High Nutrient Research Articles

The influence of soil factors on the different vegetation formations of the Dunas Park, Salvador, Bahia, Brazil

This article was conducted in a restinga ecosystem on quaternary sandy deposits of Parque das Dunas, Salvador, Bahia, Brazil; located north of Salvador, this area comprises a landscape formed by different edaphic gradients with varied vegetation formations. An edaphic characterization of the sections of these remnants was carried out to understand the influence of edaphic factors on the distribution of the plant composition of this environment. For this purpose, a transect was delimited perpendicular to the coastline. In this transect, 08 plots of 25x25m were implanted, 100m apart. In the Centre of each plot, a 1m wide and 60 cm deep trench was opened, where soil samples were collected to determine edaphic and granulometric parameters. These samples in each plot followed the distribution of the vegetation formations of this environment. It was found that the different water regimes and topography of the area influence the soil factors, which interferes with the distribution and heterogeneity of the vegetation. The highest levels of fine, very fine and medium sand fractions and calcium and phosphorus were found in the highest portions. These areas, with better drainage, have a higher plant density. There is a lower vegetation density with open sandbanks in lower areas, lower levels of fine, very fine and medium sand fractions, and lower nutrient retention. In these environments, some areas are partially flooded with adapted species. It was also found that most of the plots had a very acidic pH with the presence of exchangeable Al, which could indicate high nutrient unavailability. Thus, the sandbanks' soil conditions influence the vegetation's development, inducing the plant species to develop adaptive mechanisms to maintain their biological organization.

Animal breeding and feeding tools may close human nutrition gaps

The last century has witnessed many innovations in agriculture and food technologies that have ensured the production of sufficient quantities of good hygienic food. Animal scientists have contributed substantially to efficient breeding and feeding practices by adapting animals for faster growth and improving feed efficiency and utilization. Breeding goals and feeding recommendations have been proposed with a primary focus on profitability to promote significant changes in the macronutrient content, i.e., animal body protein and fat reduction. However, improving the nutritional quality of meat was not included in the profit assessment. Increasing the lean meat fraction is consistent with the goal of public dietary guidelines for human nutrition proposed in 1980, emphasizing the importance of reducing the consumption of animal fat, particularly saturated fat. The application of breeding and feeding tools to modify and improve the fatty acid composition has been partly implemented in pigs and broiler chickens to supplement the dietary recommendations for humans. The health benefits of lean “red meat” have been questioned in recent years, with dietary guidelines and upper limits being introduced for human intake. Animal breeding indirectly reduces the total and heme iron (the redness generator) content in meat, due to covariation with priority breeding goals. Two micronutrients play important roles in the human diet and are derived largely from meat (selenium) and milk (iodine) if the amount provided and absorbed is sufficient and predictable. The iodine content can be highly dependent on the use of novel (more sustainable) feeds. The micronutrients discussed in this study (Fe, Se, I, and vitamin D) highlight opportunities for the utilization of breeding and feeding knowledge to adjust their levels to procure meat with a high nutrient density. The gaps in micronutrient levels in humans must be addressed by navigating within approved animal feeding levels. Animal scientists must recognize the nutritional impact of breeding and feeding and advertise them. In addition, human nutritionists must acknowledge the existing and potential changes in animal production to meet the dietary guidelines. Sustainable food production within the “One Health” concept can only be achieved through cooperation.

Drying Methods for Black Soldier Fly (Hermetia illucens) Larvae as a Feed Ingredient for Pigs Affect In Vitro Nutrient Disappearance

