Sharp contrasts between freshwater and marine microbial enzymatic capabilities, community composition, and DOM pools in a NE Greenland fjord

John Paul Balmonte, Harald Hasler-Sheetal, Ronnie N. Glud, Thorbjørn J. Andersen, Mikael K. Sejr, Mathias Middelboe, Andreas Teske, Carol Arnosti

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Abstract Increasing glacial discharge can lower salinity and alter organic matter (OM) supply in fjords, but assessing the biogeochemical effects of enhanced freshwater fluxes requires understanding of microbial interactions with OM across salinity gradients. Here, we examined microbial enzymatic capabilities?in bulk waters (nonsize-fractionated) and on particles (≥?1.6 ?m)?to hydrolyze common OM constituents (peptides, glucose, polysaccharides) along a freshwater?marine continuum within Tyrolerfjord-Young Sound. Bulk peptidase activities were up to 15-fold higher in the fjord than in glacial rivers, whereas bulk glucosidase activities in rivers were twofold greater, despite fourfold lower cell counts. Particle-associated glucosidase activities showed similar trends by salinity, but particle-associated peptidase activities were up to fivefold higher?or, for several peptidases, only detectable?in the fjord. Bulk polysaccharide hydrolase activities also exhibited freshwater?marine contrasts: xylan hydrolysis rates were fivefold higher in rivers, while chondroitin hydrolysis rates were 30-fold greater in the fjord. Contrasting enzymatic patterns paralleled variations in bacterial community structure, with most robust compositional shifts in river-to-fjord transitions, signifying a taxonomic and genetic basis for functional differences in freshwater and marine waters. However, distinct dissolved organic matter (DOM) pools across the salinity gradient, as well as a positive relationship between several enzymatic activities and DOM compounds, indicate that DOM supply exerts a more proximate control on microbial activities. Thus, differing microbial enzymatic capabilities, community structure, and DOM composition?interwoven with salinity and water mass origins?suggest that increased meltwater may alter OM retention and processing in fjords, changing the pool of OM supplied to coastal Arctic microbial communities.
Original languageEnglish
JournalLimnology and Oceanography
Volume0
Issue number0
ISSN0024-3590
DOIs
Publication statusE-pub ahead of print - 19. Jul 2019

Fingerprint

dissolved organic matter
Greenland
fjord
community composition
organic matter
salinity
peptidases
glucosidases
rivers
polysaccharide
river
community structure
polysaccharides
hydrolysis
fold
xylan
snowmelt
hydrolases
bacterial communities
microbial activity

Cite this

@article{41a42c6e0d0c4579adb5f2dcf1348fe4,
title = "Sharp contrasts between freshwater and marine microbial enzymatic capabilities, community composition, and DOM pools in a NE Greenland fjord",
abstract = "Abstract Increasing glacial discharge can lower salinity and alter organic matter (OM) supply in fjords, but assessing the biogeochemical effects of enhanced freshwater fluxes requires understanding of microbial interactions with OM across salinity gradients. Here, we examined microbial enzymatic capabilities?in bulk waters (nonsize-fractionated) and on particles (≥?1.6 ?m)?to hydrolyze common OM constituents (peptides, glucose, polysaccharides) along a freshwater?marine continuum within Tyrolerfjord-Young Sound. Bulk peptidase activities were up to 15-fold higher in the fjord than in glacial rivers, whereas bulk glucosidase activities in rivers were twofold greater, despite fourfold lower cell counts. Particle-associated glucosidase activities showed similar trends by salinity, but particle-associated peptidase activities were up to fivefold higher?or, for several peptidases, only detectable?in the fjord. Bulk polysaccharide hydrolase activities also exhibited freshwater?marine contrasts: xylan hydrolysis rates were fivefold higher in rivers, while chondroitin hydrolysis rates were 30-fold greater in the fjord. Contrasting enzymatic patterns paralleled variations in bacterial community structure, with most robust compositional shifts in river-to-fjord transitions, signifying a taxonomic and genetic basis for functional differences in freshwater and marine waters. However, distinct dissolved organic matter (DOM) pools across the salinity gradient, as well as a positive relationship between several enzymatic activities and DOM compounds, indicate that DOM supply exerts a more proximate control on microbial activities. Thus, differing microbial enzymatic capabilities, community structure, and DOM composition?interwoven with salinity and water mass origins?suggest that increased meltwater may alter OM retention and processing in fjords, changing the pool of OM supplied to coastal Arctic microbial communities.",
author = "Balmonte, {John Paul} and Harald Hasler-Sheetal and Glud, {Ronnie N.} and Andersen, {Thorbj{\o}rn J.} and Sejr, {Mikael K.} and Mathias Middelboe and Andreas Teske and Carol Arnosti",
note = "doi: 10.1002/lno.11253",
year = "2019",
month = "7",
day = "19",
doi = "10.1002/lno.11253",
language = "English",
volume = "0",
journal = "Limnology and Oceanography",
issn = "0024-3590",
publisher = "JohnWiley & Sons, Inc.",
number = "0",

}

Sharp contrasts between freshwater and marine microbial enzymatic capabilities, community composition, and DOM pools in a NE Greenland fjord. / Balmonte, John Paul; Hasler-Sheetal, Harald; Glud, Ronnie N.; Andersen, Thorbjørn J.; Sejr, Mikael K.; Middelboe, Mathias; Teske, Andreas; Arnosti, Carol.

