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This article evaluates the present global condition of solar and wind energy adoption and explores their benefits and limitations in meeting energy needs. It examines the historical and evolutionary growth of solar and wind energy, global trends in the usage of renewable energy, and upcoming technologies, including floating solar and vertical‐axis wind turbines. The importance of smart grid technology and energy storage alternatives for enhancing the effectiveness and dependability of renewable energy is explored. In addition, the role of Electric Vehicles (EVs) in a modern smart grid has been assessed. Furthermore, the economic benefits, and most recent technological developments of solar and wind energy and their environmental and social ramifications. The potential of solar and wind energy to meet the increasing global energy demand and the problems and opportunities facing the renewable energy industry have shown excellent promise. Machine learning applications for solar and wind energy generation are vital for sustainable energy production. Machine learning can help in design, optimization, cost reduction, and, most importantly, in improving the efficacy of solar and wind energy, including advancing energy storage. This assessment is a crucial resource for policymakers, industry leaders, and researchers who aim to make the world cleaner and more sustainable. Ultimately, this review has shown the great potential of solar and wind energy in meeting global energy demands and sustainable goals. [ABSTRACT FROM AUTHOR]

Great hope has been pinned on seaweed cultivation as being a potent way of removing CO2 to reduce rates of sea surface warming and acidification. Marine heatwaves and nitrogen pollution in coastal ecosystems are serious current issues that need to be better understood to inform decision making and policy. Here, we investigated the effects of a simulated heatwave and nitrogen pollution on carbon sequestration by an important seaweed crop species and its phycosphere bacteria. Gracilaria lemaneiformis was grown in ambient and high nitrogen conditions (14 and 200 μM L−1). Photosynthetic rate, seaweed biomass and particulate organic carbon accumulation were significantly increased in "high nitrogen‐no heatwave" conditions. In "ambient nitrogen heatwave" conditions, the expression of genes related to photosynthesis was down regulated and the seaweeds lost more dissolved organic carbon (DOC) to the surrounding water, resulting in more refractory dissolved organic carbon (RDOC). In "high nitrogen heatwave" conditions, photosynthetic gene expression was upregulated; bacterial abundance was also increased that can explain the reduced DOC and RDOC accumulation. The simulated heatwave reduced bacterial diversity while high nitrogen alleviated this effect. These findings suggest that the economically important alga G. lemaneiformis may lose more DOC and RDOC to nearshore waters during marine heatwave events, enhancing carbon sequestration, while nitrogen enrichment has a counteractive effect. [ABSTRACT FROM AUTHOR]

To improve the quality of Sargassum fusiforme seedlings, suitable strains of juveniles regenerated from holdfasts need to be bred. In this study, effects of different temperatures (16, 20, and 24 °C) and irradiances (100, 120, and 160 µmol photons·m−2·s−1) on the growth of juveniles (new individuals) from the holdfasts of S. fusiforme were investigated to provide strategies for the cultivation of vegetative propagation seedlings of S. fusiforme. The results demonstrated that during cultivation at 24 °C, the regenerated juveniles rotted after twenty-one days, and their relative growth rate, photosynthetic activity and pigment content decreased substantially. The low temperature of 16 °C also decreased their photosynthetic activity and growth considerably. At a high irradiance of 160 µmol photons·m−2·s−1, the growth rate and photosynthetic activity decreased. Under conditions of 20 °C and 120 µmol photons·m−2·s−1, juveniles showed higher photosynthetic activity and nitrate uptake rates, which increased the growth of the juveniles and lateral branches and promoted the accumulation of photosynthetic pigment. Therefore, culture conditions of 20 °C and 120 µmol photons·m−2·s−1 can be applied for early indoor cultivation of regenerated juveniles of S. fusiforme. This study provided technical support for solving the problem of single provenance of S. fusiforme seedlings. [ABSTRACT FROM AUTHOR]

Epiphytism commonly occurs in marine benthic macroalgae and seagrass communities under natural conditions and those of mariculture. This can greatly obstruct the cultivation of commercial seaweeds and ultimately impacts the seaweed aquaculture industry negatively. Against a background of climate change and a rapidly increasing market demand, the commercial Sargassum species is experiencing increasing challenges posed by epiphytic macroalgae. Severely reduced growth, lower quality, the emergence of diseases, and the ultimate death of the algae can lead to a commercial loss. Attempts to limit epiphytic macroalgae in aquaculture have so far been inefficient. However, epiphytic macroalgae are also rich in nutritional compounds and their relative biomass could be used as efficiently as the cultivated seaweed. As epiphytes cannot effectively be controlled by the current physical, chemical, and other methods in most cases, the perspective of comprehensive utilization could be an alternative over complete prevention and control by traditional methods. Compared to the existing strategies for controlling the growth and spread of epiphytes in seaweed aquaculture, the integrated and indiscriminate harvest and utilization of epiphytic macroalgae as fertilizer, animal food additive agents, as well as the development of biodegradable materials, might prove to be alternative valorization. However, the implementation of epiphytic macroalgae utilizations still needs to overcome the technical obstacles. [ABSTRACT FROM AUTHOR]

At present, studies on the relationship between endogenous phytohormones and growth and development of macroalgae are still lacking. In this study liquid chromatography-mass spectrometry (LC–MS) was used to investigate the temporal and spatial changes of the types and contents of major endogenous plant hormones in Sargassum fusiforme holdfasts during the juvenile's regeneration. The results showed that six endogenous hormones or hormone precursor substances including auxins (Aux/IAA), gibberellins (GAs), isopentenyl adenine (2-iP), 1-aminocyclopropanecarboxylic acid (ACC), salicylic acid (SA) and dihydrojasmonic acid (DHJA) were detected at different temporal change and in different parts of S. fusiforme holdfasts and the regenerated juveniles. The contents of Aux/IAA, 2- iP, ACC, SA and DHJA decreased gradually from non-regenerated (NG) to initial regeneration (IG) of juveniles. From the perspective of spatial distribution, among the leaves (SL), stems (SS) and new holdfast filaments (SR) of the regenerated juvenile, Aux/IAA and GAs contents were the highest in SL and the lowest in SR, while the contents of DHJA and SA were the opposite. The endogenous hormones during the regeneration of juveniles from holdfasts had dynamic pattern of temporal and spatial changes. When compared with other brown algae by the clustering analysis, it was found that the regenerated juveniles had a higher Aux/IAA and SA contents, while the gibberellin (GA3) content varied greatly. This may be the potential cause of regeneration of juveniles from S. fusiforme holdfasts. This study lays the foundation for the study of hormone regulation mechanism during the regeneration of juveniles from S. fusiforme holdfasts and provides a theoretical basis for S. fusiforme holdfasts seedlings. [ABSTRACT FROM AUTHOR]

