization takes place, while minimizing sperm dilution and maximizing the opportunity for gamete encounters during a spawning event. To date, there are few studies that focus on the formation and structure of egg–sperm bundle. This study explores formation, ultrastructure, and longevity of the egg–sperm bundle in Montipora capitata, a major reef building coral in Hawai‘i. Our results show that the egg–sperm bundle is formed by a mucus layer secreted by the oocytes. The sperm package is located at the center of each bundle, possibly reflecting the development of male and female gametes in different mesenteries. Once the egg–sperm bundle has reached the ocean surface, it breaks open within 10–35 min, depending on the environmental conditions (i.e., wind, water turbulence). Although the bundle has an ephemeral life span, the formation of an egg–sperm bundle is a fundamental part of the reproductive process that could be strongly influenced by climate change and deterioration of water quality (due to anthropogenic effects) and thus requires further investigation.

The earliest record of animals (Metazoa) consists of trace and body fossils restricted to the last 35 Myr of the Precambrian. It has been proposed that animals arose much earlier and underwent significant evolution as a cryptic fauna; however, the need for any unrecorded prelude of significant duration has been disputed. In this context, we consider recent published research on the nature and chronology of the earliest fossil record of metazoans and on the molecular-based analysis that yielded older dates for the appearance of major animal groups. We review recent work on the climatic, geochemical, and ecological events that preceded animal fossils and consider their portent for metazoan evolution. We also discuss inferences about the physiology and gene content of the last common ancestor of animals and their closest unicellular relatives. We propose that the recorded Precambrian evolution of animals includes three intervals of advancement that begin with sponge-grade organisms, and that any preceding cryptic fauna would be no more complex than sponges. The molecular data do not require that more complex animals appeared well before the recognized fossil record; nor, however, do they rule the possibility out, particularly if the interval of simpler metazoan ancestors lasted no more than about 100 or 200 Myr. The geological record of abrupt changes in climate, biogeochemistry, and phytoplankton diversity can be taken to be the result of changes in the carbon cycle triggered by the appearance and diversification of metazoans in an organic carbon-rich ocean, but as yet no compelling evidence exists for this interpretation. By the end of this cryptic period, animals would already have possessed sophisticated systems of cell‐cell signalling, adhesion, apoptosis, and segregated germ cells, possibly with a rudimentary body plan based on anterior‐posterior organization. The controls on the timing and tempo of the earliest steps in metazoan evolution are unknown, but it seems likely that oxygen was a key factor in later diversification and increase in body size. We consider several recent scenarios describing how oxygen increased near the end of the Precambrian and propose that grazing and filter-feeding animals depleted a marine reservoir of suspended organic matter, releasing a microbial ‘clamp’ on atmospheric oxygen.

Laurencia is a globally distributed genus with about 80 species (order Ceramiales) that inhabit tropical, subtropical, and warm-temperate regions of both sides of the Atlantic and Indo-Pacific oceans. This study investigated how two species of Laurencia distributed in different thermal environments (California and Hawaii) varied in their photosynthetic responses to temperature. The thermal ecophysiology of both species was investigated at different temporal scales (short-term responses and seasonal acclimatization) using oxygen evolution and pulse-amplitude-modulated (PAM) fluorometry. Our results indicated that seasonal acclimatization of both species of Laurencia influenced the short-term photosynthetic response at both locations. Greater seasonal differences in the photosynthetic performance were observed for L. pacifica Kylin, which reflects the ability of this species to acclimatize to local environmental conditions characterized by short-term fluctuations and a broader annual temperature range. Photosynthetic performance of L. nidifica J. Agardh was consistent with the less variable local environment (no short-term fluctuations and a narrower temperature range). These results suggest that acclimatization to temperature variability in the environment can influence the degree of flexibility of physiological responses of species in this genus.

We studied the photosynthetic acclimatization of two populations of Asparagopsis taxiformis from two biogeographic regions (Santa Catalina Island, California, and Kaneohe Bay, Hawaii) in two seasons. We compared thermal variability between locations and estimated the environmental optima and tolerance limits of photosynthesis to understand the relationship between phenotypic plasticity and thermal variability at each location. Photosynthetic performance was assessed using oxygen evolution and pulsed amplitude modulated fluorometry to quantify responses to thermal variation. A. taxiformis from both locations had similar high temperature tolerances for maximum net photosynthesis (Pnetmax) and maximum relative electron transport rate rETRmax (~30°C), but different cold temperature tolerances. Respiration rates from both locations (summer and winter) always increased above 25°C. Chlorophyll fluorescence yield from dark-adapted samples from both locations decreased at warmer temperatures in the winter and at colder temperatures during the summer. Populations exposed to greater thermal variability (across both short and long time scales) displayed greater capacity for photosynthetic acclimatization. A. taxiformis from California showed seasonal changes in photosynthetic performance within the environmental temperature range (14–21°C), whereas individuals from Hawaii did not. The narrower temperature tolerance (short-term response) of subtropical Asparagopsis may make it more susceptible than temperate populations to the predicted increases in global sea surface temperatures. Acclimatization of photosynthesis may play an important role in enabling A. taxiformis to respond to a variable environment and to persist in different biogeographic regions.