In: Limnology and Oceanography, Vol. 0, No. 0, 19.07.2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Sharp contrasts between freshwater and marine microbial enzymatic capabilities, community composition, and DOM pools in a NE Greenland fjord

AU - Balmonte, John Paul

AU - Hasler-Sheetal, Harald

AU - Glud, Ronnie N.

AU - Andersen, Thorbjørn J.

AU - Sejr, Mikael K.

AU - Middelboe, Mathias

AU - Teske, Andreas

AU - Arnosti, Carol

N1 - doi: 10.1002/lno.11253

PY - 2019/7/19

Y1 - 2019/7/19

N2 - Abstract Increasing glacial discharge can lower salinity and alter organic matter (OM) supply in fjords, but assessing the biogeochemical effects of enhanced freshwater fluxes requires understanding of microbial interactions with OM across salinity gradients. Here, we examined microbial enzymatic capabilities?in bulk waters (nonsize-fractionated) and on particles (≥?1.6 ?m)?to hydrolyze common OM constituents (peptides, glucose, polysaccharides) along a freshwater?marine continuum within Tyrolerfjord-Young Sound. Bulk peptidase activities were up to 15-fold higher in the fjord than in glacial rivers, whereas bulk glucosidase activities in rivers were twofold greater, despite fourfold lower cell counts. Particle-associated glucosidase activities showed similar trends by salinity, but particle-associated peptidase activities were up to fivefold higher?or, for several peptidases, only detectable?in the fjord. Bulk polysaccharide hydrolase activities also exhibited freshwater?marine contrasts: xylan hydrolysis rates were fivefold higher in rivers, while chondroitin hydrolysis rates were 30-fold greater in the fjord. Contrasting enzymatic patterns paralleled variations in bacterial community structure, with most robust compositional shifts in river-to-fjord transitions, signifying a taxonomic and genetic basis for functional differences in freshwater and marine waters. However, distinct dissolved organic matter (DOM) pools across the salinity gradient, as well as a positive relationship between several enzymatic activities and DOM compounds, indicate that DOM supply exerts a more proximate control on microbial activities. Thus, differing microbial enzymatic capabilities, community structure, and DOM composition?interwoven with salinity and water mass origins?suggest that increased meltwater may alter OM retention and processing in fjords, changing the pool of OM supplied to coastal Arctic microbial communities.

AB - Abstract Increasing glacial discharge can lower salinity and alter organic matter (OM) supply in fjords, but assessing the biogeochemical effects of enhanced freshwater fluxes requires understanding of microbial interactions with OM across salinity gradients. Here, we examined microbial enzymatic capabilities?in bulk waters (nonsize-fractionated) and on particles (≥?1.6 ?m)?to hydrolyze common OM constituents (peptides, glucose, polysaccharides) along a freshwater?marine continuum within Tyrolerfjord-Young Sound. Bulk peptidase activities were up to 15-fold higher in the fjord than in glacial rivers, whereas bulk glucosidase activities in rivers were twofold greater, despite fourfold lower cell counts. Particle-associated glucosidase activities showed similar trends by salinity, but particle-associated peptidase activities were up to fivefold higher?or, for several peptidases, only detectable?in the fjord. Bulk polysaccharide hydrolase activities also exhibited freshwater?marine contrasts: xylan hydrolysis rates were fivefold higher in rivers, while chondroitin hydrolysis rates were 30-fold greater in the fjord. Contrasting enzymatic patterns paralleled variations in bacterial community structure, with most robust compositional shifts in river-to-fjord transitions, signifying a taxonomic and genetic basis for functional differences in freshwater and marine waters. However, distinct dissolved organic matter (DOM) pools across the salinity gradient, as well as a positive relationship between several enzymatic activities and DOM compounds, indicate that DOM supply exerts a more proximate control on microbial activities. Thus, differing microbial enzymatic capabilities, community structure, and DOM composition?interwoven with salinity and water mass origins?suggest that increased meltwater may alter OM retention and processing in fjords, changing the pool of OM supplied to coastal Arctic microbial communities.

U2 - 10.1002/lno.11253

DO - 10.1002/lno.11253

M3 - Journal article

VL - 0

JO - Limnology and Oceanography

JF - Limnology and Oceanography

SN - 0024-3590

IS - 0

ER -