The Arctic-derived fungus Eutypella sp. D-1 can produce numerous secondary metabolites, and some compounds exhibit excellent biological activity. Seven pimarane-type diterpenes, including three new compounds eutypellenone F (1), libertellenone Y (2), and libertellenone Z (3), and four known compounds (4–7), were isolated from fermentation broth of Eutypella sp. D-1 by the OSMAC strategy of adding ethanol as a promoter in the culture medium. Compound 2 has a rare tetrahydrofuran-fused pimarane diterpene skeleton. The anti-inflammatory activity of all compounds was evaluated. Compounds 3–6 showed a significant inhibitory effect on cell NO release at 10 μmol/L by in vitro experiments, of which 3–5 had inhibitory rates over 60% on nitric oxide (NO) release. Subsequently, the anti-inflammatory activity of 3–5 was evaluated based on a zebrafish model, and the results showed that 3 had a significant inhibitory effect on inflammatory cells migration at 40 μmol/L, while 4 and 5 had a significant inhibitory effect at 20 μmol/L. Moreover, compounds 3–5 have the same conjugated double bond structure, which may be an important group for these compounds to exert anti-inflammatory activity. [ABSTRACT FROM AUTHOR]

Macroalgae provide food for microbial, meio- and macro-faunal communities in coastal ecosystems, thus mediating nutrient dynamics and functions in these ecosystems. Because of this vital role, it is important to clarify physiological information about macroalgae as it reflects their growth potential in the field. In this study, we examined the biomass, pigment content, and photosynthetic O2 evolution rate versus irradiance curves of 18 macroalgal species from the intertidal zone of the Guangdong–Hong Kong–Macao Greater Bay Area, China, and investigated their photosynthetic patterns in relation to phyla characteristics, morphology, and growth locations. The results showed that green algae had the highest maximum photosynthetic O2 evolution rate (Pmax), light utilization efficiency (α), and dark respiration (Rd) among the three macroalgal phyla; the sheet-like macroalgal species had the highest Pmax, α, and Rd among the four morphological categories. The macroalgal species in the upper intertidal zone showed higher Pmax and α and lower saturation irradiance (EK) and compensation irradiance (EC) than those species in the lower intertidal location. The PCA results showed that the biomass of sheet-like macroalgal species was positively correlated with factor PC1 (50.34%), and that of finely branched species was negatively correlated with factor PC2 (25.17%). In addition, our results indicate that the light absorption and utilization capabilities of macroalgae could determine whether they could dominate the intertidal zone and that their photosynthetic characteristics could be used as a potential indicator of their biomass distribution in the Greater Bay Area. [ABSTRACT FROM AUTHOR]

Harmful algal blooms have been a serious environmental problem. The flocculation of Microcystis aeruginosa by oyster shell powders prepared by aerobic calcination (CO), anaerobic calcination (CN), acidification anaerobic calcination (CAN), and deacetylation anaerobic calcination (CHN) was studied. The CO800 (100 mesh) and CN800 (160 mesh) presented the highest flocculation rate of 89.46% and 77.39% when they were stirred for 1 min with speed of 750 r/min and 250 r/min, respectively. The photosynthesis and viability of the algae cells flocculated by CO800 with particle size of 100 mesh were not significantly damaged. The phosphorus nutrient could be removed by CO800 and CN800 effectively due to the presence of Ca2+, which also limited Microcystis aeruginosa growth. The study showed that the processing of oyster shell powder could be used as an effective flocculating material. [ABSTRACT FROM AUTHOR]

The increase in global temperature calls for ambitious action to reduce the release of greenhouse gases into the atmosphere. The transportation sector contributes up to 25% of the total emissions released, mainly from the burning of vehicle fuel. Therefore, scientists from all around the world are focusing on finding a sustainable alternative to conventional vehicle fuel. Biofuel has attracted much attention, as it shows great potential for the replacement of traditional fossil fuels. However, the main bottlenecks of biofuel are the ongoing controversial conflict between food security with biofuel production. Therefore, this study focuses on a sustainable extraction of lipids from microalgae for the production of biofuel using a liquid biphasic flotation system coupled with sugaring-out method. This is the first study to combine the methods of liquid biphasic flotation system with the sugaring-out technique. It represents a holistic study of optimum and effective conditions needed to extract lipids from the system and to understand the reliability of sugar solution as the agent of cell disruption. At the 15-min flotation time, 150 g/L of fructose solution with a 1:2 mass separating agent-acetonitrile ratio successfully extracted up to 74% of lipid from Chlorella sorokiniana CY-1. Two types of fatty acid methyl esters were recovered from the study, with C5:0 being the main component extracted. [ABSTRACT FROM AUTHOR]

Harmful cyanobacterial blooms occur worldwide and pose a great threat to aquatic ecosystems and public health. The application of algicidal bacteria represents an eco-friendly strategy for controlling harmful cyanobacterial blooms; thus, searching for a high efficiency of algicidal bacteria has been becoming an important and continuous task in science. Herein, we identified a bacterial strain coded Streptomyces sp. HY with a highly algicidal activity, and investigated its algicidal efficiency and mechanism against Microcystis aeruginosa. The strain HY displayed high algicidal activity toward Microcystis aeruginosa cells, with a removal rate of 93.04% within 2 days via indirect attack. Streptomyces sp. HY also showed the ability to lyse several genera of cyanobacterial strains, including Dolichospermum, Pseudanabaena, Anabaena, and Synechocystis, whereas it showed a minor impact on the green alga Scenedesmus obliquus, demonstrating its selectivity specially for targeting cyanobacteria. Its algicidal mechanism involved damages to the photosynthesis system, morphological injury of algal cells, oxidative stress, and dysfunction of the DNA repair system. Furthermore, HY treatment reduced the expression levels of genes (mcyB and mcyD) related to microcystin biosynthesis and decreased the total content of microcystin-leucine-arginine by 79.18%. Collectively, these findings suggested that the algicidal bacteria HY is a promising candidate for harmful cyanobacterial bloom control. [ABSTRACT FROM AUTHOR]

