National Sea Simulator

Abstract Elevated CO 2 levels associated with ocean acidification (OA) have been shown to alter behavioural responses in coral reef fishes. However, all studies to date have used stable p CO 2 treatments, not considering the substantial diel p CO 2 variation that occurs in shallow reef habitats. Here, we reared juvenile damselfish, Acanthochromis polyacanthus , and clownfish, Amphiprion percula , at stable and diel cycling p CO 2 treatments in two experiments. As expected, absolute lateralization of A. polyacanthus and response to predator cue of Am. percula were negatively affected in fish reared at stable, elevated p CO 2 in both experiments. However, diel p CO 2 fluctuations reduced the negative effects of OA on behaviour. Importantly, in experiment two, behavioural abnormalities that were present in fish reared at stable 750 µatm CO 2 were largely absent in fish reared at 750 ± 300 µatm CO 2 . Overall, we show that diel p CO 2 cycles can substantially reduce the severity of behavioural abnormalities caused by elevated CO 2 . Thus, past studies may have over-estimated the impacts of OA on the behavioural performance of coral reef fishes. Furthermore, our results suggest that diel p CO 2 cycles will delay the onset of behavioural abnormalities in natural populations.

Heterotrophic feeding in newly-settled coral planulae can potentially improve survivorship and accelerate early development in some species; however, an optimal diet to facilitate this does not currently exist. This study evaluated the efficacy of three heterotrophic feeding regimes (enriched rotifers, unfiltered seawater, and a novel, particulate diet), against a wholly-phototrophic treatment on Acropora hyacinthus, A. loripes, A. millepora, and A. tenuis recruits, over 93 days post-settlement. The unfiltered seawater treatment recorded maximum survival for all species (A. hyacinthus 95.9±8.0%, A. loripes: 74.3±11.5%, A. millepora: 67±12.7%, A. tenuis: 53.2±11.3%), although not significant. Growth (% surface area gain) was also greatest in the unfiltered seawater, and this was significant for A. millepora (870±307%) and A. tenuis (693±91.8%) (p<0.05). Although total lipid concentration was relatively stable across treatments, the lipid class composition exhibited species-specific responses to each treatment. Lower saturated and higher polyunsaturated fatty acids appeared beneficial to recruit performance, particularly in the unfiltered seawater, which generally contained the highest levels of 20:5n-3 (EPA), 22:6n-3 (DHA), and 20:4n-6 (ARA). The present study demonstrates the capacity of a nutritionally adequate and readily accepted heterotrophic feeding regime to increase coral recruit survival, growth, and health, which can greatly reduce the time required in cost- and labour-intensive culture.

Scleractinian corals are colonial organisms comprising multiple physiologically integrated polyps and branches. Colonialism in corals is highly beneficial, and allows a single colony to undergo several life processes at once through physiological integration and compartmentalised functioning. Elucidating differences in the biochemical composition of intra-colonial branch positions will provide valuable insight into the nutritional reserves underlying different regions in individual coral colonies. This will also ascertain prudent harvesting strategies of wild donor-colonies to generate coral stock with high survival and vigour prospects for reef-rehabilitation efforts and captive husbandry. This study examined the effects of colony branch position on the nutritional profile of two different colony sizes of the common scleractinian, Acropora millepora . For smaller colonies, branches were sampled at three locations: the colony centre (S-centre), 50% of the longitudinal radius length (LRL) (S-50), and the colony edge (S-edge). For larger colonies, four locations were sampled: the colony centre (L-centre), 33.3% of the LRL (L-33), 66.6% of the LRL (L-66), and the edge (L-edge). Results demonstrate significant branch position effects, with the edge regions containing higher protein, likely due to increased tissue synthesis and calcification. Meanwhile, storage lipid and total fatty acid concentrations were lower at the edges, possibly reflecting catabolism of high-energy nutrients to support proliferating cells. Results also showed a significant effect of colony size in the two classes examined. While the major protein and structural lipid sink was exhibited at the edge for both sizes, the major sink for high-energy lipids and fatty acids appeared to be the L-66 position of the larger colonies and the S-centre and S-50 positions for the smaller colonies. These results confirm that the scleractinian coral colony is not nutritionally homogeneous, and while different regions of the coral colony are functionally specialised, so too are their nutritional profiles geared toward meeting specific energetic demands.

