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Current Biology : CB Oct 2020LaJeunesse introduces the group of unicellular microalgae referred to as 'zooxanthellae'.
LaJeunesse introduces the group of unicellular microalgae referred to as 'zooxanthellae'.
Topics: Animals; Anthozoa; Dinoflagellida; Symbiosis
PubMed: 33022248
DOI: 10.1016/j.cub.2020.03.058 -
Current Biology : CB Jan 2021Tracy Ainsworth and Barbara Brown introduce the causes and consequences of coral bleaching.
Tracy Ainsworth and Barbara Brown introduce the causes and consequences of coral bleaching.
Topics: Animals; Anthozoa; Chlorophyll; Color; Conservation of Natural Resources; Coral Reefs; Dinoflagellida; Global Warming; Hot Temperature; Photobleaching; Symbiosis
PubMed: 33434489
DOI: 10.1016/j.cub.2020.10.048 -
Annual Review of Animal Biosciences Feb 2021The use of Beneficial Microorganisms for Corals (BMCs) has been proposed recently as a tool for the improvement of coral health, with knowledge in this research topic... (Review)
Review
The use of Beneficial Microorganisms for Corals (BMCs) has been proposed recently as a tool for the improvement of coral health, with knowledge in this research topic advancing rapidly. BMCs are defined as consortia of microorganisms that contribute to coral health through mechanisms that include () promoting coral nutrition and growth, () mitigating stress and impacts of toxic compounds, () deterring pathogens, and () benefiting early life-stage development. Here, we review the current proposed BMC approach and outline the studies that have proven its potential to increase coral resilience to stress. We revisit and expand the list of putative beneficial microorganisms associated with corals and their proposed mechanismsthat facilitate improved host performance. Further, we discuss the caveats and bottlenecks affecting the efficacy of BMCs and close by focusing on the next steps to facilitate application at larger scales that can improve outcomes for corals and reefs globally.
Topics: Animals; Anthozoa; Dinoflagellida; Microbiota; Probiotics; Symbiosis
PubMed: 33321044
DOI: 10.1146/annurev-animal-090120-115444 -
Philosophical Transactions of the Royal... Sep 2020This review explores how microbial symbioses may have influenced and continue to influence the evolution of reef-building corals (Cnidaria; Scleractinia). The coral... (Review)
Review
This review explores how microbial symbioses may have influenced and continue to influence the evolution of reef-building corals (Cnidaria; Scleractinia). The coral holobiont comprises a diverse microbiome including dinoflagellate algae (Dinophyceae; Symbiodiniaceae), bacteria, archaea, fungi and viruses, but here we focus on the Symbiodiniaceae as knowledge of the impact of other microbial symbionts on coral evolution is scant. Symbiosis with Symbiodiniaceae has extended the coral's metabolic capacity through metabolic handoffs and horizontal gene transfer (HGT) and has contributed to the ecological success of these iconic organisms. It necessitated the prior existence or the evolution of a series of adaptations of the host to attract and select the right symbionts, to provide them with a suitable environment and to remove disfunctional symbionts. Signatures of microbial symbiosis in the coral genome include HGT from Symbiodiniaceae and bacteria, gene family expansions, and a broad repertoire of oxidative stress response and innate immunity genes. Symbiosis with Symbiodiniaceae has permitted corals to occupy oligotrophic waters as the algae provide most corals with the majority of their nutrition. However, the coral-Symbiodiniaceae symbiosis is sensitive to climate warming, which disrupts this intimate relationship, causing coral bleaching, mortality and a worldwide decline of coral reefs. This article is part of the theme issue 'The role of the microbiome in host evolution'.
Topics: Animals; Anthozoa; Biological Evolution; Dinoflagellida; Global Warming; Microbiota; Symbiosis
PubMed: 32772672
DOI: 10.1098/rstb.2019.0591 -
Proceedings of the National Academy of... Jan 2021Biominerals such as seashells, coral skeletons, bone, and tooth enamel are optically anisotropic crystalline materials with unique nanoscale and microscale organization...