Bismuth phosphate (BiPO4), a very attractive candidate for organics electrodegradation, harbors tremendous potential on removing contaminants from water. Here, four carbon microtube electrodes were prepared from corncob, each coated with BiPO4 by a different method to study the electrodegradation of methylene blue (MB). A thorough insight into the composite features of four electrodes was characterized. Better reversibility and electrocatalytic activity of the fourth electrode (BCC4) prepared by digital signal generator was presented with a current density of 5.71 mA cm−2 at a potential of 1.6 V vs Ag/AgCl. The electrochemical impedances and actual lifetime of BCC4 were 125 Ω and 833 h, respectively. The effectiveness of each kind of BiPO4/carbon electrode was preliminarily evaluated by analyzing the actual conversion rate of the MB concentration, which confirms MB electrodegradation by the BiPO4/carbon electrode was mainly dominated by the hydroxyl radical oxidation. The mass transfer rate was increased by carbon microtube; thereby, electrocatalysis of BiPO4/carbon electrode increased as revealed by an increase in the MB degradation rate. The rate constants k obtained for the degradation of MB by BiPO4/carbon electrode at 20 ℃ was 0.0046 mM−1 s−1, which was 11 times than that of BiPO4. The diffusion layer was decreased by carbon microtube, resulting in MB electrodegradation rate increased. The BiPO4 coated on the surface of the carbon microtube electrodes strengthened their electrocatalytic performance, which shed new light on effective selection of suitable carbon electrode for degradation of organics. Therefore, BiPO4/carbon electrode could be potentially applied in the electrodegradation of organic pollutants. [ABSTRACT FROM AUTHOR]

The persistent fight against global environmental threats and energy catastrophe is currently a major concern for the economic development of bioenergy across the entire country. Hence, traditional fuel-based reserves are overburdened to cope with the rapid energy crisis, necessitating an urgent need for an innovative carbon-neutral green-energy resource. In order to address these critical bottlenecks, microalgae with incredible metabolic versatility have paved the way for a pivotal attention towards sustainable biofuel production. However, due to high operational costs and low lipid productivity, the microalgae-based biofuel resource is still in its infancy. As a result, this problem can be overcome by incorporating engineered microalgal strains which can pave the way for significant lipid augmentation for biofuel production. Thus, our current review depicts an in-depth understanding of a multi-omics approach to microalgae, the broad scope of self-sustaining microalgae cultivation, lipid-extraction strategies, and conversion processes to improve economic commercialization in the bioenergy framework. The present review also provides a detailed analysis of the international and national status of bioenergy development by several federal agencies. [ABSTRACT FROM AUTHOR]

Although high CO2 and warming could act interactively on marine phytoplankton, little is known about the molecular basis for this interaction on an evolutionary scale. Here we explored the adaptation to high CO2 in combination with warming in a model marine diatom Phaeodactylum tricornutum. Whole-genome re-sequencing identifies, in comparison to populations grown under control conditions, a larger genetic diversity loss and a higher genetic differentiation in the populations adapted for 2 years to warming than in those adapted to high CO2. However, this diversity loss was less under high CO2 combined with warming, suggesting that the evolution driven by warming was constrained by high CO2. By integrating genomics, transcriptomics, and physiological data, we found that the underlying molecular basis for this constraint is associated with the expression of genes involved in some key metabolic pathways or biological processes, such as the glyoxylate pathway, amino acid and fatty acid metabolism, and diel variability. Our results shed new light on the evolutionary responses of marine phytoplankton to multiple environmental changes in the context of global change and provide new insights into the molecular basis underpinning interactions among those multiple drivers. [ABSTRACT FROM AUTHOR]

The occurrence of cyanobacterial species, especially toxic ones, poses a great threat to coastal and estuary areas. In this study, the toxigenic Microcystis aeruginosa (M. aeruginosa) FACHB-905 was exposed to BG-11 medium with different salinities (1, 4, 7, 10 and 15 ppt) to investigate the physiological responses of this species in terms of oxidative stress, chl a fluorescence and microcystins (MCs) contamination. The results showed that low salinity (≤7 ppt) favored the electron transfer of photosystem II, which promoted the growth and photosynthesis of M. aeruginosa and induced MCs production. However, increased salinity (≥10 ppt) suppressed the growth and photosynthesis of M. aeruginosa and aggravated the oxidative stress of the strain. Salinity of 15 ppt reduced MCs contamination and caused irreversible damage to the photosynthetic system of M. aeruginosa, leading to the lysis and death of algal cells. These results indicated that changes in salinity exerted important regulations on the growth and MCs contamination of the toxic M. aeruginosa, which may provide a reference for the risk assessment of the harmful cyanobacterial species in the coastal and estuary areas. [ABSTRACT FROM AUTHOR]

For estuaries, inland lakes play a vital role in the ecological balance under the impact of tides. The effect of tides-induced water exchange on phytoplankton community in a semi-closed lake was studied and compared with that of an adjacent closed lake in the Oujiang River mouth in Zhejiang, East China Sea, from June 29, 2020 to June 14, 2021. Results show that the dominant species, abundance, dominance, and diversity of the phytoplankton species between the two lakes were significantly different. In the closed lake, cyanobacteria were the dominant species during the study period. However, in the semi-closed lake, the diversification of the dominant species was greater, and some species of diatoms and green algae became dominant. The average phytoplankton abundance in the closed lake was 6 times of that in the semi-closed lake. The average dominance of cyanobacteria in the closed lake was 0.96, and those in the semi-closed lake and the Oujiang River were 0.51 and 0.22, respectively. Cyanobacterial blooms occurred throughout the study time in the closed lake but not in the semi-closed one. Furthermore, the species diversity richness of the phytoplankton in the semi-closed lake was higher than that of the closed one, and the phytoplankton community between the closed lake and semi-closed lake could be divided into distinctly different groups based on non-metric multidimensional scaling analysis (NMDS) and analysis of similarities (ANOSIM) analysis. The salinity of the water was significantly greater and the transparency significantly smaller in the semi-closed lake than those in the closed lake. Therefore, water exchange driven by local tidal movement increased salinity and decreased transparency of water, which consequently shaped the community structures of different phytoplankton and reduced the risk of a cyanobacterial bloom outbreak in the semi-closed lake. [ABSTRACT FROM AUTHOR]