The objective of the present research was to determine the nutrient utilization of full-fat black soldier fly larvae (Hermetia illucens; BSFL), which were processed by various drying methods, using in vitro procedures for pigs. Four sources of BSFL were prepared using various drying methods: (1) hot-air drying at 65 °C for 24 h; (2) microwave drying at 700 W for 5 min, three times; (3) freeze drying at −40 °C for 72 h; (4) infrared drying at medium infrared region (ranged from 2.0 to 6.0 μm) and at 95 °C for 12 min. In vitro ileal disappearance (IVID) of nutrients in the BSFL was measured using a procedure simulating the nutrient digestion and absorption in the stomach and small intestine of pigs. In vitro total tract disappearance (IVTTD) of nutrients in the BSFL was also measured using a procedure that simulated the total intestine of pigs. The contents of dry matter, ether extract, and crude protein in the dried-BSFL ranged from 94.6 to 96.8%, 49.2 to 52.8%, and 30.0 to 36.8%, respectively, on an as-is basis. Microwave drying resulted in a greater (p < 0.05) IVID of dry matter in BSFL, compared with the freeze drying or infrared drying method, which caused the least IVID of dry matter. Hot air-dried BSFL, microwave-dried BSFL, and freeze-dried BSFL had a greater (p < 0.05) IVID of crude protein and a greater (p < 0.05) IVTTD of dry matter and organic matter, compared with infrared-dried BSFL. In conclusion, the hot-air drying, microwave drying, and freeze drying of full-fat black soldier fly larvae resulted in fairly comparable and relatively high nutrient digestibility based on the present in vitro study for pigs. However, the infrared drying method impaired nutrient utilization of full-fat black soldier fly larvae for pigs.

Optimizing the final rest period of sludge treatment wetlands: Assessment of biosolids quality

Wastewater Treatment Plants (WWTPs) generate a substantial amount of sludge as a residue of the wastewater treatment process. The management of this sludge requires the adoption of cost-effective and environmentally friendly techniques. Sludge Treatment Wetlands (STW) have emerged as an effective means to manage and treat sludge, resulting in the production of biosolids suitable for agricultural purposes. This study aimed to ascertain the optimal operation in terms of final rest period for STWs in the Mediterranean region to boost the production of biosolids for agricultural applications. Two WWTPs in Spain were monitored for a period of 9 months, during which several physic-chemical parameters were monitored to determine the optimal final rest period. The findings revealed that, when sludge feeding period was stopped in summer, a final rest period of 6 months was sufficient to reach biosolids suitable for agricultural re-use. These biosolids displayed a content of 53% total solids (TS), a mineralization rate of 40% volatile solids (VS/TS), a stabilization degree (SD) of 40%, and a high nutrient content. Moreover, the presence of heavy metals, pathogens, antimicrobial resistance genes (ARGs), antibiotics, and pesticides was generally low. Overall, this study demonstrates that, in the Mediterranean Region, 6 months of rest period starting in summer are appropriate for sludge treatment wetlands to effectively generate biosolids with suitable characteristics to be safely re-used as a bio-based fertilizer.

Enhanced remediation of real agricultural runoff in surface-flow constructed wetlands by coupling composite substrate-packed bio-balls, submerged plants and functional bacteria: Performance and mechanisms

Import of agricultural runoff containing nutrients considerably contributes to eutrophication of receiving water bodies. Surface-flow constructed wetlands (SFCWs) are commonly applied for agricultural runoff purification, but the performance is usually unsatisfactory. In this study, suspended bio-balls filled with zeolite and iron-carbon (Fe-C) composite substrates, submerged macrophyte (Ceratophyllum demersum) and functional denitrifying bacteria were collectively added into SFCW microcosms to enhance the remediation efficiency for real agricultural runoff with high nutrient concentrations and low content of bioavailable organic matter. The bio-ball added SFCWs achieved notably higher pollutant removal efficiencies (21.1%, 80.2% and 47.5% for chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP), respectively) than the control (COD: 6.9%, TN: 64.4%, TP: 27.9%), because of the versatile functions of filling materials for pollutant removal. C. demersum plantation (COD: 44.2%, TN: 82.8% and TP: 53.7%) and functional bacteria inoculation (COD: 51.8%, TN: 85.8% and TP: 55.1%) further enhanced the efficiency of the SFCWs for agricultural runoff remediation. Bio-ball addition and C. demersum plantation significantly increased the humification degree and reduced the molecular weight of dissolved organic matter (DOM) in the agricultural runoff. Moreover, the two intensification measures also notably reduced organic and nitrogen contents in the wetland sediment. Remarkable distinction in bacterial community distribution patterns was observed in the SFCW sediment and filling substrates in bio-balls. Keystone genera including Clostridium_sensu_stricto_1 and Bacillus in the zeolite, Sphingomonas and Exiguobacterium in the Fe-C substrates and Sediminibacterium in the sediment might be critical for agricultural runoff remediation in the SFCW microcosms. The study highlights a high potential of the intensified SFCWs by these coupling measures for agricultural runoff remediation.