Biominerals such as seashells, coral skeletons, bone, and tooth enamel are optically anisotropic crystalline materials with unique nanoscale and microscale organization that translates into exceptional macroscopic mechanical properties, providing inspiration for engineering new and superior biomimetic structures. Using coral skeleton as a model, here, we experimentally demonstrate X-ray linear dichroic ptychography and map the -axis orientations of the aragonite (CaCO) crystals. Linear dichroic phase imaging at the oxygen K-edge energy shows strong polarization-dependent contrast and reveals the presence of both narrow (<35°) and wide (>35°) -axis angular spread in the coral samples. These X-ray ptychography results are corroborated by four-dimensional (4D) scanning transmission electron microscopy (STEM) on the same samples. Evidence of co-oriented, but disconnected, corallite subdomains indicates jagged crystal boundaries consistent with formation by amorphous nanoparticle attachment. We expect that the combination of X-ray linear dichroic ptychography and 4D STEM could be an important multimodal tool to study nano-crystallites, interfaces, nucleation, and mineral growth of optically anisotropic materials at multiple length scales.
Topics: Animals; Anisotropy; Anthozoa; Biomimetics; Biomineralization; Calcium Carbonate; Crystallins; Microscopy, Electron, Scanning Transmission; Minerals; Radiography; Tissue Engineering; X-Rays
PubMed: 33436411
DOI: 10.1073/pnas.2019068118 -
BMC Biology Apr 2023Predation pressure and herbivory exert cascading effects on coral reef health and stability. However, the extent of these cascading effects can vary considerably across...
BACKGROUND
Predation pressure and herbivory exert cascading effects on coral reef health and stability. However, the extent of these cascading effects can vary considerably across space and time. This variability is likely a result of the complex interactions between coral reefs' biotic and abiotic dimensions. A major biological component that has been poorly integrated into the reefs' trophic studies is the microbial community, despite its role in coral death and bleaching susceptibility. Viruses that infect bacteria can control microbial densities and may positively affect coral health by controlling microbialization. We hypothesize that viral predation of bacteria has analogous effects to the top-down pressure of macroorganisms on the trophic structure and reef health.
RESULTS
Here, we investigated the relationships between live coral cover and viruses, bacteria, benthic algae, fish biomass, and water chemistry in 110 reefs spanning inhabited and uninhabited islands and atolls across the Pacific Ocean. Statistical learning showed that the abundance of turf algae, viruses, and bacteria, in that order, were the variables best predicting the variance in coral cover. While fish biomass was not a strong predictor of coral cover, the relationship between fish and corals became apparent when analyzed in the context of viral predation: high coral cover (> 50%) occurred on reefs with a combination of high predator fish biomass (sum of sharks and piscivores > 200 g m) and high virus-to-bacteria ratios (> 10), an indicator of viral predation pressure. However, these relationships were non-linear, with reefs at the higher and lower ends of the coral cover continuum displaying a narrow combination of abiotic and biotic variables, while reefs at intermediate coral cover showed a wider range of parameter combinations.
CONCLUSIONS
The results presented here support the hypothesis that viral predation of bacteria is associated with high coral cover and, thus, coral health and stability. We propose that combined predation pressures from fishes and viruses control energy fluxes, inhibiting the detrimental accumulation of ecosystem energy in the microbial food web.
Topics: Coral Reefs; Predatory Behavior; Anthozoa; Animals; Fishes; Pacific Ocean; Biomass; Islands; Bacteria; Food Chain; Seawater; Human Activities; Statistics, Nonparametric
PubMed: 37038111
DOI: 10.1186/s12915-023-01571-9 -
Nature Communications Apr 2020Corals have evolved as optimized photon augmentation systems, leading to space-efficient microalgal growth and outstanding photosynthetic quantum efficiencies. Light...
Corals have evolved as optimized photon augmentation systems, leading to space-efficient microalgal growth and outstanding photosynthetic quantum efficiencies. Light attenuation due to algal self-shading is a key limiting factor for the upscaling of microalgal cultivation. Coral-inspired light management systems could overcome this limitation and facilitate scalable bioenergy and bioproduct generation. Here, we develop 3D printed bionic corals capable of growing microalgae with high spatial cell densities of up to 10 cells mL. The hybrid photosynthetic biomaterials are produced with a 3D bioprinting platform which mimics morphological features of living coral tissue and the underlying skeleton with micron resolution, including their optical and mechanical properties. The programmable synthetic microenvironment thus allows for replicating both structural and functional traits of the coral-algal symbiosis. Our work defines a class of bionic materials that is capable of interacting with living organisms and can be exploited for applied coral reef research and photobioreactor design.
