Eukaryotic community composition in the sea surface microlayer
across an east-west transect in the Mediterranean Sea

Zäncker, Birthe; Cunliffe, Michael; Engel, Anja

doi:10.5194/bg-2020-249

Cited by 3 publications

(3 citation statements)

References 43 publications

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“…The separation of different autotrophic populations (Synechococcus, picoeukaryotes and small nanophytoplankton) was based on their scattering and fluorescence signals according to Marie et al (2000) and Larsen et al (2001). The abundance of Prochlorococcus was determined on 2 mL samples, also fixed with glutaraldehyde grade I (1 % final concentration) and analysed with a FACSCalibur flow cytometer (Becton Dickinson) using a flow rate of 39-41 µL min −1 (Zäncker et al, 2020). To obtain estimates of carbon biomass, we applied different values of cellular carbon content for each group.…”

Section: Phytoplankton Abundance and Biomassmentioning

confidence: 99%

Deep maxima of phytoplankton biomass, primary production and bacterial production in the Mediterranean Sea

et al. 2021

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Abstract. The deep chlorophyll maximum (DCM) is a ubiquitous feature of phytoplankton vertical distribution in stratified waters that is relevant to our understanding of the mechanisms that underpin the variability in photoautotroph ecophysiology across environmental gradients and has implications for remote sensing of aquatic productivity. During the PEACETIME (Process studies at the air-sea interface after dust deposition in the Mediterranean Sea) cruise, carried out from 10 May to 11 June 2017, we obtained 23 concurrent vertical profiles of phytoplankton chlorophyll a, carbon biomass and primary production, as well as heterotrophic prokaryotic production, in the western and central Mediterranean basins. Our main aims were to quantify the relative role of photoacclimation and enhanced growth as underlying mechanisms of the DCM and to assess the trophic coupling between phytoplankton and heterotrophic prokaryotic production. We found that the DCM coincided with a maximum in both the biomass and primary production but not in the growth rate of phytoplankton, which averaged 0.3 d−1 and was relatively constant across the euphotic layer. Photoacclimation explained most of the increased chlorophyll a at the DCM, as the ratio of carbon to chlorophyll a (C:Chl a) decreased from ca. 90–100 (g:g) at the surface to 20–30 at the base of the euphotic layer, while phytoplankton carbon biomass increased from ca. 6 mg C m−3 at the surface to 10–15 mg C m−3 at the DCM. As a result of photoacclimation, there was an uncoupling between chlorophyll a-specific and carbon-specific productivity across the euphotic layer. The ratio of fucoxanthin to total chlorophyll a increased markedly with depth, suggesting an increased contribution of diatoms at the DCM. The increased biomass and carbon fixation at the base of the euphotic zone was associated with enhanced rates of heterotrophic prokaryotic activity, which also showed a surface peak linked with warmer temperatures. Considering the phytoplankton biomass and turnover rates measured at the DCM, nutrient diffusive fluxes across the nutricline were able to supply only a minor fraction of the photoautotroph nitrogen and phosphorus requirements. Thus the deep maxima in biomass and primary production were not fuelled by new nutrients but likely resulted from cell sinking from the upper layers in combination with the high photosynthetic efficiency of a diatom-rich, low-light acclimated community largely sustained by regenerated nutrients. Further studies with increased temporal and spatial resolution will be required to ascertain if the peaks of deep primary production associated with the DCM persist across the western and central Mediterranean Sea throughout the stratification season.

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Section: Phytoplankton Abundance and Biomassmentioning

confidence: 99%

Deep maxima of phytoplankton biomass, primary production and bacterial production in the Mediterranean Sea

et al. 2021

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“…Fungi in the SML (i.e., myconeuston) are so far very poorly studied. Environmental DNA (eDNA)-based assessment of myconeuston diversity has been conducted in coastal marine waters in the Western English Channel (Taylor & Cunliffe, 2014) and in the open waters of the Mediterranean Sea (Zäncker et al, 2021), with both studies showing that fungal diversity in the SML is distinct from the underlying water column. In the Mediterranean Sea study, particularly for samples collected from the Ionian Sea, fungi were a major eukaryote group in the SML, with the dominant fungal taxon in the study belonging to the genus Cladosporium.…”

