Статті в журналах: "Heterogeneity in phytoplankton stoichiometry"

1

Paul, Allanah Joy, Lennart Thomas Bach, Javier Arístegui, Elisabeth von der Esch, Nauzet Hernández-Hernández, Jonna Piiparinen, Laura Ramajo, Kristian Spilling, and Ulf Riebesell. "Upwelled plankton community modulates surface bloom succession and nutrient availability in a natural plankton assemblage." Biogeosciences 19, no. 24 (December 21, 2022): 5911–26. http://dx.doi.org/10.5194/bg-19-5911-2022.

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Abstract. Upwelling of nutrient-rich waters into the sunlit surface layer of the ocean supports high primary productivity in eastern boundary upwelling systems (EBUSs). However, subsurface waters contain not only macronutrients (N, P, Si) but also micronutrients, organic matter and seed microbial communities that may modify the response to macronutrient inputs via upwelling. These additional factors are often neglected when investigating upwelling impacts on surface ocean productivity. Here, we investigated how different components of upwelled water (macronutrients, organic nutrients and seed communities) drive the response of surface plankton communities to upwelling in the Peruvian coastal zone. Results from our short-term (10 d) study show that the most influential drivers in upwelled deep water are (1) the ratio of inorganic nutrients (NOx : PO43-) and (2) the microbial community present that can seed heterogeneity in phytoplankton succession and modify the stoichiometry of residual inorganic nutrients after phytoplankton blooms. Hence, this study suggests that phytoplankton succession after upwelling is modified by factors other than the physical supply of inorganic nutrients. This would likely affect trophic transfer and overall productivity in these highly fertile marine ecosystems.

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2

Conan, Pascal, Mireille Pujo-Pay, Marina Agab, Laura Calva-Benítez, Sandrine Chifflet, Pascal Douillet, Claire Dussud, et al. "Biogeochemical cycling and phyto- and bacterioplankton communities in a large and shallow tropical lagoon (Términos Lagoon, Mexico) under 2009–2010 El Niño Modoki drought conditions." Biogeosciences 14, no. 4 (March 2, 2017): 959–75. http://dx.doi.org/10.5194/bg-14-959-2017.

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Abstract. The 2009–2010 period was marked by an episode of intense drought known as the El Niño Modoki event. Sampling of the Términos Lagoon (Mexico) was carried out in November 2009 in order to understand the influence of these particular environmental conditions on organic matter fluxes within the lagoon's pelagic ecosystem and, more specifically, on the relationship between phyto- and bacterioplankton communities. The measurements presented here concern biogeochemical parameters (nutrients, dissolved and particulate organic matter [POM], and dissolved polycyclic aromatic hydrocarbons [PAHs]), phytoplankton (biomass and photosynthesis), and bacteria (diversity and abundance, including PAH degradation bacteria and ectoenzymatic activities). During the studied period, the water column of the Términos Lagoon functioned globally as a sink and, more precisely, as a nitrogen assimilator. This was due to the high production of particulate and dissolved organic matter (DOM), even though exportation of autochthonous matter to the Gulf of Mexico was weak. We found that bottom-up control accounted for a large portion of the variability of phytoplankton productivity. Nitrogen and phosphorus stoichiometry mostly accounted for the heterogeneity in phytoplankton and free-living prokaryote distribution in the lagoon. In the eastern part, we found a clear decoupling between areas enriched in dissolved inorganic nitrogen near the Puerto Real coastal inlet and areas enriched in phosphate (PO4) near the Candelaria estuary. Such a decoupling limited the potential for primary production, resulting in an accumulation of dissolved organic carbon and nitrogen (DOC and DON, respectively) near the river mouths. In the western part of the lagoon, maximal phytoplankton development resulted from bacterial activity transforming particulate organic phosphorus (PP) and dissolved organic phosphorus (DOP) to available PO4 and the coupling between Palizada River inputs of nitrate (NO3) and PP. The Chumpan River contributed only marginally to PO4 inputs due to its very low contribution to overall river inputs. The highest dissolved total PAH concentrations were measured in the El Carmen Inlet, suggesting that the anthropogenic pollution of the zone is probably related to the oil-platform exploitation activities in the shallow waters of the southern of the Gulf of Mexico. We also found that a complex array of biogeochemical and phytoplanktonic parameters were the driving force behind the geographical distribution of bacterial community structure and activities. Finally, we showed that nutrients brought by the Palizada River supported an abundant bacterial community of PAH degraders, which are of significance in this important oil-production zone.

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Klausmeier, C. A., E. Litchman, T. Daufresne, and S. A. Levin. "Phytoplankton stoichiometry." Ecological Research 23, no. 3 (March 6, 2008): 479–85. http://dx.doi.org/10.1007/s11284-008-0470-8.

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Klausmeier, Christopher A., Elena Litchman, Tanguy Daufresne, and Simon A. Levin. "Optimal nitrogen-to-phosphorus stoichiometry of phytoplankton." Nature 429, no. 6988 (May 2004): 171–74. http://dx.doi.org/10.1038/nature02454.

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Quigg, Antonietta, Andrew J. Irwin, and Zoe V. Finkel. "Evolutionary inheritance of elemental stoichiometry in phytoplankton." Proceedings of the Royal Society B: Biological Sciences 278, no. 1705 (September 8, 2010): 526–34. http://dx.doi.org/10.1098/rspb.2010.1356.

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The elemental composition of phytoplankton is a fusion of the evolutionary history of the host and plastid, resulting in differences in genetic constraints and selection pressures associated with environmental conditions. The evolutionary inheritance hypothesis predicts similarities in elemental composition within related taxonomic lineages of phytoplankton. To test this hypothesis, we measured the elemental composition (C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Cd and Mo) of 14 phytoplankton species and combined these with published data from 15 more species from both marine and freshwater environments grown under nutrient-replete conditions. The largest differences in the elemental profiles of the species distinguish between the prokaryotic Cyanophyta and primary endosymbiotic events that resulted in the green and red plastid lineages. Smaller differences in trace element stoichiometry within the red and green plastid lineages are consistent with changes in trace elemental stoichiometry owing to the processes associated with secondary endosymbioses and inheritance by descent with modification.

