Varying influence of phytoplankton biodiversity and stoichiometric plasticity on bulk particulate stoichiometry across ocean basins

AbstractConcentrations and elemental ratios of suspended particulate organic matter influence many biogeochemical processes in the ocean, including patterns of phytoplankton nutrient limitation and links between carbon, nitrogen and phosphorus cycles. Here we present direct measurements of cellular nutrient content and stoichiometric ratios for discrete phytoplankton populations spanning broad environmental conditions across several ocean basins. Median cellular carbon-to-phosphorus and nitrogen-to-phosphorus ratios were positively correlated with vertical nitrate-to-phosphate flux for all phytoplankton groups and were consistently higher for cyanobacteria than eukaryotes. Light and temperature were inconsistent predictors of stoichiometric ratios. Across nutrient-rich and phosphorus-stressed biomes in the North Atlantic, but not in the nitrogen-stressed tropical North Pacific, we find that a combination of taxonomic composition and environmental acclimation best predict bulk particulate organic matter composition. Our findings demonstrate the central role of plankton biodiversity and plasticity in controlling linkages between ocean nutrient and carbon cycles in some regions.

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Stable C and N Isotope Composition of Suspended Particulate Organic Matter in the Neva Estuary: The Role of Abiotic Factors, Productivity, and Phytoplankton Taxonomic Composition

Journal of Marine Science and Engineering ◽

10.3390/jmse8120959 ◽

2020 ◽

Vol 8 (12) ◽

pp. 959 ◽

Cited By ~ 1

Author(s):

Mikhail S. Golubkov ◽

Vera N. Nikulina ◽

Alexei V. Tiunov ◽

Sergey M. Golubkov

Keyword(s):

Organic Matter ◽

Particulate Organic Matter ◽

Abiotic Factors ◽

Taxonomic Composition ◽

Isotopic Ratios ◽

Abiotic Factor ◽

Δ13c And Δ15n ◽

Neva Estuary ◽

Suspended Particulate ◽

Suspended Particulate Organic Matter

Knowledge of carbon and nitrogen isotopic ratios in organic matter and their changes is important when studying nutrient cycles in aquatic ecosystems. Relationships between δ13C and δ15N values of suspended particulate organic matter (POM), water temperature, salinity, pH, redox potential, chlorophyll a concentration, primary production, and biomasses of different taxonomic groups of phytoplankton in the Neva Estuary were statistically analyzed. We tested the hypothesis that the studied physicochemical and biogeochemical characteristics, as well as the species composition of phytoplankton and its productivity, can be significant predictors of changes in the isotopic ratios of suspended particulate organic matter in estuaries. In the Neva Estuary, δ13CPOM (−16.8–−27.6‰) and δ15NPOM (2.3–7.3‰) changed synchronously. Statistical analysis showed that for both isotopes, the photosynthetic activity and taxonomic composition of phytoplankton are important. For 13CPOM, the second most important factor was water salinity, which was apparently associated with the transition of algae from CO2 to HCO3 consumption during photosynthesis in estuarine waters. For 15NPOM changes, the most important abiotic factor was pH. The study showed that the dependences of POM isotopic ratios on environmental variables obtained for continental and oceanic waters are also valid in transitional zones such as the Neva Estuary.

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Macrophyte-derived detritus in shallow coastal waters contributes to suspended particulate organic matter and increases growth rates of Mytilus edulis

Marine Ecology Progress Series ◽

10.3354/meps13314 ◽

2020 ◽

Vol 644 ◽

pp. 91-103

Author(s):

D Bearham ◽

MA Vanderklift ◽

RA Downie ◽

DP Thomson ◽

LA Clementson

Keyword(s):

Organic Matter ◽

Mytilus Edulis ◽

Particulate Organic Matter ◽

Coastal Waters ◽

Gill Tissue ◽

Suspension Feeder ◽

Food Sources ◽

Suspension Feeders ◽

Blue Mussels ◽

Suspended Particulate

Benthic suspension feeders, such as bivalves, potentially have several different food sources, including plankton and resuspended detritus of benthic origin. We hypothesised that suspension feeders are likely to feed on detritus if it is present. This inference would be further strengthened if there was a correlation between δ13C of suspension feeder tissue and δ13C of particulate organic matter (POM). Since detritus is characterised by high particulate organic matter (POC):chl a ratios, we would also predict a positive correlation between POM δ13C and POC:chl a. We hypothesised that increasing depth and greater distance from shore would produce a greater nutritional reliance by experimentally transplanted blue mussels Mytilus edulis on plankton rather than macrophyte-derived detritus. After deployments of 3 mo duration in 2 different years at depths from 3 to 40 m, M. edulis sizes were positively correlated with POM concentrations. POC:chl a ratios and δ13C of POM and M. edulis gill tissue decreased with increasing depth (and greater distance from shore). δ13C of POM was correlated with δ13C of M. edulis. Our results suggest that detritus comprised a large proportion of POM at shallow depths (<15 m), that M. edulis ingested and assimilated carbon in proportion to its availability in POM, and that growth of M. edulis was higher where detritus was present and POM concentrations were higher.

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15N and 13C natural abundance in suspended particulate organic matter from a Kuroshio warm-core ring

Deep Sea Research Part A Oceanographic Research Papers ◽

10.1016/s0198-0149(11)80019-1 ◽

1992 ◽

Vol 39 ◽

pp. S347-S362 ◽

Cited By ~ 15

Author(s):

Toshiro Saino

Keyword(s):

Organic Matter ◽

Particulate Organic Matter ◽

Natural Abundance ◽

13C Natural Abundance ◽

Warm Core ◽

Warm Core Ring ◽

Suspended Particulate ◽

Suspended Particulate Organic Matter

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A model for variable phytoplankton stoichiometry based on cell protein regulation

Biogeosciences Discussions ◽

10.5194/bgd-10-3241-2013 ◽

2013 ◽

Vol 10 (2) ◽

pp. 3241-3279

Author(s):

J. A. Bonachela ◽

S. D. Allison ◽

A. C. Martiny ◽

S. A. Levin

Keyword(s):

Physiological State ◽

Single Point ◽

Nutrient Content ◽

Growth Conditions ◽

Marine Phytoplankton ◽

Cell Protein ◽

Nitrogen And Phosphorus ◽

Elemental Ratios ◽

Regulatory Processes ◽

Complex Interactions

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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