Diversity of marine microbes in a changing Mediterranean Sea

Luna, Gian Marco

doi:10.1007/s12210-014-0333-x

Cited by 18 publications

(16 citation statements)

References 81 publications

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“…3a). Overall, the surface bacterioplankton at all stations was dominated by Proteobacteria (ϳ69%), followed by Bacteriodetes (ϳ27%), as in other studies from the Mediterranean Sea (39). Proteobacteria was also the most diverse bacterial group, comprising the highest number of retrieved OTUs (47.2% of the whole data set).…”

Section: Resultssupporting

confidence: 63%

Distribution, Community Composition, and Potential Metabolic Activity of Bacterioplankton in an Urbanized Mediterranean Sea Coastal Zone

Kumari

Balestra

Piredda

et al. 2017

Appl Environ Microbiol

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Bacterioplankton are fundamental components of marine ecosystems and influence the entire biosphere by contributing to the global biogeochemical cycles of key elements. Yet, there is a significant gap in knowledge about their diversity and specific activities, as well as environmental factors that shape their community composition and function. Here, the distribution and diversity of surface bacterioplankton along the coastline of the Gulf of Naples (GON; Italy) were investigated using flow cytometry coupled with high-throughput sequencing of the 16S rRNA gene. Heterotrophic bacteria numerically dominated the bacterioplankton and comprised mainly ,, and Distinct communities occupied river-influenced, coastal, and offshore sites, as indicated by Bray-Curtis dissimilarity, distance metric (UniFrac), linear discriminant analysis effect size (LEfSe), and multivariate analyses. The heterogeneity in diversity and community composition was mainly due to salinity and changes in environmental conditions across sites, as defined by nutrient and chlorophyll concentrations. Bacterioplankton communities were composed of a few dominant taxa and a large proportion (92%) of rare taxa (here defined as operational taxonomic units [OTUs] accounting for <0.1% of the total sequence abundance), the majority of which were unique to each site. The relationship between 16S rRNA and the 16S rRNA gene, i.e., between potential metabolic activity and abundance, was positive for the whole community. However, analysis of individual OTUs revealed high rRNA-to-rRNA gene ratios for most (71.6% ± 16.7%) of the rare taxa, suggesting that these low-abundance organisms were potentially active and hence might be playing an important role in ecosystem diversity and functioning in the GON. The study of bacterioplankton in coastal zones is of critical importance, considering that these areas are highly productive and anthropogenically impacted. Their richness and evenness, as well as their potential activity, are very important to assess ecosystem health and functioning. Here, we investigated bacterial distribution, community composition, and potential metabolic activity in the GON, which is an ideal test site due to its heterogeneous environment characterized by a complex hydrodynamics and terrestrial inputs of varied quantities and quality. Our study demonstrates that bacterioplankton communities in this region are highly diverse and strongly regulated by a combination of different environmental factors leading to their heterogeneous distribution, with the rare taxa contributing to a major proportion of diversity and shifts in community composition and potentially holding a key role in ecosystem functioning.

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Section: Resultssupporting

confidence: 63%

Distribution, Community Composition, and Potential Metabolic Activity of Bacterioplankton in an Urbanized Mediterranean Sea Coastal Zone

Kumari

Balestra

Piredda

et al. 2017

Appl Environ Microbiol

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“…We speculate that these differences should be attributed to the persistently higher temperature that characterizes the meso‐and bathypelagic Mediterranean (> 12°C vs 0‐4°C found in other systems) or to structurally diverse assemblages involved in the process. It is known that the Mediterranean Sea can be considered as a peculiar oceanic region as highlighted by its metagenomic fingerprint (Sunagawa et al ., ), including the dark portion of the water column (Martín‐Cuadrado et al ., ; Smedile et al ., ; Luna, ). Both these aspects are known to affect the bulk microbial metabolism (Pomeroy and Wiebe, ; Kirchman, ), although no direct evidence of their strength have been provided for dark primary production.…”

Section: Discussionmentioning

confidence: 99%

Uptake‐release dynamics of the inorganic and organic carbon pool mediated by planktonic prokaryotes in the deep Mediterranean Sea

Celussi

Malfatti

Ziveri

et al. 2017

Environmental Microbiology

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Understanding the ecosystem functioning in the dark portion of the ocean is a challenge that microbial ecologists are still facing. Due to the large volume, the global deep Ocean plays a central role in the regulation of climate, possibly buffering the rise of atmospheric carbon dioxide if processes of CO fixation compensate for respiration. We investigated the rates of several prokaryotic activities (dissolved and particulate primary production, heterotrophic carbon production and respiration) in meso- and bathypelagic waters of the Mediterranean Sea, covering all sub-basins. Chemosynthesis was the main process for C uptake. The rates of organic C (OC) excretion (or viral-induced cell lysis) inferred from the dissolved primary production measurements were noteworthy, being comparable to particulate primary production, and possibly contributing to the formation of non-sinking particulate organic matter. Inorganic C fixation rates were significantly higher than those reported for other deep-sea systems, probably as a consequence of the persistently higher temperature of dark Mediterranean waters or to phylogenetically diverse communities involved in the process. Primary production was negatively correlated with dissolved organic carbon concentration and showed an inverse pattern to heterotrophic carbon production, indicating a niche partitioning between heterotrophs and autotrophs. In sum, the deep Mediterranean Sea harbors active autotrophic communities able to fix inorganic carbon faster than the heterotrophic carbon production rates.

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“…S1). Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria were expected to be found in marine surface water (Gl€ ockner et al 1999;Schattenhofer et al 2009;Silovi c et al 2012;Vojvoda et al 2014;Luna 2015;Tinta et al 2015). By contrast, sequences affiliated to the Actinobacteria were retrieved from freshwater, which therefore could indicate the importance of the freshwater input.…”

Section: Bacterioplankton Diversitymentioning

confidence: 99%

Influence of the Po River runoff on the bacterioplankton community along trophic and salinity gradients in the Northern Adriatic Sea

et al. 2016

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The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (−65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.

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Diversity of marine microbes in a changing Mediterranean Sea

Cited by 18 publications

References 81 publications

Distribution, Community Composition, and Potential Metabolic Activity of Bacterioplankton in an Urbanized Mediterranean Sea Coastal Zone

Distribution, Community Composition, and Potential Metabolic Activity of Bacterioplankton in an Urbanized Mediterranean Sea Coastal Zone

Uptake‐release dynamics of the inorganic and organic carbon pool mediated by planktonic prokaryotes in the deep Mediterranean Sea

Influence of the Po River runoff on the bacterioplankton community along trophic and salinity gradients in the Northern Adriatic Sea

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