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Ulva prolifera is the main species of green tide algae in the Yellow Sea, China, and its growth process is significantly affected by light intensity. The work used four omics to reveal the molecular mechanism of U. prolifera responding to high light. Four-omics conjoint analysis showed the interconversion of sugars in the algae, fatty acid synthesis, steroid synthesis, photosynthesis, pyrimidine metabolism and carbohydrate metabolism. After 12 hours of high light, the photosynthetic capacity of U. prolifera increased and the carbon sequestration mode changed from C3 pathway to C4 pathway. At the same time, the glucose metabolism pathway was enhanced, but the energy metabolism pathway was weakened, and the overall energy consumption showed a decreasing trend. Different resistance modes have different response mechanisms to high light stress. In addition, the growth, development and reproduction of U. prolifera were inhibited, indicating that U. prolifera may be in a dormant state after 12 hours of hight light stress, reducing energy consumption caused by unnecessary developmental physiological processes. The response mechanism of U. prolifera to high light stress was preliminarily obtained through the combined analysis of four kinds of omics, which provided the basis for future research.

As global ecological disasters, green tide outbreaks have been observed in the Southern Yellow Sea (SYS) of China since 2007, resulting in considerable economic losses and environmental damage to the coastal cities of Jiangsu and Shandong Provinces. Therefore, prevention of green tides is crucial. Previous studies have revealed that a relatively small green tide outbreak scale in the SYS was observed in 2018 and 2020, with the green tides covering areas of 193 km

The inhibitory effect of plants on algae offers a new and promising alternative method for controlling harmful algal blooms. Previous studies showed that anti-algal effects might be obvious from extracts of fallen leaves from terrestrial plants, which had great potential for cyanobacterial control in field tests. To investigate the anti-algal activities and main algicidal mechanisms of Ginkgo biloba fallen leaves extracts (GBE) on Microcystis flos-aquae, the cell density, photosynthetic fluorescence, and gene expression under different concentrations of GBE treatments were tested. GBE (3.00 g L−1) showed a strong inhibitory effect against M. flos-aquae with an IC50 (96h) of 0.79 g L−1. All the inhibition rates of maximal quantum yield (Fv/Fm), effective quantum yield (Fq’/Fm’), and maximal relative electron transfer rate (rETRmax) were more than 70% at 96 h at 3.00 g L−1 and more than 90% at 6.00 g L−1. Further results of gene expression of the core proteins of PSII (psbD), limiting enzyme in carbon assimilation (rbcL), and phycobilisome degradation protein (nblA) were downregulated after exposure. These findings emphasized that photosynthetic damage is one of the main toxic mechanisms of GBE on M. flos-aquae. When exposed to 12.00 g L−1 GBE, no significant influence on the death rate of zebrafish or photosynthetic activity of the three submerged plants was found. Therefore, appropriate use of GBE could control the expansion of M. flos-aquae colonies without potential risks to the ecological safety of aquatic environments, which means that GBE could actually be used to regulate cyanobacterial blooms in natural waters. Graphical abstract: [Figure not available: see fulltext.]

Aims Greenhouses are widely used in agriculture systems to shield crops from unfavourable weather to achieve a year-round food supply. In recent years, aquaculture ponds have been placed in greenhouses in many regions. The impacts of the greenhouses on planktonic bacterial communities should be uncovered. Methods and Results In this study, two polyolefin film greenhouses accommodating aquaculture ponds were established and planktonic bacterial communities were compared from samples taken in aquaculture ponds inside and outside the greenhouses, using Illumina 16S rRNA sequencing. Conclusions The results showed there were significant variations in bacterial community structure between indoor and outdoor samples. Obvious differences were also found between two greenhouses, whereas the differences in indoor samples were weaker than outdoor samples. Significantly higher temperature (in summer), pH and permanganate index were found in the outdoor pond samples. Results of redundancy analysis showed that Proteobacteria and Bacteroidota were positively related to the dissolved oxygen, total nitrogen and total phosphorus, and Actinobacteriota were positively related to pH, temperature and permanganate index, whereas Cyanobacteria were positively related to the salinity, conductivity, total dissolved solids and ammonia nitrogen. Significance and Impact of the Study The results of this study revealed that greenhouses significantly influenced planktonic bacterial communities in aquaculture ponds. This study is expected to provide a scientific basis for aquaculture in greenhouses.