Microcystis aeruginosa has always been regarded as the main culprit of cyanobacterial blooms in freshwater. However, in recent years, Raphidiopsis raciborskii has gradually replaced M. aeruginosa as the culprit of cyanobacterial blooms in some tropical and subtropical shallow lakes. To reveal which one plays a more dominant role, interactions between cylindrospermospin (CYN)-producing R. raciborskii and microcystins (MCs)-producing or non-MCs-producing M. aeruginosa strains were studied using bialgal cultures at different initial ratios of biomasses of the two species at 25 °C. During the co-cultivation, the M. aeruginosa strains inhibited the growth and heterocyst formation of R. raciborskii filaments, and thus occupied a dominant position during the co-cultivation regardless of the initial biomass ratios in the cultures. In addition, the MCs-producing M. aeruginosa strain contributed to a higher portion of the total biomass and exerted a stronger inhibitory effect on R. raciborskii compared with the non-MCs-producing strain. However, the growth of both MCs-producing and non-MCs-producing M. aeruginosa strains was stimulated by R. raciborskii in the co-cultures compared with M. aeruginosa monoculture, indicating that M. aeruginosa could outcompete R. raciborskii if given enough time, enabling it to develop into the dominant species even in very low initial concentration. To our best knowledge, this is the first report on the loss of heterocyst formation by a species of cyanobacteria that resulted from interactions between two different species of cyanobacteria. These findings indicate that it is difficult for R. raciborskii to replace the dominant position of M. aeruginosa under the experimental environmental condition, and the allelopathic effects of M. aeruginosa on R. raciborskii could significantly contribute to the success of M. aeruginosa. [ABSTRACT FROM AUTHOR]

The changes in underwater light in field usually occur not only in intensity but in spectrum, affecting the photophysiology of marine photoautotrophs. In this study, we comparably examined the photosynthesis of two dominating macroalgae in the Daya Bay, Chlorophyta Ulva fasciata and Phaeophyta Sargassum thunbergii, under white light, as well as under red, green and blue light. The results showed that the net photosynthetic O2 evolution rate (Pn) of U. fasciata under field light increased from 25.2 ± 3.06 to 168 ± 1.2 µmol O2 g FW−1 h−1 from dawn to noon, then decreased to 42.4 ± 0.20 µmol O2 g FW−1 h−1 at dusk. The Pn of S. thunbergii exhibited a similar diel change pattern, but was over 50% lower than that of U. fasciata. The maximal photosynthetic rate (Pmax) of U. fasciata derived from the photosynthesis vs. irradiance curve under white light (i.e., 148 ± 15.8 µmol O2 g FW−1 h−1) was ~30% higher than that under blue light, while the Pmax of S. thunbergii under white light (i.e., 39.2 ± 3.44 µmol O2 g FW−1 h−1) was over 50% lower than that under red, green and blue light. Furthermore, the daily primary production (PP) of U. fasciata was ~20% higher under white than blue light, while that of S. thunbergii was 34% lower, indicating the varied light spectral compositions influence algal photosynthetic ability and thus their primary production in field, and such an influence is species-specific. [ABSTRACT FROM AUTHOR]

Sargassum fusiforme is often adversely affected by epiphytic algae during its cultivation. However, the biological differences between S. fusiforme and the epiphytic algae have not yet been elucidated detrimental to the management of S. fusiforme culture. In this study, we sampled S. fusiforme and main epiphytic algae Ulva lactuca in a marine culture cycle and compared their biological characteristics. It indicated that, except during low‐temperature months (January and March), the photosynthetic electron activity of U. lactuca were generally higher than S. fusiforme. The nitrogen uptake rates of S. fusiforme and U. lactuca were all significantly higher in the earlier growth stage than other stages. In most cases, the nitrogen uptake and utilization of U. lactuca was higher than those of S. fusiforme. Although S. fusiforme absorbed more trace elements, U. lactuca had relatively strong photosynthesis and nutrient absorption performance; thus, the latter accumulated more soluble carbohydrate and protein and may have stress effect on S. fusiforme. This study will be helpful for understanding the differences in the biological characteristics of economic seaweed and its epiphytic macroalgae and provides a reference for the friendly management and healthy development of seaweed cultivation. [ABSTRACT FROM AUTHOR]

In the past decades, the taxonomic status of the cyanobacterial family Phormidiaceae has always been chaotic and problematic. In this study, filamentous cyanobacteria were investigated in the east of China, and twenty strains isolated from different locations of Zhejiang Province were characterized. Using the polyphasic approach combining morphological, molecular and phylogenetic features, these strains were grouped within the members of the genera Ancylothrix and Potamolinea, the newly recorded genera of cyanobacteria in China. Based on the collected taxonomic information of the family Phormidiaceae, cyanobacterial systematics at family level were further discussed. This study provided a simple and efficient example to perform the phylogenetic evaluation for the monophyly and rationality of currently used families of cyanobacteria by using the regional strains based on the polyphasic approach. [ABSTRACT FROM AUTHOR]

Harmful algal bloom (HAB) is an ecological disaster to local mariculture. At present, its impact on macrophytes has not been well studied. In this study, we cultivated sexually propagated embryos of Sargassum fusiformis— an edible seaweed—in Prorocentrum donghaiense suspensions at different cell densities (0, 0.50×105, 0.75×105, 1.00×105, and 1.50×105 cells/mL) for 10 days, during which growth and photosynthetic activities of the embryos were determined, and a monocultivation was set up for comparison. Results show that the relative growth rate and photosynthetic activities of the embryos co-cultivated with P. donghaiense were inhibited mostly and significantly in the cell densities of 0.75×105, 1.00×105, and 1.50×105 cells/mL, and the inhibitory effects increased in overall with increased cell densities. The maximum relative electron transport rates (rETRmax) and apparent photosynthetic efficiency (α) of co-cultivated embryos were all significantly lower than monocultivation ones on the 10th day. Furthermore, the photosynthetic activity detected by chlorophyll-a fluorescence transient (i.e., OJIP), the electron transport among electron transfer accepters of PSII (photosystem II) and that from PSII to PSI (photosystem I) was restricted, which is probably responsible for the decreases of rETRmax and α in the co-cultivated embryos. In addition, parts of the photosynthetic reaction centers of PSII in the co-cultivated embryos were inactivated. Therefore, P. donghaiense bloom could restrain the development and photosynthetic activities of S. fusiformis embryos, reduce the seedlings stock, and eventually hinder the development of S. fusiformis production industry. [ABSTRACT FROM AUTHOR]