Studies have identified chemicals within the stony coral genus Montipora that have significant biological activities. For example, Montiporic acids A and B and other compounds have been isolated from the adult tissue and eggs of Montipora spp. and have displayed antimicrobial activity and cytotoxicity in cultured cells. The ecological role of these toxic compounds is currently unclear. This study examines the role these toxins play in reproduction. Toxins were found in the eggs and larvae of the coral Montipora capitata. Releasing these toxins by crushing both the eggs and larvae resulted in irreversible inhibition of photosynthesis in endogenous and exogenous zooxanthellae within minutes. Moreover, these toxins were stable, as frozen storage of eggs and larvae did not affect toxicity. Photosynthetic competency of Porites compressa zooxanthellae treated with either frozen or fresh, crushed eggs was inhibited similarly (P > 0.05, ANCOVA). Addition of toxic eggs plugs to live P. compressa fragments caused complete tissue necrosis under the exposed area on the fragments within 1 week. Small volumes of M. capitata crushed eggs added to sperm suspensions reduced in vitro fertilization success by killing the sperm. After 30 min, untreated sperm maintained 90 ± 1.9% SEM motility while those treated with crushed eggs were rendered immotile, 4 ± 1.4% SEM. Flow cytometry indicated membrane disruption of the immotile sperm. Fertilization success using untreated sperm was 79 ± 4% SEM, whereas the success rate dropped significantly after exposure to the crushed eggs, 1.3 ± 0% SEM. Unlike the eggs and the larvae, M. capitata sperm did not reduce the photosynthetic competency of P. compressa zooxanthellae, suggesting the sperm was nontoxic. The identity of the toxins, cellular mechanism of action, advantage of the toxins for M. capitata and their role on the reef are still unknown.

Compiled abundances of juvenile corals revealed no change over time in the Pacific, but a decline in the Caribbean. Using these analyses as a rationale, we explored recruitment and post-settlement success in determining coral cover using studies in the Caribbean (St John, Bonaire) and Pacific (Moorea, Okinawa). Juvenile corals, coral recruits, and coral cover have been censused in these locations for years, and the ratio of juvenile (J) to recruiting (R) corals was used to measure post-settlement success. In St John and Bonaire, coral cover was stable but different between studies, with the ratio of the density of juveniles to density of recruits (J:R) ~0.10; in Moorea, declines in coral cover were followed by recovery that was related to the density of juvenile corals 3 years before, with J:R ~0.40; and in Okinawa, a decline in coral cover in 1998 was followed by a slow recovery with J/R ~0.01. Coral cover was associated positively with juvenile corals in St John, and in Okinawa, the density of juvenile corals was associated positively with recruits the year before. J:R varied among studies, and standardised densities of juvenile corals declined in the Caribbean, but increased in the Pacific. These results suggest that differences in the post-settlement success may drive variation in coral community structure.

Rising atmospheric CO 2 is expected to increase global temperatures and partial pressure of CO 2 in surface waters, causing ocean warming and acidification. These changes may have important consequences for the physiological performance of early life-history stages of marine organisms. In this study we investigated the potential for interactive effects of ecologically relevant levels of temperature and pCO 2 on germination, dormancy and mortality of zoospores of the giant kelp Macrocystis pyrifera , a foundation species of temperate reef ecosystems. Newly settled kelp spores were cultured in the laboratory for seven days in a factorial design with temperature (13 °C and 18 °C) and pCO 2 (~ 370 and ~ 1800 μatm) as experimental factors. The two levels of temperature and the low-pCO 2 treatment in our design were consistent with present-day environmental conditions in the kelp forest as measured by autonomous temperature and pH sensors, while the high-pCO 2 treatment reflects an extreme, future acidification scenario. Our results revealed that the combined effects of increased temperature and pCO 2 can significantly decrease germination rates and increase the mortality of kelp spores. Interactive effects of temperature and pCO 2 were detected on spore mortality and dormancy. Spore mortality only differed between pCO 2 treatments at high temperature. In contrast, spore dormancy was higher in the treatment with low temperature and high pCO 2 , which is similar to the environmental conditions experienced during upwelling events in southern California. Our results highlight the importance of considering multiple stressors to understand how the early-stages of foundation species such as M. pyrifera will be affected by global change.