Interannual and seasonal variability of the air–sea CO2 exchange at Utö in the coastal region of the Baltic Sea

Abstract. Oceans alleviate the accumulation of atmospheric CO2 by absorbing approximately a quarter of all anthropogenic emissions. In the deep oceans, carbon uptake is dominated by aquatic phase chemistry, whereas in biologically active coastal seas the marine ecosystem and biogeochemistry play an important role in the carbon uptake. Coastal seas are hotspots of organic and inorganic matter transport between the land and the oceans, and thus they are important for the marine carbon cycling. In this study, we investigate the net air–sea CO2 exchange at the Utö Atmospheric and Marine Research Station, located at the southern edge of the Archipelago Sea within the Baltic Sea, using the data collected during 2017–2021. The air–sea fluxes of CO2 were measured using the eddy covariance technique, supported by the flux parameterization based on the pCO2 and wind speed measurements. During the spring–summer months (April–August), the sea was gaining carbon dioxide from the atmosphere, with the highest monthly sink fluxes typically occurring in May, being −0.26 µmol m−2 s−1 on average. The sea was releasing the CO2 to the atmosphere in September–March, and the highest source fluxes were typically observed in September, being 0.42 µmol m−2 s−1 on average. On an annual basis, the study region was found to be a net source of atmospheric CO2, and on average, the annual net exchange was 27.1 gC m−1 yr−1, which is comparable to the exchange observed in the Gulf of Bothnia, the Baltic Sea. The annual net air–sea CO2 exchanges varied between 18.2 (2018) and 39.1 gC m−1 yr−1 (2017). During the coldest year, 2017, the spring–summer sink fluxes remained low compared to the other years, as a result of relatively high seawater pCO2 in summer, which never fell below 220 µatm during that year. The spring–summer phytoplankton blooms of 2017 were weak, possibly due to the cloudy summer and deeply mixed surface layer, which restrained the photosynthetic fixation of dissolved inorganic carbon in the surface waters. The algal blooms in spring–summer 2018 and the consequent pCO2 drawdown were strong, fueled by high pre-spring nutrient concentrations. The systematic positive annual CO2 balances suggest that our coastal study site is affected by carbon flows originating from elsewhere, possibly as organic carbon, which is remineralized and released to the atmosphere as CO2. This coastal source of CO2 fueled by the organic matter originating probably from land ecosystems stresses the importance of understanding the carbon cycling in the land–sea continuum.

Spatial and Temporal Variability in the Bottom Sediment Characteristics of a Shallow Lake under Backwater Separation and Application of Effective Microorganisms

Lake Konin is a small and shallow lake under the influence of highly eutrophic riverine waters. Feeding the lake as a backwater during high water level periods, the River Obra had exerted a decisive impact on lake water quality, and thus a new dike with a closing device was created. Protective measures were followed by the application of Effective Microorganisms (EM), aiming at a reduction in nutrient concentrations and CyanoHABs. Positive changes in the ecosystem were initiated (increased phytoplankton diversity), but cyanobacteria blooms were still present due to high nutrient content. Some changes were observed in the lake sediments (phosphorus (P) and its fractions, P in pore waters, organic matter and experimental assessment of internal P loading) studied before and during treatment. A slight increase in P content in sediments was noted, as a result of an increase in the Res-P fraction. Simultaneously, a decrease in the most mobile fractions was observed. Summer internal P load was reduced from 5.4 kgP d−1 before the treatment to less than 1 kgP d−1 in the first year, but increased again in the second year to 4.5 kgP d−1. Similarly to lake water quality, positive changes were induced in the lake sediments; nevertheless, they still acted as an important source of nutrients for primary producers. Additional restoration methods shall be considered, as combined treatments used simultaneously are reported to be the most effective for water quality improvement.

