Coral species-specific loss and physiological legacy effects are elicited by an extended marine heatwave.

Marine heatwaves are increasing in frequency and intensity, with potentially catastrophic consequences for marine ecosystems such as coral reefs. An extended heatwave and recovery time-series that incorporates multiple stressors and is environmentally realistic can provide enhanced predictive capacity for performance under climate change conditions. We exposed common reef-building corals in Hawai'i, Montipora capitata and Pocillopora acuta, to a 2-month period of high temperature and high PCO2 conditions or ambient conditions in a factorial design, followed by 2 months of ambient conditions. High temperature, rather than high PCO2, drove multivariate physiology shifts through time in both species, including decreases in respiration rates and endosymbiont densities. Pocillopora acuta exhibited more significantly negatively altered physiology, and substantially higher bleaching and mortality than M. capitata. The sensitivity of P. acuta appears to be driven by higher baseline rates of photosynthesis paired with lower host antioxidant capacity, creating an increased sensitivity to oxidative stress. Thermal tolerance of M. capitata may be partly due to harboring a mixture of Cladocopium and Durusdinium spp., whereas P. acuta was dominated by other distinct Cladocopium spp. Only M. capitata survived the experiment, but physiological state in heatwave-exposed M. capitata remained significantly diverged at the end of recovery relative to individuals that experienced ambient conditions. In future climate scenarios, particularly marine heatwaves, our results indicate a species-specific loss of corals that is driven by baseline host and symbiont physiological differences as well as Symbiodiniaceae community compositions, with the surviving species experiencing physiological legacies that are likely to influence future stress responses.

Characterizing transcriptomic responses to sediment stress across location and morphology in reef-building corals.

Anthropogenic activities increase sediment suspended in the water column and deposition on reefs can be largely dependent on colony morphology. Massive and plating corals have a high capacity to trap sediments, and active removal mechanisms can be energetically costly. Branching corals trap less sediment but are more susceptible to light limitation caused by suspended sediment. Despite deleterious effects of sediments on corals, few studies have examined the molecular response of corals with different morphological characteristics to sediment stress. To address this knowledge gap, this study assessed the transcriptomic responses of branching and massive corals in Florida and Hawai'i to varying levels of sediment exposure. Gene expression analysis revealed a molecular responsiveness to sediments across species and sites. Differential Gene Expression followed by Gene Ontology (GO) enrichment analysis identified that branching corals had the largest transcriptomic response to sediments, in developmental processes and metabolism, while significantly enriched GO terms were highly variable between massive corals, despite similar morphologies. Comparison of DEGs within orthogroups revealed that while all corals had DEGs in response to sediment, there was not a concerted gene set response by morphology or location. These findings illuminate the species specificity and genetic basis underlying coral susceptibility to sediments.

Divergent bleaching and recovery trajectories in reef-building corals following a decade of successive marine heatwaves.

Increasingly frequent marine heatwaves are devastating coral reefs. Corals that survive these extreme events must rapidly recover if they are to withstand subsequent events, and long-term survival in the face of rising ocean temperatures may hinge on recovery capacity and acclimatory gains in heat tolerance over an individual's lifespan. To better understand coral recovery trajectories in the face of successive marine heatwaves, we monitored the responses of bleaching-susceptible and bleaching-resistant individuals of two dominant coral species in Hawai'i, Montipora capitata and Porites compressa, over a decade that included three marine heatwaves. Bleaching-susceptible colonies of P. compressa exhibited beneficial acclimatization to heat stress (i.e., less bleaching) following repeat heatwaves, becoming indistinguishable from bleaching-resistant conspecifics during the third heatwave. In contrast, bleaching-susceptible M. capitata repeatedly bleached during all successive heatwaves and exhibited seasonal bleaching and substantial mortality for up to 3 y following the third heatwave. Encouragingly, bleaching-resistant individuals of both species remained pigmented across the entire time series; however, pigmentation did not necessarily indicate physiological resilience. Specifically, M. capitata displayed incremental yet only partial recovery of symbiont density and tissue biomass across both bleaching phenotypes up to 35 mo following the third heatwave as well as considerable partial mortality. Conversely, P. compressa appeared to recover across most physiological metrics within 2 y and experienced little to no mortality. Ultimately, these results indicate that even some visually robust, bleaching-resistant corals can carry the cost of recurring heatwaves over multiple years, leading to divergent recovery trajectories that may erode coral reef resilience in the Anthropocene.