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6

Bahamondes Dominguez, Angela A., Anna E. Hickman, Robert Marsh, and C. Mark Moore. "Constraining the response of phytoplankton to zooplankton grazing and photo-acclimation in a temperate shelf sea with a 1-D model – towards S2P3 v8.0." Geoscientific Model Development 13, no. 9 (September 4, 2020): 4019–40. http://dx.doi.org/10.5194/gmd-13-4019-2020.

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Abstract. An established one-dimensional Shelf Sea Physics and Primary Production (S2P3) model has been developed into three different new models: S2P3-NPZ which includes a nutrient–phytoplankton–zooplankton (NPZ) framework, where the grazing rate is no longer fixed but instead varies over time depending on different functions chosen to represent the predator–prey relationship between zooplankton and phytoplankton; S2P3-Photoacclim which includes a representation of the process of photo-acclimation and flexible stoichiometry in phytoplankton; and S2P3 v8.0 which combines the NPZ framework and the variable stoichiometry of phytoplankton at the same time. These model formulations are compared to buoy and conductivity–temperature–depth (CTD) observations, as well as zooplankton biomass and in situ phytoplankton physiological parameters obtained in the central Celtic Sea (CCS). Models were calibrated by comparison to observations of the timing and magnitude of the spring phytoplankton bloom, magnitude of the spring zooplankton bloom, and phytoplankton physiological parameters obtained throughout the water column. A sensitivity study was also performed for each model to understand the effects of individual parameters on model dynamics. Results demonstrate that better agreement with biological observations can be obtained through the addition of representations of photo-acclimation, flexible stoichiometry, and grazing provided these can be adequately constrained.

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Wagner, Nicole D., Felicia S. Osburn, Jingyu Wang, Raegyn B. Taylor, Ashlynn R. Boedecker, C. Kevin Chambliss, Bryan W. Brooks, and J. Thad Scott. "Biological Stoichiometry Regulates Toxin Production in Microcystis aeruginosa (UTEX 2385)." Toxins 11, no. 10 (October 16, 2019): 601. http://dx.doi.org/10.3390/toxins11100601.

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Harmful algal blooms (HABs) are increasing in magnitude, frequency, and duration globally. Even though a limited number of phytoplankton species can be toxic, they are becoming one of the greatest water quality threats to public health and ecosystems due to their intrinsic toxicity to humans and the numerous interacting factors that undermine HAB forecasting. Here, we show that the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of a common toxic phytoplankton species, Microcystis, regulates toxin quotas during blooms through a tradeoff between primary and secondary metabolism. Populations with optimal C:N (< 8) and C:P (< 200) cellular stoichiometry consistently produced more toxins than populations exhibiting stoichiometric plasticity. Phosphorus availability in water exerted a strong control on population biomass and C:P stoichiometry, but N availability exerted a stronger control on toxin quotas by regulating population biomass and C:N:P stoichiometry. Microcystin-LR, like many phytoplankton toxins, is an N-rich secondary metabolite with a C:N stoichiometry that is similar to the optimal growth stoichiometry of Microcystis. Thus, N availability relative to P and light provides a dual regulatory mechanism that controls both biomass production and cellular toxin synthesis. Overall, our results provide a quantitative framework for improving forecasting of toxin production during HABs and compelling support for water quality management that limit both N and P inputs from anthropogenic sources.

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8

Gormley-Gallagher, Aine M., Richard W. Douglas, and Brian Rippey. "Metal to phosphorus stoichiometries for freshwater phytoplankton in three remote lakes." PeerJ 4 (December 20, 2016): e2749. http://dx.doi.org/10.7717/peerj.2749.

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Simultaneous measurements of changes in phytoplankton biomass and the metal and phosphorus (P) content of cells have been captured to attest to metal to P stoichiometries for freshwater phytoplankton. Three Scottish lakes that had received high, medium or low metal contamination from the atmosphere were selected for study. Phytoplankton cells were collected and Inductively Coupled Plasma-Mass Spectrometry was used to measure their lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu), zinc (Zn), nickel (Ni), chromium (Cr), manganese (Mn), cobalt (Co) and P content. Increased phytoplankton growth in the lakes resulted in significant algae growth dilution of the mass-specific Pb, Cd, Hg, Cu, Ni and Cr in the phytoplankton. Changes in the phytoplankton cell count and their Hg, Pb, Cd, Cu, Mn, Co, Ni and Cr concentrations showed the process of algae bloom dilution to be subject to exponential decay, which accelerated in the order of Mn < Cu < Ni < Pb and Cd < Cr and Hg < Co. This indicated a metabolic and detoxification mechanism was involved in the active selection of metals. For the first time simultaneous measurements of metals and P stoichiometry in freshwater phytoplankton are reported. The mean metal to P stoichiometry generated was (C106P1N16)1000Pb0.019Hg0.00004Cu0.013Cd0.005Cr0.2Co0.0008Mn0.2Ni0.012based on field measurements and the Redfield average C, N and P stoichiometry of (CH2O)106(NH3)16H3PO4.

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9

李, 子尧. "Ecological Stoichiometry Characteristics of Phytoplankton in Taizicheng River." Advances in Environmental Protection 12, no. 02 (2022): 350–59. http://dx.doi.org/10.12677/aep.2022.122048.

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10

Martin, Ronald E., Antonietta Quigg, and Victor Podkovyrov. "Marine biodiversification in response to evolving phytoplankton stoichiometry." Palaeogeography, Palaeoclimatology, Palaeoecology 258, no. 4 (February 2008): 277–91. http://dx.doi.org/10.1016/j.palaeo.2007.11.003.

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11

Klausmeier, Christopher A., Elena Litchman, and Simon A. Levin. "Phytoplankton growth and stoichiometry under multiple nutrient limitation." Limnology and Oceanography 49, no. 4part2 (January 31, 2004): 1463–70. http://dx.doi.org/10.4319/lo.2004.49.4_part_2.1463.

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12

Finkel, Z. V., A. Quigg, J. A. Raven, J. R. Reinfelder, O. E. Schofield, and P. G. Falkowski. "Irradiance and the elemental stoichiometry of marine phytoplankton." Limnology and Oceanography 51, no. 6 (November 2006): 2690–701. http://dx.doi.org/10.4319/lo.2006.51.6.2690.

