Nitrogen Fixation in a Coral Reef Community

Wiebe, W. J.; Johannes, R. E.; Webb, Katie

doi:10.1126/science.188.4185.257

Cited by 163 publications

(68 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Hence, phytoplanktivory may be the principal pathway through which allochthonous N is imported to the reef. Note however, that the rate of N fixation at the reef (Wiebe et al 1975;Lesser et al 2004), a challenging measurement for the scale of the whole community (Atkinson and Falter 2003), is yet unknown.…”

Section: Discussionmentioning

confidence: 99%

Intense Benthic Grazing on Phytoplankton in Coral Reefs Revealed Using the Control Volume Approach

Genin¹,

Yahel²,

Reidenbach³

et al. 2002

oceanog

View full text Add to dashboard Cite

Grazing on phytoplankton by a section of the fringing coral reef in Eilat, the Gulf of Aqaba, Red Sea, was studied using the control-volume approach, a direct, nonintrusive technique common in engineering studies. Concentrations of chlorophyll a were measured using four vertical arrays of pumps, 10 pumps on each, that defined an imaginary box (i.e., the control volume), extending from the bed to surface, overlying a section of the sloping fore-reef .100 m 2 in size. Concurrent velocity measurements were made at the center of the box using a vertical array of acoustic current meters. Together, the concentration and velocity measurements allowed us to compute phytoplankton fluxes in and out of the control volume. While phytoplankton patchiness and other turbulent variations in concentration introduced significant variability, mass balances of fluxes into and out of the box indicate a flow-dependent grazing rate of approximately 10 m d 21 to 20 m d 21 . This value was larger than, but not statistically different from, values derived from an ''a priori estimate'' (calculated based on the density and feeding rates of benthic grazers) and an estimate computed from the observed near-bed gradient of Chl a. Phytoplankton grazing is a principal pathway through which allochthonous nutrients are imported to the reef community from the flowing water.

show abstract

Section: Discussionmentioning

confidence: 99%

Intense Benthic Grazing on Phytoplankton in Coral Reefs Revealed Using the Control Volume Approach

Genin¹,

Yahel²,

Reidenbach³

et al. 2002

oceanog

View full text Add to dashboard Cite

show abstract

“…Studies on biological N 2 fixation in tropical reef environments started with the early work of Wiebe et al (1975) on the algal reef flats of Enewetak Atoll, (Marshall Islands) and Capone et al's (1977) study on the macroalgae of Caribbean reefs. Since then, the volume of published papers and data available has continuously and rapidly increased to reach ca.…”

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

confidence: 99%

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

2017

View full text Add to dashboard Cite

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.

show abstract

“…Thus, we believe that uptake of both nitrate and ammonia are operating at mass-transfer-limited rates but that they cannot be observed because of the remineralization of particulate nitrogen. Unfortunately, we do not yet have enough data to estimate the flux of nitrogen from nitrogen fixation (Wiebe et al 1975;Wilkinson et al 1984;Larkum et al 1988).…”

Section: Dissolved Nh and No Mass Transfer: N Versus P Lim-mentioning

confidence: 99%

Mass‐transfer limitation of nutrient uptake by a wave‐dominated reef flat community

Falter

Atkinson

Merrifield

2004

Limnology & Oceanography

144

134

View full text Add to dashboard Cite

Maximum rates of phosphate, nitrate, and ammonium uptake by a reef flat community were estimated from rates of frictional dissipation that were calculated from the attenuation of waves propagating over the Kaneohe Bay Barrier Reef flat. Time-averaged flow speeds across the entire study area ranged from 0.08 to 0.22 m s Ϫ1 . Observed decreases in wave energy fluxes and near-bottom orbital velocities gave a mean estimate for the bottom friction coefficient (c f ) of 0.22 Ϯ 0.03. Friction coefficients were used to estimate nutrient mass-transfer coefficients of 5-9 m d Ϫ1 for phosphate and 9-16 m d Ϫ1 for ammonium and nitrate. Wave heights offshore of Kaneohe Bay were also used to estimate an annual phosphate mass-transfer coefficient of 8 Ϯ 2 m d Ϫ1 . This value is similar to a published value of 9 Ϯ 2 m d Ϫ1 that was determined from measured changes in phosphate concentrations across the reef flat. We conclude that rates of phosphate uptake by the Kaneohe Bay Barrier Reef flat community are occurring near the limits of mass transfer.Net primary production is a major pathway by which mass and energy flow into coral reef ecosystems. The uptake of dissolved nutrients is often the rate-limiting step for net primary production in marine ecosystems. Thus, a knowledge of the kinetics of nutrient uptake by coral reef communities is necessary for assessing how nutrient loading rates change in response to natural or anthropogenic increases in nutrient concentrations. Bilger and Atkinson (1992) proposed that nutrient uptake by shallow reef communities was limited by mass transfer, the physical transfer of nutrients across concentration boundary layers covering the surfaces of reef autotrophs. These authors used mass-transfer correlations for rough surfaces taken from the engineering literature to correlate maximum rates of nutrient uptake with the frictional characteristics of experimental reef communities. Subsequent studies demonstrated the ability of such mass-transfer correlations to predict nutrient uptake kinetics for experimental reef communities within closed, recirculating flumes (Atkinson and Bilger 1992;Bilger and Atkinson 1995;Thomas and Atkinson 1997) and a large experimental mesocosm (Atkinson et al. 2001). The results of these studies made it clear that shallow-water reef communities are capable of taking up nutrients from the water column at rates that are limited by mass transfer. However, it had not yet been demonstrated whether in situ rates of nutrient uptake 1 Corresponding author (falter@hawaii.edu). AcknowledgmentsSpecial thanks to Jim Fleming, Kimball Millikan, Eric Hochberg, Jerome Aucan, Serge Andrefouet, and Kim Anthony for helpful suggestions and aid in doing field work. Additional thanks to Eric Hochberg for processing of the AURORA image.

show abstract

Nitrogen Fixation in a Coral Reef Community

Cited by 163 publications

References 15 publications

Intense Benthic Grazing on Phytoplankton in Coral Reefs Revealed Using the Control Volume Approach

Intense Benthic Grazing on Phytoplankton in Coral Reefs Revealed Using the Control Volume Approach

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

Mass‐transfer limitation of nutrient uptake by a wave‐dominated reef flat community

Contact Info

Product

Resources

About