Occurrence of Nitrogen Fixing Cyanobacterium Trichodesmium under Elevated pCO2 Conditions in the Western Bay of Bengal

Shetye, S.R.; Sudhakar, M.; Jena, Babula; Mohan, Rahul

doi:10.1155/2013/350465

Cited by 22 publications

(17 citation statements)

References 45 publications

(67 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1c). This is in line with earlier suggestions of riverine-nutrient runoff promoting primary production close to the shelf, where nutrients are consumed rapidly, thus preventing their offshore transport Singh et al, 2012;Singh and Ramesh, 2011;Krishna et al, 2016). Chlorophyll concentrations in the BoB during the time of the cruise detected via satellite monitoring ranged between 0.08 mg m −3 in open waters and 15 mg m −3 at the northern coast and were consistent with previous in situ measurements during low productivity periods in the BoB (Kumar et al, 2010).…”

Section: Resultssupporting

confidence: 91%

No nitrogen fixation in the Bay of Bengal?

et al. 2020

View full text Add to dashboard Cite

The Bay of Bengal (BoB) has long stood as a biogeochemical enigma, with subsurface waters containing extremely low, but persistent, concentrations of oxygen in the nanomolar range which -for some, yet unconstrained, reason -are prevented from becoming anoxic. One reason for this may be the low productivity of the BoB waters due to nutrient limitation and the resulting lack of respiration of organic material at intermediate waters. Thus, the parameters determining primary production are key in understanding what prevents the BoB from developing anoxia. Primary productivity in the sunlit surface layers of tropical oceans is mostly limited by the supply of reactive nitrogen through upwelling, riverine flux, atmospheric deposition, and biological dinitrogen (N 2 ) fixation. In the BoB, a stable stratification limits nutrient supply via upwelling in the open waters, and riverine or atmospheric fluxes have been shown to support only less than one-quarter of the nitrogen for primary production. This leaves a large uncertainty for most of the BoB's nitrogen input, suggesting a potential role of N 2 fixation in those waters.Here, we present a survey of N 2 fixation and carbon fixation in the BoB during the winter monsoon season. We detected a community of N 2 fixers comparable to other oxygen minimum zone (OMZ) regions, with only a few cyanobacterial clades and a broad diversity of non-phototrophic N 2 fixers present throughout the water column (samples collected between 10 and 560 m water depth). While similar communities of N 2 fixers were shown to actively fix N 2 in other OMZs, N 2 fixation rates were below the detection limit in our samples covering the water column between the deep chlorophyll maximum and the OMZ. Consistent with this, no N 2 fixation signal was visible in δ 15 N signatures. We sug-gest that the absence of N 2 fixation may be a consequence of a micronutrient limitation or of an O 2 sensitivity of the OMZ diazotrophs in the BoB. Exploring how the onset of N 2 fixation by cyanobacteria compared to non-phototrophic N 2 fixers would impact on OMZ O 2 concentrations, a simple model exercise was carried out. We observed that both photic-zone-based and OMZ-based N 2 fixation are very sensitive to even minimal changes in water column stratification, with stronger mixing increasing organic matter production and export, which can exhaust remaining O 2 traces in the BoB.

show abstract

Section: Resultssupporting

confidence: 91%

No nitrogen fixation in the Bay of Bengal?

et al. 2020

View full text Add to dashboard Cite

show abstract

“…These variations in response of marine photosynthetic microbial community towards elevated pCO 2 confirm that response towards OA is species specific (Price et al, 2011). This species specificity entails that the action of natural selection could differ among (Eggers et al, 2014;Shetye et al, 2013) Trace gases emission Global climate change Decline in pH can decrease trace gases emission from marine source (Hopkins et al, 2010) Nitrogen fixation Nitrogen source to ocean Effect of pH shift depends on the organism and availability of trace metals N 2 fixation may increase or decrease (Shetye et al, 2013;Shi et al, 2010) Community composition Ecological balance Can considerably transform the community composition of ocean. Thus, affects overall microbial loop (Weinbauer et al, 2011) Organic matter degradation Nutrient recycling Decline in pH increases the polysaccharide and other organic matter degradation (Piontek et al, 2010) Enzymatic activity Degradation and recycling Protease and glucosidase activity decreases at low pH whereas lipase activity declines at elevated pCO 2 (Yamada and Suzumura, 2010) Quorum sensing Cell-cell interaction Increase the growth of pathogenic microbes nearby corals (Generous, 2014) organisms (Collins et al, 2014).…”

Section: Microbial Based Primary Productivitysupporting

confidence: 53%

“…Short-term studies on Trichodesmium spp. reveal that OA or elevated pCO 2 will substantially increase the N 2 fixation Levitan et al, 2007;Shetye et al, 2013). This enhanced N 2 fixation is due to an increase in the availability of energetic resources for cellular processes under elevated CO 2 , which also catalyzes the conversion between CO 2 and HCO 3 À (Kranz et al, 2009(Kranz et al, , 2010.…”

Section: Nitrogen Fixationmentioning

confidence: 98%

Ocean acidification and marine microorganisms: responses and consequences

Das

Mangwani

2015

Oceanologia

View full text Add to dashboard Cite

“…At elevated temperature due to recent ocean warming, the higher rates of respiration and the relative low oxygen concentration in warm seawater are advantageous to keep the nitrogen-fixing cells anoxic for a better nitrogenase activity. Trichodesmium erythraeum bloom in high pCO 2 waters of the Bay has been reported (Shetye et al 2013). Therefore, in future, as climate becomes warmer due to rise in CO 2 , increase in N 2 fixation could be observed due to increase in temperature (Boyd and Doney 2002) or high CO 2 (Hutchins et al 2007, Levitan et al 2007, Fu et al 2008.…”

Section: Discussionmentioning

confidence: 98%

Dinitrogen fixation rates in the Bay of Bengal during summer monsoon

Saxena

Sahoo

Khan

et al. 2020

Environ. Res. Commun.

View full text Add to dashboard Cite

Biological dinitrogen (N 2 ) fixation exerts an important control on oceanic primary production by providing bioavailable form of nitrogen (such as ammonium) to photosynthetic microorganisms. N 2 fixation is dominant in nutrient poor and warm surface waters. The Bay of Bengal is one such region where no measurements of phototrophic N 2 fixation rates exist. The surface water of the Bay of Bengal is generally nitrate-poor and warm due to prevailing stratification and thus, could favour N 2 fixation. We commenced the first N 2 fixation study in the photic zone of the Bay of Bengal using 15 N 2 gas tracer incubation experiment during summer monsoon 2018. We collected seawater samples from four depths (covering the mixed layer depth of up to 75 m) at eight stations. N 2 fixation rates varied from 4 to 75 μmol N m −2 d −1 . The contribution of N 2 fixation to primary production was negligible (<1%). However, the upper bound of observed N 2 fixation rates is higher than the rates measured in other oceanic regimes, such as the Eastern Tropical South Pacific, the Tropical Northwest Atlantic, and the Equatorial and Southern Indian Ocean.

show abstract

Occurrence of Nitrogen Fixing Cyanobacterium Trichodesmium under Elevated pCO₂ Conditions in the Western Bay of Bengal

Cited by 22 publications

References 45 publications

No nitrogen fixation in the Bay of Bengal?

No nitrogen fixation in the Bay of Bengal?

Ocean acidification and marine microorganisms: responses and consequences

Dinitrogen fixation rates in the Bay of Bengal during summer monsoon

Contact Info

Product

Resources

About