The restoration of reefs damaged by global and local pressures remains constrained by the scale of intervention currently feasible. Traditional methods for ex situ sexual propagation of corals produce limited materials, typically of limited genetic diversity and only sufficient for small field trials. The development and validation of new technologies to upscale and automate coral propagation is required to achieve logistically and financially feasible reef restoration at ecologically relevant scales. To address the need for upscaled production of genetically diverse material for use in reef restoration we designed an automated system (the AutoSpawner) for harvesting, fertilising and washing gametes from tropical broadcast-spawning corals. The system includes a novel high density dynamic fertilisation process, which enables the production of large numbers of fertilised coral eggs (>7 million per night for highly fecund species) without any downstream negative effects on larval quality. The functionality of the system and the quality of the produced larvae was assessed using multiple species from two coral families (Acroporidae and Merulinidae) across a range of spawning and gamete characteristics. We present the schematics and protocols required for automated sexual propagation of high-quality coral larvae using this novel system; and demonstrate that the time demands, and labour costs, associated with traditional manual-based sexual propagation of corals can be reduced by up to 113-fold using the AutoSpawner.

Animal guts contain numerous microbes, which are critical for nutrient assimilation and pathogen defence. While corals and other Cnidaria lack a true differentiated gut, they possess semi-enclosed gastrovascular cavities (GVCs), where vital processes such as digestion, reproduction and symbiotic exchanges take place. The microbiome harboured in GVCs is therefore likely key to holobiont fitness, but remains severely understudied due to challenges of working in these small compartments. Here, we developed minimally invasive methodologies to sample the GVC of coral polyps and characterise the microbial communities harboured within. We used glass capillaries, low dead volume microneedles, or nylon microswabs to sample the gastrovascular microbiome of individual polyps from six species of corals, then applied low-input DNA extraction to characterise the microbial communities from these microliter volume samples. Microsensor measurements of GVCs revealed anoxic or hypoxic micro-niches, which persist even under prolonged illumination with saturating irradiance. These niches harboured microbial communities enriched in putatively microaerophilic or facultatively anaerobic taxa, such as Epsilonproteobacteria. Some core taxa found in the GVC of Lobophyllia hemprichii from the Great Barrier Reef were also detected in conspecific colonies held in aquaria, indicating that these associations are unlikely to be transient. Our findings suggest that the coral GVC is chemically and microbiologically similar to the gut of higher Metazoa. Given the importance of gut microbiomes in mediating animal health, harnessing the coral "gut microbiome" may foster novel active interventions aimed at increasing the resilience of coral reefs to the climate crisis.

Adult corals are among the most sensitive marine organisms to dissolved manganese and experience tissue sloughing without bleaching (i.e., no loss of Symbiodinium spp.) but there are no chronic toxicity data for this sensitive endpoint. We exposed adult Acropora millepora to manganese in 2-d acute and 14-d chronic experiments using tissue sloughing as the toxicity endpoint. The acute tissue sloughing median effect concentration (EC50) was 2560 μg Mn/L. There was no chronic toxicity to A. millepora at concentrations up to and including the highest concentration of 1090 μg Mn/L i.e., the chronic no observed effect concentration (NOEC). A coral-specific acute-to-chronic ratio (ACR) (EC50/NOEC) of 2.3 was derived. These data were combined with chronic toxicity data for other marine organisms in a species sensitivity distribution (SSD). Marine manganese guidelines were 190, 300, 390 and 570 μg Mn/L to provide long-term protection of 99, 95, 90, and 80 % of marine species, respectively.

Intensifying anthropogenic stressors have contributed to declines in reef-building corals in many regions. These disturbances result in reduced live coral cover, impacting key population-level processes such as coral larval settlement and recruitment that are essential for reef recovery. Reef restoration efforts that rely on enhanced larval supply provide a pathway for the recovery of degraded reefs. However, corals at very early life stages experience high post-settlement mortality bottlenecks, which impede stock-recruitment processes. Overcoming these bottlenecks is a high priority goal in coral restoration. Some coral larvae are known to be capable of gaining exogenous nutrients. Therefore, we hypothesised that the capacity to access exogenous nutrients may confer advantages to larval survival, settlement and post-settlement success. The present study aimed to quantify the effect of larval feeding on coral larvae settlement and early post-settlement survival. We completed an ex-situ experiment using aposymbiotic larvae of two broadcast spawning reef-building coral species - Acropora tenuis and Acropora millepora. Larvae were randomly assigned to either fed or unfed treatment groups for each species. Fed larvae received homogenised Artemia once a day, for three days. Results show that for both species, feeding significantly increased larval settlement. Feeding A. millepora larvae more than doubled mean settlement (13.0 ± 1.17 SE vs 31.4 ± 2.88 SE; p &amp;lt; 0.001). Similarly, feeding A. tenuis larvae increased mean settlement from 18.2 ( ± 1.85 SE) to 29.9 ( ± 2.22 SE; p &amp;lt; 0.001). Larval feeding had an immediate positive effect on spat survival, such that A. millepora and A. tenuis spat from fed treatments had increased survival three days post-settlement (89.5% ± 3.75 SE vs 70.6% ± 2.59 SE, p &amp;lt; 0.001; 88.8% ± 2.21 SE vs 71.4% ± 3.80 SE, p &amp;lt;0.001, respectively). Therefore, enhancing settlement and early post-settlement survival by feeding larvae homogenised Artemia has the potential to improve the effectiveness of larval rearing protocols and coral restoration efforts.