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13

Franz, J. M. S., H. Hauss, U. Sommer, T. Dittmar, and U. Riebesell. "Production, partitioning and stoichiometry of organic matter under variable nutrient supply during mesocosm experiments in the tropical Pacific and Atlantic Ocean." Biogeosciences Discussions 9, no. 5 (May 15, 2012): 5755–91. http://dx.doi.org/10.5194/bgd-9-5755-2012.

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Abstract. Oxygen-deficient waters in the ocean, generally referred to as oxygen minimum zones (OMZ), are expected to expand as a consequence of global climate change. Poor oxygenation is promoting microbial loss of inorganic nitrogen (N) and increasing release of sediment-bound phosphate (P) into the water column. These intermediate water masses, nutrient-loaded but with an N deficit relative to the canonical N:P Redfield ratio of 16:1, are transported via coastal upwelling into the euphotic zone. To test the impact of nutrient supply and nutrient stoichiometry on production, partitioning and elemental composition of phytoplankton-derived dissolved (DOC, DON, DOP) and particulate (POC, PON, POP) organic matter, three nutrient enrichment experiments were conducted with natural phytoplankton communities in shipboard mesocosms, during research cruises in the tropical waters of the South East Pacific and the North East Atlantic. Maximum accumulation of POC and PON was observed under high N supply conditions, indicating that primary production was controlled by N availability. The stoichiometry of photoautotrophic biomass was unaffected by nutrient N:P supply during exponential growth under nutrient saturation, while it was highly variable under conditions of nutrient limitation and closely correlated to the N:P supply ratio, although PON:POP of accumulated phytoplankton generally exceeded the supply ratio. Phytoplankton N:P composition was constrained by a general lower limit of 5:1. Channelling of assimilated P into DOP appears to be the mechanism responsible for the consistent offset of cellular stoichiometry relative to inorganic nutrient supply and nutrient drawdown, as DOP build-up was observed to intensify under decreasing N:P supply. Low nutrient N:P conditions in coastal upwelling areas overlying O2-deficient waters seem to represent a net source for DOP, which may stimulate growth of diazotrophic phytoplankton. These results demonstrate that microalgal nutrient assimilation and partitioning of phytoplankton-derived organic matter between the particulate and the dissolved phase are controlled by the N:P ratio of upwelled nutrients, implying substantial consequences for nutrient cycling and organic matter pools in the course of decreasing nutrient N:P stoichiometry.

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14

Yin, Kedong, Hao Liu, and Paul J. Harrison. "Sequential nutrient uptake as a potential mechanism for phytoplankton to maintain high primary productivity and balanced nutrient stoichiometry." Biogeosciences 14, no. 9 (May 16, 2017): 2469–80. http://dx.doi.org/10.5194/bg-14-2469-2017.

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Abstract. We hypothesize that phytoplankton have the sequential nutrient uptake strategy to maintain nutrient stoichiometry and high primary productivity in the water column. According to this hypothesis, phytoplankton take up the most limiting nutrient first until depletion, continue to draw down non-limiting nutrients and then take up the most limiting nutrient rapidly when it is available. These processes would result in the variation of ambient nutrient ratios in the water column around the Redfield ratio. We used high-resolution continuous vertical profiles of nutrients, nutrient ratios and on-board ship incubation experiments to test this hypothesis in the Strait of Georgia. At the surface in summer, ambient NO3− was depleted with excess PO43− and SiO4− remaining, and as a result, both N : P and N : Si ratios were low. The two ratios increased to about 10 : 1 and 0. 45 : 1, respectively, at 20 m. Time series of vertical profiles showed that the leftover PO43− continued to be removed, resulting in additional phosphorus storage by phytoplankton. The N : P ratios at the nutricline in vertical profiles responded differently to mixing events. Field incubation of seawater samples also demonstrated the sequential uptake of NO3− (the most limiting nutrient) and then PO43− and SiO4− (the non-limiting nutrients). This sequential uptake strategy allows phytoplankton to acquire additional cellular phosphorus and silicon when they are available and wait for nitrogen to become available through frequent mixing of NO3− (or pulsed regenerated NH4). Thus, phytoplankton are able to maintain high productivity and balance nutrient stoichiometry by taking advantage of vigorous mixing regimes with the capacity of the stoichiometric plasticity. To our knowledge, this is the first study to show the in situ dynamics of continuous vertical profiles of N : P and N : Si ratios, which can provide insight into the in situ dynamics of nutrient stoichiometry in the water column and the inference of the transient status of phytoplankton nutrient stoichiometry in the coastal ocean.

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Lenton, T. M., and C. A. Klausmeier. "Biotic stoichiometric controls on the deep ocean N:P ratio." Biogeosciences Discussions 4, no. 1 (February 8, 2007): 417–54. http://dx.doi.org/10.5194/bgd-4-417-2007.

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Abstract. We re-examine what controls the deep ocean N:P ratio in the light of recent findings that the C:N:P stoichiometry of phytoplankton varies with growth rate, nutrient and light limitation, species and phylum, and that N2-fixation may be limited by Fe or light in large parts of the world ocean. In particular, we assess whether a systematic change in phytoplankton stoichiometry can alter the deep ocean N:P ratio. To do this we adapt recent models to include non-Redfieldian stoichiometry of phytoplankton and restriction of N2-fixers to a fraction of the surface ocean. We show that a systematic change in phytoplankton C:N:P can alter the concentrations of NO3 and PO4 in the deep ocean but cannot greatly alter their ratio, unless it also alters the N:P threshold for N2-fixation. This occurs if competitive dynamics set the N:P threshold for N2-fixation, in which case it remains close to the N:P requirement of non-fixers (rather than that of N2-fixers) and consequently so does the deep ocean N:P ratio. Then, even if N2-fixers are restricted to a fraction of the surface ocean, they reach higher densities there, minimising variations in deep ocean N:P. Theoretical limits on the N:P requirements of phytoplankton suggest that since the deep ocean became well oxygenated, its N:P ratio is unlikely to have varied by more than a factor of two in either direction. Within these bounds, evolutionary changes in phytoplankton composition, and increased phosphorus weathering due to the biological colonisation of the land surface, are predicted to have driven long-term changes in ocean composition.

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Martin, Ronald, and Antonietta Quigg. "Evolving Phytoplankton Stoichiometry Fueled Diversification of the Marine Biosphere." Geosciences 2, no. 2 (May 31, 2012): 130–46. http://dx.doi.org/10.3390/geosciences2020130.

