scholarly journals Temperate southern Australian coastal waters are characterised by surprisingly high rates of nitrogen fixation and diversity of diazotrophs

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10809
Author(s):  
Lauren F. Messer ◽  
Mark V. Brown ◽  
Paul D. Van Ruth ◽  
Mark Doubell ◽  
Justin R. Seymour
Keyword(s):  
Continental Shelf ◽  
Coastal Waters ◽  
Heterotrophic Bacteria ◽  
Pseudomonas Stutzeri ◽  
Amplicon Sequencing ◽  
Open Ocean ◽  
Sulfate Reducing ◽  
Isotope Tracer ◽  
Low Concentrations ◽  
Inverse Estuary

Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotrophs) can ameliorate nitrogen (N) limitation. Historically, rates of N2 fixation were believed to be limited outside of the low nutrient tropical and subtropical open ocean; however, emerging evidence suggests that N2 fixation is also a significant process within temperate coastal waters. Using a combination of amplicon sequencing, targeting the nitrogenase reductase gene (nifH), quantitative nifH PCR, and 15N2 stable isotope tracer experiments, we investigated spatial patterns of diazotroph assemblage structure and N2 fixation rates within the temperate coastal waters of southern Australia during Austral autumn and summer. Relative to previous studies in open ocean environments, including tropical northern Australia, and tropical and temperate estuaries, our results indicate that high rates of N2 fixation (10–64 nmol L−1 d−1) can occur within the large inverse estuary Spencer Gulf, while comparatively low rates of N2 fixation (2 nmol L−1 d−1) were observed in the adjacent continental shelf waters. Across the dataset, low concentrations of NO3/NO2 were significantly correlated with the highest N2 fixation rates, suggesting that N2 fixation could be an important source of new N in the region as dissolved inorganic N concentrations are typically limiting. Overall, the underlying diazotrophic community was dominated by nifH sequences from Cluster 1 unicellular cyanobacteria of the UCYN-A clade, as well as non-cyanobacterial diazotrophs related to Pseudomonas stutzeri, and Cluster 3 sulfate-reducing deltaproteobacteria. Diazotroph community composition was significantly influenced by salinity and SiO4 concentrations, reflecting the transition from UCYN-A-dominated assemblages in the continental shelf waters, to Cluster 3-dominated assemblages in the hypersaline waters of the inverse estuary. Diverse, transitional diazotrophic communities, comprised of a mixture of UCYN-A and putative heterotrophic bacteria, were observed at the mouth and southern edge of Spencer Gulf, where the highest N2 fixation rates were observed. In contrast to observations in other environments, no seasonal patterns in N2 fixation rates and diazotroph community structure were apparent. Collectively, our findings are consistent with the emerging view that N2 fixation within temperate coastal waters is a previously overlooked dynamic and potentially important component of the marine N cycle.

scholarly journals The Chaetognaths of Western Canadian Coastal Waters

1955 ◽  
Vol 12 (4) ◽  
pp. 593-617 ◽  
Author(s):  
Helen E. Lea
Keyword(s):  
Continental Shelf ◽  
Coastal Waters ◽  
Deep Sea ◽  
Open Ocean ◽  
Inland Waters ◽  
Western Canada ◽  
Outer Limit

Four species of chaetognaths were found in samples from 11 representative areas along the coastline of western Canada. Sagitta elegans was the most abundant and widely distributed species, occurring, at least in small numbers, in all the areas sampled. It was characteristic of the mixed coastal waters over the continental shelf and of the inland waters. Eukrohnia hamata, an oceanic form, occurred in most regions in small numbers as an immigrant, and was abundant toward the edge of the continental shelf. Sagitta lyra, strictly a deep sea species, was found only in the open waters along the outer coasts, and a few specimens of Sagitta decipiens, another oceanic form, were also taken in deep hauls from areas exposed to open ocean influence. The outer limit of Sagitta elegans corresponded with the inner limits of all three oceanic forms, though Eukrohnia hamata invaded the inland waters to some extent.

Biological Mechanisms of H2S Formation in Sewer Pipes

1992 ◽  
Vol 26 (3-4) ◽  
pp. 907-914 ◽  
Author(s):  
A. Attal ◽  
M. Brigodiot ◽  
P. Camacho ◽  
J. Manem
Keyword(s):  
Suspended Solid ◽  
Urban Wastewater ◽  
Biological Mechanisms ◽  
Sewer Pipes ◽  
Sulfate Reducing ◽  
Biological Phenomena ◽  
Low Concentrations ◽  
Production Of Hydrogen ◽  
High Concentrations ◽  
Reducing Bacteria