Manganese (Mn) is an essential element and is generally considered to be one of the least toxic metals to aquatic organisms, with chronic effects rarely seen at concentrations below 1000 µg/L. Anthropogenic activities lead to elevated concentrations of Mn in tropical marine waters. Limited data suggest that Mn is more acutely toxic to adults than to early life stages of scleractinian corals in static renewal tests. However, to enable the inclusion of sufficient sensitive coral data in species sensitivity distributions to derive water quality guideline values for Mn, we determined the acute toxicity of Mn to the adult scleractinian coral, Acropora muricata, in flow-through exposures. The 48-h median effective concentration was 824 µg Mn/L (based on time-weighted average, measured, dissolved Mn). The endpoint was tissue sloughing, a lethal process by which coral tissue detaches from the coral skeleton. Tissue sloughing was unrelated to superoxidase dismutase activity in coral tissue, and occurred in the absence of bleaching, that is, toxic effects were observed for the coral host, but not for algal symbionts. We confirm that adult scleractinian corals are uniquely sensitive to Mn in acute exposures at concentrations 10-340 times lower than those reported to cause acute or chronic toxicity to coral early life stages, challenging the traditional notion that early life stages are more sensitive than mature organisms. Environ Toxicol Chem 2023;42:1359-1370. © 2023 Commonwealth Scientific and Industrial Research Organisation. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Organismal phenotyping to identify fitness traits is transforming our understanding of adaptive responses and ecological interactions of species within changing environments. Here we present a portable Multi-Taxa Phenotyping (MTP) system that can retrieve a suite of metabolic and photophysiological parameter across light, temperature, and/or chemical gradients, using real time bio-optical (oxygen and chlorophyll a fluorescence) measurements. The MTP system integrates three well-established technologies for the first time: an imaging Pulse Amplitude Modulated (PAM) chlorophyll a fluorometer, custom-designed well plates equipped with optical oxygen sensors, and a thermocycler. We demonstrate the ability of the MTP system to distinguish phenotypic performance characteristics of diverse aquatic taxa spanning corals, mangroves and algae based on metabolic parameters and Photosystem II dynamics, in a high-throughput capacity and accounting for interactions of different environmental gradients on performance. Extracted metrics from the MTP system can not only provide information on the performance of aquatic taxa exposed to differing environmental gradients, but also provide predicted phenotypic responses of key aquatic organisms to environmental change. Further work validating how rapid phenotyping tools such as the MTP system predict phenotypic responses to long term environmental changes in situ are urgently required to best inform how these tools can support management efforts.

Researchers embrace a radical idea: engineering coral to cope with climate change.