The evolutionary and population demographic history of marine red algae in East Asia is poorly understood. Here, we reconstructed the phylogeographies of two upper intertidal species endemic to East Asia, Gelidiophycus divaricatus and G. freshwateri. Phylogenetic and phylogeographic inferences of 393 mitochondrial cox1, 128 plastid rbcL, and 342 nuclear ITS2 sequences were complemented with ecological niche models. Gelidiophycus divaricatus, a southern species adapted to warm water, is characterized by a high genetic diversity and a strong geographical population structure, characteristic of stable population sizes and sudden reduction to recent expansion. In contrast, G. freshwateri, a northern species adapted to cold temperate conditions, is genetically relatively homogeneous with a shallow population structure resulting from steady population growth and recent equilibrium. The overlap zone of the two species roughly matches summer and winter isotherms, indicating that surface seawater temperature is a key feature influencing species range. Unidirectional genetic introgression was detected at two sites on Jeju Island where G. divaricatus was rare while G. freshwateri was common, suggesting the occurrence of asymmetric natural hybrids, a rarely reported event for rhodophytes. Our results illustrate that Quaternary climate oscillations have left strong imprints on the current day genetic structure and highlight the importance of seawater temperature and sea level change in driving speciation in upper intertidal seaweed species.

Since 2007, large-scale blooms have periodically broken out in the Yellow Sea, leading to serious economic and ecological problems in the surrounding coastal environments. Previous studies ...

New macroalgal blooms caused by the genus Sargassum have been occurring along the coast of China. In particular, in 2017, Sargassum blooms covered up to 188 km2 and drifted into the offshor...

The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Utermohl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×103 to 269.78×103 cell/L with an average of 41.80×103 cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×103 cell/L with the range of 1.78×103 to 574.96×103 cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis (RDA) showed that turbidity, temperature, salinity, pH, dissolved oxygen (DO), the ratio of dissolved inorganic nitrogen to silicate and SiO4-Si (DIN/SiO4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.

In this study, we conducted a comparative analysis of the abundance and diversity of bacteria on the surface of the submerged macrophyte Myriophyllum spicatum, as well as in the surrounding water column and sediment in the low-salinity area of Hangzhou Bay, China. Bacterial clones from three clone libraries were classified into 2089 operational taxonomic units (OTUs), most of which affiliated with bacterial divisions commonly found in marine ecosystems. Alphaproteobacteria, Cyanobacteria and Gammaproteobacteria were the most abundant groups of bacteria on the surface of plants, in the water column and sediment, respectively. Epiphytic bacterial communities were more closely related to those in the sediment than bacterioplankton, and some species of epiphytic bacteria were found only on the surface of M. spicatum. The relative abundance of epiphytic bacterial genera associated with breakdown of organic compounds and with cellulose digestion was higher in October than that in July. These results suggested that bacterial communities on the surface of M. spicatum may originate from sediment bacterial communities and their specific structure was gradually formed on the surface of M. spicatum after being cultivated in low-salinity seawater.

The Ulva prolifera green tides in the Yellow Sea, China, which have been occurring since 2007, are a serious environmental problem attracting worldwide attention. Despite extensive research, the outbreak mechanisms have not been fully understood. Comprehensive analysis of anthropogenic and natural biotic and abiotic factors reveals that human activities, regional physicochemical conditions and algal physiological characteristics as well as ocean warming and biological interactions (with microorganism or other macroalgae) are closely related to the occurrence of green tides. Dynamics of these factors and their interactions could explain why green tides suddenly occurred in 2007 and decreased abruptly in 2017. Moreover, the consequence of green tides is serious. The decay of macroalgal biomass could result in hypoxia and acidification, possibly induce red tide and even have a long-lasting impact on coastal carbon cycles and the ecosystem. Accordingly, corresponding countermeasures have been proposed in our study for future reference in ecosystem management strategies and sustainable development policy.

Green macroalgal blooms caused by Ulva species have influenced the Shandong Province for 15 consecutive years since 2007, leading to serious damage to the marine environment. Great biomasses of attached Ulva prolifera on Neopyropia aquaculture rafts in the Yellow Sea were considered as sources of blooms. However, it is still unclear whether U. prolifera could survive and settle in the Qingdao coastal environment, Shandong, thus leading to local Ulva blooms in the future. In this research, sampling of Ulva macroalgae in seven Portunus trituberculatus aquaculture ponds along the coast of Qingdao was conducted on August 21, 2019. In total, 24 samples collected from the ponds were analyzed through methods of molecular biological identification (ITS, 5S, and rps2-trnL sequences) and genetic analysis. All the aquaculture ponds contained large amounts of floating Ulva macroalgae, which consisted of three species: U. prolifera, Ulva meridionalis, and Ulva pertusa. Among these species, U. meridionalis, which is usually found in southern Japan, also causes the green tide. In addition, all Ulva macroalgae floated on the surfaces of aquaculture ponds, and were discarded into the local coastal area by aquaculturist. This research raised our awareness of the importance of controlling the spread of the green tide related macroalgae.