Morphological and genetic mechanisms underlying the plasticity of the coral Porites astreoides across depths in Bermuda.

The widespread decline of shallow-water coral reefs has fueled interest in assessing whether mesophotic reefs can act as refugia replenishing deteriorated shallower reefs through larval exchange. Here we explore the morphological and molecular basis facilitating survival of planulae and adults of the coral Porites astreoides (Lamarck, 1816; Hexacorallia: Poritidae) along the vertical depth gradient in Bermuda. We found differences in micro-skeletal features such as bigger calyxes and coarser surface of the skeletal spines in shallow corals. Yet, tomographic reconstructions reveal an analogous mineral distribution between shallow and mesophotic adults, pointing to similar skeleton growth dynamics. Our study reveals patterns of host genetic connectivity and minimal symbiont depth-zonation across a broader depth range than previously known for this species in Bermuda. Transcriptional variations across life stages showed different regulation of metabolism and stress response functions, unraveling molecular responses to environmental conditions at different depths. Overall, these findings increase our understanding of coral acclimatory capability across broad vertical gradients, ultimately allowing better evaluation of the refugia potential of mesophotic reefs.

Reconciling the variability in the biological response of marine invertebrates to climate change.

As climate change increases the rate of environmental change and the frequency and intensity of disturbance events, selective forces intensify. However, given the complicated interplay between plasticity and selection for ecological - and thus evolutionary - outcomes, understanding the proximate signals, molecular mechanisms and the role of environmental history becomes increasingly critical for eco-evolutionary forecasting. To enhance the accuracy of our forecasting, we must characterize environmental signals at a level of resolution that is relevant to the organism, such as the microhabitat it inhabits and its intracellular conditions, while also quantifying the biological responses to these signals in the appropriate cells and tissues. In this Commentary, we provide historical context to some of the long-standing challenges in global change biology that constrain our capacity for eco-evolutionary forecasting using reef-building corals as a focal model. We then describe examples of mismatches between the scales of external signals relative to the sensors and signal transduction cascades that initiate and maintain cellular responses. Studying cellular responses at this scale is crucial because these responses are the basis of acclimation to changing environmental conditions and the potential for environmental 'memory' of prior or historical conditions through molecular mechanisms. To challenge the field, we outline some unresolved questions and suggest approaches to align experimental work with an organism's perception of the environment; these aspects are discussed with respect to human interventions.

Characterization of a sperm motility signalling pathway in a gonochoric coral suggests conservation across cnidarian sexual systems.

Most stony corals liberate their gametes into the water column via broadcast spawning, where fertilization hinges upon the activation of directional sperm motility. Sperm from gonochoric and hermaphroditic corals display distinct morphological and molecular phenotypes, yet it is unknown whether the signalling pathways controlling sperm motility are also distinct between these sexual systems. Here, we addressed this knowledge gap using the gonochoric, broadcast spawning coral Astrangia poculata. We found that cytosolic alkalinization of sperm activates the pH-sensing enzyme soluble adenylyl cyclase (sAC), which is required for motility. Additionally, we demonstrate for the first time in any cnidarian that sAC activity leads to protein kinase A (PKA) activation, and that PKA activity contributes to sperm motility activation. Ultrastructures of A. poculata sperm displayed morphological homology with other gonochoric cnidarians, and sAC exhibited broad structural and functional conservation across this phylum. These results indicate a conserved role for pH-dependent sAC-cAMP-PKA signalling in sperm motility across coral sexual systems, and suggest that the role of this pathway in sperm motility may be ancestral in metazoans. Finally, the dynamics of this pH-sensitive pathway may play a critical role in determining the sensitivity of marine invertebrate reproduction to anthropogenic ocean acidification.

Ploidy Variation and Its Implications for Reproduction and Population Dynamics in Two Sympatric Hawaiian Coral Species.