The purpose of this study is to gain a better understanding of the biological phenomena involved in the production of hydrogen sulfide in urban wastewater (UWW) systems. It is found that the UWW itself naturally possesses the biomass needed to consume the sulfates. These heterotrophic sulfate-reducing bacteria populations, though immediately active in strict anaerobic conditions, are present only in very low concentrations in the UWW. A concentration of them was studied within the pressure pipes, in the form of deposits, and this justifies the high concentrations of sulfides measured in certain wastewater networks. There are two reasons why the ferrous sulfate used as a treatment in any wastewater networks should not cause the production of additional sulfides. Firstly, the sulfate consumption kinetics are always too slow, relative to the residence time of the water in the pipe, for all of the sulfates to be consumed anyway. Secondly, the amount of assimilable carbon, soluble carbon, and carbon from suspended solid (SS) hydrolysis is insufficient.

scholarly journals The role of continental shelves in nitrogen and carbon cycling

2010 ◽  
Vol 7 (1) ◽  
pp. 177-205
Author(s):  
K. Fennel
Keyword(s):  
Continental Shelf ◽  
North Atlantic ◽  
Deep Ocean ◽  
Open Ocean ◽  
Biogeochemical Models ◽  
Inorganic Matter ◽  
Continental Shelves ◽  
Shelf Region ◽  
Transformation Processes

Abstract. Continental shelves play a key role in the cycling of nitrogen and carbon. Here the physical transport and biogeochemical transformation processes affecting the fluxes into and out of continental shelf systems are reviewed, and their role in the global cycling of both elements is discussed. Uncertainties in observation-based estimates of nitrogen and carbon fluxes mostly result from uncertainties in the shelf-open ocean exchange of organic and inorganic matter, which is hard to quantify based on observations alone, but can be inferred from biogeochemical models. Model-based nitrogen and carbon budgets are presented for the Northwestern North Atlantic continental shelf. Results indicate that shelves are an important sink for fixed nitrogen and a source of alkalinity, but are not much more efficient in exporting organic carbon to the deep ocean than the adjacent open ocean for the shelf region considered.

scholarly journals Simulating the Impact of the Internal Structure of Phytoplankton on the Bulk Particulate Backscattering Ratio using a Two-Layered Spherical Geometry for Cells

2018 ◽  
Author(s):  
Lucile Duforêt-Gaurier ◽  
David Dessailly ◽  
William Moutier ◽  
Hubert Loisel
Keyword(s):  
Coastal Waters ◽  
Natural Waters ◽  
Heterotrophic Bacteria ◽  
Relative Concentration ◽  
Spherical Geometry ◽  
The Third ◽  
Study Case ◽  
Coated Spheres ◽  
The Impact ◽  
Phytoplankton Cells

The bulk backscattering ratio ($\tilde{b_{bp}}$) is commonly used as a descriptor of the bulk real refractive index of the particulate assemblage in natural waters. Based on numerical simulations, we analyze the impact of heterogeneity of phytoplankton cells on $\tilde{b_{bp}}$. $\tilde{b_{bp}}$ is modeled considering viruses, heterotrophic bacteria, phytoplankton, detritus, and minerals. Three study cases are defined according to the relative abundance of these different components. Two study cases represent typical situations in open ocean, outside (No-B/No-M) and inside bloom (B/No-M). The third study case is typical of coastal waters with the presence of minerals. Phytoplankton cells are modeled by a two-layered spherical geometry representing a chloroplast surrounding the cytoplasm. The $\tilde{b_{bp}}$ values are higher when heterogeneity is considered because the contribution of coated spheres to backscattering is higher than homogeneous spheres. The impact of heterogeneity is however strongly conditioned by the hyperbolic slope $\xi$ of the particle size distribution. Even if the relative concentration of phytoplankton is small (<1%), $\tilde{b_{bp}}$ increases by about 60% (for $\xi=4.3$ and for the No-B/No-M water body), when the heterogeneity is taken into account, in comparison with a particulate population only composed by homogeneous spheres. As expected, heterogeneity has a much smaller impact (about 5$\%$ for $\xi=4.3$) on $\tilde{b_{bp}}$ when minerals are added.

scholarly journals Quorum Sensing Regulates the Hydrolytic Enzyme Production and Community Composition of Heterotrophic Bacteria in Coastal Waters

2021 ◽  
Vol 12 ◽  
Author(s):  
Marion Urvoy ◽  
Raphaël Lami ◽  
Catherine Dreanno ◽  
Daniel Delmas ◽  
Stéphane L’Helguen ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Community Composition ◽  
Coastal Waters ◽  
Bacterial Communities ◽  
Heterotrophic Bacteria ◽  
Bacterial Community Composition ◽  
Marine Ecosystem ◽  
Hydrolytic Enzyme ◽  
Enzymatic Activities ◽  
Hydrolytic Activities