Eutrophication is threatening coastal ecosystems globally. Using 15 mesocosms, we explored how nitrogen (N) and phosphorus (P) enrichment affects the dynamics of plankton communities over 15-day (winter) and 10-day (summer) experimental enrichments in Daya Bay, a mesotrophic bay in the northern South China Sea. P enrichment had no obvious effect on the plankton community, whereas N or N+P enrichment stimulated two phytoplankton blooms, with the dominant species shifting from diatoms to dinoflagellates across enrichment periods in both winter and summer. Coinciding with increases in phytoplankton (i.e. chlorophyll- a concentrations and cell abundance), the N+P enrichment enhanced primary productivity on Experimental Day 6 by a maximum of ~8.0-fold (i.e. from a mean ± s.d., 4.49 ± 0.31 to 36.5 ± 8.4 μg C L–1 h–1) in winter and ~7.5-fold (i.e. from 8.16 ± 0.22 to 60.6 ± 10.1 μg C L–1 h–1) in summer. The N+P enrichment increased the abundance of heterotrophic bacteria in both seasons, as well as bacterial productivity. Moreover, the N+P enrichment increased both community respiration and the variation in net community production in both winter and summer, indicating that the marine ecosystems in Daya Bay may become more fragile in the future with continuing inputs of land-derived nutrients. Using 15 mesocosms we showed N or N+P enrichment stimulated two phytoplankton blooms across enrichment periods, with the dominant species shifting from diatoms to dinoflagellates in both winter and summer in Daya Bay. Accordingly, N+P enrichment enhanced phytoplankton primary production, as well as the abundance and productivity of bacteria. N+P enrichment increased both community respiration and the variation in net community production, indicating that this coastal ecosystem may become more fragile in the future as inputs of land-derived nutrients continue. [ABSTRACT FROM AUTHOR]

Global warming increases seawater temperature, causing high temperature stress to marine organisms, including algae. This study aimed to explore the global proteomic response of Sargassum fusiforme under high temperature stress. Sargassum fusiforme seedlings were cultured in natural seawater for 24 hr and subjected to different temperatures (22°C, control group; 27°C and 32°C, high temperature stress group) for 1, 3, 5 and 7 days. Changes in their membrane lipid peroxidation after high temperature stress were investigated. Proteomic changes in the air bladders of S. fusiforme were analysed using isobaric tags for relative and absolute quantification, along with liquid chromatography–tandem mass spectrometry. Data were analysed using bioinformatics methods. Results showed that high temperature stress destroyed the cell membrane of the air bladders. Further, 28 and 53 differentially expressed proteins (DEPs) were found in the 27°C and 32°C treatment groups respectively. These DEPs were mainly involved in glycolysis, single‐organism catabolism, purine nucleoside diphosphate metabolism and carbohydrate catabolism. In addition, DEPs were significantly enriched in 10 pathways, such as glycolytic process, biosynthesis of antibiotics, ribosome, biosynthesis of secondary metabolites and biosynthesis of amino acids. Proteomics analyses indicated that proteins associated with synthesis, folding, degradation, photosynthesis and energy and carbohydrate metabolism are differentially expressed under high temperature stress and normal conditions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a common heavy metal pollutant in the aquatic environment, generally toxic to plant growth and leading to growth inhibition and biomass reduction. To study the oxidation resistance in Sargassum fusiforme seedlings in response to inorganic Cd stress, we cultured the seedlings under two different Cd levels: natural seawater and high Cd stress. High Cd stress significantly inhibited the seedlings growth, and darkened the thalli color. Additionally, the pigment contents, growth rate, peroxidase (POD) activity, dehydroascorbic acid (DHA) content, and glutathione reductase (GR) activity in S. fusiforme were significantly reduced by high Cd treatment. Contrarily, the Cd accumulation, Cd2+ absorption rate, dark respiration/net photosynthetic rate (Rd/Pn), ascorbic acid (Vc) content, soluble protein (SP) content, glutathione (GSH), and the activities of superoxide dismutase (SOD) and catalase (CAT) of S. fusiforme under Cd treatment significantly increased compared to the control group. The decrease of malondialdehyde (MDA) was not significant. Although S. fusiforme seedlings increased the antioxidant activities of POD, SOD, Vc, and the AsA-GSH cycle to disseminate H2O2 and maintain healthy metabolism, high Cd stress caused Cd accumulation in the stem and leaves of S. fusiforme seedlings. The excessive Cd significantly restricted photosynthesis and reduced photosynthetic pigments in the seedlings, resulting in growth inhibition and deep morphological color, especially of the stems. High levels of Cd in seawater had toxic effects on commercial S. fusiforme seedlings, and risked this edible seaweed for human food. [ABSTRACT FROM AUTHOR]

In this paper, a heterogeneous diffusive prey-predator system is first proposed and then studied analytically and numerically. Some sufficient conditions are derived, including permanence and extinction of system and the boundedness of the solution. The existence of periodic solution and its stability are discussed as well. Furthermore, numerical results indicate that both the spatial heterogeneity and the time-periodic environment can influence the permanence and extinction of the system directly. Our numerical results are consistent with the analytical analysis. [ABSTRACT FROM AUTHOR]

The sexual reproduction period (May–June) of Sargassum fusiformis, an important aquaculture seaweed in China, coincides with a time of high frequency of algal blooms caused by dinoflagellates such as Karenia mikimotoi. We studied the effects of dense K. mikimotoi suspensions on the sexual reproduction and subsequent development of the fertilized eggs of S. fusiformis in the laboratory. The results showed that K. mikimotoi did not inhibit the egg fertilization, but significantly (P < 0.05) inhibited the relative growth rate (RGR), chlorophyll (Chl) a content and maximum relative electron transport rate (rETRmax) of the embryos. On the fifth day of the culture period, the size of the embryos co-cultivated with K. mikimotoi at 1000 μmol Chl a L−1 began to decline significantly (P < 0.05) compared with the mono-cultured embryos and the difference increased with prolonged exposure. After 10 days, the RGR, Chl a content, and rETRmax of the embryos cultivated with K. mikimotoi decreased by 28.44%, 4.99%, and 63.99%, respectively, as compared with the ones cultivated without K. mikimotoi. These results indicated that the blooms formed by K. mikimotoi had little suppression on the fertilization of S. fusiforme eggs, but it did significantly inhibit the development and photosynthetic activities of the embryos, which would have adverse effects on the S. fusiforme farming industry. [ABSTRACT FROM AUTHOR]