Standing genetic variation is a major driver of fitness and resilience and therefore of fundamental importance for threatened species such as stony corals. We analyzed RNA-seq data generated from 132 Montipora capitata and 119 Pocillopora acuta coral colonies collected from Kane'ohe Bay, O'ahu, Hawai'i. Our goals were to determine the extent of colony genetic variation and to study reproductive strategies in these two sympatric species. Surprisingly, we found that 63% of the P. acuta colonies were triploid, with putative independent origins of the different triploid clades. These corals have spread primarily via asexual reproduction and are descended from a small number of genotypes, whose diploid ancestor invaded the bay. In contrast, all M. capitata colonies are diploid and outbreeding, with almost all colonies genetically distinct. Only two cases of asexual reproduction, likely via fragmentation, were identified in this species. We report two distinct strategies in sympatric coral species that inhabit the largest sheltered body of water in the main Hawaiian Islands. These data highlight divergence in reproductive behavior and genome biology, both of which contribute to coral resilience and persistence.

Building consensus around the assessment and interpretation of Symbiodiniaceae diversity.

Within microeukaryotes, genetic variation and functional variation sometimes accumulate more quickly than morphological differences. To understand the evolutionary history and ecology of such lineages, it is key to examine diversity at multiple levels of organization. In the dinoflagellate family Symbiodiniaceae, which can form endosymbioses with cnidarians (e.g., corals, octocorals, sea anemones, jellyfish), other marine invertebrates (e.g., sponges, molluscs, flatworms), and protists (e.g., foraminifera), molecular data have been used extensively over the past three decades to describe phenotypes and to make evolutionary and ecological inferences. Despite advances in Symbiodiniaceae genomics, a lack of consensus among researchers with respect to interpreting genetic data has slowed progress in the field and acted as a barrier to reconciling observations. Here, we identify key challenges regarding the assessment and interpretation of Symbiodiniaceae genetic diversity across three levels: species, populations, and communities. We summarize areas of agreement and highlight techniques and approaches that are broadly accepted. In areas where debate remains, we identify unresolved issues and discuss technologies and approaches that can help to fill knowledge gaps related to genetic and phenotypic diversity. We also discuss ways to stimulate progress, in particular by fostering a more inclusive and collaborative research community. We hope that this perspective will inspire and accelerate coral reef science by serving as a resource to those designing experiments, publishing research, and applying for funding related to Symbiodiniaceae and their symbiotic partnerships.

High-frequency imagery to capture coral tissue (Montipora capricornis) response to environmental stress, a pilot study.

Environment stress is a major threat to the existence of coral reefs and has generated a lot of interest in the coral research community. Under the environmental stress, corals can experience tissue loss and/or the breakdown of symbiosis between the cnidarian host and its symbiotic algae causing the coral tissue to appear white as the skeleton can be seen by transparency. Image analysis is a common method used to assess tissue response under the environmental stress. However, the traditional approach is limited by the dynamic nature of the coral-algae symbiosis. Here, we observed coral tissue response in the scleractinian coral, Montipora capricornis, using high frequency image analysis throughout the experiment, as opposed to the typical start/end point assessment method. Color analysis reveals that the process can be divided into five stages with two critical stages according to coral tissue morphology and color ratio. We further explore changes to the morphology of individual polyps by means of the Pearson correlation coefficient and recurrence plots, where the quasi-periodic and nonstationary dynamics can be identified. The recurrence quantification analysis also allows the comparison between the different polyps. Our research provides a detailed visual and mathematical analysis of coral tissue response to environmental stress, which potentially shows universal applicability. Moreover, our approach provides a robust quantitative advancement for improving our insight into a suite of biotic responses in the perspective of coral health evaluation and fate prediction.

The trace metal economy of the coral holobiont: supplies, demands and exchanges.

The juxtaposition of highly productive coral reef ecosystems in oligotrophic waters has spurred substantial interest and progress in our understanding of macronutrient uptake, exchange, and recycling among coral holobiont partners (host coral, dinoflagellate endosymbiont, endolithic algae, fungi, viruses, bacterial communities). By contrast, the contribution of trace metals to the physiological performance of the coral holobiont and, in turn, the functional ecology of reef-building corals remains unclear. The coral holobiont's trace metal economy is a network of supply, demand, and exchanges upheld by cross-kingdom symbiotic partnerships. Each partner has unique trace metal requirements that are central to their biochemical functions and the metabolic stability of the holobiont. Organismal homeostasis and the exchanges among partners determine the ability of the coral holobiont to adjust to fluctuating trace metal supplies in heterogeneous reef environments. This review details the requirements for trace metals in core biological processes and describes how metal exchanges among holobiont partners are key to sustaining complex nutritional symbioses in oligotrophic environments. Specifically, we discuss how trace metals contribute to partner compatibility, ability to cope with stress, and thereby to organismal fitness and distribution. Beyond holobiont trace metal cycling, we outline how the dynamic nature of the availability of environmental trace metal supplies can be influenced by a variability of abiotic factors (e.g. temperature, light, pH, etc.). Climate change will have profound consequences on the availability of trace metals and further intensify the myriad stressors that influence coral survival. Lastly, we suggest future research directions necessary for understanding the impacts of trace metals on the coral holobiont symbioses spanning subcellular to organismal levels, which will inform nutrient cycling in coral ecosystems more broadly. Collectively, this cross-scale elucidation of the role of trace metals for the coral holobiont will allow us to improve forecasts of future coral reef function.

