Ocean acidification effect on prokaryotic metabolism tested in two diverse trophic regimes in the Mediterranean Sea

Celussi, Mauro; Malfatti, Francesca; Franzo, Annalisa; Gazeau, Frédéric; Giannakourou, Antonia; Pitta, Paraskevi; Tsiola, Anastasia; Negro, Paola Del

doi:10.1016/j.ecss.2015.08.015

Cited by 25 publications

(23 citation statements)

References 62 publications

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“…6a), agreeing with other ocean acidification studies globally that have reported an increase in abundance of picophytoplankton at elevated CO 2 levels (e.g. Brussaard et al, 2013;Schulz et al, 2013;Biswas et al, 2015;Crawfurd et al, 2017). However, studies on phytoplankton communities in other Antarctic regions have reported shifts towards larger diatom species (Ross Sea; Feng et al, 2010;Tortell et al, 2008) or no change (Antarctic Peninsula;Young et al, 2015).…”

Section: Nano-and Picophytoplanktonsupporting

confidence: 86%

“…Despite the apparent resilience of prokaryotes to ocean acidification, several authors suggest they may be indirectly affected by changes in substrate availability due to changes in phytoplankton composition and abundance (e.g. Piontek et al, 2010;Celussi et al, 2017). Given the critical role of heterotrophic prokaryotes in remineralisation and carbon flux, it is vital to better understand the direct and indirect effects of ocean acidification on their communities.…”

Section: Introductionmentioning

confidence: 99%

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Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

et al. 2020

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Abstract. High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. At CO2 levels ≥634 µatm, HNF abundance was reduced, coinciding with increased abundance of picophytoplankton and prokaryotes. This increase in picophytoplankton and prokaryote abundance was likely due to a reduction in top-down control of grazing HNFs. Nanophytoplankton abundance was elevated in the 634 µatm treatment, suggesting that moderate increases in CO2 may stimulate growth. The taxonomic and morphological differences in CO2 tolerance we observed are likely to favour dominance of microbial communities by prokaryotes, nanophytoplankton, and picophytoplankton. Such changes in predator–prey interactions with ocean acidification could have a significant effect on the food web and biogeochemistry in the Southern Ocean, intensifying organic-matter recycling in surface waters; reducing vertical carbon flux; and reducing the quality, quantity, and availability of food for higher trophic levels.

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Section: Nano-and Picophytoplanktonsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

et al. 2020

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“…For the field measurement of enzymatic activities, the fluorimetric method is a widespread technique generally used in aquatic environments, even if specific knowledge about the macromolecular structure of the organic matter in the ocean is lacking. According to the Hoppe's method [30], specific artificial substrates are widely used to measure potential enzyme activities in seawater and sediments. These substrate analogues consist of a monomer [an amino acid or a monosaccharide analogue] linked to a fluorophore, such as L-leucine-7-amido-4-methylcoumarin hydrochloride (leucine-MCA), used to measure leucine aminopeptidase; 4-methylumbelliferyl-β-D-glucopyranoside (MUF-β-glucose), and methylumbelliferyl-phosphate, used to measure β-glucosidase and phosphatase activities respectively.…”

Section: Enzymatic Activitiesmentioning

confidence: 99%

“…According to the kinetic approach, it is possible to determine also the Michaelis-Menten constant (Km), which expresses the affinity of an enzyme for its substrate [6],[30].…”