In this paper, we analytically and numerically study the dynamics of a stochastic toxin-producing phytoplankton–fish system with harvesting. Mathematically, we give the existence and stability of the positive equilibrium in the deterministic system (i.e., the system without environmental noise fluctuations). In the case of the stochastic system (i.e., the system with environmental noise fluctuations), in addition to the existence and uniqueness of the positive solution, we provide the properties of the stochastic dynamics including the stochastic extinction and persistence in the mean, almost sure permanence and uniform boundedness, and the existence of ergodic stationary distribution for the phytoplankton and fish. Ecologically, via numerical analysis, we find that (1) the small random environmental fluctuations can ensure the persistence of phytoplankton and fish, but the larger one can result in the extinction of these populations; (2) an appropriate increase in harvest rate can reduce the irregular random variation of phytoplankton and fish; (3) the increase of toxin liberate rate is capable to decrease the height of probability density function of phytoplankton. These results may help us to better understand the phytoplankton–fish dynamics. [ABSTRACT FROM AUTHOR]

If the atmospheric CO2 continues to increase as predicted, Pyropia haitanensis would experience the coupled effects of ocean acidification (OA) and interference from the epiphyte alga Ulva lactuca. In the current study, we evaluated the carbon (C) and nitrogen (N) accumulation in P. haitanensis and U. lactuca under OA conditions, as well as the interspecific competition between these two algae. We found that, under mono-culture conditions, OA significantly enhanced the growth of both P. haitanensis and U. lactuca and markedly increased the soluble carbohydrate (SC) content and C/N ratios in P. haitanensis, but reduced its soluble proteins (SP) content. In U. lactuca, OA reduced its SP content, but increased C/N ratios, while its SC content was not significantly affected. Under biculture conditions, the rapid growth of U. lactuca and its comparatively more efficient use of nutrients resulted in insufficient available N sources for P. haitanensis. Biculture with U. lactuca increased SC but declined SP content. This also resulted in some membrane injuries that were indicated by increased malondialdehyde (MDA) content and depressed growth in P. haitanensis. Biculture with U. lactuca was disadvantageous for carbon and nitrogen accumulation in P. haitanensis. The results demonstrated that under conditions of OA, the negative effects caused by the epiphyte U. lactuca were more pronounced. If the CO2 levels rise as predicted, Ulva algae would severely interfere with maricultivation of P. haitanensis. [ABSTRACT FROM AUTHOR]

Mariculture of the economically important seaweed will likely be affected by the combined conditions of ocean acidification that resulting from increasing CO2 rising and decreased light levels, especially under high culture intensity and high biomass accumulation. To examine this coupling effect on the photosynthetic performance of Sargassum fusiforme seedlings, we cultured seedlings of this alga under different light and CO2 levels. Under low light conditions, elevated CO2 significantly decreased the photosynthesis of S. fusiforme seedlings, including a decreased photosynthetic electron transport rate. Seedlings grown under the low light intensity exhibited higher photosynthetic rates and compensation irradiance, and displayed higher photosynthetic pigment contents and light absorption than seedlings grown under high light intensity, providing strong evidence of photosynthetic acclimation to low light. However, the captured light and energy were insufficient to support photosynthesis in acidified seawater regardless of increased dissolved inorganic carbon, resulting in declined carbohydrate and biomass accumulation. This indicated that S. fusiforme photosynthesis was more sensitive to acidified seawater in its early growth stage, and strongly affected by light intensity. Future research should evaluate the practical manipulation of biomass accumulation and mariculture densities during the early culture period at the CO2 level predicted for the end of the century. [ABSTRACT FROM AUTHOR]

To explore the effects of temperature changes on dinoflagellate bloom succession in the coastal waters of the East China Sea, changes in the growth, photophysiology, and Rubisco gene expression of Prorocentrum donghaiense and Karenia mikimotoi, two harmful algal species, were investigated at different temperatures (16 to 28°C). The maximal specific growth rate and the maximal mRNA expression of Rubisco gene in P. donghaiense and K. mikimotoi occurred at 20 and 24°C, respectively. The photosynthetic activity of P. donghaiense was generally stable, but K. mikimotoi photosynthesis increased when temperatures rose from 16 to 28°C. The effective photochemical efficiency ( F / F ) and the maximal relative electron transfer rate (rETR) of K. mikimotoi increased significantly with increasing temperature, and the lowest and highest values occurred at 16 and 28°C, respectively. It seems that P. donghaiense has higher photosynthetic capacity than K. mikimotoi due to its higher F / F , rETR, and photosynthetic efficiency (α). However, K. mikimotoi has a higher growth rate than P. donghaiense. These results suggest that the photosynthetic activity and genetic responses of dinoflagellates are species-dependent. It is likely that temperature changes affect species composition during blooms, leading to the observed patterns of bloom succession. [ABSTRACT FROM AUTHOR]

A wetland ecosystem is studied theoretically and numerically to reveal the rules of dynamics which can be quite accurate to better describe the observed spatial regularity of tussock vegetation. Mathematical theoretical works mainly investigate the stability of constant steady states, the existence of nonconstant steady states, and bifurcation, which can deduce a standard parameter control relation and in return can provide a theoretical basis for the numerical simulation. Numerical analysis indicates that the theoretical works are correct and the wetland ecosystem can show rich dynamical behaviors not only regular spatial patterns. Our results further deepen and expand the study of dynamics in the wetland ecosystem. In addition, it is successful to display tussock formation in the wetland ecosystem may have important consequences for aquatic community structure, especially for species interactions and biodiversity. All these results are expected to be useful in the study of the dynamic complexity of wetland ecosystems. [ABSTRACT FROM AUTHOR]