Abstract In fishes, swimming performance is considered an important metric to measure fitness, dispersal and migratory abilities. The swimming performance of individual larval fishes is often integrated into models to make inferences on how environmental parameters affect population-level dynamics (e.g. connectivity). However, little information exists regarding how experimental protocols affect the swimming performance of marine fish larvae. In addition, the technical setups used to measure larval fish swimming performance often lack automation and accurate control of water quality parameters and flow velocity. In this study, we automated the control of multi-lane swimming chambers for small fishes by developing an open-source algorithm. This automation allowed us to execute repeatable flow scenarios and reduce operator interference and inaccuracies in flow velocity typically associated with manual control. Furthermore, we made structural modifications to a prior design to reduce the areas of lower flow velocity. We then validated the flow dynamics of the new chambers using computational fluid dynamics and particle-tracking software. The algorithm provided an accurate alignment between the set and measured flow velocities and we used it to test whether faster critical swimming speed (Ucrit) protocols (i.e. shorter time intervals and higher velocity increments) would increase Ucrit of early life stages of two tropical fish species [4–10-mm standard length (SL)]. The Ucrit of barramundi (Lates calcarifer) and cinnamon anemonefish (Amphiprion melanopus) increased linearly with fish length, but in cinnamon anemonefish, Ucrit started to decrease upon metamorphosis. Swimming protocols using longer time intervals (more than 2.5 times increase) negatively affected Ucrit in cinnamon anemonefish but not in barramundi. These species-specific differences in swimming performance highlight the importance of testing suitable Ucrit protocols prior to experimentation. The automated control of flow velocity will create more accurate and repeatable data on swimming performance of larval fishes. Integrating refined measurements into individual-based models will support future research on the effects of environmental change.

Abstract Oxygen (O 2 ) availability is essential for healthy coral reef functioning, yet how continued loss of dissolved O 2 via ocean deoxygenation impacts performance of reef building corals remains unclear. Here, we examine how intra‐colony spatial geometry of important Great Barrier Reef (GBR) coral species Acropora may influence variation in hypoxic thresholds for upregulation, to better understand capacity to tolerate future reductions in O 2 availability. We first evaluate the application of more streamlined models used to parameterise Hypoxia Response Curve data, models that have been used historically to identify variable oxyregulatory capacity. Using closed‐system respirometry to analyse O 2 drawdown rate, we show that a two‐parameter model returns similar outputs as previous 12th‐order models for descriptive statistics such as the average oxyregulation capacity (T pos ) and the ambient O 2 level at which the coral exerts maximum regulation effort (P cmax ), for diverse Acropora species. Following an experiment to evaluate whether stress induced by coral fragmentation for respirometry affected O 2 drawdown rate, we subsequently identify differences in hypoxic response for the interior and exterior colony locations for the species Acropora abrotanoides , Acropora cf. microphthalma and Acropora elseyi . Average regulation capacity across species was greater (0.78–1.03 ± SE 0.08) at the colony interior compared with exterior (0.60–0.85 ± SE 0.08). Moreover, P cmax occurred at relatively low p O 2 of &lt;30% (±1.24; SE) air saturation for all species, across the colony. When compared against ambient O 2 availability, these factors corresponded to differences in mean intra‐colony oxyregulation, suggesting that lower variation in dissolved O 2 corresponds with higher capacity for oxyregulation. Collectively, our data show that intra‐colony spatial variation affects coral oxyregulation hypoxic thresholds, potentially driving differences in Acropora oxyregulatory capacity.

Corals at very early life stages face high mortality bottlenecks, limiting natural stock-recruitment and the success of restoration and aquaculture strategies reliant on sexual reproduction. Nutrient availability and quality, particularly lipids, are critical for larval survival, dispersal, and settlement, yet the specific lipids influencing early-stage fitness remain unclear. Since measuring lipid depletion in non-surviving larvae is impractical, we developed a targeted supplementation approach to identify nutrients that enhance larval fitness. Supplementing Acropora spathulata larvae with nanoparticle-encapsulated triacylglycerols and sterols significantly improved swimming distance and speed, indicating enhanced dispersal potential. Supplementation with sterols, which are essential for cell structure and metamorphosis, also increased settlement rates. Furthermore, juveniles developed from larvae fed with sterols and omega-3-rich fish oils demonstrated superior performance under controlled and thermal stress conditions during the first six months, while those supplemented with Calanus oil also enhanced survival under elevated temperatures. Lipid profiling revealed key sphingolipids, glycerophospholipids, and fatty acids likely responsible for the improved fitness of fed larvae. Our approach highlights the critical role of lipid composition and availability during coral early life stages and demonstrates the potential of targeted nutritional supplementation to address nutrient deficiencies, enhance coral resilience, and support restoration and aquaculture efforts.