Section: Enzymatic Activitiesmentioning

confidence: 99%

Microbial enzymes in the Mediterranean Sea: relationship with climate changes

Zaccone¹,

Caruso²

2019

AIMS Microbiology

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In most of the aquatic ecosystems, microorganisms are major players in the biogeochemical and nutrients cycles (Carbon Nitrogen, Phosphorus), through their enzymatic activities (leucine aminopeptidase, alkaline phosphatase and beta-glucosidase) on organic polymers such as polypeptides, organophosphate esters and polysaccharides, respectively. The small monomers released by decomposition are metabolised by microbes, supporting their growth. Most of the extracellular enzymes are adaptative and their synthesis and activity is strongly affected by environmental factors, consequently the relative importance of leucine aminopeptidase, alkaline phosphatase and beta-glucosidase reflects differences in the composition of organic matter and assume a different meaning.Since more than two decades, at the CNR the influence of climate changes, seasonal variability, depth and coastal input on the patterns of enzymatic activities in the Mediterranean Sea have been studied. Its particular characteristics of a semi-closed basin, high summer evaporation and the occurrence of important water dynamics, make this ecosystem particularly suitable as a model site for climate changes-related observations.The present paper reviews the current information of environmental changes on extracellular enzymatic activity obtained in the Mediterranean areas with the aim of evaluating the effects of environmental changes on the microbial activities. The obtained results revealed significant variations in the rates of hydrolytic activities in relation to space and time, with the highest levels generally found in the epipelagic layer (0–100m) and in coastal zones during warm periods. In the Central Mediterranean Sea their relationship with temperature changes was demonstrated.Spatial variations in the relative enzyme activities also suggested a modulation in the metabolic profiles of the prokaryotic communities, with biogeochemical implications in nutrient regeneration.Long term studies on microbial activity and abundances in relation with rising temperatures can have a predictive value to describe the evolutionary scenario of microbial processes and the response of microbial metabolism to climate changes in the Mediterranean Sea.

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“…Our new data showed that in low‐latitude, oligotrophic warm waters, when the growth of phytoplankton was suppressed, the bacterioplankton community could be significantly affected by acidification in the early phases of incubation (first 6 days), while acidification had little effect in nutrient depleted conditions (postbloom). Other studies have also observed that changes to bacterial community composition after acidification may be linked to nutrient conditions (Bunse et al, ; Celussi et al, ; Hornick et al, ). We observed relatively low bacterial diversity (Figure ) and relatively simple network of microbial community (Figure ) under high CO 2 compared to the control microcosm.…”

Section: Discussionmentioning

confidence: 94%

Ocean Acidification Regulates the Activity, Community Structure, and Functional Potential of Heterotrophic Bacterioplankton in an Oligotrophic Gyre

et al. 2019

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Ocean acidification (OA), a consequence of increased global carbon dioxide (CO 2 ) emissions, is considered a major threat to marine ecosystems. Its effects on bacterioplankton activity, diversity, and community composition have received considerable attention. However, the direct impact of OA on heterotrophic bacterioplankton is often masked by the significant response of phytoplankton due to the close coupling of heterotrophic bacterioplankton and autotrophs. Here we investigated the responses of a heterotrophic bacterioplankton assemblage to high pCO 2 (790-ppm) treatment in warm tropical western Pacific waters by conducting a microcosm experiment in dark for 12 days. Heterotrophic bacterioplankton abundance and production were enhanced by OA over the first 6 days of incubation, while the diversity and species richness were negatively affected. Bacterioplankton community composition in the high pCO 2 treatment changed faster than that in the control. The molecular ecological network analysis showed that the elevated CO 2 changed the overall connections among the bacterial community and resulted in a simple network under high CO 2 condition. Species-specific responses to OA were observed and could be attributed to the different life strategies and to the ability of a given species to adapt to environmental conditions. In addition, high-throughput functional gene array analysis revealed that genes related to carbon and nitrogen cycling were positively affected by acidification. Together, our findings suggest that OA has direct effects on heterotrophic bacterioplankton in a low-latitude warm ocean and may therefore affect global biogeochemical cycles.

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Ocean acidification effect on prokaryotic metabolism tested in two diverse trophic regimes in the Mediterranean Sea

Cited by 25 publications

References 62 publications

Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

Microbial enzymes in the Mediterranean Sea: relationship with climate changes

Ocean Acidification Regulates the Activity, Community Structure, and Functional Potential of Heterotrophic Bacterioplankton in an Oligotrophic Gyre

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