Heterotrophic microbial communities play a central role in biogeochemical cycles in the ocean by degrading organic matter through the synthesis of extracellular hydrolytic enzymes. Their hydrolysis rates result from the community’s genomic potential and the differential expression of this genomic potential. Cell-cell communication pathways such as quorum sensing (QS) could impact both aspects and, consequently, structure marine ecosystem functioning. However, the role of QS communications in complex natural assemblages remains largely unknown. In this study, we investigated whether N-acylhomoserine lactones (AHLs), a type of QS signal, could regulate both hydrolytic activities and the bacterial community composition (BCC) of marine planktonic assemblages. To this extent, we carried out two microcosm experiments, adding five different AHLs to bacterial communities sampled in coastal waters (during early and peak bloom) and monitoring their impact on enzymatic activities and diversity over 48 h. Several specific enzymatic activities were impacted during both experiments, as early as 6 h after the AHL amendments. The BCC was also significantly impacted by the treatments after 48 h, and correlated with the expression of the hydrolytic activities, suggesting that changes in hydrolytic intensities may drive changes in BCC. Overall, our results suggest that QS communication could participate in structuring both the function and diversity of marine bacterial communities.

scholarly journals The Role of Heterotrophic Bacteria and Archaea in the Transformation of Lignin in the Open Ocean

2019 ◽  
Vol 6 ◽  
Author(s):  
Natasha McDonald ◽  
Eric P. Achterberg ◽  
Craig A. Carlson ◽  
Martha Gledhill ◽  
Shuting Liu ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Open Ocean

Distribution of Tailor (Pomatomus saltatrix) Larvae along the Coast of New South Wales, Australia

1996 ◽  
Vol 47 (2) ◽  
pp. 331 ◽  
Author(s):  
AG Miskiewicz ◽  
BD Bruce ◽  
P Dixon
Keyword(s):  
Continental Shelf ◽  
Coastal Waters ◽  
East Coast ◽  
New South ◽  
New South Wales ◽  
Eastern Coast ◽  
Pomatomus Saltatrix ◽  
Outer Continental Shelf ◽  
Survey Period ◽  
South Wales

The distribution of tailor (Pomatomus saltatrix) larvae is described on the basis of the results of four plankton surveys undertaken in northern and central New South Wales (NSW) coastal waters. These comprised a single survey during May 1989 along the northern NSW coast and multiple surveys in January, March and May 1983 between Sydney and Brisbane. Pomatomus saltatrix larvae occurred throughout the survey period, with the highest abundances on the northern NSW coast. Most larvae were caught in mid and outer continental shelf waters at water temperatures of ≥22�C. The only known spawning locality for P. saltatrix is in the vicinity of Fraser Island in southern Queensland from August to October. The occurrence of larvae along the NSW coast from January to May indicates that the spawning season of P. saltatrix is more extensive than previously reported and that spawning occurs along the east coast of Australia in localities other than Fraser Island. Further surveys of larvae in southern Queensland and northern NSW waters, especially from August to December, are required to determine if P. saltatrix has one extended or two discrete spawning seasons along the eastern coast of Australia.

scholarly journals Microbial insights from Antarctic and Mediterranean shallow-water bone-eating worms

Polar Biology ◽  
2020 ◽  
Vol 43 (10) ◽  
pp. 1605-1621 ◽  
Author(s):  
Olivia H. Hewitt ◽  
Cristina Díez-Vives ◽  
Sergi Taboada
Keyword(s):  
16S Rrna ◽  
Shallow Water ◽  
Host Species ◽  
Heterotrophic Bacteria ◽  
Amplicon Sequencing ◽  
Body Tissue ◽  
16S Rrna Amplicon Sequencing ◽  
Degrading Bacteria ◽  
Contrasting Habitats ◽  
Root Tissues

Abstract Bone-eating worms of the genus Osedax (Annelida, Siboglinidae) form unique holobionts (functional entity comprising host and associated microbiota), highly adapted to inhabit bone tissue of marine vertebrates. These gutless worms have developed nutritional symbioses housing intracellular, horizontally acquired, heterotrophic bacteria hypothesised to harness nutrients from organic compounds, sequestered within the bone. Despite previous efforts, critical mechanisms mediating activity and acquisition of diverse bacterial assemblages remain unclear. Using 16S rRNA amplicon sequencing, we performed detailed taxonomic and predicted functional analyses shedding light on the microbial communities of two shallow-water Osedax species (Osedax deceptionensis and Osedax ‘mediterranea’) from contrasting habitats (Antarctic and Mediterranean Sea), in two tissue types (roots and palps). Comparative assessments between host species revealed distinct microbial assemblages whilst, within host species and body tissue, relative symbiont frequencies retained high variability. We reported relatively high abundances of microbes previously classified as primary endosymbionts, Ribotype 1 (order Oceanospirillales), and diverse likely secondary epibionts warranting further exploration as recurrent Osedax associates. Surprisingly, O. ‘mediterranea’ exhibited relatively low abundance of Oceanospirillales, but increased abundance of other potentially hydrocarbon degrading bacteria from the family Alteromonadaceae. We hypothesise the presence of functionally similar, non-Oceanospirillales primary endosymbionts within O. ‘mediterranea’. Functional metagenomic profiling (using 16S rRNA sequences) predicted broad metabolic capabilities, encompassing relatively large abundances of genes associated with amino acid metabolism. Comparative analyses between host body tissue communities highlighted several genes potentially providing critical functions to the Osedax host or that confer adaptations for intracellular life, housed within bone embedded host root tissues.

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