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Beardall, John, Drew Allen, Jason Bragg, Zoe V. Finkel, Kevin J. Flynn, Antonietta Quigg, T. Alwyn V. Rees, Anthony Richardson, and John A. Raven. "Allometry and stoichiometry of unicellular, colonial and multicellular phytoplankton." New Phytologist 181, no. 2 (November 5, 2008): 295–309. http://dx.doi.org/10.1111/j.1469-8137.2008.02660.x.

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18

Quigg, Antonietta, Zoe V. Finkel, Andrew J. Irwin, Yair Rosenthal, Tung-Yuan Ho, John R. Reinfelder, Oscar Schofield, Francois M. M. Morel, and Paul G. Falkowski. "The evolutionary inheritance of elemental stoichiometry in marine phytoplankton." Nature 425, no. 6955 (September 2003): 291–94. http://dx.doi.org/10.1038/nature01953.

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DANGER, M., C. OUMAROU, D. BENEST, and G. LACROIX. "Bacteria can control stoichiometry and nutrient limitation of phytoplankton." Functional Ecology 21, no. 2 (April 2007): 202–10. http://dx.doi.org/10.1111/j.1365-2435.2006.01222.x.

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20

Dickman, Elizabeth M., Michael J. Vanni, and Martin J. Horgan. "Interactive effects of light and nutrients on phytoplankton stoichiometry." Oecologia 149, no. 4 (July 6, 2006): 676–89. http://dx.doi.org/10.1007/s00442-006-0473-5.

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21

Moreno, Allison R., George I. Hagstrom, Francois W. Primeau, Simon A. Levin, and Adam C. Martiny. "Marine phytoplankton stoichiometry mediates nonlinear interactions between nutrient supply, temperature, and atmospheric CO<sub>2</sub>." Biogeosciences 15, no. 9 (May 9, 2018): 2761–79. http://dx.doi.org/10.5194/bg-15-2761-2018.

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Abstract. Marine phytoplankton stoichiometry links nutrient supply to marine carbon export. Deviations of phytoplankton stoichiometry from Redfield proportions (106C : 1P) could therefore have a significant impact on carbon cycling, and understanding which environmental factors drive these deviations may reveal new mechanisms regulating the carbon cycle. To explore the links between environmental conditions, stoichiometry, and carbon cycling, we compared four different models of phytoplankton C : P: a fixed Redfield model, a model with C : P given as a function of surface phosphorus concentration (P), a model with C P given as a function of temperature, and a new multi-environmental model that predicts C : P as a function of light, temperature, and P. These stoichiometric models were embedded into a five-box ocean circulation model, which resolves the three major ocean biomes (high-latitude, subtropical gyres, and tropical upwelling regions). Contrary to the expectation of a monotonic relationship between surface nutrient drawdown and carbon export, we found that lateral nutrient transport from lower C : P tropical waters to high C : P subtropical waters could cause carbon export to decrease with increased tropical nutrient utilization. It has been hypothesized that a positive feedback between temperature and pCO2, atm will play an important role in anthropogenic climate change, with changes in the biological pump playing at most a secondary role. Here we show that environmentally driven shifts in stoichiometry make the biological pump more influential, and may reverse the expected positive relationship between temperature and pCO2, atm. In the temperature-only model, changes in tropical temperature have more impact on the Δ pCO2, atm (∼ 41 ppm) compared to subtropical temperature changes (∼ 4.5 ppm). Our multi-environmental model predicted a decline in pCO2, atm of ∼ 46 ppm when temperature spanned a change of 10 °C. Thus, we find that variation in marine phytoplankton stoichiometry and its environmental controlling factors can lead to nonlinear controls on pCO2, atm, suggesting the need for further studies of ocean C : P and the impact on ocean carbon cycling.

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22

Lenton, T. M., and C. A. Klausmeier. "Biotic stoichiometric controls on the deep ocean N:P ratio." Biogeosciences 4, no. 3 (June 20, 2007): 353–67. http://dx.doi.org/10.5194/bg-4-353-2007.

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Abstract. We re-examine what controls the deep ocean N:P ratio in the light of recent findings that the C:N:P stoichiometry of phytoplankton varies with growth rate, nutrient and light limitation, species and phylum, and that N2-fixation may be limited by Fe, temperature and/or light in large parts of the world ocean. In particular, we assess whether a systematic change in phytoplankton stoichiometry can alter the deep ocean N:P ratio. To do this we adapt recent models to include non-Redfieldian stoichiometry of phytoplankton and restriction of N2-fixers to a fraction of the surface ocean. We show that a systematic change in phytoplankton C:N:P can alter the concentrations of NO3 and PO4 in the deep ocean but cannot greatly alter their ratio, unless it also alters the N:P threshold for N2-fixation. This occurs if competitive dynamics set the N:P threshold for N2-fixation, in which case it remains close to the N:P requirement of non-fixers (rather than that of N2-fixers) and consequently so does the deep ocean N:P ratio. Then, even if N2-fixers are restricted to a fraction of the surface ocean, they reach higher densities there, minimising variations in deep ocean N:P. Theoretical limits on the N:P requirements of phytoplankton suggest that whilst the deep ocean has been well oxygenated (i.e. since the Neoproterozoic, with the possible exception of Oceanic Anoxic Events), its N:P ratio is unlikely to have varied by more than a factor of two in either direction. Within these bounds, evolutionary changes in phytoplankton composition, and increased phosphorus weathering due to the biological colonisation of the land surface, are predicted to have driven long-term changes in ocean composition.

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23

Bonachela, J. A., S. D. Allison, A. C. Martiny, and S. A. Levin. "A model for variable phytoplankton stoichiometry based on cell protein regulation." Biogeosciences 10, no. 6 (June 27, 2013): 4341–56. http://dx.doi.org/10.5194/bg-10-4341-2013.

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Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. When different species compete, the existence of a wide co-limitation zone implies a more complex pattern of coexistence and exclusion compared to previous model predictions. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.

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Bonachela, J. A., S. D. Allison, A. C. Martiny, and S. A. Levin. "A model for variable phytoplankton stoichiometry based on cell protein regulation." Biogeosciences Discussions 10, no. 2 (February 21, 2013): 3241–79. http://dx.doi.org/10.5194/bgd-10-3241-2013.

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Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. The existence of a wide co-limitation zone affects the standard picture for species competing for nitrogen and phosphorus, which shows here a much richer pattern. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.