Sustainable pre-treatment of tempeh industry wastewater: Efficiency of vermifiltration in pollutant mitigation and compost production

This study investigated the efficacy of vermifiltration (VF) as a sustainable pre-treatment method for tempeh industry wastewater. Three lab-scale VF reactors using different earthworm feeds - cow dung (VF-1), tofu dregs (VF-2), and a combination of both (VF-3) - were used to evaluate their ability to reduce chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), and total suspended solids (TSS), as well as pH. VF-3 exhibited superior performance, achieving reductions of 94.51 % in COD, 95.59 % in BOD₅, and 88.59 % in TSS with maintaining pH values between 6.73 and 6.87. The resulting vermicompost (VC) had high nutrient content, particularly in the VF-3 reactor, with values of 7.66 % C-organic, 1.19 % nitrogen (N), and a C/N ratio of 10.33, phosphate (P) 1.65 %, and potassium (K) of 0.37 %. Additionally, significant earthworm growth was noted in VF-3, suggesting enhanced organic matter breakdown. These results indicate that VF technology not only effectively reduces pollutants in wastewater but also produces nutrient-rich compost, offering a dual benefit for sustainable wastewater management in the tempeh industry.

Yields, nutrient-use efficiencies and production economics of wheat (Triticum aestivum) as influenced by foliar nano urea

The nano fertilizers are becoming popular in crop production sector due to their higher nutrient use efficiency and also enhance the productivity and quality while requiring less input and being environmentally safe. In order to assess the effect of foliar application of nano urea on growth and yield performances of wheat (Triticum aestivum L.) and to evaluate nitrogen-use efficiency under integrated use of nano urea, this study was undertaken during the rabi seasons of 2021–22 and 2022–23 at the Uttar Banga Krishi Viswavidyalaya, Pundibari, West Bengal. The experiment was laid-out in a randomized block design (RBD) having 13 treatments consisting of foliar application of water, nano urea (once at tillering and twice at tillering and jointing) and 5% urea in combination with each of 50,75 and 100% of recommended nitrogen doses (RDN) along with a control (without N), and each treatment was replicated thrice. It was observed that foliar application of nano urea (0.4%) twice at tillering and jointing stages with 100% (RDN 5,759 kg/ha) was statistically at par with 100% RDN + 5% foliar spray of urea twice at tillering and jointing stage (5,985 kg/ha) in terms of grain yield, the latter being the highest yielder. Foliar application of either urea or nano urea by curtailing 25-50% RDN did not brought about superior growth and yield performances. Under each level of RDN (100%, 75% and 50%), foliar application of 5% urea was a bit superior to nano urea, though the difference was not statistically significant. However, nano urea reflected higher nitrogen-use efficiency under all levels RDN; partial factor productivity of nitrogen (PFPN) and agronomic nitrogen-use efficiency (ANUE) values be- ing the highest under 50% RDN along with two spraying of nano urea (56.76 and 24.50 kg grain/kg N). The treat- ment comprising 100% RDN+ 5% spray of urea at tillering and jointing stages resulted in the highest net return (69608 `/ha) and B: C ratio (2.58), closely followed by the treatment comprising nano urea application twice (gross return, net return and B: C ratio of 109,426 `/ha, 63,748 `/ha and 2.40, respectively) with 100% RDN, being statis- tically at par with each other. It can be concluded from this two-year trial that only foliar application of nano urea by curtailing soil nitrogen application to 25-50% resulted in reduced yield performances of wheat; nano urea had pro- motive effects on yields when it was applied along with 100% RDN.

