Climate change and diminishing seasonality in Arctic benthic processes

The iconic picture of Arctic marine ecosystems shows an intense pulse of biological productivity around the spring bloom that is sustained while fresh organic matter (OM) is available, after which ecosystem activity declines to basal levels in autumn and winter. We investigated seasonality in benthi...

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Bibliographic Details
Published in:Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Main Authors: Morata, Nathalie, Michaud, Emma, Poullaouec, Marie-aude, Devesa, Jérémy, Le Goff, Manon, Corvaisier, Rudolph, Renaud, Pierre Antoine
Format: Article in Journal/Newspaper
Language:English
Published: The Royal Society 2020
Subjects:
bioturbation
Kongsfjorden
nutrient fluxes
phytodetritus
respiration
Svalbard
Arctic
Arctic Ocean
Climate change
Kongsfjord*
Online Access:https://archimer.ifremer.fr/doc/00646/75812/76755.pdf
https://archimer.ifremer.fr/doc/00646/75812/76756.pdf
https://doi.org/10.1098/rsta.2019.0369
https://archimer.ifremer.fr/doc/00646/75812/
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Summary:The iconic picture of Arctic marine ecosystems shows an intense pulse of biological productivity around the spring bloom that is sustained while fresh organic matter (OM) is available, after which ecosystem activity declines to basal levels in autumn and winter. We investigated seasonality in benthic biogeochemical cycling at three stations in a high Arctic fjord that has recently lost much of its seasonal ice-cover. Unlike observations from other Arctic locations, we find little seasonality in sediment community respiration and bioturbation rates, although different sediment reworking modes varied through the year. Nutrient fluxes did vary, suggesting that, although OM was processed at similar rates, seasonality in its quality led to spring/summer peaks in inorganic nitrogen and silicate fluxes. These patterns correspond to published information on seasonality in vertical flux at the stations. Largely ice-free Kongsfjorden has a considerable detrital pool in soft sediments which sustain benthic communities over the year. Sources of this include macroalgae and terrestrial runoff. Climate change leading to less ice cover, higher light availability and expanded benthic habitat may lead to more detrital carbon in the system, dampening the quantitative importance of seasonal pulses of phytodetritus to seafloor communities in some areas of the Arctic. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

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