Transfer of knowledge from model organisms to evolutionarily distant non-model organisms: The coral Pocillopora damicornis membrane signaling receptome.

With the ease of gene sequencing and the technology available to study and manipulate non-model organisms, the extension of the methodological toolbox required to translate our understanding of model organisms to non-model organisms has become an urgent problem. For example, mining of large coral and their symbiont sequence data is a challenge, but also provides an opportunity for understanding functionality and evolution of these and other non-model organisms. Much more information than for any other eukaryotic species is available for humans, especially related to signal transduction and diseases. However, the coral cnidarian host and human have diverged over 700 million years ago and homologies between proteins in the two species are therefore often in the gray zone, or at least often undetectable with traditional BLAST searches. We introduce a two-stage approach to identifying putative coral homologues of human proteins. First, through remote homology detection using Hidden Markov Models, we identify candidate human homologues in the cnidarian genome. However, for many proteins, the human genome alone contains multiple family members with similar or even more divergence in sequence. In the second stage, therefore, we filter the remote homology results based on the functional and structural plausibility of each coral candidate, shortlisting the coral proteins likely to have conserved some of the functions of the human proteins. We demonstrate our approach with a pipeline for mapping membrane receptors in humans to membrane receptors in corals, with specific focus on the stony coral, P. damicornis. More than 1000 human membrane receptors mapped to 335 coral receptors, including 151 G protein coupled receptors (GPCRs). To validate specific sub-families, we chose opsin proteins, representative GPCRs that confer light sensitivity, and Toll-like receptors, representative non-GPCRs, which function in the immune response, and their ability to communicate with microorganisms. Through detailed structure-function analysis of their ligand-binding pockets and downstream signaling cascades, we selected those candidate remote homologues likely to carry out related functions in the corals. This pipeline may prove generally useful for other non-model organisms, such as to support the growing field of synthetic biology.

Unified methods in collecting, preserving, and archiving coral bleaching and restoration specimens to increase sample utility and interdisciplinary collaboration.

Coral reefs are declining worldwide primarily because of bleaching and subsequent mortality resulting from thermal stress. Currently, extensive efforts to engage in more holistic research and restoration endeavors have considerably expanded the techniques applied to examine coral samples. Despite such advances, coral bleaching and restoration studies are often conducted within a specific disciplinary focus, where specimens are collected, preserved, and archived in ways that are not always conducive to further downstream analyses by specialists in other disciplines. This approach may prevent the full utilization of unexpended specimens, leading to siloed research, duplicative efforts, unnecessary loss of additional corals to research endeavors, and overall increased costs. A recent US National Science Foundation-sponsored workshop set out to consolidate our collective knowledge across the disciplines of Omics, Physiology, and Microscopy and Imaging regarding the methods used for coral sample collection, preservation, and archiving. Here, we highlight knowledge gaps and propose some simple steps for collecting, preserving, and archiving coral-bleaching specimens that can increase the impact of individual coral bleaching and restoration studies, as well as foster additional analyses and future discoveries through collaboration. Rapid freezing of samples in liquid nitrogen or placing at -80 °C to -20 °C is optimal for most Omics and Physiology studies with a few exceptions; however, freezing samples removes the potential for many Microscopy and Imaging-based analyses due to the alteration of tissue integrity during freezing. For Microscopy and Imaging, samples are best stored in aldehydes. The use of sterile gloves and receptacles during collection supports the downstream analysis of host-associated bacterial and viral communities which are particularly germane to disease and restoration efforts. Across all disciplines, the use of aseptic techniques during collection, preservation, and archiving maximizes the research potential of coral specimens and allows for the greatest number of possible downstream analyses.