White spot syndrome virus (WSSV) is the most destructive virus among invertebrates. In this study, we analyzed the immune response after WSSV infection in Pacific white shrimp Litopenaeus vannamei using isobaric tags for relative and absolute quantitation (iTRAQ). We identified 325 differentially expressed proteins (DEPs) in the hepatopancreas of L. vannamei. Among them, 212 were up-regulated proteins, and several of them might be related to immunity (e.g. arginine kinase and peroxiredoxin). Of the 113 down-regulated proteins, some were related to immunity (e.g. cathepsin C and cathepsin L) and others to the antioxidant defense process (e.g. glutathione peroxidase and catalase). One down-regulated DEP (C7M84_014268) and 3 up-regulated DEPs (C7M84_003456, C7M84_020702, and C7M84_007135) were randomly selected and analyzed using parallel reaction monitoring. This study is an important step for a comprehensive understanding of the immune relationship between L. vannamei and WSSV and provides valuable information for the prevention of viral diseases in the crustacean aquaculture industry.

Green tides dominated by Ulva prolifera have be present in the Southern Yellow Sea for 15 consecutive years. They not only damage the marine environment, but also cause economic losses to coastal cities. However, there is still no fully effective approach for preventing green tides. In this article, approaches for the prevention of U. prolifera taken over recent years are reviewed. They can be generally divided into physical, chemical, and biological approaches. Physical approaches have been used to control the overwhelming green macroalgae bloom and inhibit the germination of U. prolifera, including physical salvage approach, refrigeration net technology, improved farming methods and raft technology, and modified clay method. These approaches require significant labor and material resources. Many chemical reagents have been used to eliminate U. prolifera early germination and growth, such as oxidative algaecide, acid treatment, heavy metal compounds, antifouling coating, and alkaloids. Chemical approaches have high efficiency, high economic benefit, and simple operation. Presently, biological control approaches remain in the exploratory stage. The verification of pilot and large-scale experiment results in sea areas is lacking, including the application of large organisms and microorganisms to control U. prolifera, and some of the mechanisms have not been thoroughly studied. This article introduces the three types of approaches, and evaluates the advantages and disadvantages of different methods to facilitate the reduction of the green tide bloom scale in the Southern Yellow Sea.

Ulva prolifera (U. prolifera), a green macroalgae, is widely known as the dominant species of the world’s largest macroalgal blooms in the Yellow Sea, China. In this study, we sequenced and annotated the complete mitochondrial genome of U. prolifera (GenBank accession number: KU161104). The genome consists of circular chromosomes of 61 962 bp and encodes a total of 26 protein-coding genes include nine ribosomal protein genes, five atp genes, three cox genes, eight nad genes and cob gene. Phylogenetic analysis showed U. prolifera clustered into Ulvo phyceae clade and had close genetic relationship with algae Ulva fasciata.

The purpose of this paper is to understand the sources of potentially toxic elements (PTE) and provide some suggestions to control PTE pollution. For this purpose, data from 30 monitoring stations for 2009-2018 were used to assess the PTE concentrations of Hg, Cu, Pb, Cd, Zn, and As in the Yangtze River Estuary. The PTE concentrations varied significantly (P < 0.05) by one-way ANOVA in the ranges of 0.002-0.224 (Hg, 0.043 ± 0.032), 0-9.700 (Cu, 1.600 ± 1.000), 0-3.900 (Pb, 1.000 ± 0.700), 0.002-0.370 (Cd, 0.050 ± 1.000), 0.100-85.000 (Zn, 14.000 ± 13.000), and 0.998-3.290 μg/L (As, 1.857 ± 0.455). Generally, the PTE concentrations decreased from year to year and were consistently satisfied the "grade-one seawater" quality standard after 2014. The concentrations of Cu, Cd, Zn, and As decreased as far from inshore, while increased closer to land in the estuary. Concentrations of Pb and Hg showed differences because of local industrial and aquacultural activities. This study identified three clusters and two PTE sources and provided some constructive suggestions for pollution control in PTE.

Large-scale green tide disasters have been occurring for more than 10 years in China, with serious ecological consequences. However, limited research has focused on epiphytes that feed on macroalgae. In this study, amphipods were found living on the surface of Ulva lactuca, a green-tide-forming alga, around Gouqi Island, China. Through morphological and molecular methods, the amphipods were identified as Ampithoe lacertosa Bate, 1858, which has not previously been recorded in China. Sequence information about cytochrome c oxidase subunit I (mitochondrial COI) gene from China was compared to sequences reported from 5 coastal countries around the Pacific region. Network diagrams, phylogenetic trees and other methods of analysis revealed evidence of genetically distinct subspecies in the northeastern and northwestern Pacific. We believe that research on herbivorous amphipods will provide preventative strategies and control measures against green tide algae. International cooperation among Asian and North American biologists within the Pacific region will lead to a better understanding of the family Ampithoidae in the future.