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25

Lenton, T. M., and C. A. Klausmeier. "Co-evolution of phytoplankton C:N:P stoichiometry and the deep ocean N:P ratio." Biogeosciences Discussions 3, no. 4 (July 17, 2006): 1023–47. http://dx.doi.org/10.5194/bgd-3-1023-2006.

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Abstract. There is a long-established, remarkable correspondence between the nitrogen-to-phosphorus ratio N:P~15 of deep ocean water and the ''Redfield ratio'' of N:P~16 required by phytoplankton. Redfield and subsequent workers have suggested that it is due to N-fixing organisms being selected when N:P<16 but being out-competed when N:P>16. Models have shown this mechanism can work, but recent observations reveal that the real system is more complex. First, the C:N:P stoichiometry of phytoplankton varies with growth rate, nutrient and light limitation, species and phylum. Second, although N-fixation is sometimes P-limited and suppressed by N-addition, there is also evidence for Fe-limitation, light-limitation and P and Fe co-limitation of N-fixers. Here we adapt recent models to include non-Redfieldian stoichiometry of phytoplankton and limitation of N-fixers by resources other than P. We show that the deep ocean N:P is set by the N:P threshold that triggers N-fixation, and is not directly related to the N:P ratio of sinking material. However, assuming competitive dynamics set the N:P threshold for N-fixation, it will be close to the N:P requirement of non-fixers (rather than that of N-fixers) and consequently so will the deep ocean N:P ratio. Theoretical limits on the N:P requirements of phytoplankton suggest that since the deep ocean became well oxygenated, its N:P has remained within the range 7.7–32.3. Decreases in phytoplankton C:P and N:P ratios over the past ~1 Gyr are predicted to have driven a decrease in deep ocean N:P, probably via increasing PO4. Even if Fe or light limitation restrict N-fixers to a fraction of the surface ocean, they reach higher densities there, minimising variations in deep ocean N:P. Thus Redfield's mechanism is robust and we expand it to suggest that phytoplankton C:N:P and deep ocean N:P have co-evolved.

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Beisner, Beatrix E. "Herbivory in variable environments: an experimental test of the effects of vertical mixing and Daphnia on phytoplankton community structure." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 7 (July 1, 2001): 1371–79. http://dx.doi.org/10.1139/f01-080.

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Phytoplankton communities in lakes are exposed to different within-season frequencies of heterogeneity in resource supply because of wind-induced vertical mixing. Effects of such heterogeneity, in conjunction with herbivory, on phytoplankton community structure have rarely been simultaneously examined, despite the fact that each factor can have large effects on phytoplankton composition and diversity. This study uses replicated oligotrophic mesocosms to examine the effects of herbivory and different scales of temporal heterogeneity in deepwater mixing. The pattern of vertical mixing alone had minor effects on phytoplankton community diversity and composition. The herbivore Daphnia caused a shift in phytoplankton composition to less edible types, based mainly on morphological features (spiny shapes and trichomes on cell walls) rather than size structure alone. Phytoplankton richness depended jointly on mixing frequency and large Daphnia biomasses. When systems were well mixed, with high encounter rates between predator and prey populations, phytoplankton community richness was lowest. By contrast, the systems that were least often mixed had highest richness. These results are related to limited encounter rates with infrequent mixing and to the availability of refuges from predation. Responses to different scales of temporal heterogeneity in these oligotrophic phytoplankton communities depend more on Daphnia feeding than on resource pulsing.

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Matsumoto, Katsumi, Tatsuro Tanioka, and Jacob Zahn. "MESMO 3: Flexible phytoplankton stoichiometry and refractory dissolved organic matter." Geoscientific Model Development 14, no. 4 (April 30, 2021): 2265–88. http://dx.doi.org/10.5194/gmd-14-2265-2021.

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Abstract. We describe the third version of Minnesota Earth System Model for Ocean biogeochemistry (MESMO 3), an Earth system model of intermediate complexity, with a dynamical ocean, dynamic–thermodynamic sea ice, and an energy–moisture-balanced atmosphere. A major feature of version 3 is the flexible C:N:P ratio for the three phytoplankton functional types represented in the model. The flexible stoichiometry is based on the power law formulation with environmental dependence on phosphate, nitrate, temperature, and light. Other new features include nitrogen fixation, water column denitrification, oxygen and temperature-dependent organic matter remineralization, and CaCO3 production based on the concept of the residual nitrate potential growth. In addition, we describe the semi-labile and refractory dissolved organic pools of C, N, P, and Fe that can be enabled in MESMO 3 as an optional feature. The refractory dissolved organic matter can be degraded by photodegradation at the surface and hydrothermal vent degradation at the bottom. These improvements provide a basis for using MESMO 3 in further investigations of the global marine carbon cycle to changes in the environmental conditions of the past, present, and future.

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McCain, J. Scott P., and Erin M. Bertrand. "Phytoplankton antioxidant systems and their contributions to cellular elemental stoichiometry." Limnology and Oceanography Letters 7, no. 2 (December 25, 2021): 96–111. http://dx.doi.org/10.1002/lol2.10233.

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29

Sañudo-Wilhelmy, Sergio A., Antonio Tovar-Sanchez, Fei-Xue Fu, Douglas G. Capone, Edward J. Carpenter, and David A. Hutchins. "The impact of surface-adsorbed phosphorus on phytoplankton Redfield stoichiometry." Nature 432, no. 7019 (December 2004): 897–901. http://dx.doi.org/10.1038/nature03125.

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30

Finkel, Z. V., J. Beardall, K. J. Flynn, A. Quigg, T. A. V. Rees, and J. A. Raven. "Phytoplankton in a changing world: cell size and elemental stoichiometry." Journal of Plankton Research 32, no. 1 (October 28, 2009): 119–37. http://dx.doi.org/10.1093/plankt/fbp098.

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31

Bonachela, Juan A., Christopher A. Klausmeier, Kyle F. Edwards, Elena Litchman, and Simon A. Levin. "The role of phytoplankton diversity in the emergent oceanic stoichiometry." Journal of Plankton Research 38, no. 4 (October 19, 2015): 1021–35. http://dx.doi.org/10.1093/plankt/fbv087.