The coral holobiont is underpinned by complex metabolic exchanges between different symbiotic partners, which are impacted by environmental stressors. The chemical diversity of the compounds produced by the holobiont is high and includes primary and secondary metabolites, as well as volatiles. However, metabolites and volatiles have only been characterised in isolation so far. Here, we applied a paired metabolomic-volatilomic approach to characterise holistically the chemical response of the holobiont under stress. Montipora mollis fragments were subjected to high-light stress (8-fold higher than the controls) for 30 min. Photosystem II (PSII) photochemical efficiency values were 7-fold higher in control versus treatment corals immediately following high-light exposure, but returned to pre-stress levels after 30 min of recovery. Under high-light stress, we identified an increase in carbohydrates (> 5-fold increase in arabinose and fructose) and saturated fatty acids (7-fold increase in myristic and oleic acid), together with a decrease in fatty acid derivatives in both metabolites and volatiles (e.g., 80% decrease in oleamide and nonanal), and other antioxidants (~ 85% decrease in sorbitol and galactitol). These changes suggest short-term light stress induces oxidative stress. Correlation analysis between volatiles and metabolites identified positive links between sorbitol, galactitol, six other metabolites and 11 volatiles, with four of these compounds previously identified as antioxidants. This suggests that these 19 compounds may be related and share similar functions. Taken together, our findings demonstrate how paired metabolomics-volatilomics may illuminate broader metabolic shifts occurring under stress and identify linkages between uncharacterised compounds to putatively determine their functions.

Abstract Animal guts contain numerous microbes, which are critical for nutrient assimilation and pathogen defence. While corals and other Cnidaria lack a true differentiated gut, they possess gastrovascular cavities (GVCs), semi-enclosed compartments where vital processes such as digestion, reproduction and symbiotic exchanges take place. The microbiome harboured in GVCs is therefore likely key to holobiont fitness, but remains severely understudied due to challenges of working in these small compartments. Here, we developed minimally invasive methodologies to sample the GVC of coral polyps and characterise the microbial communities harboured within. We used glass capillaries, low dead volume microneedles, or nylon microswabs to sample the gastric microbiome of individual polyps from six species of corals, then applied low-input DNA extraction to characterise the microbial communities from these microliter volume samples. Microsensor measurements of GVCs revealed anoxic or hypoxic micro-niches, which persist even under prolonged illumination with saturating irradiance. These niches harboured microbial communities enriched in putatively microaerophilic or facultatively anaerobic taxa, such as Epsilonproteobacteria. Some core taxa found in the GVC of Lobophyllia hemprichii from the Great Barrier Reef were also detected in conspecific colonies held in aquaria, indicating that these associations are unlikely to be transient. Our findings suggest that the coral GVC is chemically and microbiologically similar to the gut of higher Metazoa. Given the importance of gut microbiomes in mediating animal health, harnessing the coral “gut microbiome” may foster novel active interventions aimed at increasing the resilience of coral reefs to the climate crisis.

The global climate crisis has heightened the urgency for developing interventions to enhance resilience and recovery of coral reef ecosystems. However, research programmes are often bottlenecked by availability of coral early life stage material owing to the annual nature of coral mass spawning. We present a proof-of-concept of ‘out-of-season’ spawning, utilizing aquarium control technology to induce spawning in multiple Great Barrier Reef (GBR) corals held in long-term indoor aquaria. By applying a six-month offset environmental profile encompassing seasonal temperature, photoperiod and lunar cues, we induced synchronized coral spawning during austral autumn/winter between 2022 and 2023. We also ‘phase-shifted’ the hour of sunset by four hours on spawning nights, creating a more favourable time window (i.e. minimizing late nights) for gamete fertilization. Spawning occurred on comparable nights after full moon (NAFM) and at similar times after sunset (TAS) to wild conspecifics, with 2023 cohorts showing the closer alignment. Gamete fertilization was successful for six species: Acropora millepora , Acropora loripes , Acropora hyacinthus , Acropora elseyi , Acropora austera , and Montipora aequituberculata , producing ca 2 million larvae. We outline physiological insights into environmental regulation of coral spawning synchronicity and discuss the potential for out-of-season spawning to accelerate coral research and enhance reef restoration programmes.