Theory of self-organization, i.e., scale-dependent feedback (SDF), has been widely used to explain mechanisms of spatial patterns in different ecosystems. Studies have demonstrated that self-organization is one of the mechanisms through which ecosystem resilience is maintained. However, the application of SDF in real ecological restoration practices is a challenge due to the lack of a controlled experimental validation. In the present study, multiple scales of vegetation patches were constructed along an elevation gradient in the saltmarsh ecosystem on Nanhui coasts and were investigated to verify if there was an effect of SDF. Results of the density-variation curves analyses revealed that most constructed self-organized patches could survive and an optimal curve was found of which the density-dependent feedback was proven through fitting with the asymptotic regression model. The large vegetation patches exhibited considerable increases in density when compared to the small vegetation patches, which occurred in challenging environments, i.e., on the verges of elevation thresholds, and with a tendency to shrink. Analyses using one-way ANOVA revealed that there was an optimal patch scale and elevation in the study area, i.e., 1 m × 1 m scale and 3.2 m, respectively. Optimal scale and elevation provide a comprehensively explanations of SDF, although with the positive effects gradually decreased along the distance away from the optimal condition. The present study provides novel insights on applying the theory of SDF in facilitating the restoration process of coastal saltmarshes.

Fluorescent proteins can be used as probes to investigate intercellular molecular interactions and trace the pathway of specific metabolites, thus providing a detailed and accurate description of various metabolic processes and cellular pathways in living cells. Nowadays, the existing fluorescent proteins cover almost all spectral bands from ultraviolet to far-red. These fluorescent proteins have been applied in many fields of bioscience with the help of high-resolution microscopy, making great contributions to the development of biology. It is generally agreed that orange fluorescent proteins refer to the fluorescent proteins at the spectral range of 540-570 nm. In recent years, researches on orange fluorescent proteins have made great progress, and they have been widely applied in the field of biology and medicine as reporter protein and fluorescence resonance energy transfer as fluorescent receptor. This paper reviews the studies in the field of orange fluorescent proteins over the last 15 years, with the special focus on the development and application of orange fluorescent proteins to provide the basis for the future studies.荧光蛋白 (Fluorescent protein，FPs) 可作为探针用以探究细胞内分子间相互作用，追踪特定代谢物的代谢途径，对活细胞内的各种代谢过程和细胞通路进行详细、准确的描述。目前已有的FPs 几乎已经覆盖了从紫外光到远红外光的所有光谱波段，这些FPs 借助高分辨率显微技术应用于生命科学的诸多领域，为生物学的发展作出巨大贡献。橙色FPs 通常指光谱区间在540–570 nm 的FPs，近几年来关于橙色FPs 的研究进展较快，并且其作为标记蛋白以及荧光共振能量转移技术 (Fluorescence resonance energy transfer，FRET) 中的荧光受体在生物学及医学领域得到较多的应用。文中综述了近15 年橙色FPs 领域的相关研究，重点聚焦橙色FPs 的发展和应用，为今后橙色FPs 的研究提供依据。.

The growth and nutrient uptake of Gracilaria lemaneiformis under different nutrient conditions, with implications for ecosystem services, were evaluated in the laboratory and in an enclosed mariculture sea area in Yantian Bay at the coast of East China Sea. In laboratory experiments, the specific growth rate (SGR) ranged 1.29%/d–7.99%/d, and nitrogen (N), phosphorus (P), and dissolved inorganic carbon (C) uptake rate was 0.067–1.603 μmol/(g∙h), 0.002–0.069 μmol/(g∙h), and 4.01–31.25 μmol/(g∙h), respectively, under different nutrient conditions. In field experiments, the SGR ranged from 6.30%/d to 13.00%/d, and the average C sequestration rate was 9.25 mg/(g DW·h) and 6.68 mg/(g DW·h) in the G. lemaneiformis cultivation area (region 1) and fish cage area (region 4), respectively. The NH4+-N uptake rate of G. lemaneiformis was the highest in region 1 and region 4 with 56.98 ± 4.81 μg/(g DW·h) and 38.68 ± 7.12 μg/(g DW·h), respectively. The maximum removal efficiency of NH4+-N, NO3−-N, NO2--N, and PO43--P were 45.99–59.79%, 13.10–30.21%, 12.88–14.11%, and 27.07–31.49% in G. lemaneiformis cultivated areas compared with those in fish cage area. The extrapolated results showed that 1192.03 tonnes of C, 128.10 tonnes of N and 15.89 tonnes of P would be simultaneously sequestered from the seawater through G. lemaneiformis cultivation in Yantian Bay. Results indicated that G. lemaneiformis had high growth rates and nutrient removal efficiencies under different nutrient conditions, which made it a good candidate for seaweed/animals integrated multi-trophic aquaculture in nutrient bioextraction and economic diversification.