Topics: Animals; Anthozoa; Bionics; Conservation of Natural Resources; Coral Reefs; Ecosystem; Light; Microalgae; Photosynthesis; Printing, Three-Dimensional; Symbiosis
PubMed: 32273516
DOI: 10.1038/s41467-020-15486-4 -
Annual Review of Marine Science Jan 2021The interaction of coral reefs, both chemically and physically, with the surrounding seawater is governed, at the smallest scales, by turbulence. Here, we review recent... (Review)
Review
The interaction of coral reefs, both chemically and physically, with the surrounding seawater is governed, at the smallest scales, by turbulence. Here, we review recent progress in understanding turbulence in the unique setting of coral reefs-how it influences flow and the exchange of mass and momentum both above and within the complex geometry of coral reef canopies. Flow above reefs diverges from canonical rough boundary layers due to their large and highly heterogeneous roughness and the influence of surface waves. Within coral canopies, turbulence is dominated by large coherent structures that transport momentum both into and away from the canopy, but it is also generated at smaller scales as flow is forced to move around branches or blades, creating wakes. Future work interpreting reef-related observations or numerical models should carefully consider the influence that spatial variation has on momentum and scalar flux.
Topics: Animals; Anthozoa; Coral Reefs; Models, Theoretical; Seawater; Water Movements
PubMed: 32762591
DOI: 10.1146/annurev-marine-042120-071823 -
Current Opinion in Biotechnology Feb 2022Globally, coral reefs are under pressure from climate change, with concerning declines in coral abundance observed due to increasing cumulative impacts. Active... (Review)
Review
Globally, coral reefs are under pressure from climate change, with concerning declines in coral abundance observed due to increasing cumulative impacts. Active intervention measures that mitigate the declines are increasingly being applied to buy time for coral reefs as the world transitions to a low-carbon economy. One such mitigation strategy is coral restoration based on large-scale coral aquaculture to provide stock for reseeding reefs, with the added potential of selecting corals that better tolerate environmental stress. Application of probiotics during production and deployment, to modulate the naturally occurring bacteria associated with corals, may confer health benefits such as disease resistance, increased environmental tolerance or improved coral nutrition. Here, we briefly describe coral associated bacteria and their role in the coral holobiont, identify probiotics traits potentially beneficial to coral, and discuss current research directions required to develop, test and verify the feasibility for probiotics to improve coral aquaculture at industrial scales.
Topics: Animals; Anthozoa; Aquaculture; Climate Change; Coral Reefs; Probiotics
PubMed: 34749049
DOI: 10.1016/j.copbio.2021.09.009 -
Scientific Reports Jan 2021The declining reproductive viability of corals threatens their ability to adapt to changing ocean conditions. It is vital that we monitor this viability quantitatively...
The declining reproductive viability of corals threatens their ability to adapt to changing ocean conditions. It is vital that we monitor this viability quantitatively and comparatively. Computer-assisted sperm analysis (CASA) systems offer in-depth analysis used regularly for domestic and wildlife species, but not yet for coral. This study proposes quality control procedures and CASA settings that are effective for coral sperm analysis. To resolve disparities between CASA measurements and evaluations by eye, two negative effects on motility had to be resolved, slide adhesion (procedural) and sperm dilution (biological). We showed that the addition of bovine serum albumin, or caffeine, or both to fresh sperm reduced adhesion in the CASA cassettes, improved motility and motile sperm concentration (P < 0.0001), yet these additions did not affect measurements of total sperm concentration. Diluting coral sperm reduced sperm motility (P = 0.039), especially from heat-stressed corals. We found CASA concentration counts comparable to haemocytometer and flow cytometer measures (P = 0.54). We also found that motile sperm per egg is a useful predictor of fertilisation success, using cryopreserved sperm. Standard measurements of coral reproductive characteristics inform our understanding of the impacts of climate change on reef populations; this study provides a benchmark to begin this comparative work.
Topics: Animals; Anthozoa; Male; Sperm Motility; Spermatozoa
PubMed: 33420097
DOI: 10.1038/s41598-020-79732-x