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32

Ward, Ben A. "Assessing an efficient “Instant Acclimation” approximation of dynamic phytoplankton stoichiometry." Journal of Plankton Research 39, no. 5 (August 10, 2017): 803–14. http://dx.doi.org/10.1093/plankt/fbx040.

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33

Li, Y., G. Gal, V. Makler-Pick, A. M. Waite, L. C. Bruce, and M. R. Hipsey. "Examination of the role of the microbial loop in regulating lake nutrient stoichiometry and phytoplankton dynamics." Biogeosciences 11, no. 11 (June 5, 2014): 2939–60. http://dx.doi.org/10.5194/bg-11-2939-2014.

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Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton has been investigated in Lake Kinneret (Israel) using a coupled hydrodynamic–ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering (i) the role of bacterial mineralisation, (ii) the effect of micrograzer excretion, and (iii) bacterial ability to compete for dissolved inorganic nutrients. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

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34

Li, Y., G. Gal, V. Makler-Pick, A. M. Waite, L. C. Bruce, and M. R. Hipsey. "A numerical analysis of the role of the microbial loop in regulating nutrient stoichiometry and phytoplankton dynamics in a eutrophic lake." Biogeosciences Discussions 10, no. 12 (December 16, 2013): 19731–72. http://dx.doi.org/10.5194/bgd-10-19731-2013.

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Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton is investigated in Lake Kinneret (Israel) using a coupled hydrodynamic-ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering: (i) the role of bacterial mineralization, (ii) bacterial ability to compete for dissolved inorganic nutrients, and (iii) the effect of micrograzer excretion. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

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35

Galbraith, Eric D., and Adam C. Martiny. "A simple nutrient-dependence mechanism for predicting the stoichiometry of marine ecosystems." Proceedings of the National Academy of Sciences 112, no. 27 (June 8, 2015): 8199–204. http://dx.doi.org/10.1073/pnas.1423917112.

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It is widely recognized that the stoichiometry of nutrient elements in phytoplankton varies within the ocean. However, there are many conflicting mechanistic explanations for this variability, and it is often ignored in global biogeochemical models and carbon cycle simulations. Here we show that globally distributed particulate P:C varies as a linear function of ambient phosphate concentrations, whereas the N:C varies with ambient nitrate concentrations, but only when nitrate is most scarce. This observation is consistent with the adjustment of the phytoplankton community to local nutrient availability, with greater flexibility of phytoplankton P:C because P is a less abundant cellular component than N. This simple relationship is shown to predict the large-scale, long-term average composition of surface particles throughout large parts of the ocean remarkably well. The relationship implies that most of the observed variation in N:P actually arises from a greater plasticity in the cellular P:C content, relative to N:C, such that as overall macronutrient concentrations decrease, N:P rises. Although other mechanisms are certainly also relevant, this simple relationship can be applied as a first-order basis for predicting organic matter stoichiometry in large-scale biogeochemical models, as illustrated using a simple box model. The results show that including variable P:C makes atmospheric CO2 more sensitive to changes in low latitude export and ocean circulation than a fixed-stoichiometry model. In addition, variable P:C weakens the relationship between preformed phosphate and atmospheric CO2 while implying a more important role for the nitrogen cycle.

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36

Duforêt-Gaurier, Lucile, David Dessailly, William Moutier, and Hubert Loisel. "Assessing the Impact of a Two-Layered Spherical Geometry of Phytoplankton Cells on the Bulk Backscattering Ratio of Marine Particulate Matter." Applied Sciences 8, no. 12 (December 19, 2018): 2689. http://dx.doi.org/10.3390/app8122689.

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The bulk backscattering ratio ( b b p ˜ ) is commonly used as a descriptor of the bulk real refractive index of the particulate assemblage in natural waters. Based on numerical simulations, we analyze the impact of modeled structural heterogeneity of phytoplankton cells on b b p ˜ . b b p ˜ is modeled considering viruses, heterotrophic bacteria, phytoplankton, organic detritus, and minerals. Three case studies are defined according to the relative abundance of the components. Two case studies represent typical situations in open ocean, oligotrophic waters, and phytoplankton bloom. The third case study is typical of coastal waters with the presence of minerals. Phytoplankton cells are modeled by a two-layered spherical geometry representing a chloroplast surrounding the cytoplasm. The b b p ˜ values are higher when structural heterogeneity is considered because the contribution of coated spheres to light backscattering is higher than homogeneous spheres. The impact of heterogeneity is; however, strongly conditioned by the hyperbolic slope ξ of the particle size distribution. Even if the relative abundance of phytoplankton is small (<1%), b b p ˜ increases by about 58% (for ξ = 4 and for oligotrophic waters), when the heterogeneity is taken into account, in comparison with a particulate population composed only of homogeneous spheres. As expected, heterogeneity has a much smaller impact (about 12% for ξ = 4 ) on b b p ˜ in the presence of suspended minerals, whose increased light scattering overwhelms that of phytoplankton.

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37

Armin, Gabrielle, and Keisuke Inomura. "Modeled temperature dependencies of macromolecular allocation and elemental stoichiometry in phytoplankton." Computational and Structural Biotechnology Journal 19 (2021): 5421–27. http://dx.doi.org/10.1016/j.csbj.2021.09.028.

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38

Diehl, Sebastian, Stella Berger, and Rainer Wöhrl. "FLEXIBLE NUTRIENT STOICHIOMETRY MEDIATES ENVIRONMENTAL INFLUENCES ON PHYTOPLANKTON AND ITS RESOURCES." Ecology 86, no. 11 (November 2005): 2931–45. http://dx.doi.org/10.1890/04-1512.

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39

Jäger, Christoph G., Sebastian Diehl, and Maximilian Emans. "Physical Determinants of Phytoplankton Production, Algal Stoichiometry, and Vertical Nutrient Fluxes." American Naturalist 175, no. 4 (April 2010): E91—E104. http://dx.doi.org/10.1086/650728.

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40

Font-Muñoz, Joan S., Antoni Jordi, Idan Tuval, Jorge Arrieta, Sílvia Anglès, and Gotzon Basterretxea. "Advection by ocean currents modifies phytoplankton size structure." Journal of The Royal Society Interface 14, no. 130 (May 2017): 20170046. http://dx.doi.org/10.1098/rsif.2017.0046.