Macroalgal blooms have become a serious threat to public health, fisheries, ecosystems, and global economies. Since 2007, in the Yellow Sea, China, Ulva green tides have occurred for 15 consecutive years. However, effective control methods are limited. Ulva prolifera attached to Neopyropia aquaculture rafts are believed to be the main source of blooms, therefore eliminating Ulva from rafts could effectively prevent and control blooms. We investigated this phenomenon and showed that macroalgae germination was significantly inhibited by dried Neopyropia yezoensis at concentrations of 1.2, 2.4, and 4.8 g DW

Since 2008, the green seaweed Ulva prolifera has caused the world's largest green tide in the Yellow Sea, China. It has subsequently attracted considerable research interest. However, species identification is an essential step for advancing this research. Based on phylogenetic analyses using molecular sequences such as internal transcribed spacer (ITS) or ribulose bisphosphate carboxylase large chain (rbcL), specimens of U. prolifera collected worldwide were separated into a European clade and the Ulva linza–procera–prolifera (LPP) complex clade that included the Chinese bloom-forming strains and Japanese brackish strains. This has resulted in considerable controversy as to the identity of U. prolifera and the bloom-forming species in the Yellow Sea. To resolve this issue, we examined populations of U. prolifera from the type locality at Lolland Island, Denmark, and globally significant sites including sites from Japan and China using morphological, developmental, molecular and crossing studies....

This study sampled U. prolifera and surface seawater from the same locations where green tide broke out in the southern Yellow Sea, in both the year 2016 and 2017. The revealed nutritive components of U. prolifera samples characterized U. prolifera as a high-protein, high-Fe, high ratio of unsaturated lipid acids and low-fat seaweed food, with an ideal ratio of essential and nonessential amino acids. The concentrations and health risk assessment of major micropollutants (heavy metals, pesticides and polycyclic aromatic hydrocarbon (PAHs)) in U. prolifera were also analyzed, respectively. The results showed that the Target Hazard Quotient values of five heavy metals (

The relationship between Microcystis abundance and environmental variables was studied during a Microcystis bloom in the summer months of 2016 in an artificial lagoon of Hangzhou Bay, China. It was determined that Microcystis abundance increased from 0.16 × 104 cell/L to 5.8 × 107 cell/L within 17 days from 28 July to 14 August, contributing to 96.84–99.56% of the total phytoplankton abundance. Then, Microcystis gradually disappeared 57 days afterwards. The results showed that the growth of Microcystis, including the stage of recovery, outbreak, subsidence and disappearance, was significantly correlated with water temperature, salinity, soluble reactive phosphorus (PO4-P), dissolved inorganic nutrients (DIN), silicate (SiO4-Si), the ratio of DIN/SiO4-Si and zooplankton abundance, and the key environmental triggers which promoted the outbreak of Microcystis were water temperature, PO4-P concentration and zooplankton abundance in this artificial lagoon.

The distribution of phytoplankton and its correlation with environmental factors were studied monthly during August 2012 to July 2013 in the Yantian Bay. A total of 147 taxa of phytoplankton were identified, and the average abundance was in the range of 0.57×104 to 7.73×104 cell/L. A total of 19 species dominated the phytoplankton assemblages, and several species that are widely reported to be responsible for microalgae blooms were the absolutely dominant species, such as Skeletonema costatum, Navicula sp., Thalassionema nitzschioides, Pleurosigma sp., and Licmophora abbreviata. The monthly variabilities in phytoplankton abundance could be explained by water temperature, dissolved oxygen, salinity, dissolved inorganic nitrogen (DIN), and suspended solids. The results of a redundancy analysis showed that pH and nutrients, including DIN and silicate (SiO4), were the most important environmental factors controlling phytoplankton assemblages in specific months. It was found that nutrients and pH levels that were mainly influenced by mariculture played a vital role in influencing the variation of phytoplankton assemblages in the Yantian Bay. Thus, a reduction of mariculture activities would be an effective way to control microalgae blooms in an enclosed and intensively eutrophic bay.

Dense mat formed by duckweeds is a significant threat to fisheries, landscape, ecological environment, and economies around the world. Effective biological management strategies to control duckweeds are quite limited. In the present study, we determined the effect of the extract of Coptis chinensis, a traditional Chinese medicinal herb, on the growth of duckweed (Spirodela polyrhiza). The growth of S. polyrhiza was strongly inhibited by the C. chinensis extract. The number of fronds and fresh weight of the plants were significantly decreased after a 96-h treatment. Furthermore, the chlorophyll (a, b, and a + b) content was remarkably decreased by the C. chinensis extract. The 24-, 48-, 72- and 96-h-IC50 of the C. chinensis extract to S. polyrhiza were 6.56, 1.06, 0.81, and 0.33 g DW eq. extract L−1, respectively. In addition, the C. chinensis extract was found to be safer for the submerged macrophytes (such as Vallisneria natans: 96-h-EC50 was 10.39 g DW eq. extract L−1) and aquatic animals (such as zebrafish: 96-h-LC50 was 20.35 g DW eq. extract L−1). These results showed that the C. chinensis extract was inhibitory to the growth and reproduction of S. polyrhiza. Moreover, the field test results also confirmed that the inhibitory effect of C. chinensis extract on S. polyrhiza. Thus, we recommend the use of the C. chinensis extract as an effective and safe botanical herbicide for duckweed management in water ecosystems.