Arthrospira species grow well under highly enriched inorganic carbon concentrations, but little is known on the effects of inorganic carbon (Ci) limitation on its physiological performance. When Arthrospira platensis D-0083 was grown in a modified medium without NaHCO under ambient air of 380 ppm CO, its trichomes became disassembled while the growth and photosynthetic rates were severely reduced. Phycocyanin and allophycocyanin contents decreased but the carotenoid content increased under the Ci limitation. Compared with the cells grown in Zarrouk medium, the trichomes grown under the Ci limitation increased their photosynthetic apparent affinity for Ci by about 14 times but photochemical quenching capacity was reduced. It appeared that A. platensis increased its CO concentrating mechanism by inducing HCO transporters and reducing the trichome size which increased filamentous surface to volume ratio. [ABSTRACT FROM AUTHOR]

It is known that copepods can sense solar UV and avoid it vertically or horizontally, but no in situ studies have been documented to monitor their responses to diurnal solar radiation changes. Here, we provided in situ evidence that zooplankton sense changes in solar radiation during a diurnal solar cycle. By comparing the abundance of the zooplankton in a shaded water column with that in the non-shaded adjacent area, we found that, on a cloudy day with low solar radiation levels, the ratios of zooplankton biomass in the shaded areas to those in nearby non-shaded water ranged from 0.90 to 1.49. However, on sunny days with high solar radiation levels, the ratios ranged from 0.83 to 2.88, with the amount of zooplankton in the shaded water being higher than that in the non-shaded area and higher during the periods of higher irradiance levels. These results indicated that the horizontal migration of zooplankton may be a protective strategy against stressful solar radiation. [ABSTRACT FROM AUTHOR]

Solar ultraviolet radiation (UVR) is known to harm aquatic organisms by damaging key molecules. Here, we showed that UV-A as well as UV-B affected differentially the respiration, ammonia excretion, and mortality of the copepods Pseudodiaptomus marinus (herbivorous) and Labidocera bipinnata (omnivorous). Adding UV-A (320-400 nm, 62.4 W m) to PAR (400-700 nm, 278 W m) decreased respiration by 10.2% in P. marinus and 46.1% in L. bipinnata, and additionally, the presence of UV-B (280-320 nm, 2.63 W m) further decreased it by 8.1 and 18.8%, respectively. The ammonia excretion of P. marinus was suppressed by 13.9% in 30 min exposures to PAR + UV-A compared with those receiving PAR only; however, in the presence of UV-B, it decreased by 13.8% compared to the control. In L. bipinnata, exposure to PAR decreased the ammonia excretion by 33.4%, while the presence of UV-B caused additional suppression by 15.8%. The mortalities of both copepod species increased with prolonged duration under all radiation treatments. More carotenoids and UV-absorbing compounds were found in P. marinus than in L. bipinnata, which could have been responsible for the higher resistance of the former to solar UVR. [ABSTRACT FROM AUTHOR]

To test the effects of photosynthetic active radiation (PAR, 400-700 nm) and ultraviolet radiation (UVR, 280-400 nm) on phototaxis and photosynthesis of free swimming microalgae, experiments were performed with Tetraselmis subcordiformis (Wille) Butcher under a solar simulator. In particular, we evaluated the effects of different PAR levels and radiation regimes (i.e., PAR only and PAR+UVR) on those two processes. We found that the cells preferred to move to a particular area (e.g., receiving 100 W m PAR) with little photochemical suppression or inhibition of carbon fixation. Adding UV-A to high PAR decreased its swimming capacity and photosynthetic capability, and further adding UV-B led to more inhibition. The suppression of the moving capability of T. subcordiformis was reversible but the cells exposed to PAR combined with UVR needed longer time intervals to recover their motility as compared with those irradiated only with PAR. Based on the above results, we postulate that in nature, the motile capability and photosynthesis of free swimming the green microalga might be impaired by enhanced solar UVR. On the other hand, the cells can reduce the damage caused by high irradiances (and even get the optimum light level for photosynthesis) by a behavioral swimming response. [ABSTRACT FROM AUTHOR]

UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynthetically active radiation (PAR, 400-700 nm), ultraviolet-A (UV-A, 320-400 nm) and ultraviolet-B (UV-B, 280-320 nm) radiation on grazing, mortality and lipids oxidation of the copepod Acartia pacifica collected from the Xiamen Bay. After 30 min of the exposures, the copepod was fed in darkness with the diatom Phaeodactylum tricornutum at two cell concentrations (2.5×10 and 2.5×10 cells/ml). At the low cell concentration, the individuals pre-exposed to PAR (218.0 W/m)+UV-A (48.2 W/m) or PAR+UV-A+UV-B (2.1 W/m) showed suppressed clearance and grazing activities compared with those receiving PAR alone, by 22.7% and 17.1% for clearance and by 22.6% and 5.5% for grazing rates, respectively. However, the suppression on clearance and grazing became indistinctive at the high food concentration. Exposures to UV-A and UV-B led to increased lipid oxidation and higher mortality, furthermore, the mortality linearly increased with enhanced oxidation of lipid. [ABSTRACT FROM AUTHOR]

The sea surface temperature (SST) of the East China Sea (ECS) increased in the past decades, which may have a great impact on the ecosystem of the ECS, including the changes in planktonpopulation structure. In this paper, the changes in peaked abundance of Calanus sinicus in the Changjiang River (Yangtze River) Estuary were compared between 1959 and 2002, based on the data collected from the seasonally oceanographic cruises and those performed in spring of 2005. It was much higher in spring compared with that in other seasons both in 1959 and 2002. Furthermore, in spring 2005, the time for occurrence and decrease of the peaked C. sinicus abundance advanced about one month, accompanying the increase in the sea surface water temperature (SST). It peaked in June and decreased in July in 1959, however, in 2005, it peaked in May and attenuated sharply in early June. The earlier decrease of peaked C. sinicus abundance may further deteriorate the ecosystem in the Changjiang River Estuary and north nearshore of the ECS. [ABSTRACT FROM AUTHOR]

In this study, the authors investigated the effects of residual chlorine on mortality, grazing and respiration of Labidocera euchaeta in laboratory. The grazing rate was evaluated by subtraction method of food concentration and respiration rate was measured using oxygen electrode. It was found that the lethal effect of residual chlorine on L. euchaeta increased with enhanced concentration and prolonged duration. The medium lethal concentration ( LC) of chlorine for L. euchaeta in 24 h was about 0.58 mg/L and the safe concentration was about 0.21 mg/L. However, the grazing and respiration of L. euchaeta decreased by 32.6% and 18.9% when exposed to 0.2 mg/L residual chlorine for 4 h. It indicated that the physiological activities of zooplankton could be suppressed by the residual chlorine less than the safety concentration. Therefore, both survival and physiological activities of the organisms living in the thermal (nuclear) power plant discharging waters should be considered when carrying out the ecological risks assessment. [ABSTRACT FROM AUTHOR]