High-quality genome assembles from key Hawaiian coral species.

BACKGROUND: Coral reefs house about 25% of marine biodiversity and are critical for the livelihood of many communities by providing food, tourism revenue, and protection from wave surge. These magnificent ecosystems are under existential threat from anthropogenic climate change. Whereas extensive ecological and physiological studies have addressed coral response to environmental stress, high-quality reference genome data are lacking for many of these species. The latter issue hinders efforts to understand the genetic basis of stress resistance and to design informed coral conservation strategies. RESULTS: We report genome assemblies from 4 key Hawaiian coral species, Montipora capitata, Pocillopora acuta, Pocillopora meandrina, and Porites compressa. These species, or members of these genera, are distributed worldwide and therefore of broad scientific and ecological importance. For M. capitata, an initial assembly was generated from short-read Illumina and long-read PacBio data, which was then scaffolded into 14 putative chromosomes using Omni-C sequencing. For P. acuta, P. meandrina, and P. compressa, high-quality assemblies were generated using short-read Illumina and long-read PacBio data. The P. acuta assembly is from a triploid individual, making it the first reference genome of a nondiploid coral animal. CONCLUSIONS: These assemblies are significant improvements over available data and provide invaluable resources for supporting multiomics studies into coral biology, not just in Hawai'i but also in other regions, where related species exist. The P. acuta assembly provides a platform for studying polyploidy in corals and its role in genome evolution and stress adaptation in these organisms.

Acclimatory gene expression of primed clams enhances robustness to elevated pCO2.

Sublethal exposure to environmental challenges may enhance ability to cope with chronic or repeated change, a process known as priming. In a previous study, pre-exposure to seawater enriched with pCO2 improved growth and reduced antioxidant capacity of juvenile Pacific geoduck Panopea generosa clams, suggesting that transcriptional shifts may drive phenotypic modifications post-priming. To this end, juvenile clams were sampled and TagSeq gene expression data were analysed after (i) a 110-day acclimation under ambient (921 µatm, naïve) and moderately elevated pCO2 (2870 µatm, pre-exposed); then following (ii) a second 7-day exposure to three pCO2 treatments (ambient: 754 µatm; moderately elevated: 2750 µatm; severely elevated: 4940 µatm), a 7-day return to ambient pCO2 and a third 7-day exposure to two pCO2 treatments (ambient: 967 µatm; moderately elevated: 3030 µatm). Pre-exposed geoducks frontloaded genes for stress and apoptosis/innate immune response, homeostatic processes, protein degradation and transcriptional modifiers. Pre-exposed geoducks were also responsive to subsequent encounters, with gene sets enriched for mitochondrial recycling and immune defence under elevated pCO2 and energy metabolism and biosynthesis under ambient recovery. In contrast, gene sets with higher expression in naïve clams were enriched for fatty-acid degradation and glutathione components, suggesting naïve clams could be depleting endogenous fuels, with unsustainable energetic requirements if changes in carbonate chemistry persist. Collectively, our transcriptomic data indicate that pCO2 priming during post-larval periods could, via gene expression regulation, enhance robustness in bivalves to environmental change. Such priming approaches may be beneficial for aquaculture, as seafood demand intensifies concurrent with increasing climate change in marine systems.

MEDFORD: A human- and machine-readable metadata markup language.

Reproducibility of research is essential for science. However, in the way modern computational biology research is done, it is easy to lose track of small, but extremely critical, details. Key details, such as the specific version of a software used or iteration of a genome can easily be lost in the shuffle or perhaps not noted at all. Much work is being done on the database and storage side of things, ensuring that there exists a space-to-store experiment-specific details, but current mechanisms for recording details are cumbersome for scientists to use. We propose a new metadata description language, named MEtaData Format for Open Reef Data (MEDFORD), in which scientists can record all details relevant to their research. Being human-readable, easily editable and templatable, MEDFORD serves as a collection point for all notes that a researcher could find relevant to their research, be it for internal use or for future replication. MEDFORD has been applied to coral research, documenting research from RNA-seq analyses to photo collections.

Bioinformatics of Corals: Investigating Heterogeneous Omics Data from Coral Holobionts for Insight into Reef Health and Resilience.