Section: Fungi At the Ocean Atmosphere Interfacementioning

confidence: 99%

“…In the Mediterranean Sea study, particularly for samples collected from the Ionian Sea, fungi were a major eukaryote group in the SML, with the dominant fungal taxon in the study belonging to the genus Cladosporium. Other studies have manuscript submitted to JGR: Biogeosciences shown, using stable isotope probing, that marine Cladosporium actively degrade phytoplanktonproduced high-molecular-weight polysaccharides that form gels (Cunliffe et al, 2017), indicating that myconeuston may have a role in processing SML organic material (Zäncker et al, 2021) and therefore impact the physicochemical composition of the ocean-atmosphere interface.…”

Section: Fungi At the Ocean Atmosphere Interfacementioning

confidence: 99%

Planktonic marine fungi: A review

Peng,

Amend,

Baltar

et al. 2023

Preprint

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Fungi in marine ecosystems play crucial roles as saprotrophs, parasites, and pathogens. The definition of marine fungi has evolved over the past century. Currently, “marine fungi” are defined as any fungi recovered repeatedly from marine habitats that are able to grow and/or sporulate in marine environments, form symbiotic relationships with other marine organisms, adapt and evolve at the genetic level, or are active metabolically in marine environments. While there are a number of recent reviews synthesizing our knowledge derived from over a century of research on marine fungi, this review article focuses on the state of knowledge on planktonic marine fungi from the coastal and open ocean, defined as fungi that are in suspension or attached to particles, substrates or in association with hosts in the pelagic zone of the ocean, and their roles in remineralization of organic matter and major biogeochemical cycles. This review differs from previous ones by focusing on biogeochemical impacts of planktonic marine fungi and methodological considerations for investigating their diversity and ecological functions. Importantly, we point out gaps in our knowledge and the potential methodological biases that might have contributed to these gaps. Finally, we highlight recommendations that will facilitate future studies of marine fungi. This article first provides a brief overview of the diversity of planktonic marine fungi, followed by a discussion of the biogeochemical impacts of planktonic marine fungi, and a wide range of methods that can be used to study marine fungi.

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Introduction: Process studies at the air–sea interface after atmospheric deposition in the Mediterranean Sea – objectives and strategy of the PEACETIME oceanographic campaign (May–June 2017)

et al. 2020

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Abstract. In spring, the Mediterranean Sea, a well-stratified low-nutrient–low-chlorophyll region, receives atmospheric deposition by both desert dust from the Sahara and airborne particles from anthropogenic sources. Such deposition translates into a supply of new nutrients and trace metals for the surface waters that likely impact biogeochemical cycles. However, the relative impacts of the processes involved are still far from being assessed in situ. After summarizing the knowledge on dust deposition and its impact on the Mediterranean Sea biogeochemistry, we present in this context the objectives and strategy of the PEACETIME project and cruise. Atmospheric and marine in situ observations and process studies have been conducted in contrasted areas encountering different atmospheric deposition context, including a dust deposition event that our dedicated “fast-action” strategy allowed us to catch. Process studies also include artificial dust seeding experiments conducted on board in large tanks in three ecoregions of the open waters of the Mediterranean Sea for the first time. This paper summarizes the work performed at sea and the type of data acquired in the atmosphere, at the air–sea interface and in the water column. An overview of the results presented in papers of this special issue (and in some others published elsewhere) is presented.

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Eukaryotic community composition in the sea surface microlayer across an east-west transect in the Mediterranean Sea

Cited by 3 publications

References 43 publications

Deep maxima of phytoplankton biomass, primary production and bacterial production in the Mediterranean Sea

Deep maxima of phytoplankton biomass, primary production and bacterial production in the Mediterranean Sea

Planktonic marine fungi: A review

Introduction: Process studies at the air–sea interface after atmospheric deposition in the Mediterranean Sea – objectives and strategy of the PEACETIME oceanographic campaign (May–June 2017)

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