Ocean warming enhances the competitive advantage of Ulva prolifera over a golden tide alga, Sargassum horneri under eutrophication

Recent years have seen the Ulva green tide and Sargassum golden tide become commonplace in the coastal waters of China. However, little is known on how the combination of ocean warming and eutrophication would affect the interaction of green and golden tides. In this study, we cultured the green tide alga Ulva prolifera and the golden tide alga Sargassum horneri under different temperatures (5, 10, 15, 20, 25, and 30°C) and two nutrient concentrations (Low nutrient, LN: 5 μM-nitrate and 0.5 μM-phosphate; High nutrient, HN: 500 μM-N and 50 μM-P) in both monoculture and coculture systems to investigate the physiological responses and their competitive relationships. In monocultures, the growth of U. prolifera and S. horneri, along with pigment concentrations and photosynthesis, increased with rising temperature, reaching a plateau at 15 - 25°C. However, when the temperature increased to 30°C, the growth of U. prolifera and S. horneri decreased abruptly, with S. horneri even suffering death. In coculture, the growth of both U. prolifera and S. horneri was inhibited compared to the monoculture, with the greatest decline observed in S. horneri at 25°C under two nutrient conditions. Our results show that U. prolifera would outcompete S. horneri under high temperature in coculture, suggesting that ocean warming would enhance the competitive advantage of green tide over golden tide under eutrophication in the future.

Nutrient dynamics and biogeochemical processes at the Polar front of Indian sector of the Southern Ocean: Influence of Circumpolar deep water intrusion

The Circumpolar Deep water (CDW) is one of the largest water masses in the Southern Ocean. The cross-frontal flow of the CDW is a vital mode of redistribution and transport of heat, salts, nutrients, etc. in the ocean. The present study aims to understand the role of the CDW intrusion on nutrient dynamics and biogeochemical processes at the Polar frontal region. The study noted a patch of high nutrients layer at ∼300-400 m in the Polar Front-II, underlying the dicothermal layer or the temperature minimum layer. This high nutrient patch was attributed to the intrusion of the CDW at the Polar front, influencing the physico-chemical processes in the water column. It was evident that, the density gradient, stratification and overall, the combined effect of physico-chemical and biological factors as a consequence of intrusion of the CDW contributed to the formation of the high nitrate patch at the Polar Front-II. Even though, the CDW intrusion did not significantly impact the photic layer dynamics during this study, the possible barrier effect during austral summer contribute to the formation of the high nitrate layer. This feature may be responsible for trapping nutrients in the subsurface due to stratification, made available to the photic region via upwelling processes, consequently triggering changes in the biological community structure and biogeochemical processes.

Integrating desertification control and wastewater treatment: Novel insights from the induction of artificial biocrusts using municipal wastewater-cultivated cyanobacterium

Desertification and wastewater discharge are two global issues that severely threaten the sustainable use of available natural resources. This study aimed to explore the potential for transferring nutrients from municipal wastewater to drylands by inducing artificial biocrusts through the inoculation of wastewater-cultured Scytonema javanicum onto the sand surface in Gurbantunggut Desert. The results demonstrated that wastewater cultured S. javanicum effectively induced artificial biocrusts, achieving high photosynthetic biomass and nutrient accumulation (Chl-a, AP and OC) comparable to those induced by S. javanicum cultured in synthetic medium. In addition, the risk index (RI) value of 124.32 suggested a low ecological risk using wastewater cultured S. javanicum to induce artificial biocrusts. This study substantiates the feasibility of using municipal wastewater-cultured cyanobacteria to induce artificial biocrusts, thereby providing a dual benefit: enhancing soil stability in drylands and utilizing wastewater as a resource, thus presenting a significant stride towards the sustainable management of natural resources.

Efficacy of P-sorbent material combined with aquatic plants in controlling nutrient release from urban lake sediment: Field investigation

The release of stored nutrients from sediments is thought to substantially affect water quality in urban lakes. To explore the efficiency of different in-situ remediation methods on controlling high internal urban lake sediments, 120 days of field-enclosure experiments were conducted to investigate the efficacy of P-sorbent materials combined with aquatic plants in controlling nutrient release from urban-lake sediments. The lanthanum-modified clay (LMC) effectively reduced sediment P release flux and could temporarily lead to a small increase in N concentration in the overlying water. In contrast, Vallisneria spiralis (V. spiralis) has a relatively weak effect on controlling nutrient release and can even cause an increase in P concentration. The combined restoration technique of V. spiralis + LMC can overcome the drawbacks of a single method, reduce the nutrient content in overlying water, and inhibit the sediment internal release. Relative to the control, the V. spiralis + LMC treatment reduced mobile P content by 52.5% and increased Ca-P content by 34.5%. The added lanthanum contained material can quickly bind the readily released P in sediment and porewater, transforming it into intert P over time. Submerged macrophytes can absorb active P in water and sediments and transport oxygen to sediments promoting denitrification and N removal. The combined restoration technique synergistically combines the high P sorption affinity of LMC and the substrate improvement effect of V. spiralis, thus realizing the long-term control of endogenous release in urban lakes. This approach holds great promise for restoring urban lakes with high endogenous nutrient loading.