Ocean warming and ocean acidification, both consequences of anthropogenic production of CO 2 , will combine to influence the physiological performance of many species in the marine environment. In this study, we used an integrative approach to forecast the impact of future ocean conditions on larval purple sea urchins ( Strongylocentrotus purpuratus ) from the northeast Pacific Ocean. In laboratory experiments that simulated ocean warming and ocean acidification, we examined larval development, skeletal growth, metabolism and patterns of gene expression using an orthogonal comparison of two temperature (13°C and 18°C) and pCO 2 (400 and 1100 μatm) conditions. Simultaneous exposure to increased temperature and pCO 2 significantly reduced larval metabolism and triggered a widespread downregulation of histone encoding genes. pCO 2 but not temperature impaired skeletal growth and reduced the expression of a major spicule matrix protein, suggesting that skeletal growth will not be further inhibited by ocean warming. Importantly, shifts in skeletal growth were not associated with developmental delay. Collectively, our results indicate that global change variables will have additive effects that exceed thresholds for optimized physiological performance in this keystone marine species.

A rapidly growing body of literature documents the potential negative effects of CO2 -driven ocean acidification (OA) on marine organisms. However, nearly all this work has focused on the effects of future conditions on modern populations, neglecting the role of adaptation. Rapid evolution can alter demographic responses to environmental change, ultimately affecting the likelihood of population persistence, but the capacity for adaptation will differ among populations and species. Here, we measure the capacity of the ecologically important purple sea urchin Strongylocentrotus purpuratus to adapt to OA, using a breeding experiment to estimate additive genetic variance for larval size (an important component of fitness) under future high-pCO2 /low-pH conditions. Although larvae reared under future conditions were smaller than those reared under present-day conditions, we show that there is also abundant genetic variation for body size under elevated pCO2 , indicating that this trait can evolve. The observed heritability of size was 0.40 ± 0.32 (95% CI) under low pCO2 , and 0.50 ± 0.30 under high-pCO2 conditions. Accounting for the observed genetic variation in models of future larval size and demographic rates substantially alters projections of performance for this species in the future ocean. Importantly, our model shows that after incorporating the effects of adaptation, the OA-driven decrease in population growth rate is up to 50% smaller, than that predicted by the 'no-adaptation' scenario. Adults used in the experiment were collected from two sites on the coast of the Northeast Pacific that are characterized by different pH regimes, as measured by autonomous sensors. Comparing results between sites, we also found subtle differences in larval size under high-pCO2 rearing conditions, consistent with local adaptation to carbonate chemistry in the field. These results suggest that spatially varying selection may help to maintain genetic variation necessary for adaptation to future OA.

Parental effects are ubiquitous in nature and in many organisms play a particularly critical role in the transfer of symbionts across generations; however, their influence and relative importance in the marine environment has rarely been considered. Coral reefs are biologically diverse and productive marine ecosystems, whose success is framed by symbiosis between reef-building corals and unicellular dinoflagellates in the genus Symbiodinium. Many corals produce aposymbiotic larvae that are infected by Symbiodinium from the environment (horizontal transmission), which allows for the acquisition of new endosymbionts (different from their parents) each generation. In the remaining species, Symbiodinium are transmitted directly from parent to offspring via eggs (vertical transmission), a mechanism that perpetuates the relationship between some or all of the Symbiodinium diversity found in the parent through multiple generations. Here we examine vertical transmission in the Hawaiian coral Montipora capitata by comparing the Symbiodinium ITS2 sequence assemblages in parent colonies and the eggs they produce. Parental effects on sequence assemblages in eggs are explored in the context of the coral genotype, colony morphology, and the environment of parent colonies. Our results indicate that ITS2 sequence assemblages in eggs are generally similar to their parents, and patterns in parental assemblages are different, and reflect environmental conditions, but not colony morphology or coral genotype. We conclude that eggs released by parent colonies during mass spawning events are seeded with different ITS2 sequence assemblages, which encompass phylogenetic variability that may have profound implications for the development, settlement and survival of coral offspring.

Corals at the lower limits of mesophotic habitats are likely to have unique photosynthetic adaptations that allow them to persist and dominate in these extreme low light ecosystems. We examined the host–symbiont relationships from the dominant coral genus Leptoseris in mesophotic environments from Hawai'i collected by submersibles across a depth gradient of 65–125 m. Coral and Symbiodinium genotypes were compared with three distinct molecular markers including coral ( COX1–1-rRNA intron) and Symbiodinium ( COI ) mitochondrial markers and nuclear ITS2 . The phylogenetic reconstruction clearly resolved five Leptoseris species, including one species ( Leptoseris hawaiiensis ) exclusively found in deeper habitats (115–125 m). The Symbiodinium mitochondrial marker resolved three unambiguous haplotypes in clade C, which were found at significantly different frequencies between host species and depths, with one haplotype exclusively found at the lower mesophotic extremes (95–125 m). These patterns of host–symbiont depth specialization indicate that there are limits to connectivity between upper and lower mesophotic zones, suggesting that niche specialization plays a critical role in host–symbiont evolution at mesophotic extremes.