The functional roles of surgeonfishes on coral reefs: past, present and future

Review: Formation and Metabolic Function of Coral Rubble Biofilms in the Reef Ecosystem

Gulf and Caribbean Research ◽

10.18785/gcr.3201.07 ◽

2021 ◽

Vol 32 ◽

pp. 46-56

Author(s):

Andres Sanchez-Quinto ◽

Luisa Falcon

Keyword(s):

Nitrogen Fixation ◽

Coral Reefs ◽

Sulfate Reduction ◽

Sulfide Oxidation ◽

Taxonomic Composition ◽

Coralline Algae ◽

Metabolic Processes ◽

Coral Rubble ◽

Functional Roles ◽

Healthy Coral

When coral dies, their calcareous skeletons constitute coral rubble in conjunction with the cementing activity of coralline algae and bacteria, creating a secondary reef structure which takes from years to decades to form. Healthy coral reefs differ from coral—rubble dominated reefs in microbial taxonomic composition and metabolic functional roles. The metabolisms of healthy reefs are dominated by autotrophic pathways, where carbon and nitrogen fixation dominate, while the metabolism of rubble—dominated reefs predominate in degradation of organic matter. Nitrogen fixation is 3 orders of magnitude lower in rubble—dominated reefs than in healthy reefs. Coral—rubble harbors a vast diversity of microbes that can precipitate carbonate through coupling several metabolic processes including photosynthesis, ureolysis, ammonification, denitrification, sulfate reduction, methane oxidation, and anaerobic sulfide oxidation. All these metabolic processes were found in rubble microbial communities, but ammonification and sulfate reduction were most prevalent. Anthropogenic and non—anthropogenic perturbations of healthy coral reefs in the past decades have led to the prevalence of rubble—dominated reefs in areas of the Caribbean where the ecological and functional shifts of the community still need further study.

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A Zeaxanthin-Producing Bacterium Isolated from the Algal Phycosphere Protects Coral Endosymbionts from Environmental Stress

mBio ◽

10.1128/mbio.01019-19 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 3

Author(s):

Keisuke Motone ◽

Toshiyuki Takagi ◽

Shunsuke Aburaya ◽

Natsuko Miura ◽

Wataru Aoki ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Coral Reefs ◽

Reactive Oxygen ◽

Ros Production ◽

Oxygen Species ◽

Form Complex ◽

Associated Bacteria ◽

Functional Roles ◽

Coral Holobiont ◽

The Family

ABSTRACT Reef-building corals form a complex consortium with photosynthetic algae in the family Symbiodiniaceae and bacteria, collectively termed the coral holobiont. These bacteria are hypothesized to be involved in the stress resistance of the coral holobiont, but their functional roles remain largely elusive. Here, we show that cultured Symbiodiniaceae algae isolated from the reef-building coral Galaxea fascicularis are associated with novel bacteria affiliated with the family Flavobacteriaceae. Antibiotic treatment eliminated the bacteria from cultured Symbiodiniaceae, resulting in a decreased maximum quantum yield of PSII (variable fluorescence divided by maximum fluorescence [Fv/Fm]) and an increased production of reactive oxygen species (ROS) under thermal and light stresses. We then isolated this bacterial strain, named GF1. GF1 inoculation in the antibiotic-treated Symbiodiniaceae cultures restored the Fv/Fm and reduced the ROS production. Furthermore, we found that GF1 produces the carotenoid zeaxanthin, which possesses potent antioxidant activity. Zeaxanthin supplementation to cultured Symbiodiniaceae ameliorated the Fv/Fm and ROS production, suggesting that GF1 mitigates thermal and light stresses in cultured Symbiodiniaceae via zeaxanthin production. These findings could advance our understanding of the roles of bacteria in Symbiodiniaceae and the coral holobiont, thereby contributing to the development of novel approaches toward coral protection through the use of symbiotic bacteria and their metabolites. IMPORTANCE Occupying less than 1% of the seas, coral reefs are estimated to harbor ∼25% of all marine species. However, the destruction of coral reefs has intensified in the face of global climate changes, such as rising seawater temperatures, which induce the overproduction of reactive oxygen species harmful to corals. Although reef-building corals form complex consortia with bacteria and photosynthetic endosymbiotic algae of the family Symbiodiniaceae, the functional roles of coral-associated bacteria remain largely elusive. By manipulating the Symbiodiniaceae bacterial community, we demonstrated that a bacterium that produces an antioxidant carotenoid could mitigate thermal and light stresses in cultured Symbiodiniaceae isolated from a reef-building coral. Therefore, this study illuminates the unexplored roles of coral-associated bacteria under stressful conditions.

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Molecular characterization reveals the complexity of previously overlooked coral-exosymbiont interactions and the implications for coral-guild ecology

Scientific Reports ◽

10.1038/srep44923 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

H. Rouzé ◽

M. Leray ◽

H. Magalon ◽

L. Penin ◽

P. Gélin ◽

...

Keyword(s):

Coral Reefs ◽

Environmental Conditions ◽

New Caledonia ◽

Coral Host ◽

Cryptic Diversity ◽

Pocillopora Damicornis ◽

Ecological Studies ◽

Functional Roles ◽

Associated Species ◽

Interaction Webs

Abstract Several obligate associate crabs and shrimps species may co-occur and interact within a single coral host, leading to patterns of associations that can provide essential ecological services. However, knowledge of the dynamics of interactions in this system is limited, partly because identifying species involved in the network remains challenging. In this study, we assessed the diversity of the decapods involved in exosymbiotic assemblages for juvenile and adult Pocillopora damicornis types α and β on reefs of New Caledonia and Reunion Island. This approach revealed complex patterns of association at regional and local scales with a prevalence of assemblages involving crab-shrimp partnerships. Furthermore, the distinction of two lineages in the snapping shrimp Alpheus lottini complex, rarely recognized in ecological studies, reveals a key role for cryptic diversity in structuring communities of mutualists. The existence of partnerships between species that occurred more commonly than expected by chance suggests an increased advantage for the host or a better adaptation of associated species to local environmental conditions. The consideration of cryptic diversity helps to accurately describe the complexity of interaction webs for diverse systems such as coral reefs, as well as the functional roles of dominant associated species for the persistence of coral populations.

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Human activity selectively impacts the ecosystem roles of parrotfishes on coral reefs

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.1906 ◽

2011 ◽

Vol 279 (1733) ◽

pp. 1621-1629 ◽

Cited By ~ 145

Author(s):

David R. Bellwood ◽

Andrew S. Hoey ◽

Terence P. Hughes

Keyword(s):

Coral Reefs ◽

Human Activity ◽

Ecosystem Functions ◽

Functional Roles ◽

Sediment Removal ◽

Human Footprint ◽

Highly Sensitive ◽

Potential Impact ◽

Fishing Impacts ◽

Coral Predation

Around the globe, coral reefs and other marine ecosystems are increasingly overfished. Conventionally, studies of fishing impacts have focused on the population size and dynamics of targeted stocks rather than the broader ecosystem-wide effects of harvesting. Using parrotfishes as an example, we show how coral reef fish populations respond to escalating fishing pressure across the Indian and Pacific Oceans. Based on these fish abundance data, we infer the potential impact on four key functional roles performed by parrotfishes. Rates of bioerosion and coral predation are highly sensitive to human activity, whereas grazing and sediment removal are resilient to fishing. Our results offer new insights into the vulnerability and resilience of coral reefs to the ever-growing human footprint. The depletion of fishes causes differential decline of key ecosystem functions, radically changing the dynamics of coral reefs and setting the stage for future ecological surprises.

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