Coral reefs are home to over two million species and provide habitat for roughly 25% of all marine animals, but they are being severely threatened by pollution and climate change. A large amount of genomic, transcriptomic, and other omics data is becoming increasingly available from different species of reef-building corals, the unicellular dinoflagellates, and the coral microbiome (bacteria, archaea, viruses, fungi, etc.). Such new data present an opportunity for bioinformatics researchers and computational biologists to contribute to a timely, compelling, and urgent investigation of critical factors that influence reef health and resilience.

Impacts of ocean warming and acidification on calcifying coral reef taxa: mechanisms responsible and adaptive capacity.

Ocean warming (OW) and acidification (OA) are two of the greatest global threats to the persistence of coral reefs. Calcifying reef taxa such as corals and coralline algae provide the essential substrate and habitat in tropical reefs but are at particular risk due to their susceptibility to both OW and OA. OW poses the greater threat to future reef growth and function, via its capacity to destabilise the productivity of both taxa, and to cause mass bleaching events and mortality of corals. Marine heatwaves are projected to increase in frequency, intensity, and duration over the coming decades, raising the question of whether coral reefs will be able to persist as functioning ecosystems and in what form. OA should not be overlooked, as its negative impacts on the calcification of reef-building corals and coralline algae will have consequences for global reef accretion. Given that OA can have negative impacts on the reproduction and early life stages of both coralline algae and corals, the interdependence of these taxa may result in negative feedbacks for reef replenishment. However, there is little evidence that OA causes coral bleaching or exacerbates the effects of OW on coral bleaching. Instead, there is some evidence that OA alters the photo-physiology of both taxa. Tropical coralline algal possess shorter generation times than corals, which could enable more rapid evolutionary responses. Future reefs will be dominated by taxa with shorter generation times and high plasticity, or those individuals inherently resistant and resilient to both marine heatwaves and OA.

The genome of the mustard hill coral, Porites astreoides.

Anthropogenic effects have contributed to substantial declines in coral reefs worldwide. However, some corals are more resilient to environmental changes and have increased in relative abundance, thus these species may shape future reef communities. Here, we provide the first draft reference genome for the mustard hill coral, Porites astreoides, collected in Bermuda. DNA was sequenced via Pacific Biosciences (PacBio) HiFi long-read technology. PacBio read assembly with FALCON UnZip resulted in a 678-Mbp assembly with 3051 contigs with an N50 of 412,256 and the BUSCO completeness analysis resulted in 90.9% of the metazoan gene set. An ab initio transcriptome was also produced with 64,636 gene models with a transcriptome BUSCO completeness analysis of 77.5% versus the metazoan gene set. Functional annotation was completed for 86.6% of proteins. These data are valuable resources for improving biological knowledge of P. astreoides, facilitating comparative genomics for corals, and supporting evidence-based restoration and human-assisted evolution of corals.

Invertebrate methylomes provide insight into mechanisms of environmental tolerance and reveal methodological biases.

There is a growing focus on the role of DNA methylation in the ability of marine invertebrates to rapidly respond to changing environmental factors and anthropogenic impacts. However, genome-wide DNA methylation studies in nonmodel organisms are currently hampered by a limited understanding of methodological biases. Here, we compare three methods for quantifying DNA methylation at single base-pair resolution-whole genome bisulfite sequencing (WGBS), reduced representation bisulfite sequencing (RRBS), and methyl-CpG binding domain bisulfite sequencing (MBDBS)-using multiple individuals from two reef-building coral species with contrasting environmental sensitivity. All methods reveal substantially greater methylation in Montipora capitata (11.4%) than the more sensitive Pocillopora acuta (2.9%). The majority of CpG methylation in both species occurs in gene bodies and flanking regions. In both species, MBDBS has the greatest capacity for detecting CpGs in coding regions at our sequencing depth, but MBDBS may be influenced by intrasample methylation heterogeneity. RRBS yields robust information for specific loci albeit without enrichment of any particular genome feature and with significantly reduced genome coverage. Relative genome size strongly influences the number and location of CpGs detected by each method when sequencing depth is limited, illuminating nuances in cross-species comparisons. As genome-wide methylation differences, supported by data across bisulfite sequencing methods, may contribute to environmental sensitivity phenotypes in critical marine invertebrate taxa, these data provide a genomic resource for investigating the functional role of DNA methylation in environmental tolerance.