The marine planktonic cyanobacteria Trichodesmium spp.: photosynthetic rate measurements in the SW Atlantic Ocean

Carpenter, E. J.; Roenneberg, Till

doi:10.3354/meps118267

Cited by 61 publications

(58 citation statements)

References 18 publications

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“…4 below) or gross N utilization may be underestimated if alternative N sources are taken up Mulholland et al, 1999a, b). On the other hand, carbon fixation rates may be stoichiometrically higher than expected, based on the elemental ratio of cells, if carbon is used as ballast for vertical migration (Villareal and Carpenter, 1990;Romans et al, 1994;Gallon et al, 1996), if substantial carbon is excreted as mucilage or extracellular polymeric substances (Stal, 1995;Sellner, 1997), to support the high observed respiration rates by Trichodesmium (Kana, 1993;Carpenter and Roenneberg, 1995), or if cells "overfix" carbon to support Mehler reactions to reduce cellular oxygen concentrations or support the production of ATP (Kana, 1992(Kana, , 1993. Kana (1993) estimated that 48% of gross photosynthetic electron flow went to oxygen reduction.…”

Section: Carbon Fixationmentioning

confidence: 99%

The fate of nitrogen fixed by diazotrophs in the ocean

2007

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Abstract. While we now know that N 2 fixation is a significant source of new nitrogen (N) in the marine environment, little is known about the fate of this N (and associated C), despite the importance of diazotrophs to global carbon and nutrient cycles. Specifically, does N fixed during N 2 fixation fuel autotrophic or heterotrophic growth and thus facilitate carbon (C) export from the euphotic zone, or does it contribute primarily to bacterial productivity and respiration in the euphotic zone? For Trichodesmium, the diazotroph we know the most about, the transfer of recently fixed N 2 (and C) appears to be primarily through dissolved pools. The release of N varies among and within populations and as a result of the changing physiological state of cells and populations. The net result of trophic transfers appears to depend on the co-occurring organisms and the complexity of the colonizing community. In order to understand the impact of diazotrophy on carbon flow and export in marine systems, we need a better understanding of the trophic flow of elements in Trichodesmium-dominated communities and other diazotrophic communities under various defined physiological states. Nitrogen and carbon fixation rates themselves vary by orders of magnitude within and among studies of Trichodesmium, highlighting the difficulty in extrapolating global rates of N 2 fixation from direct measurements. Because the stoichiometry of N 2 and C fixation does not appear to be in balance with that of particles, and the relationship between C and N 2 fixation rates is also variable, it is equally difficult to derive global rates of one from the other. This paper seeks to synthesize what is known about the fate of diazotrophic production in the environment. A better understanding of the physiology and physiological ecology of Trichodesmium and other marine diazotrophs is necessary to quantify and predict the effects of increased or decreased diazotrophy in the context of the carbon cycle and global change.

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Section: Carbon Fixationmentioning

confidence: 99%

The fate of nitrogen fixed by diazotrophs in the ocean

2007

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“…As reported in both culture and field studies, Trichodesmium usually exhibits a higher CF : NF ratio than the expected stoichiometric value of 6.6 (Mulholland, 2007). Several hypotheses have been proposed: (1) the underestimation of gross NF rates by overlooking the 15 N signal in the dissolved pool (Glibert and Bronk, 1994;Mulholland et al, 2004); (2) the underestimation of N assimilation rates if there is uptake of other N sources such as nitrate or ammonium (Mulholland et al, 1999); (3) high carbon requirements to synthesize carbohydrate as a ballast for vertical migration (Villareal and Carpenter, 1990); (4) the support of the high energy cost, high respiration and Mehler reaction pathways (Carpenter and Roenneberg, 1995); and (5) the CF by non-diazotrophic phytoplankton. Here, the low DDN net release rate is not supportive of the first hypothesis.…”

Section: Metabolism Tradeoff Between Carbon and Nitrogen Fixation Undmentioning

confidence: 99%

“…Regarding the light response of Trichodesmium, several previous field studies put efforts into carbon fixation (CF) and oxygen production in response to irradiance (PI curve) and showed that photosynthetic rates of Trichodesmium were proportional to light intensities, and a relatively high irradiance requirement and a high respiration rate were needed to protect the nitrogenase enzyme from O 2 deactivation (Lewis et al, 1988;Carpenter and Roenneberg, 1995). By using the C 2 H 2 reduction method, Carpenter et al (1993) investigated the light response of nitrogenase activity for the fieldtowed Trichodesmium, which showed a response pattern as a function of irradiance and resembling the PI curve.…”