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Advection by ocean currents modifies phytoplankton size structure at small scales (1–10 cm) by aggregating cells in different regions of the flow depending on their size. This effect is caused by the inertia of the cells relative to the displaced fluid. It is considered that, at larger scales (greater than or equal to 1 km), biological processes regulate the heterogeneity in size structure. Here, we provide observational evidence of heterogeneity in phytoplankton size structure driven by ocean currents at relatively large scales (1–10 km). Our results reveal changes in the phytoplankton size distribution associated with the coastal circulation patterns. A numerical model that incorporates the inertial properties of phytoplankton confirms the role of advection on the distribution of phytoplankton according to their size except in areas with enhanced nutrient inputs where phytoplankton dynamics is ruled by other processes. The observed preferential concentration mechanism has important ecological consequences that range from the phytoplankton level to the whole ecosystem.

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41

Petkuviene, Jolita, Diana Vaiciute, Marija Katarzyte, Iveta Gecaite, Giorgio Rossato, Irma Vybernaite-Lubiene, and Marco Bartoli. "Feces from Piscivorous and Herbivorous Birds Stimulate Differentially Phytoplankton Growth." Water 11, no. 12 (December 5, 2019): 2567. http://dx.doi.org/10.3390/w11122567.

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Aquatic birds may impact shallow ecosystems via organic and nutrient enrichment with feces. Such input may alleviate nutrient limitation, unbalance their ecological stoichiometry, and stimulate primary production. Herbivorous and piscivorous birds may produce different effects on aquatic ecosystems due to different physiology, diet and feces elemental composition. We analyze the effects of droppings from swans (herbivorous) and cormorants (piscivorous) on phytoplankton growth via a laboratory experiment. These birds are well represented in the Curonian Lagoon, where they form large colonies. As this lagoon displays summer algal hyper-blooms, we hypothesize an active, direct role of birds via defecation on algal growth. Short-term incubations of phytoplankton under low and high feces addition produces different stimulation of algal growth, significantly higher with high inputs of cormorant feces. The latter produces a major effect on reactive phosphorus concentration that augments significantly, as compared to treatments with swan feces, and determines an unbalanced, N-limited stoichiometry along with the duration of the experiment. During the incubation period, the dominant algal groups switch from blue-green to green algae, but such switch is independent of the level of feces input and from their origin. Heterotrophic bacteria also are stimulated by feces addition, but their increase is transient.

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42

McCain, J. Scott P., Alessandro Tagliabue, Edward Susko, Eric P. Achterberg, Andrew E. Allen, and Erin M. Bertrand. "Cellular costs underpin micronutrient limitation in phytoplankton." Science Advances 7, no. 32 (August 2021): eabg6501. http://dx.doi.org/10.1126/sciadv.abg6501.

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Micronutrients control phytoplankton growth in the ocean, influencing carbon export and fisheries. It is currently unclear how micronutrient scarcity affects cellular processes and how interdependence across micronutrients arises. We show that proximate causes of micronutrient growth limitation and interdependence are governed by cumulative cellular costs of acquiring and using micronutrients. Using a mechanistic proteomic allocation model of a polar diatom focused on iron and manganese, we demonstrate how cellular processes fundamentally underpin micronutrient limitation, and how they interact and compensate for each other to shape cellular elemental stoichiometry and resource interdependence. We coupled our model with metaproteomic and environmental data, yielding an approach for estimating biogeochemical metrics, including taxon-specific growth rates. Our results show that cumulative cellular costs govern how environmental conditions modify phytoplankton growth.

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43

Kerimoglu, Onur, Prima Anugerahanti, and Sherwood Lan Smith. "FABM-NflexPD 1.0: assessing an instantaneous acclimation approach for modeling phytoplankton growth." Geoscientific Model Development 14, no. 10 (October 8, 2021): 6025–47. http://dx.doi.org/10.5194/gmd-14-6025-2021.

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Abstract. Coupled physical–biogeochemical models can generally reproduce large-scale patterns of primary production and biogeochemistry, but they often underestimate observed variability and gradients. This is partially caused by insufficient representation of systematic variations in the elemental composition and pigment density of phytoplankton. Although progress has been made through approaches accounting for the dynamics of phytoplankton composition with additional state variables, formidable computational challenges arise when these are applied in spatially explicit setups. The instantaneous acclimation (IA) approach addresses these challenges by assuming that Chl:C:nutrient ratios are instantly optimized locally (within each modeled grid cell, at each time step), such that they can be resolved as diagnostic variables. Here, we present the first tests of IA in an idealized 1-D setup: we implemented the IA in the Framework for Aquatic Biogeochemical Models (FABM) and coupled it with the General Ocean Turbulence Model (GOTM) to simulate the spatiotemporal dynamics in a 1-D water column. We compare the IA model against a fully dynamic, otherwise equivalently acclimative (dynamic acclimation; DA) variant with an additional state variable and a third, non-acclimative and fixed-stoichiometry (FS) variant. We find that the IA and DA variants, which require the same parameter set, behave similarly in many respects, although some differences do emerge especially during the winter–spring and autumn–winter transitions. These differences however are relatively small in comparison to the differences between the DA and FS variants, suggesting that the IA approach can be used as a cost-effective improvement over a fixed-stoichiometry approach. Our analysis provides insights into the roles of acclimative flexibilities in simulated primary production and nutrient drawdown rates, seasonal and vertical distribution of phytoplankton biomass, formation of thin chlorophyll layers and stoichiometry of detrital material.

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44

Rakocevic, Jelena. "Spatial and temporal distribution of phytoplankton in Lake Skadar." Archives of Biological Sciences 64, no. 2 (2012): 585–95. http://dx.doi.org/10.2298/abs1202585r.

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Phytoplankton seasonal succession and spatial heterogeneity were studied in Lake Skadar from February to December 2004. A total of 167 taxa from 6 algal divisions were observed, with Bacillariophyta being best represented (52.8%). The general pattern of phytoplankton seasonal succession in Lake Skadar was: Bacillariophyta in the spring, Chlorophyta in early summer, Cyanobacteria and Chlorophyta in late summer and Bacillariophyta and Chlorophyta in autumn and winter. Distinct spatial heterogeneity was observed. The central, open part of the lake (pelagic zone) was characterized by dominant euplanktonic species, mostly diatoms, whereas the western and northwestern parts (more isolated and shallower) had higher abundance of greens and blue-greens and a higher percentage of resuspended benthic-epiphytic forms in the phytoplankton community. Comparison with former phytoplankton data showed distinct differences in terms of the qualitative and quantitative composition of the phytoplankton community of Lake Skadar, which indicates lake deterioration.

