Dataset Information

Warming and CO₂ Enhance Arctic Heterotrophic Microbial Activity.

ABSTRACT: Ocean acidification and warming are two main consequences of climate change that can directly affect biological and ecosystem processes in marine habitats. The Arctic Ocean is the region of the world experiencing climate change at the steepest rate compared with other latitudes. Since marine planktonic microorganisms play a key role in the biogeochemical cycles in the ocean it is crucial to simultaneously evaluate the effect of warming and increasing CO₂ on marine microbial communities. In 20 L experimental microcosms filled with water from a high-Arctic fjord (Svalbard), we examined changes in phototrophic and heterotrophic microbial abundances and processes [bacterial production (BP) and mortality], and viral activity (lytic and lysogenic) in relation to warming and elevated CO₂. The summer microbial plankton community living at 1.4°C in situ temperature, was exposed to increased CO₂ concentrations (135-2,318 ?atm) in three controlled temperature treatments (1, 6, and 10°C) at the UNIS installations in Longyearbyen (Svalbard), in summer 2010. Results showed that chlorophyll a concentration decreased at increasing temperatures, while BP significantly increased with pCO₂ at 6 and 10°C. Lytic viral production was not affected by changes in pCO₂ and temperature, while lysogeny increased significantly at increasing levels of pCO₂, especially at 10°C (R ² = 0.858, p = 0.02). Moreover, protistan grazing rates showed a positive interaction between pCO₂ and temperature. The averaged percentage of bacteria grazed per day was higher (19.56 ± 2.77% d^-1) than the averaged percentage of lysed bacteria by virus (7.18 ± 1.50% d^-1) for all treatments. Furthermore, the relationship among microbial abundances and processes showed that BP was significantly related to phototrophic pico/nanoflagellate abundance in the 1°C and the 6°C treatments, and BP triggered viral activity, mainly lysogeny at 6 and 10°C, while bacterial mortality rates was significantly related to bacterial abundances at 6°C. Consequently, our experimental results suggested that future increases in water temperature and pCO₂ in Arctic waters will produce a decrease of phytoplankton biomass, enhancement of BP and changes in the carbon fluxes within the microbial food web. All these heterotrophic processes will contribute to weakening the CO₂ sink capacity of the Arctic plankton community.

SUBMITTER: Vaque D

PROVIDER: S-EPMC6436474 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Warming and CO<sub>2</sub> Enhance Arctic Heterotrophic Microbial Activity.

Vaqué Dolors D Lara Elena E Arrieta Jesús M JM Holding Johnna J Sà Elisabet L EL Hendriks Iris E IE Coello-Camba Alexandra A Alvarez Marta M Agustí Susana S Wassmann Paul F PF Duarte Carlos M CM

Frontiers in microbiology 20190320

Ocean acidification and warming are two main consequences of climate change that can directly affect biological and ecosystem processes in marine habitats. The Arctic Ocean is the region of the world experiencing climate change at the steepest rate compared with other latitudes. Since marine planktonic microorganisms play a key role in the biogeochemical cycles in the ocean it is crucial to simultaneously evaluate the effect of warming and increasing CO<sub>2</sub> on marine microbial communitie ...[more]

PMID: 30949141

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Project description:Meltwater streams connect the glacial cryosphere with downstream ecosystems. Dissolved and particulate matter exported from glacial ecosystems originates from contrasting supraglacial and subglacial environments, and exported microbial cells have the potential to serve as ecological and hydrological indicators for glacial ecosystem processes. Here, we compare exported microbial assemblages from the meltwater of 24 glaciers from six (sub)Arctic regions - the southwestern Greenland Ice Sheet, Qeqertarsuaq (Disko Island) in west Greenland, Iceland, Svalbard, western Norway, and southeast Alaska - differing in their lithology, catchment size, and climatic characteristics, to investigate spatial and environmental factors structuring exported meltwater assemblages. We found that 16S rRNA gene sequences of all samples were dominated by the phyla Proteobacteria, Bacteroidetes, and Actinobacteria, with Verrucomicrobia also common in Greenland localities. Clustered OTUs were largely composed of aerobic and anaerobic heterotrophs capable of degrading a wide variety of carbon substrates. A small number of OTUs dominated all assemblages, with the most abundant being from the genera Polaromonas, Methylophilus, and Nitrotoga. However, 16-32% of a region's OTUs were unique to that region, and rare taxa revealed unique metabolic potentials and reflected differences between regions, such as the elevated relative abundances of sulfur oxidizers Sulfuricurvum sp. and Thiobacillus sp. at Svalbard sites. Meltwater alpha diversity showed a pronounced decrease with increasing latitude, and multivariate analyses of assemblages revealed significant regional clusters. Distance-based redundancy and correlation analyses further resolved associations between whole assemblages and individual OTUs with variables primarily corresponding with the sampled regions. Interestingly, some OTUs indicating specific metabolic processes were not strongly associated with corresponding meltwater characteristics (e.g., nitrification and inorganic nitrogen concentrations). Thus, while exported assemblage structure appears regionally specific, and probably reflects differences in dominant hydrological flowpaths, OTUs can also serve as indicators for more localized microbially mediated processes not captured by the traditional characterization of bulk meltwater hydrochemistry. These results collectively promote a better understanding of microbial distributions across the Arctic, as well as linkages between the terrestrial cryosphere habitats and downstream ecosystems.

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Warming and CO₂ Enhance Arctic Heterotrophic Microbial Activity.

Publications

Warming and CO<sub>2</sub> Enhance Arctic Heterotrophic Microbial Activity.

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Dataset Information

Warming and CO2 Enhance Arctic Heterotrophic Microbial Activity.

Publications

Warming and CO<sub>2</sub> Enhance Arctic Heterotrophic Microbial Activity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

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Warming and CO₂ Enhance Arctic Heterotrophic Microbial Activity.