scholarly journals Empirical leucine-to-carbon conversion factors in north-eastern Atlantic waters (50–2000 m) shaped by bacterial community composition and optical signature of DOM

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Pamela Orta-Ponce ◽  
Tamara Rodríguez-Ramos ◽  
Mar Nieto-Cid ◽  
Eva Teira ◽  
Elisa Guerrero-Feijóo ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
North Atlantic Ocean ◽  
Bacterial Community Composition ◽  
Multiple Linear Regression Model ◽  
Carbon Conversion ◽  
Phylogenetic Groups ◽  
Conversion Factors ◽  
The North ◽  
Microbial Utilization ◽  
Optical Signature

AbstractMicrobial heterotrophic activity is a major process regulating the flux of dissolved organic matter (DOM) in the ocean, while the characteristics of this DOM strongly influence its microbial utilization and fate in the ocean. In order to broaden the vertical resolution of leucine-to-carbon conversion factors (CFs), needed for converting substrate incorporation into biomass production by heterotrophic bacteria, 20 dilution experiments were performed in the North Atlantic Ocean. We found a depth-stratification in empirical CFs values from epipelagic to bathypelagic waters (4.00 ± 1.09 to 0.10 ± 0.00 kg C mol Leu−1). Our results demonstrated that the customarily used theoretical CF of 1.55 kg C mol Leu−1 in oceanic samples can lead to an underestimation of prokaryotic heterotrophic production in epi- and mesopelagic waters, while it can overestimate it in the bathypelagic ocean. Pearson correlations showed that CFs were related not only to hydrographic variables such as temperature, but also to specific phylogenetic groups and DOM quality and quantity indices. Furthermore, a multiple linear regression model predicting CFs from relatively simple hydrographic and optical spectroscopic measurements was attempted. Taken together, our results suggest that differences in CFs throughout the water column are significantly connected to DOM, and also reflect differences linked to specific prokaryotic groups.

scholarly journals Empirical Leucine-to-Carbon Conversion Factors for Estimating Heterotrophic Bacterial Production: Seasonality and Predictability in a Temperate Coastal Ecosystem

2009 ◽  
Vol 75 (10) ◽  
pp. 3216-3221 ◽  
Author(s):  
Alejandra Calvo-D�az ◽  
Xos� Anxelu G. Mor�n
Keyword(s):  
Protein Synthesis ◽  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
Spatiotemporal Variability ◽  
Leucine Incorporation ◽  
Carbon Conversion ◽  
Conversion Factors ◽  
Production Studies ◽  
Favorable Conditions

ABSTRACT Leucine-to-carbon conversion factors (CFs) are needed for converting substrate incorporation into biomass production of heterotrophic bacteria. During 2006 we performed 20 dilution experiments for determining the spatiotemporal variability of empirical CFs in temperate Atlantic coastal waters. Values (0.49 to 1.92 kg C mol Leu−1) showed maxima in autumn to early winter and minima in summer. Spatially averaged CFs were significantly negatively correlated with in situ leucine incorporation rates (r = −0.91) and positively correlated with phosphate concentrations (r = 0.76). These relationships, together with a strong positive covariation between cell-specific leucine incorporation rates and carbon contents (r = 0.85), were interpreted as a strategy to maximize survival through protein synthesis and low growth rates under nutrient limitation (low CFs) until favorable conditions stimulate cell division relative to protein synthesis (high CFs). A multiple regression with in situ leucine incorporation rates and cellular carbon contents explained 96% of CF variance in our ecosystem, suggesting their potential prediction from more easily measurable routine variables. The use of the theoretical CF of 1.55 kg C mol Leu−1 would have resulted in a serious overestimation (73%) of annual bacterial production rates. Our results emphasize the need for considering the temporal scale in CFs for bacterial production studies.

scholarly journals Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

2015 ◽  
Vol 81 (23) ◽  
pp. 8224-8232 ◽  
Author(s):  
Eva Teira ◽  
Víctor Hernando-Morales ◽  
Francisco M. Cornejo-Castillo ◽  
Laura Alonso-Sáez ◽  
Hugo Sarmento ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Community Composition ◽  
Nucleic Acid Content ◽  
Carbon Conversion ◽  
Production Rates ◽  
Conversion Factors ◽  
Content Type ◽  
Carbon Production ◽  
The Impact

ABSTRACTThe transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu−1and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyllaconcentration, picocyanobacterial abundance (mostlyProchlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that bothProchlorococcusand HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean.