Species composition and seasonal variations of free-floating Ulva species were investigated in the source area of the world's largest macroalgal blooms during 2009-2015. Based on a combination of a morphological analysis and sequences of nuclear-encoded ITS and 5S rDNA spacer regions, the dominant species in the free-floating Ulva community at the early stage of green tides were Ulva compressa, Ulva flexuosa, and Ulva linza. The first appearance of Ulva prolifera on the sea surface was in mid-May and it dominated the floating Ulva community in June from 2009 to 2011. From 2012-2015, U. prolifera was not only the first species to appear on the sea surface but also the dominant species during the whole early stage of green tides. To explain the successional mechanism, the effects of environmental factors on the growth of four Ulva species were examined in the laboratory under different combinations of light intensity and temperature. It was found that the highest growth rate of U. prolifera was 44.9%/d, which was much higher than the other three Ulva species. The strong tolerance of U. prolifera to extreme conditions also helps it survive and bloom in the Yellow Sea.

Polar microbial derived antibiotics have potential as alternatives to traditional antibiotics in treating fish against pathogenic bacteria. In this paper, 23 strains of polar fungi were fermented to detect bacteriostatic products on three aquatic pathogenic bacteria, subsequently the active fungus was identified. It was indicated that secondary metabolites of 23 strains weredistinct; of these, the extract of strain B-7 (belonging toBjerkanderaaccording to molecular identification) demonstrated a strong antibacterial activity toStreptococcus agalactiae,Vibrio anguillarumandAeromonas hydrophilaATCC7966 by Kirby-Bauerpaper strip method. During one fermentation cycle, the pH curve of the fermentation liquor became lowest (4.0) on the 4thday and rose back to 7.6 finally after 5 days, The residual sugar curve was decreased before stablising on the 6thday. It is presumed that a large amount of alkaline secondary metabolites might have been produced during fermentation. This study focuses on antagonism between aquatic pathogenic bacteria and fermentation metabolites from Antarctic fungi for the first time, which may provide data on research of antibiotics against aquatic pathogenic bacteria.

Blooms of Ulva have been recorded for 10 consecutive years since 2007 in the Yellow Sea, China. There have been many studies estimating economic, environmental and social costs of these blooms. The present study evaluated potential environmental benefits of the removal of blooms. During the blooms of Ulva in 2013, the fresh biomass of Ulva increased from 1.01 × 104 metric tons to 4.1 × 106 tons in about 50 days, with the average growth rate of 12.80% d−1. The potential maximum nitrogen, phosphorus and carbon removal by the green tide was about 7.46 × 103, 1.05 × 103 and 1.73 × 105 tons, respectively. These results suggest that the harvest of Ulva from the Yellow Sea may provide invaluable ecosystem services by removing nutrients from these eutrophic waters prior to the onset of the death phase of Ulva.

Myriophyllum spicatum was cultivated in a low salinity area of Hangzhou Bay (salinity 5.8-6.5), from August to October in 2016, to evaluate the abilities of its nutrient bioextraction and microalgae growth inhibition. During the 72-day cultivation period, M. spicatum had a specific growth rate (SGR) of 6.23%day-1 and increased 20-fold in biomass (wet weight). Tissue C, N and P assimilation quantities of M. spicatum were found to be 3279.39kg, 360.61kg and 26.97kg, respectively. The concentration of NH4-N, NO3-N, NO2-N and PO4-P after M. spicatum cultivation was decreased by 47.92%, 58.28%, 36.40% and 55.57%, respectively. The phytoplankton density was decreased from 1064.60×104cellsL-1 to 12.85×104cellsL-1. These results indicated that cultivation of M. spicatum can help in nutrient bioextraction and microalgae growth inhibition in low salinity marine water bodies.

Phylogenetic clades based on DNA sequence data are heavily used to delimit species in the current taxonomy of Ulva. However, because hybridisation within clades and among other clades for other species has been seldom tested, it remains unclear if molecular clades agree with species boundaries based on the biological species concept. An ITS-based Ulva clade including many specimens collected worldwide was provisionally named ‘U. flexuosa'; its species boundary is ambiguous, and in the literature this group has been variously merged with the closely related U. californica clade. In the present study, we clarified the species boundary of this clade and its taxonomic status. Namely reproductive relationships among strains in this and closely related clades were examined by culturing and hybridisation. The culture experiment demonstrated that the ITS-based clade includes a sexual variant and an obligate asexual variant. The sexual strains having 0%–0.4% divergence in ITS2 sequence successfully cross...

