nutrient ratios
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Ocean Science ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. 1775-1789
Author(s):  
Zhuo Chen ◽  
Jun Sun ◽  
Ting Gu ◽  
Guicheng Zhang ◽  
Yuqiu Wei

Abstract. The stratification of the upper oligotrophic ocean has a direct impact on biogeochemistry by regulating the components of the upper-ocean environment that are critical to biological productivity, such as light availability for photosynthesis and nutrient supply from the deep ocean. We investigated the spatial distribution pattern and diversity of phytoplankton communities in the western Pacific Ocean (WPO) in the autumn of 2016, 2017, and 2018. Our results showed the phytoplankton community structure mainly consisted of cyanobacteria, diatoms, and dinoflagellates, while the abundance of Chrysophyceae was negligible. Phytoplankton abundance was high from the equatorial region to 10∘ N and decreased with increasing latitude in spatial distribution. Phytoplankton also showed a strong variation in the vertical distribution. The potential influences of physicochemical parameters on phytoplankton abundance were analyzed by a structural equation model (SEM) to determine nutrient ratios driven by vertical stratification to regulate phytoplankton community structure in the typical oligotrophic ocean. Regions with strong vertical stratification were more favorable for cyanobacteria, whereas weak vertical stratification was more conducive to diatoms and dinoflagellates. Our study shows that stratification is a major determinant of phytoplankton community structure and highlights that physical processes in the ocean control phytoplankton community structure by driving the balance of chemical elements, providing a database to better predict models of changes in phytoplankton community structure under future ocean scenarios.


Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3164
Author(s):  
Ida Judyta Malesza ◽  
Michał Malesza ◽  
Jarosław Walkowiak ◽  
Nadiar Mussin ◽  
Dariusz Walkowiak ◽  
...  

The gut microbiota is responsible for recovering energy from food, providing hosts with vitamins, and providing a barrier function against exogenous pathogens. In addition, it is involved in maintaining the integrity of the intestinal epithelial barrier, crucial for the functional maturation of the gut immune system. The Western diet (WD)—an unhealthy diet with high consumption of fats—can be broadly characterized by overeating, frequent snacking, and a prolonged postprandial state. The term WD is commonly known and intuitively understood. However, the strict digital expression of nutrient ratios is not precisely defined. Based on the US data for 1908–1989, the calory intake available from fats increased from 32% to 45%. Besides the metabolic aspects (hyperinsulinemia, insulin resistance, dyslipidemia, sympathetic nervous system and renin-angiotensin system overstimulation, and oxidative stress), the consequences of excessive fat consumption (high-fat diet—HFD) comprise dysbiosis, gut barrier dysfunction, increased intestinal permeability, and leakage of toxic bacterial metabolites into the circulation. These can strongly contribute to the development of low-grade systemic inflammation. This narrative review highlights the most important recent advances linking HFD-driven dysbiosis and HFD-related inflammation, presents the pathomechanisms for these phenomena, and examines the possible causative relationship between pro-inflammatory status and gut microbiota changes.


2021 ◽  
pp. 29-38
Author(s):  
Oyeyiola Y.B ◽  
Omueti J.A.I. ◽  
Ewetola E.A.

