Nitrogen fixation (acetylene reduction) associated with the living coral Acropora variabilis

Williams, W. M.; Viner, A. B.; Broughton, W. J.

doi:10.1007/bf00431399

Cited by 86 publications

(79 citation statements)

References 5 publications

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“…Coral tissue and skeleton exhibit nitrogen fixation activity (e.g. Crossland & Barnes 1976, Williams et al 1987, Shashar et al 1994. Interestingly, many anoxygenic phototrophic bacteria can fix nitrogen, and we speculate that such bacteria may contribute to the nitrogen budget of corals and endoliths in addition to the recently discovered symbiotic cyanobacteria in corals (Lesser et al 2004).…”

Section: Photopigment Diversitymentioning

confidence: 75%

Light microclimate of endolithic phototrophs in the scleractinian corals Montipora monasteriata and Porites cylindrica

Magnusson¹,

Fine²,

Kühl³

2007

Mar. Ecol. Prog. Ser.

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Section: Photopigment Diversitymentioning

confidence: 75%

Light microclimate of endolithic phototrophs in the scleractinian corals Montipora monasteriata and Porites cylindrica

Magnusson¹,

Fine²,

Kühl³

2007

Mar. Ecol. Prog. Ser.

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“…Bacillus/Clostridium and nitrogen-fixers) have led to speculations that they function when corals become anoxic at night (Carlton & Richardson 1995, Kuhl et al 1995, Rohwer et al 2002, or that the prokaryotes are maintained in anaerobic niches in coral colonies (Williams et al 1987, Shashar et al 1994, Carlton & Richardson 1995, Rohwer et al 2002. Finding sequences from coral-associated archaeal organisms related to strict anaerobes (methanogens, Desulfurococcus), facultative anaerobes (Thermoplasma), as well as uncultivated Archaea from other types of anoxic environments, suggest that anaerobic zones may also exist in the coral mucus layer.…”

Section: Resultsmentioning

confidence: 99%

Tropical Archaea: diversity associated with the surface microlayer of corals

Kellogg¹

2004

Mar. Ecol. Prog. Ser.

140

130

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Recent 16S rDNA studies have focused on detecting uncultivated bacteria associated with Caribbean reef corals in an effort to address the ecological roles of coral-associated microbes. Reports of Archaea associated with fishes and marine invertebrates raised the question of whether Archaea might also be part of the coral-associated microbial community. DNA analysis of mucus from 3 reef-building species of Caribbean corals, Montastraea annularis complex, Diploria strigosa and D. labyrinthiformis in the US Virgin Islands yielded 34 groups of archaeal 16S ribotypes (defined at the level of 97% similarity). The majority (75%) was most closely matched by BLAST searches to sequences derived from marine water column samples, whereas the remaining ribotypes were most similar to sequences isolated from anoxic environments (15%) and hydrothermal vents (9%). Unlike previous 16S studies of coral-associated Bacteria, the results do not suggest specific associations between particular archaeal sequences and individual coral species. Marine Archaea (Groups I, II and III) in addition to Thermoplasma-like, methanogen, and marine benthic crenarchaeote phylotypes, were detected in the mucus of tropical corals. The finding of sequences from coral-associated Archaea that are closely related to strict and facultative anaerobes, as well as to uncultivated Archaea from other types of anoxic environments, suggests that anaerobic micro-niches may exist in coral mucus layers. Archaea, with their unique biogeochemical capabilities, broaden the scope of possible interactions between corals and their associated microbial communities.

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“…In pelagic N 2 fixation literature, volumetric (nmol N L −1 d −1 ) or depth-integrated (µmol N m −2 d −1 ) rates are now widely accepted (Luo et al, 2012). Coral-associated N 2 fixation rates are so far either normalized per coral dry weight or per skeletal surface area (Williams et al, 1987), while studies on other benthic reef components (e.g., other cnidarians, algae) normalized rates also per wet weight or per chlorophyll a content of the organism under study (Wilkinson and Fay, 1979;Guerinot and Patriquin, 1981;Kayanne et al, 2005). These large differences in rate normalization pose a real difficulty when it comes to compare results both among studies and among different benthic reef components.…”

Section: N 2 Fixation In Coral Reef Ecosystems Description Of N 2 Fixmentioning

confidence: 99%

“…Although corals have several ways to acquire nitrogen, either via heterotrophic feeding (Houlbrèque and Ferrier-Pagès, 2009) or via the uptake of inorganic nitrogen through their symbionts (Grover and Maguer, 2002;Pernice et al, 2012), nitrogen remains a recurrent limiting nutrient for the growth and health of corals (Béraud et al, 2013). Crossland and Barnes (1976) and Williams et al (1987) were the first to report N 2 fixation activity in the stony corals Acropora cuminata and Goniastrea australensis, and Acropora variabilis, respectively. These authors found no clear evidence of epiphytic diazotrophic cyanobacteria over the coral colonies, pointing toward an active diazotrophic community living either within the coral tissue as endosymbiotic bacteria or as endolithic bacteria within the coral skeleton.…”

Section: Diversity Of Diazotrophs In Tropical Coralsmentioning

confidence: 99%

Diazotrophs: Overlooked Key Players within the Coral Symbiosis and Tropical Reef Ecosystems?

2017

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Coral reefs are highly productive ecosystems thriving in nutrient-poor waters. Their productivity depends largely on the availability of nitrogen, the proximate limiting nutrient for primary production. In reefs, the major nitrogen pathways include regeneration, nitrification, ammonification and dinitrogen (N 2 ) fixation. N 2 fixation is performed by prokaryotes called "diazotrophs" that abound in coral rubbles, sandy bottoms, microbial mats, or seagrass meadows. Corals, which are the main reef builders, have developed a partnership with dinoflagellates which transform dissolved inorganic nitrogen into amino acids and protein, and with diazotrophs to gain diazotrophically-derived nitrogen (DDN). Pioneering studies found active diazotrophic cyanobacteria in the corals' mucus and/or tissue, and later high throughput sequencing efforts have described diverse communities of non-cyanobacterial diazotrophs associated with scleractinian corals. Yet, the metabolic processes behind these associations and how they benefit corals are currently not well understood. While genomic studies describe the diversity of diazotrophs and isotopic tracer experiments quantify N 2 fixation rates, combined advanced methods are needed to elucidate the mechanisms behind the transfer of DDN to the coral holobiont and whether these mechanisms change according to the identity of the diazotrophs or coral species. Here we review our current knowledge on N 2 fixation in corals: the diversity and localization of diazotrophs in the coral holobiont, the environmental factors controlling N 2 fixation, the fate of DDN within the coral symbiosis as well as its potential role in coral resilience. We finally summarize the unknowns: are the diversity, abundance and localization of diazotrophs within the holobiont species-and/or site-specific? Do they have an impact on DDN production? What are the metabolic mechanisms implicated? Do they change spatially, temporally or according to environmental factors? We encourage scientists to undertake research efforts to tackle these questions in order to shed light on nitrogen cycling in reef ecosystems and to understand if coral-associated N 2 fixation can improve coral's resilience in the face of climate change.

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Nitrogen fixation (acetylene reduction) associated with the living coral Acropora variabilis

Cited by 86 publications

References 5 publications

Light microclimate of endolithic phototrophs in the scleractinian corals Montipora monasteriata and Porites cylindrica

Light microclimate of endolithic phototrophs in the scleractinian corals Montipora monasteriata and Porites cylindrica

Tropical Archaea: diversity associated with the surface microlayer of corals

Diazotrophs: Overlooked Key Players within the Coral Symbiosis and Tropical Reef Ecosystems?

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