Section: Introductionmentioning

confidence: 99%

Effect of light on N<sub>2</sub> fixation and net nitrogen release of <i>Trichodesmium</i> in a field study

et al. 2018

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Abstract. Dinitrogen fixation (NF) by marine cyanobacteria is an important pathway to replenish the oceanic bioavailable nitrogen inventory. Light is the key to modulating NF; however, field studies investigating the light response curve (NF-I curve) of NF rate and the effect of light on diazotrophderived nitrogen (DDN) net release are relatively sparse in the literature, hampering prediction using models. A dissolution method was applied using uncontaminated 15 N 2 gas to examine how the light changes may influence the NF intensity and DDN net release in the oligotrophic ocean. Experiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium Trichodesmium spp. in the western Pacific and the South China Sea. The effect of light on carbon fixation (CF) was measured in parallel using the 13 C tracer method specifically for a station characterized by Trichodesmium bloom. Both NF-I and CF-I curves showed a I k (light saturation coefficient) range of 193 to 315 µE m −2 s −1 , with light saturation at around 400 µE m −2 s −1 . The proportion of DDN net release ranged from ∼ 6 to ∼ 50 %, suggesting an increasing trend as the light intensity decreased. At the Trichodesmium bloom station, we found that the CF / NF ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 200 µE m −2 s −1 . Under low-light stress, Trichodesmium physiologically preferred to allocate more energy for CF to alleviate the intensive carbon consumption by respiration; thus, there is a metabolism tradeoff between CF and NF pathways. Results showed that shortterm (< 24 h) light change modulates the physiological state, which subsequently determined the C / N metabolism and DDN net release by Trichodesmium. Reallocation of energy associated with the variation in light intensity would be helpful for prediction of the global biogeochemical cycle of N by models involving Trichodesmium blooms.

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“…nial cyanobacteria, Trichodesmium (Capone et al 1998;Carpenter and Roenneberg 1995;Davis et al 1992b). In addition to fragile forms, optical imaging also enables acquisition of high-resolution data on abundance of plankton, which can be compared with similar data on environmental variables including hydrography and fluorescence (e.g., Gallager et al 1996).…”

Section: Discussionmentioning

confidence: 99%

A three-axis fast-tow digital Video Plankton Recorder for rapid surveys of plankton taxa and hydrography

Davis

Thwaites

Gallager

et al. 2005

Limnol. Oceanogr. Methods

135

101

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A new Video Plankton Recorder (VPRII) has been developed for rapid surveys of plankton and seston in the size range of 100µm-1cm. The VPRII system includes: 1) a high-resolution digital camera (1Mpixel, 10-bits, 30Hz frame-rate), 2) a fast towfish capable of tow speeds up to 12 knots and 3-axis motion for automatic undulation and ship-wake avoidance, small diameter tow cable and winch for deployment on coastal vessels, and 3) new interface software (Visual Plankton) for automatic identification of plankton to major taxa and visualization of these taxa together with hydrographic data in real time. Camera and strobe optics are laboratory-adjusted to select the field-of-view (5-20mm), and depth-of-field is objectively calibrated using a tethered organism (e.g., copepod) and automatic focus-detection software. The VPRII towfish comprises a fuselage, a fixed main wing, and three servo-controlled tail fins: port and starboard for dive, climb, and roll control and rudder for lateral movement. Placement of the strobe (starboard wing-tip), camera (fuselage nose), and cantilevered tow-bridle minimize disturbance of the imaged volume. Compared with typical net surveys in shelf areas, the VPRII counts more plankton per station, quantifies ubiquitous fragile forms, automatically identifies plankton to major taxa and measures their size, quantifies scales of patchiness down to a few cm, and displays high-resolution distributions of plankton taxa and hydrography while underway. The VPRII is available to researchers via the Woods Hole Oceanographic Institution ship instrumentation pool. AcknowledgmentsWe thank the officers and crew of the R/V Oceanus for their support during field tests of the new VPR system. Engineers Pierre Tillier, Ken Peal, Nick Witzel, Ed Hobart, and Steve Faluotico made valuable contributions to the design and construction of the new VPR. Others involved in this project include

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The marine planktonic cyanobacteria Trichodesmium spp.: photosynthetic rate measurements in the SW Atlantic Ocean

Cited by 61 publications

References 18 publications

The fate of nitrogen fixed by diazotrophs in the ocean

The fate of nitrogen fixed by diazotrophs in the ocean

Effect of light on N<sub>2</sub> fixation and net nitrogen release of <i>Trichodesmium</i> in a field study

A three-axis fast-tow digital Video Plankton Recorder for rapid surveys of plankton taxa and hydrography

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The marine planktonic cyanobacteria Trichodesmium spp.: photosynthetic rate measurements in the SW Atlantic Ocean

Cited by 61 publications

References 18 publications

The fate of nitrogen fixed by diazotrophs in the ocean

The fate of nitrogen fixed by diazotrophs in the ocean

Effect of light on N&lt;sub&gt;2&lt;/sub&gt; fixation and net nitrogen release of &lt;i&gt;Trichodesmium&lt;/i&gt; in a field study

A three-axis fast-tow digital Video Plankton Recorder for rapid surveys of plankton taxa and hydrography

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Effect of light on N<sub>2</sub> fixation and net nitrogen release of <i>Trichodesmium</i> in a field study