Some coral species in natural reef systems derive benefits from fish which live in close association with them. This study investigates the benefits of incorporating fish in ex situ coral culture to enhance coral physiological performance. Corals that typically have fish associations ( Acropora kenti and Pocillopora verrucosa ) and those that do not ( Porites lutea and Platygyra daedalea ) were grown in aquaria under different fish‐associated treatments for 3 months. Physiological performance of the corals, including growth, protein content, symbiont density and photosynthetic efficiency were assessed in the different treatments where corals were (1) kept with a school of Chromis viridis fed a pelleted diet, (2) supplied filtered water from a tank housing C. viridis , (3) fed live feeds whilst maintained with C. viridis , (4) supplied only with live feeds, (5) supplied with a pelleted fish diet without C. viridis and (6) not supplied feeds and without C. viridis . Whilst the responses of the corals varied between species, generally, exposure to fish or fish‐water increased the protein and/or symbiont density within coral tissue. A. kenti and P. lutea , which derive a higher proportion of their energy requirement from autotrophy, displayed improved growth in the fish treatments, whilst the more heterotrophic P. verrucosa grew fastest when supplied with live feeds. The more heterotrophic, slow‐growing P. daedalea did not show significant improvements in growth under any of the treatments, and there were no major differences in photosynthetic efficiency between treatments in any of the corals. These results indicate that incorporating fish into coral culture could provide an accessible source of nitrogen and phosphorous enrichment via the dissolved portion of the fish’s wastes and, in turn, enhance the growth of corals more reliant on autotrophy, like Acroporids. The results point to potential efficiency gains for coral husbandry practices, with the aim of satisfying the growing demands of reef restoration and ornamental aquaculture.

Abstract The global climate crisis has heightened the urgency for developing interventions to enhance resilience and recovery of coral reef ecosystems. However, research programs are often bottlenecked by availability of coral early life stage material due to the seasonal (annual) nature of coral mass spawning events. Here, we present a proof-of-concept of “out-of-season” coral spawning, utilising advanced aquarium control technology to induce spawning in multiple key Great Barrier Reef (GBR) coral species held in long-term indoor aquaria. By developing a 6-month offset environmental profile encompassing seasonal temperature, photoperiod, and lunar profiles, we successfully induced synchronised mass coral spawning during austral autumn/winter (May - June) over consecutive years in 2022 and 2023. We also “phase-shifted” the hour of sunset by five hours on spawning nights, creating a more favourable time window (i.e., minimising late nights) for gamete fertilisation. The timing of gamete release in captive corals closely matched previous GBR field observations for both nights after full moon (NAFM) and time after sunset (TAS). Gamete fertilisation was successful for six GBR species: Acropora millepora, Acropora loripes, Acropora hyacinthus, Acropora elseyi, Acropora austera, and Montipora aequituberculata producing a total of 1.75 million larvae. We outline key physiological insights gained into environmental regulation of coral spawning synchronicity and discuss the potential for out-of-season spawning to accelerate various aspects of coral reproduction research and enhance the growing toolbox of active restoration strategies aimed at reversing global coral reef decline.

The gastrovascular cavity of corals plays a central role in internal circulation, digestion, reproduction, and symbiont acquisition. However, despite its importance, our understanding of the physic-chemical characteristics and dynamic properties of this internal microenvironment remains limited. Here, we employ high-resolution microsensor measurements to investigate the vertical distribution of O 2 within the coral gastrovascular cavity. By combining microsensor analysis with time-lapse imaging, we show that O 2 levels inside corals are strongly affected by slow, synchronized tissue movements, suggesting a mechanism of active ventilation through modulation of cavity volume and exchange with the surrounding seawater. Together with cilia beating, these movements reduce O 2 accumulation under light conditions and alleviate O 2 depletion in darkness, thereby stabilizing internal O 2 availability. These findings highlight a hitherto overlooked role of behavior in actively regulating the internal microenvironment and O 2 status of the coral holobiont and provide critical insight into the organism-environment interactions of reef-building corals.

Associations with fish can benefit corals by increasing growth and stress tolerance. To investigate microbial and nutritional responses of corals to fish associations in the context of enhancing coral aquaculture outcomes, Pocillopora verrucosa were cultured for 3 months with different combinations of live feeds and schools of juvenile Chromis viridis damselfish. The combined live feeds and fish treatment resulted in a bacterial community most similar to wild P. verrucosa, dominated by Endozoicomonas-affiliated taxa. Protein content was enhanced in corals with access to live feeds and/or dissolved fish wastes compared to unfed controls. Total lipid concentrations were elevated in captive corals with access to dissolved fish wastes and at moderate levels in those supplied live feeds, likely due to the activity of corals' symbionts and deposition of derived lipids from live feeds, respectively. However, all captive corals demonstrated a significant reduction in storage lipid concentration compared to samples from the wild. Fatty acid analysis indicated these shifts were likely the result of higher light levels in the field supporting Symbiodiniaceae photosynthesis and potentially feeding on wild zooplankton. Co-culturing captive corals with fish and providing appropriate live feeds may therefore offer an effective approach to improve coral nutrition, health and microbiome stability.