Surface liming combined with the use of monoammonium phosphate and elemental sulphur in a no‐till wheat–soybean cropping system

AbstractTropical and subtropical soils typically have high acidity and limited nutrient availability. Surface liming under no‐till systems ameliorates topsoil acidity in the short term, but it is generally slow to neutralize subsoil acidity. A field experiment was conducted in the period from 2016 to 2021 in Parana State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate the effects of surface application of lime combined with the use of monoammonium phosphate (MAP) and elemental S on soil acidity, root growth, plant nutrition and grain yields of wheat (Triticum aestivum L.) and soybean (Glycine max. [L.] Merr.) under no‐till. Treatments consisted of a control (no amendments), surface lime (SL), SL + MAP and SL + MAP + elemental S. Applying lime to the soil surface increased soil pH, exchangeable Ca2+ and Mg2+ contents and base saturation, as well as reducing Al3+ content and Al3+ saturation throughout the soil profile. Such effects were more pronounced in the 0–10 cm layer and occurred to a lesser extent in the 10–100 cm layers. The addition of MAP or MAP + elemental S did not improve the effectiveness of surface liming in alleviating soil acidity throughout the soil profile. The root length per soil surface area to a depth of 100 cm exhibited a strong correlation with wheat yield, but not with soybean yield. Surface liming increased wheat yield by 40% and when lime application was combined with MAP + elemental S, the increase in wheat yield reached 74%. Surface liming resulted in a 36% increase in soybean yield, regardless of the use of MAP and elemental S. Thus, surface application of lime was effective in reducing soil acidity to a 100‐cm depth, regardless of fertilizer application with MAP and MAP + elemental S. The improving effects of surface liming had a more favourable impact on wheat root growth than on soybean root growth, probably because wheat was more affected than soybean by insufficient rainfall during the crop development cycle. Wheat showed a greater yield response to P and S fertilizer application than soybean.

Food web structure across basins in Lake Erie, a large freshwater ecosystem

Understanding spatial variation of aquatic food web structure and how ecosystem boundaries should be delineated is important. Here, we investigated the spatial variation in food web structure within Lake Erie across its three basins using δ13C and δ15N. Fish and lower trophic level composition were similar but differences in food web structure were observed between basins. The food web in the central basin had the smallest δ13C and δ15N range and total area based on stable isotope values by the aquatic community, likely due to chronic epibenthic hypoxia in the summer that affects fish habitat and resources. The largest δ15N range was in the east, driven by the high trophic position of lake trout present in this deepest basin. The western basin had the largest mean distance to the centroid (CD) of all three basins, indicating a large trophic diversity, probably due to high nutrient loadings and productivity. This research revealed spatial variability of food web structure in large lake ecosystems and the importance of considering smaller sub-units, such as basin, in large lakes.

Picophytoplankton prevail year-round in the Elbe estuary.