Effects of three C/N mixes of groundnut husk (GNH) and Wister rat litter (RL) on stability, nutrient quality and phytotoxicity of compost were tested and compared with the conventional carbon and nitrogen feedstock mix on 1:3 w/w modality respectively. The GNH and RL were respectively composted in a windrow at three proportionate levels (14.7+105.3, 39.2+80.8 and 63.7+56.3 kg) to achieve C/N nutrient ratios of 20:1, 30:1 and 40:1 respectively using the Pearson square method. A control pile containing GNH+RL (tagged conv. 1:3) applied at 30 kg GNH and 90 kg RL using the conventional 1:3 w/w modality was compared in triplicate. Data were taken on daily compost temperature, pH, EC and nutrient content of stabilized composts. Phytotoxicity was assessed by using two compost extract concentrations of 100 and 50% per compost. There were three replications laid in CRD. Data were statistically analyzed. Number of days to compost stability was significantly influenced by C/N with values increasing with decreasing C/N in the order of 59 < 69 < 74 < 77 days for 40:1, 30:1, 20:1 and conv. 1:3 respectively. Increasing C/N decreased pH (range of 7.3 – 9.0), EC (range of 1.2 – 2.7dS/m), ash (range of 44.2 – 55.5%), total macronutrient (N+P+K) (range of 3.56 – 5.15%) and calcium content (range of 3.3 – 6.5%) and increased organic C (range of 22.4 – 29.6%) of the resultant composts and GI (range of 25 – 76%) of cowpea. The 100 and 50% concentrations supported higher GI of cowpea in composts produced from lower and higher C/N respectively.


Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2301
Author(s):  
Malin Olofsson ◽  
Mary E. Power ◽  
David A. Stahl ◽  
Yvonne Vadeboncoeur ◽  
Michael T. Brett

The interface between terrestrial ecosystems and inland waters is an important link in the global carbon cycle. However, the extent to which allochthonous organic matter entering freshwater systems plays a major role in microbial and higher-trophic-level processes is under debate. Human perturbations can alter fluxes of terrestrial carbon to aquatic environments in complex ways. The biomass and production of aquatic microbes are traditionally thought to be resource limited via stoichiometric constraints such as nutrient ratios or the carbon standing stock at a given timepoint. Low concentrations of a particular constituent, however, can be strong evidence of its importance in food webs. High fluxes of a constituent are often associated with low concentrations due to high uptake rates, particularly in aquatic food webs. A focus on biomass rather than turnover can lead investigators to misconstrue dissolved organic carbon use by bacteria. By combining tracer methods with mass balance calculations, we reveal hidden patterns in aquatic ecosystems that emphasize fluxes, turnover rates, and molecular interactions. We suggest that this approach will improve forecasts of aquatic ecosystem responses to warming or altered nitrogen usage.


2021 ◽  
Author(s):  
Shuaixiang Zhao ◽  
Susanne Schmidt ◽  
Hongjian Gao ◽  
Tingyu Li ◽  
Xinping Chen ◽  
...  

Abstract Compost use in agriculture has the potential to increase the productivity and sustainability of food systems and to mitigate climate change. But the use of diverse compost types in unsuitable biophysical conditions cause uncertain outcomes for crop yields, soil organic carbon (SOC) and nitrous oxide (N2O) emissions. Here, we performed a global meta-analysis with over 2000 observations to determine whether a Precision Composting Strategy (PCS) that aligns suitable composts and application methods with target crop and environment can advance sustainable food production. Eleven key predictors of compost (carbon-to-nutrient ratios, pH, salt content), management (nitrogen supply) and biophysical settings (crop type, soil texture, SOC, pH, temperature, rainfall) determined 80% of the effect on crop yield, SOC, and N2O emissions. We estimate that a PCS could increase global cereal production by 354.5 Tg annually, approximately 1.7-times Africa’s current cereal yield. We further estimate that annual Carbon sequestration could increase by 170.4 Tg Carbon, approximately 20% of the global potential of croplands. This points to a central role of PCS in current and emerging agriculture consistent with the United Nations’ Sustainable Development Goals.


2021 ◽  
Vol 18 (15) ◽  
pp. 4491-4510
Author(s):  
Owen A. Sherwood ◽  
Samuel H. Davin ◽  
Nadine Lehmann ◽  
Carolyn Buchwald ◽  
Evan N. Edinger ◽  
...  

Abstract. The flow of Pacific water to the North Atlantic exerts a globally significant control on nutrient balances between the two ocean basins and strongly influences biological productivity in the northwest Atlantic. Nutrient ratios of nitrate (NO3-) versus phosphate (PO43-) have previously been used to complement salinity characteristics in tracing the distribution of Pacific water in the North Atlantic. We expand on this premise and demonstrate that the fraction of Pacific water as determined by NO3- : PO43- ratios can be quantitatively predicted from the isotopic composition of sub-euphotic nitrate in the northwest Atlantic. Our linear model thus provides a critically important framework for interpreting δ15N signatures incorporated into both modern marine biomass and organic material in historical and paleoceanographic archives along the northwest Atlantic margin.


Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2059
Author(s):  
Savoeurn Soum ◽  
Peng Bun Ngor ◽  
Thomas E. Dilts ◽  
Sapana Lohani ◽  
Suzanne Kelson ◽  
...  

Tonle Sap lake-river floodplain ecosystem (TSE) is one of the world’s most productive freshwater systems. Changes in hydrology, climate, population density, and land use influence water quality in this system. We investigated long term water quality dynamics (22 years) in space and time and identified potential changes in nutrient limitation based on nutrient ratios of inorganic nitrogen and phosphorus. Water quality was assessed at five sites highlighting the dynamics in wet and dry seasons. Predictors of water quality included watershed land use, climate, population, and water level. Most water quality parameters varied across TSE, except pH and nitrate that remained constant at all sites. In the last decade, there is a change in the chemical nutrient ratio suggesting that nitrogen may be the primary limiting nutrient across the system. Water quality was strongly affected by development in the watershed i.e., flooded forest loss, climatic variation, population growth, and change in water level. Seasonal variations of water quality constituents were driven by precipitation and hydrology, notably the Mekong’s distinct seasonal flood pulse.


2021 ◽  
Vol 12 ◽  
Author(s):  
Sophi Marmen ◽  
Eduard Fadeev ◽  
Ashraf Al Ashhab ◽  
Ayana Benet-Perelberg ◽  
Alon Naor ◽  
...  

Aquaculture facilities such as fishponds are one of the most anthropogenically impacted freshwater ecosystems. The high fish biomass reared in aquaculture is associated with an intensive input into the water of fish-feed and fish excrements. This nutrients load may affect the microbial community in the water, which in turn can impact the fish health. To determine to what extent aquaculture practices and natural seasonal cycles affect the microbial populations, we characterized the microbiome of an inter-connected aquaculture system at monthly resolution, over 3 years. The system comprised two fishponds, where fish are grown, and an operational water reservoir in which fish are not actively stocked. Clear natural seasonal cycles of temperature and inorganic nutrients concentration, as well as recurring cyanobacterial blooms during summer, were observed in both the fishponds and the reservoir. The structure of the aquatic bacterial communities in the system, characterized using 16S rRNA sequencing, was explained primarily by the natural seasonality, whereas aquaculture-related parameters had only a minor explanatory power. However, the cyanobacterial blooms were characterized by different cyanobacterial clades dominating at each fishpond, possibly in response to distinct nitrogen and phosphate ratios. In turn, nutrient ratios may have been affected by the magnitude of fish feed input. Taken together, our results show that, even in strongly anthropogenically impacted aquatic ecosystems, the structure of bacterial communities is mainly driven by the natural seasonality, with more subtle effects of aquaculture-related factors.


2021 ◽  
Author(s):  
Joseph James Bautista

Anthropogenic nutrient loading to aquatic systems may increase atmospheric release of nitrous oxide (N₂O) greenhouse gas by enhancing denitrification and/or nitrification. High Si:N loading may favour diatom abundance, whereas low N:P loading may favour cyanobacteria dominance. Systems with diatom or green algal dominance may have greater export of organic matter to sediments, whereas systems dominated by cyanobacteria may have organic matter recycled within the water column due to differences in cell density and sinking. With increased export of organic matter to sediments, denitrification and N₂O production may be stimulated. In laboratory bench-scale microcosms, nitrous oxide production was affected by Si:N loading ratios as predicted, although N:P loading did not affect N₂O production in the manner predicted. However, the predicted effects of nutrient loading ratio on microphyte community composition were not supported by microscopy. Field mesocosm experiments indicated no significant relationship between N₂O production and nutrient loading ratios.


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