Massive Ulva blooms became an environmental disaster in the Yellow Sea from 2007 to 2015. In this study, field shipboard observations indicated that Ulva blooms originated in Pyropia aquaculture area, and the morphology of initial floating Ulva seaweed have the structure of rhizoid, which is similar with the attached Ulva on the Pyropia rafts. The spatial distribution of Ulva microscopic propagules in the southern Yellow Sea also supported that the blooms originated in the Pyropia aquaculture area. Besides, numerical model was used in this study, showing the origin of macroalgal blooms was traced to “Sansha” regions which accounted for almost 70% of the total Pyropia aquaculture area. We conclude that the significant biomass (4252 tons) of Ulva species on the Pyropia rafts during the harvesting season in “Sansha” regions played an important role in the early rapid development of blooms in the Yellow Sea.

Benthic macrofauna are considered to have important effects on the microbial-driven cycling of nutrients in sediments. The response of the microbial community to bioturbation by macrofauna is not fully understood. This study investigated variations in the microbial communities and nutrient profiles after bioturbation by the clam Meretrix meretrix and polychaete Perinereis aibuhitensis . The total nitrogen, total phosphorus, total organic carbon and dissolved inorganic nitrogen contents of sediments decreased dramatically in the presence of Meretrix meretrix and Perinereis aibuhitensis . In total, 64 bacterial phyla and three archaeal phyla were identified, where Proteobacteria were dominant and they accounted for > 30% in all reads with a stable percentage among all samples. Eleven bacterial phyla, i.e. unclassified, AC1, Acidobacteria, Actinobacteria, Cyanobacteria, Gemmatimonadetes, KSB3, Lentisphaerae, Nitrospirae, Spirochaetes, Verrucomicrobia and WS3, were influenced significantly by bioturbation using Meretrix meretrix or Perinereis aibuhitensis . Analysis of similarities and non-metric multidimensional scaling analysis demonstrated that the bacterial communities did not differ significantly in the control and macrofauna-inhabited sediments. The number of bacterial amoA copies increased significantly in the presence of macrofauna, but not the number of archaeal amoA copies. The results of this study demonstrate that bioturbation by Meretrix meretrix or Perinereis aibuhitensis can cause structural and compositional changes in sediment microbial communities by increasing the abundance of nitrogen-cycling bacteria and decreasing the nutrient levels in sediments.

A new Bis-sesquiterpene, Nanji A ( 1 ), has been isolated together with 7 known compounds, debromolaurinterol ( 2 ), laurinterol ( 3 ), laurinterol acetate ( 4 ), isolaurinterol ( 5 ), 3α-hydroperoxy-3-epiaplysin ( 6 ), 3β-hydroperoxyaplysin ( 7) , Laurokomurenene A ( 8 ), from the Nanji red alga Laurencia okamurai . The structure of 1 was elucidated on the basis of extensive spectroscopic analysis of its EIMS, 1D and 2D NMR data. Furthermore, the chemotaxonomic significance of these compounds was also summarized.

This study aimed to assess the effect of oral administration of Synechococcus sp. PCC 7942 harboring vp19, vp28, and vp(19 + 28)against infection by white spot syndrome virus (WSSV) on juveniles of Litopenaeus vannamei. L. vannamei was orally administrated by feeding with different mutants of Synechococcus for 10 days, and then challenged with WSSV. The cumulative mortality of vp19, vp28, vp (19 + 28) groups was lower than that of the positive control group (57.8%, 62.2%, 71.1%, respectively); vp (19 + 28) group had a better protection rate than vp19 and vp28 groups. The analysis of shrimp immunological parameters showed that, after WSSV injection, the activity of superoxide dismutase, phenol oxidase, catalase, and lysozyme in the hepatopancreas of vp19, vp28, and vp (19 + 28) groups was higher than in the positive group; at the same time, growth performances of L. vannamei of experimental groups were better than control groups. Results showed that the Synechococcus mutants harboring vp19, vp28, and vp (19 + 28) could be used both as drug and feed to also enhance the defensive ability of juvenile shrimp against WSSV infection by increasing the activity of immune related enzymes.

We investigated the growth and nutrient uptake of Myriophyllum spicatum under different nutrient conditions and evaluated its implications for ecosystem services in an enclosed area of Jinshan. The specific growth rate ranged from 1.29%–4.37%/day, and the dissolved inorganic carbon and nitrogen, and phosphorus uptake rates were 1.30–1.62, 0.040–0.453, and 0.003–0.027 mg/(g∙day), respectively, under different nutrient conditions. The O2-production and carbon-sequestration efficiencies in the field were 154.30 and 1.25 mg/(g DW∙h), respectively. The average removal efficiencies of NH4+-N, NO3−-N, NO2−-N, and PO43−-P were 43.05%, 97.03%, 64.26%, and 59.24%, respectively, in M. spicatum-cultivated areas compared with in the open sea. Harvesting of M. spicatum removed 12,936.87, 1289.97 and 114.81 kg of carbon, nitrogen, and phosphorus, respectively, from seawater in Jinshan in Nov, 2018. In conclusion, M. spicatum is a good candidate for integrated macrophyte/animal multi-trophic aquaculture in terms of nutrient extraction and economic diversification in low-salinity environments.