Zooplankton Biogeochemical Cycles

2017 ◽  
Author(s):  
Deborah Steinberg
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Significant Proportion ◽  
Biogeochemical Cycles ◽  
Biological Pump ◽  
The North ◽  
Particle Export ◽  
Chemical Cycling ◽  
Cycling Of Nutrients ◽  
Planktonic Communities

The structure of planktonic communities profoundly affects particle export and sequestration of organic material (the biological pump) and the chemical cycling of nutrients. This chapter describes the integral and multifaceted role zooplankton (both protozoan and metazoan) play in the export and cycling of elements in the ocean, with an emphasis on the North Atlantic Ocean and adjacent seas. Zooplankton consume a significant proportion of primary production across the world's oceans, and their metabolism plays a key role in recycling carbon, nitrogen, and other elements. The chapter also addresses how human or climate-influenced changes in North Atlantic zooplankton populations may in turn drive changes in zooplankton-mediated biogeochemical cycling.

Spatiotemporal evolution of the chlorophyll a trend in the North Atlantic Ocean

2018 ◽  
Vol 612 ◽  
pp. 1141-1148 ◽  
Author(s):  
Min Zhang ◽  
Yuanling Zhang ◽  
Qi Shu ◽  
Chang Zhao ◽  
Gang Wang ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Chlorophyll A ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Spatiotemporal Evolution ◽  
The North ◽  
The North Atlantic

scholarly journals Future Changes in Tropical Cyclone and Easterly Wave Characteristics over Tropical North America

Oceans ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 429-447
Author(s):  
Christian Dominguez ◽  
James M. Done ◽  
Cindy L. Bruyère
Keyword(s):  
North America ◽  
North Atlantic Ocean ◽  
Mitigation Strategies ◽  
Track Density ◽  
Caribbean Region ◽  
Tropical Cyclogenesis ◽  
Future Scenarios ◽  
Southern Mexico ◽  
The North ◽  
The Future

Tropical Cyclones (TCs) and Easterly Waves (EWs) are the most important phenomena in Tropical North America. Thus, examining their future changes is crucial for adaptation and mitigation strategies. The Community Earth System Model drove a three-member regional model multi-physics ensemble under the Representative Concentration Pathways 8.5 emission scenario for creating four future scenarios (2020–2030, 2030–2040, 2050–2060, 2080–2090). These future climate runs were analyzed to determine changes in EW and TC features: rainfall, track density, contribution to seasonal rainfall, and tropical cyclogenesis. Our study reveals that a mean increase of at least 40% in the mean annual TC precipitation is projected over northern Mexico and southwestern USA. Slight positive changes in EW track density are projected southwards 10° N over the North Atlantic Ocean for the 2050–2060 and 2080–2090 periods. Over the Eastern Pacific Ocean, a mean increment in the EW activity is projected westwards across the future decades. Furthermore, a mean reduction by up to 60% of EW rainfall, mainly over the Caribbean region, Gulf of Mexico, and central-southern Mexico, is projected for the future decades. Tropical cyclogenesis over both basins slightly changes in future scenarios (not significant). We concluded that these variations could have significant impacts on regional precipitation.

scholarly journals Joint Modelling of Wave Energy Flux and Wave Direction

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 460
Author(s):  
Takvor H. Soukissian ◽  
Flora E. Karathanasi
Keyword(s):  
Energy Flux ◽  
Wave Energy ◽  
Goodness Of Fit ◽  
North Atlantic Ocean ◽  
Wave Climate ◽  
Western Mediterranean ◽  
Wave Direction ◽  
Bivariate Model ◽  
The North ◽  
Wave Energy Flux

In the context of wave resource assessment, the description of wave climate is usually confined to significant wave height and energy period. However, the accurate joint description of both linear and directional wave energy characteristics is essential for the proper and detailed optimization of wave energy converters. In this work, the joint probabilistic description of wave energy flux and wave direction is performed and evaluated. Parametric univariate models are implemented for the description of wave energy flux and wave direction. For wave energy flux, conventional, and mixture distributions are examined while for wave direction proven and efficient finite mixtures of von Mises distributions are used. The bivariate modelling is based on the implementation of the Johnson–Wehrly model. The examined models are applied on long-term measured wave data at three offshore locations in Greece and hindcast numerical wave model data at three locations in the western Mediterranean, the North Sea, and the North Atlantic Ocean. A global criterion that combines five individual goodness-of-fit criteria into a single expression is used to evaluate the performance of bivariate models. From the optimum bivariate model, the expected wave energy flux as function of wave direction and the distribution of wave energy flux for the mean and most probable wave directions are also obtained.

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