Picophytoplankton are important primary producers, but not always adequately recognized, for example, due to methodological limitations. In this study, we combined flow cytometry and metabarcoding to investigate seasonal and spatial patterns of picophytoplankton abundance and community composition in the Elbe estuary. Due to the mixing of freshwater and seawater and the tidal currents this ecosystem is characterized by typical estuarine features such as salinity gradients and high turbidity. Picophytoplankton (mostly picoeukaryotes such as Mychonastes and Minidiscus) contributed on average 70% (SD = 14%) to the total phytoplankton counts. In summer picocyanobacteria (e.g., Synechococcus) played a more significant role. The contributions of picophytoplankton to the total phytoplankton were particularly high from summer to winter as well as in the mid estuary. However, at salinities of around 10 PSU in the mixing area of freshwater and seawater, the proportion of picophytoplankton was comparably low (average 49%, SD = 13%). Our results indicate that picophytoplankton prevail in the Elbe estuary year-round with respect to cell counts. Picophytoplankton could occupy important niche positions to maintain primary production under extreme conditions where larger phytoplankton might struggle (e.g., at high or low temperature, high turbidity, and in areas with high grazing pressure) and also benefit from high nutrient availability here. However, we did not find evidence that they played a particularly significant role at the salinity interface. Our study highlights the importance of including picophytoplankton when assessing estuarine phytoplankton as has been suggested for other ecosystems such as oceans.

Phycoremediation of Domestic Waste Water and Biodiesel Extraction from Fresh-Water Microalgae

ABSTRACT: Microalgae have recently drawn attention as a potential source for the sustainable production of biotechnologically valuable resources and improving the environment in various ways. They are widely distributed and can thrive even under extreme circumstances like high temperatures or high salinity. However, producing microalgae takes a lot of nutrients, which may have an adverse impact on the environment and the economy. The use of wastewater, particularly those from agro-industrial facilities, domestic waste waters, and industrial discharges, which often contain high nutrient concentrations, can serve as an alternative to synthetic culture media. Because the composition of wastewater and usual culture media is relatively similar, wastewater can be utilized to both clean itself and culture microalgae at the same time. Utilizing microalgae as wastewater bioremediation agents can efficiently remove N and P from domestic wastewater, maintain dissolved oxygen concentration, and reduce the various disease-causing pathogens and fecal bacteria that are present in domestic wastewater. The potential of microalgae to be used as a feedstock is increased by their ability to change the composition of their biomass under stress and accumulate lipids or carbohydrates that might be used to produce biodiesel. Methyl or ethyl esters of fatty acids produced from triglycerides by transesterification process by using renewable feedstocks are known as biodiesel. The microalgal biomass is considered as the next generation of feedstock for biofuel production. The Dual function of microalgae in domestic wastewater treatment and biomass growth for biodiesel production is outlined and discussed in detail in this review paper.

Anomalous 2022 deep-water formation and intense phytoplankton bloom in the Cretan area

Abstract. The Mediterranean Sea is a quasi-permanently stratified and oligotrophic basin with intense late-winter and early-spring phytoplankton blooms typically limited to few regions (i.e. northwestern Mediterranean Sea, the southern Adriatic Sea, and the Rhodes Gyre). In these areas, blooms are sustained by nutrient injection to surface layers by winter vertical mixing and convective processes. A markedly intense bloom was predicted in spring 2022 in an unusual area of the southeastern Mediterranean Sea (i.e. southeast of Crete) by the Mediterranean Sea Copernicus Marine Forecasting Centre (MED MFC) system. Combining Copernicus modelling and observation products, the 2022 event and a number of driving and concurrent features have been investigated in a multidisciplinary way. A noticeable cold spell that occurred in Eastern Europe at the beginning of 2022 has been identified as the main driver of an intense deep-water formation event, with associated high nutrient concentrations in the surface layers. Consequently, an extreme phytoplankton bloom that was 50 % more intense than usual occurred in the area southeast of Crete, starting nearly 1 month later than usual and lasting for 3–4 weeks. Impacts on primary production were also relevant in the 2022 event area and were 35 % higher than the climatological annual primary production. Furthermore, the documented link between primary productivity and fishery catches suggests possible consequences along the whole food chain up to the marine ecosystem in the eastern Mediterranean Sea.

