Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups

Peter Stief, Ann Sofie Birch Lundgaard, Hans-Peter Grossart, Torkel Gissel Nielsen, Alvaro Morales Ramirez, Alexander H. Treusch, Bo Thamdrup, Ronnie N. Glud

Research output: Contribution to conference without publisher/journalConference abstract for conferenceResearchpeer-review

Abstract

Organic aggregates sinking through marine and freshwater water bodies are increasingly perceived as abundant hotspots of anaerobic microbial metabolism that cannot take place in the surrounding oxygenated water. While the research focus is often on phytoplankton-derived aggregates, zooplankton may also provide anoxic microenvironments, such as guts, fecal pellets, and carcasses of copepods. We tested therefore, if anaerobic nitrogen cycling is associated with copepods collected from polar, temperate, and tropical marine or freshwater ecosystems and belonging to different taxonomic groups and size classes. Dissimilatory nitrogen transformations were quantified using 15N tracing with living and dead copepods and with fecal pellets at different ambient oxygen levels to mimic conditions prevailing in the respective ecosystem. Significant anaerobic nitrogen cycling was without exception associated with copepod carcasses and was also evident in living specimens and fecal pellets of Calanus hyperboreus, a key component of Arctic marine zooplankton. In this large copepod species, denitrification was the dominant pathway of anaerobic nitrogen cycling and correlated with the presence or absence of food particles in the gut, but not with ambient oxygen levels. In contrast, the carcasses of the much smaller tropical marine and temperate freshwater copepods displayed high rates of dissimilatory nitrate reduction to ammonium or nitrite that were boosted by low ambient oxygen levels. Extrapolated to their in situ carcass abundance, copepods contribute up to 28% to the total fixed-nitrogen loss in oxic/hypoxic settings and up to 14% in anoxic settings. Overall, copepods greatly expand the water volume in which anaerobic nitrogen cycling is possible.
Original languageEnglish
Publication date17. Aug 2018
Number of pages1
Publication statusPublished - 17. Aug 2018
Event17th International Symposium on Microbial Ecology (ISME) - Leipzig, Germany
Duration: 12. Aug 201817. Aug 2018
https://isme17.isme-microbes.org/

Conference

Conference17th International Symposium on Microbial Ecology (ISME)
CountryGermany
CityLeipzig
Period12/08/201817/08/2018
Internet address

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ecosystem
fecal pellet
nitrogen
oxygen
zooplankton
freshwater ecosystem
marine ecosystem
nitrite
denitrification
ammonium
metabolism
phytoplankton
nitrate
water
food

Cite this

Stief, P., Lundgaard, A. S. B., Grossart, H-P., Nielsen, T. G., Morales Ramirez, A., Treusch, A. H., ... Glud, R. N. (2018). Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups. Abstract from 17th International Symposium on Microbial Ecology (ISME), Leipzig, Germany.
Stief, Peter ; Lundgaard, Ann Sofie Birch ; Grossart, Hans-Peter ; Nielsen, Torkel Gissel ; Morales Ramirez, Alvaro ; Treusch, Alexander H. ; Thamdrup, Bo ; Glud, Ronnie N. / Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups. Abstract from 17th International Symposium on Microbial Ecology (ISME), Leipzig, Germany.1 p.
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abstract = "Organic aggregates sinking through marine and freshwater water bodies are increasingly perceived as abundant hotspots of anaerobic microbial metabolism that cannot take place in the surrounding oxygenated water. While the research focus is often on phytoplankton-derived aggregates, zooplankton may also provide anoxic microenvironments, such as guts, fecal pellets, and carcasses of copepods. We tested therefore, if anaerobic nitrogen cycling is associated with copepods collected from polar, temperate, and tropical marine or freshwater ecosystems and belonging to different taxonomic groups and size classes. Dissimilatory nitrogen transformations were quantified using 15N tracing with living and dead copepods and with fecal pellets at different ambient oxygen levels to mimic conditions prevailing in the respective ecosystem. Significant anaerobic nitrogen cycling was without exception associated with copepod carcasses and was also evident in living specimens and fecal pellets of Calanus hyperboreus, a key component of Arctic marine zooplankton. In this large copepod species, denitrification was the dominant pathway of anaerobic nitrogen cycling and correlated with the presence or absence of food particles in the gut, but not with ambient oxygen levels. In contrast, the carcasses of the much smaller tropical marine and temperate freshwater copepods displayed high rates of dissimilatory nitrate reduction to ammonium or nitrite that were boosted by low ambient oxygen levels. Extrapolated to their in situ carcass abundance, copepods contribute up to 28{\%} to the total fixed-nitrogen loss in oxic/hypoxic settings and up to 14{\%} in anoxic settings. Overall, copepods greatly expand the water volume in which anaerobic nitrogen cycling is possible.",
author = "Peter Stief and Lundgaard, {Ann Sofie Birch} and Hans-Peter Grossart and Nielsen, {Torkel Gissel} and {Morales Ramirez}, Alvaro and Treusch, {Alexander H.} and Bo Thamdrup and Glud, {Ronnie N.}",
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Stief, P, Lundgaard, ASB, Grossart, H-P, Nielsen, TG, Morales Ramirez, A, Treusch, AH, Thamdrup, B & Glud, RN 2018, 'Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups', Leipzig, Germany, 12/08/2018 - 17/08/2018, .

Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups. / Stief, Peter; Lundgaard, Ann Sofie Birch; Grossart, Hans-Peter; Nielsen, Torkel Gissel; Morales Ramirez, Alvaro; Treusch, Alexander H.; Thamdrup, Bo; Glud, Ronnie N.

2018. Abstract from 17th International Symposium on Microbial Ecology (ISME), Leipzig, Germany.

Research output: Contribution to conference without publisher/journalConference abstract for conferenceResearchpeer-review

TY - ABST

T1 - Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups

AU - Stief, Peter

AU - Lundgaard, Ann Sofie Birch

AU - Grossart, Hans-Peter

AU - Nielsen, Torkel Gissel

AU - Morales Ramirez, Alvaro

AU - Treusch, Alexander H.

AU - Thamdrup, Bo

AU - Glud, Ronnie N.

PY - 2018/8/17

Y1 - 2018/8/17

N2 - Organic aggregates sinking through marine and freshwater water bodies are increasingly perceived as abundant hotspots of anaerobic microbial metabolism that cannot take place in the surrounding oxygenated water. While the research focus is often on phytoplankton-derived aggregates, zooplankton may also provide anoxic microenvironments, such as guts, fecal pellets, and carcasses of copepods. We tested therefore, if anaerobic nitrogen cycling is associated with copepods collected from polar, temperate, and tropical marine or freshwater ecosystems and belonging to different taxonomic groups and size classes. Dissimilatory nitrogen transformations were quantified using 15N tracing with living and dead copepods and with fecal pellets at different ambient oxygen levels to mimic conditions prevailing in the respective ecosystem. Significant anaerobic nitrogen cycling was without exception associated with copepod carcasses and was also evident in living specimens and fecal pellets of Calanus hyperboreus, a key component of Arctic marine zooplankton. In this large copepod species, denitrification was the dominant pathway of anaerobic nitrogen cycling and correlated with the presence or absence of food particles in the gut, but not with ambient oxygen levels. In contrast, the carcasses of the much smaller tropical marine and temperate freshwater copepods displayed high rates of dissimilatory nitrate reduction to ammonium or nitrite that were boosted by low ambient oxygen levels. Extrapolated to their in situ carcass abundance, copepods contribute up to 28% to the total fixed-nitrogen loss in oxic/hypoxic settings and up to 14% in anoxic settings. Overall, copepods greatly expand the water volume in which anaerobic nitrogen cycling is possible.

AB - Organic aggregates sinking through marine and freshwater water bodies are increasingly perceived as abundant hotspots of anaerobic microbial metabolism that cannot take place in the surrounding oxygenated water. While the research focus is often on phytoplankton-derived aggregates, zooplankton may also provide anoxic microenvironments, such as guts, fecal pellets, and carcasses of copepods. We tested therefore, if anaerobic nitrogen cycling is associated with copepods collected from polar, temperate, and tropical marine or freshwater ecosystems and belonging to different taxonomic groups and size classes. Dissimilatory nitrogen transformations were quantified using 15N tracing with living and dead copepods and with fecal pellets at different ambient oxygen levels to mimic conditions prevailing in the respective ecosystem. Significant anaerobic nitrogen cycling was without exception associated with copepod carcasses and was also evident in living specimens and fecal pellets of Calanus hyperboreus, a key component of Arctic marine zooplankton. In this large copepod species, denitrification was the dominant pathway of anaerobic nitrogen cycling and correlated with the presence or absence of food particles in the gut, but not with ambient oxygen levels. In contrast, the carcasses of the much smaller tropical marine and temperate freshwater copepods displayed high rates of dissimilatory nitrate reduction to ammonium or nitrite that were boosted by low ambient oxygen levels. Extrapolated to their in situ carcass abundance, copepods contribute up to 28% to the total fixed-nitrogen loss in oxic/hypoxic settings and up to 14% in anoxic settings. Overall, copepods greatly expand the water volume in which anaerobic nitrogen cycling is possible.

M3 - Conference abstract for conference

ER -

Stief P, Lundgaard ASB, Grossart H-P, Nielsen TG, Morales Ramirez A, Treusch AH et al. Copepod-associated anaerobic nitrogen cycling across ecosystems and taxonomic groups. 2018. Abstract from 17th International Symposium on Microbial Ecology (ISME), Leipzig, Germany.