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45

Plum, Christoph, Matthias Hüsener, and Helmut Hillebrand. "Multiple vs. single phytoplankton species alter stoichiometry of trophic interaction with zooplankton." Ecology 96, no. 11 (November 2015): 3075–89. http://dx.doi.org/10.1890/15-0393.1.

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46

Mette, Elizabeth M., Michael J. Vanni, Jennifer M. Newell, and María J. Gonzàlez. "Phytoplankton communities and stoichiometry are interactively affected by light, nutrients, and fish." Limnology and Oceanography 56, no. 6 (September 19, 2011): 1959–75. http://dx.doi.org/10.4319/lo.2011.56.6.1959.

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47

Singh, A., S. E. Baer, U. Riebesell, A. C. Martiny, and M. W. Lomas. "C : N : P stoichiometry at the Bermuda Atlantic Time-series Study station in the North Atlantic Ocean." Biogeosciences Discussions 12, no. 12 (June 19, 2015): 9275–305. http://dx.doi.org/10.5194/bgd-12-9275-2015.

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Abstract. Nitrogen (N) and phosphorus (P) availability determine the strength of the ocean's carbon (C) uptake, and variation in the N : P ratio in inorganic nutrients is key to phytoplankton growth. A similarity between C : N : P ratios in the plankton biomass and deep-water nutrients was observed by Alfred C. Redfield around 80 years ago and suggested that biological processes in the surface ocean controlled deep ocean chemistry. Recent studies have emphasized the role of inorganic N : P ratios in governing biogeochemical processes, particularly the C : N : P ratio in suspended particulate organic matter (POM), with somewhat less attention given to exported POM and dissolved organic matter (DOM). Herein, we extend the discussion on ecosystem C : N : P stoichiometry but also examine temporal variation of stoichiometric relationships. We have analysed elemental stoichiometry in the suspended POM and total (POM + DOM) organic matter (TOM) pools in the upper 100 m, and in the exported POM and sub-euphotic zone (100–500 m) inorganic nutrient pools from the monthly data collected at the Bermuda Atlantic Time-series Study (BATS) site located in the western part of the North Atlantic Ocean. C : N : P ratios in the TOM pool were more than twice that in the POM pool. Observed C : N ratios in suspended POM were approximately equal to the canonical Redfield Ratio (C : N : P = 106 : 16 : 1), while N : P and C : P ratios in the same pool were more than twice the Redfield Ratio. Average N : P ratios in the subsurface inorganic nutrient pool were ~ 26 : 1, squarely between the suspended POM ratio and the Redfield ratio. We have further linked variation in elemental stoichiometry with that of phytoplankton cell abundance observed at the BATS site. Findings from this study suggest that the variation elemental ratios with depth in the euphotic zone was mainly due to different growth rates of cyanobacterial cells. These time-series data have also allowed us to examine the potential role of climate variability on C : N : P stoichiometry. This study strengthens our understanding of elemental stoichiometry in different organic matter pools and should improve biogeochemical models by constraining the range of non-Redfield stoichiometry.

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48

Duarte, Carlos M., Mercedes Masó, and Martín Merino. "The relationship between mesoscale phytoplankton heterogeneity and hydrographic variability." Deep Sea Research Part A. Oceanographic Research Papers 39, no. 1 (January 1992): 45–54. http://dx.doi.org/10.1016/0198-0149(92)90019-p.

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49

Toullec, Jordan, Alice Delegrange, Adélaïde Perruchon, Gwendoline Duong, Vincent Cornille, Laurent Brutier, and Michaël Hermoso. "Copepod Feeding Responses to Changes in Coccolithophore Size and Carbon Content." Journal of Marine Science and Engineering 10, no. 12 (November 23, 2022): 1807. http://dx.doi.org/10.3390/jmse10121807.

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Phytoplankton stoichiometry and cell size could result from both phenology and environmental change. Zooplankton graze on primary producers, and this drives both the balance of the ecosystem and the biogeochemical cycles. In this study, we performed incubations with copepods and coccolithophores including different prey sizes and particulate carbon contents by considering phytoplankton biovolume concentration instead of chlorophyll a level (Chl a) as is usually performed in such studies. The egestion of fecal pellet and ingestion rates were estimated based on a gut fluorescence method. The latter was calibrated through the relationship between prey Chl a level and the biovolume of the cell. Chl a/biovolume ratio in phytopkanton has to be considered in the copepod gut fluorescent content method. Both coccolithophore biovolume and particulate inorganic/organic carbon ratios affect the food foraging by copepods. Finally, we observed a non-linear relationship between ingestion rates and fecal pellet egestion, due to the presence of calcite inside the copepod’s gut. These results illustrate that both prey size and stoichiometry need to be considered in copepod feeding dynamics, specifically regarding the process leading to the formation of fecal pellets.

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50

Choudhury, A. K., and P. Bhadury. "Relationship between N : P : Si ratio and phytoplankton community composition in a tropical estuarine mangrove ecosystem." Biogeosciences Discussions 12, no. 3 (February 3, 2015): 2307–55. http://dx.doi.org/10.5194/bgd-12-2307-2015.

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Abstract. The present work aims at understanding the importance of Brzezinski–Redfield ratio (modified Redfield ratio) as a determinant of natural phytoplankton community composition in a mangrove ecosystem. Even though this ecoregion has been reported to be mostly eutrophic, localised and anthropogenic influences often result in habitat variability especially with regard to nutrient concentrations at different parts of this ecosystem. Phytoplankton, an important sentinel in aquatic ecosystems may respond differently to such alterations in habitat thereby bringing about significant changes in the community composition. Results show that even though habitat variability does exist at our study area and varied on a spatial and temporal scale, the nutrient concentrations were intricately balanced that never became limited and complemented well with the concept of modified Redfield ratio. However, an integrative approach to study phytoplankton community involving microscopy and rbcL clone library and sequencing approach revealed that it was the functional traits of individual phytoplankton taxa that determined the phytoplankton community composition rather than the nutrient concentrations of the study area. Hence we conclude that the recent concept of functional traits and elemental stoichiometry does not remain restricted to controlled environment of experimental studies only but occur in natural mangrove habitat.

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