Chronic hypoxia drives the occurrence of ferroptosis in liver of fat greening (Hexagrammos otakii) by activating HIF-1α and promoting iron production

BackgroundHypoxia caused by global climate change and human activities has become a growing concern eliciting serious effect and damages to aquatic animals. Hexagrammos otakii is usually a victim of hypoxia which caused by high density aquaculture and high nutrient input. The mechanism underlying ferroptosis regulation after hypoxia-stress in liver of H. otakii, however, remains elusive. MethodsFor a duration of 15 days, expose the H. otakii to low concentrations of dissolved oxygen (3.4 ± 0.2 mg/L). Detecting alterations in the H. otakii liver tissue by chemical staining, immunohistochemistry, and electron microscopy. The expression variations of relevant genes in the liver of the H. otakii were simultaneously detected using Western blot and qPCR. A correlation analysis was performed between HIF-1α and iron ion expression in the liver of H. otakii following hypoxic stress. ResultsIn this study, we conducted the whole ferroptosis integrated analysis of H. otakii under chronic hypoxic condition. Reactive oxygen species (ROS) are highly accumulated under the hypoxia treatment (Superoxide Dismutase, SOD; Catalase, CAT), and which results in a significantly enhanced of lipid peroxidation (Lipid Peroxidation, LPO; Malondialdehyde, MDA; Aminotransferase, AST; Alanine aminotransferase, ALT) in liver tissue. The HIF-1α signaling is activated to cope with the hypoxia stress through strategies including changing iron ion concentration (Fe3+ and TFR1) to breaking the oxidation balance (GSH and GSH-Px), and enhancing ferroptosis gene expression (GPX4). The expression of genes related to ferroptosis pathway (DMT1, FTH1, STEAP3, ACSL4, γ-GCS, SLC7A11) is significantly upregulated and associated to the expression of iron and HIF-1α. ConclusionsIt is demonstrated that the HIF-1α/Fe3+/ROS/GPX4 axis is involved in promoting ferroptosis in fat greening hepatocytes following hypoxia-stress. Ultimately, our findings unveil a process by which hypoxic stress strongly encourages ferroptosis by triggering HIF-1α and boosting iron synthesis.

Nutritional quality and diversity in Ghana’s school feeding programme: a mixed-methods exploration through caterer interviews in the Greater Accra Region

BackgroundThe Ghana School Feeding Programme (GSFP) provides public primary school pupils with a free daily meal. Each meal is expected to follow set menus, providing 30% of children’s’ (6-12 years) energy requirements. This study assessed the nutritional quality and diversity of planned and provided GSFP meals, engaging school caterers to identify how meal quality in the Greater Accra Region could be enhanced.MethodsA cross-sectional mixed methods study design was used. Multistage sampling was used to select 129 schools implementing the GSFP in six districts of the Greater Accra Region. GSFP district menus were collected as well as a one-week school caterer recall of provided school meals. The meal served on the day of data collection was recorded and photographed. Nutritional quality was evaluated based on nutrient profiling methods: energy density (low<125kcal/100g; medium 125-225kcal/100g; high>225kcal/100g) and nutrient density (low<5%; medium 5-10%; high>10%). Meal diversity was assessed by a simple count composed of 5 food groups: cereals, pulses/nuts/seeds, animal-source, vegetables and fruits. Caterers’ views on programme facilitators and barriers were also explored.ResultsPlanned menus included 14-20 weekly options, composed of eight minimally processed traditional dishes. All meals, except white rice, had a high nutrient density/100g. Energy density was varied (low, n=2; medium, n=2; high, n=4). Meals included only 2/5 or 3/5 food groups, mainly starchy staples, pulses/nuts/seeds, and sometimes vegetables. Fruit was never reported. About half of caterers (51.1%) reported deviating from the planned menus: 11.7% served alternative meals, with some including animal-sourced food (17.0%), and 39.4% repeated meals provided during the week, often based on starchy staples, influencing overall nutritional quality. Most caterers reported food item cost and lack of food purchase guidelines as barriers to providing school meals, while food safety training and guidelines for food preparation were facilitators.ConclusionsWhile school meals are composed of minimally processed, nutrient dense, local foods, there are notable gaps in meal diversity and compliance, as reflected in provided meals. Caterer compliance to planned menus varied greatly, reflecting recent food price inflation. Upwardly adjusting the current meal allocation of 1.2 cedis (0.22USD) per child per day could enhance access to more affordable, nutritious and diverse foods in school meals.