We describe the complete mitochondrial genome sequence of Sargassum fusiforme. This mitogenome is a circular molecule of 34,695 bp in length and had an overall GC content of 37.54%%. Gene annotation showed that 35 protein-coding genes, 2 open reading frames, 25 transfer RNA genes, and 3 ribosomal RNA genes. The phylogenetic tree based on Bayesian shows that S. fusiforme belongs to genus Sargassum, support current taxonomic systems. [ABSTRACT FROM AUTHOR]

The complete chloroplast genome sequence of Sargassum fusiforme is presented here. Circular mapping revealed that the complete chloroplast DNA sequence of S. fusiforme was 124,298 bp in length and had an overall AT content of 69.57%, including 137 protein-coding genes, 2 open reading frames, 28 transfer RNA genes, and 6 ribosomal RNA genes. The phylogenetic tree based on Bayesian shows that all kinds of Phaeophyceae were clustered into two monophyletic groups. [ABSTRACT FROM AUTHOR]

Cell size of phytoplankton is known to influence their physiologies and, consequently, marine primary production. To characterize the cell size-dependent photophysiology of phytoplankton, we comparably explored the photosynthetic characteristics of piconano- (<20 µm) and micro-phytoplankton cell assemblies (>20 µm) in the Daya Bay, northern South China Sea, using a 36-h in situ high-temporal-resolution experiment. During the experimental periods, the phytoplankton biomass (Chl a) in the surface water ranged from 0.92 to 5.13 μg L−1, which was lower than that in bottom layer (i.e., 1.83–6.84 μg L−1). Piconano-Chl a accounted for 72% (mean value) of the total Chl a, with no significant difference between the surface and bottom layers. The maximum photochemical quantum yield (FV/FM) of Photosystem II (PS II) and functional absorption cross-section of PS II photochemistry (σPS II) of both piconano- and micro-cells assemblies varied inversely with solar radiation, but this occurred to a lesser extent in the former than in the latter ones. The σPS II of piconano- and micro-cell assemblies showed a similar change pattern to the FV/FM in daytime, but not in nighttime. Moreover, the fluorescence light curve (FLC)-derived light utilization efficiency (α) displayed the same daily change pattern as the FV/FM, and the saturation irradiance (EK) and maximal rETR (rETRmax) mirrored the change in the solar radiation. The FV/FM and σPS II of the piconano-cells were higher than their micro-counterparts under high solar light; while the EK and rETRmax were lower, no matter in what light regimes. In addition, our results indicate that the FV/FM of the micro-cell assembly varied quicker in regard to Chl a change than that of the piconano-cell assembly, indicating the larger phytoplankton cells are more suitable to grow than the smaller ones in the Daya Bay through timely modulating the PS II activity. [ABSTRACT FROM AUTHOR]

Biochemical compositions and photosynthetic characteristics of three naturally cohabitated macroalgae, Ulva fasciata, Sargassum hemiphyllum and Grateloupia livida, were comparably explored in the field conditions in Daya Bay, northern South China Sea, as well as their responses to temperature rise. Chlorophyll a (Chl a) and carotenoids contents of U. fasciata were 1.00 ± 0.15 and 0.57 ± 0.08 mg g−1 in fresh weight (FW), being about one- and two-fold higher than that of S. hemiphyllum and G. livida; and the carbohydrate content was 20.3 ± 0.07 mg g−1 FW, being about three- and one-fold higher, respectively. Throughout the day, the maximal photochemical quantum yield (FV/FM) of Photosystem II (PS II) of these three macroalgae species decreased from morning to noon, then increased to dusk and kept steady at nighttime. Consistently, the rapid light curve-derived light utilization efficiency (α) and maximum relative electron transfer rate (rETRmax) were lower at noon than that at morning- or night-time. The FV/FM of U. fasciata (varying from 0.78 to 0.32) was 38% higher than that of G. livida throughout the day, and that of S. hemiphyllum was intermediate. The superoxide dismutase (SOD) and catalase (CAT) activities in U. fasciata were lower than that in S. hemiphyllum and G. livida. Moreover, the rises in temperature species-specifically mediated the damage (k) caused by stressful high light and the corresponding repair (r) to photosynthetic apparatus, making the r/k ratio increase with the rising temperature in U. fasciata, unchanged in S. hemiphyllum but decreased in G. livida. Our results indicate that U. fasciata may compete with S. hemiphyllum or G. livida and dominate the macroalgae community under aggravatedly warming future in the Daya Bay. [ABSTRACT FROM AUTHOR]

Shift of phytoplankton niches from low to high latitudes has altered their experienced light exposure durations and temperatures. To explore this interactive effect, the growth, physiology, and cell compositions of smaller Alexandrium minutum and larger A. catenella, globally distributed toxic red tide dinoflagellates, were studied under a matrix of photoperiods (light:dark cycles of 8:16, 16:8, and 24:0) and temperatures (18 °C, 22 °C, 25 °C, and 28 °C). Under continuous growth light condition (L:D 24:0), the growth rate (µ) of small A. minutum increased from low to medium temperature, then decreased to high temperature, while the µ of large A. catenella continuously decreased with increasing temperatures. Shortened photoperiods reduced the µ of A. minutum, but enhanced that of A. catenella. As temperature increased, cellular Chl a content increased in both A. minutum and A. catenella, while the temperature-induced effect on RubisCO content was limited. Shortened photoperiods enhanced the Chl a but reduced RubisCO contents across temperatures. Moreover, shortened photoperiods enhanced photosynthetic capacities of both A. minutum and A. catenella, i.e., promoting the PSII photochemical quantum yield (FV/FM, ΦPSII), saturation irradiance (EK), and maximum relative electron transfer rate (rETRmax). Shortened photoperiods also enhanced dark respiration of A. minutum across temperatures, but reduced that of A. catenella, as well as the antioxidant activities of both species. Overall, A. minutum and A. catenella showed differential growth responses to photoperiods across temperatures, probably with cell size. [ABSTRACT FROM AUTHOR]