Ulva usually attached to aquaculture rafts, rocks, and floating objects. Previous studies have shown that the world's largest green tides in the Yellow Sea originated from the attached Ulva on rafts. However, a large biomass of Ulva thalli has recently been found attached to Littorina sp. (periwinkles) in the Subei intertidal zone, but it is rarely observed on Bullacta exarata, Portunus sp., and other intertidal benthic animals. The population density of Littorina sp. on the Zhugen sand ridge is approximately 39.2 specimens/m2. A maximum of seven Ulva macroalgae were attached to one periwinkle, and an average of 1.24 Ulva macroalgae were attached to each periwinkle. To determine the contribution of epizoic Ulva on Littorina sp. to floating green tides, these macroalgae were identified with a molecular biology method using internal transcribed spacer (ITS) sequences. Results showed the Ulva attached to Littorina sp. comprised just one species, Ulva flexuosa. Epizoic Ulva attached to intertidal benthic animals in the Zhugen sand ridge does not appear to be the main source of the green tide (the only dominant species is Ulva prolifera) outbreaks in the Southern Yellow Sea.

To develop a more comprehensive understanding of the efficacy of trans-vp28 gene Synechocystis sp. PCC6803 and its effect on white spot syndrome virus (WSSV), this study investigated the activities of several immune-related enzymes including acid phosphatase (ACP), alkaline phosphatase (AKP) and peroxidase (POD) in muscle and hepatopancreas of Penaeus vannamei, and conducted a more intuitive analysis from the perspective of histopathology. P. vannamei were orally fed trans-vp28 gene Synechocystis sp. PCC6803 for 10 days and then challenged with WSSV. The cumulative survival rate, activities of enzymes and the histopathology were determined. The results show that on the 7th day after challenge, the survival rate of the experimental group (i.e., challenged and fed mutant Synechocystis sp. cells) and the wild type group (i.e., challenged and fed wild type Synechocystis sp. cells) were 80.2% and 26.4%, respectively, while all shrimp in the positive control group (i.e., challenged, but no vaccination) died. There was no death in the negative control group (i.e., no vaccination or challenge). After immunization, the activities of ACP, AKP and POD in both tissues were the highest in the experimental group. After challenge, the final enzyme activities of the three enzymes in the experimental group were higher than those in the positive control group and the wild type group. The results of histopathology showed that muscle fibers in the negative control group were neatly arranged with numerous and evenly distributed nuclei, while muscle fibers in the positive control group and the wild type group were wavy. The nuclei of muscle fibers in the positive control group were also swollen and unevenly distributed. The nuclei of the muscle fibers in the experimental group were slightly clustered, and the muscle fibers were arranged neatly. In hepatopancreas samples, narrow cell gaps and regular nuclei were observed in the negative control group. The connective tissue and cell walls were severely damaged and the cells were degraded in the positive control group. However, although the connective tissue of the experimental group was slightly loose, the cells were orderly and the nuclei were arranged neatly. These results indicated that trans-vp28 gene Synechocystis sp. PCC6803 could improve the immunity of shrimp.

In January 2020, golden seaweed tides accumulated in the world's largest Pyropia aquaculture areas in the Yellow Sea of China again, resulting in great economic loss to local seaweed farmers. A large number (~40,000 km2) of Sargassum thalli floated around Pyropia aquaculture areas until May 2020, drifting northeastward and becoming an ecological threat to the coastal areas of Jiangsu and Shandong provinces. In response, the local government is developing an emergency plan to prevent future golden tides, and this process requires an understanding of the mechanisms by which form the Sargassum blooms. As the global climate continues to change and the increase in human activities, sea surface temperatures rise, nutrient emissions and other factors that affect Sargassum blooms may lead to gradually enlarged ecological crises in the Pacific Northwest unless mitigation protocols are developed.

Responses of the germination and growth of Ulva prolifera parthenogametes to gradients of temperature and light were evaluated. Results showed that U. prolifera parthenogametes could not germinate at 5 °C and 35 °C, and at all temperatures combined with dark conditions, but had high germination rates at the temperature of 15–25 °C and photosynthetically active radiation (PAR) of 80–160 μmol m–2 s–1. There was a significant interaction between temperature and PAR on the growth rate of U. prolifera germlings germinated from parthenogametes (P

Green macroalgal blooms have occurred in the Yellow Sea for 13 consecutive years since 2007. However, effective control methods have not yet been successfully developed. Ulva prolifera attached on Pyropia aquaculture rafts was identified as the main source of the blooms, thus, eliminating the attached Ulva from the rafts should be the most efficient method to prevent and control these blooms. In this study, we designed a new molecular marker (rps2-trnL) to identify U. prolifera collected from the aquaculture site. Samples identified as U. prolifera were cultured, and different concentrations of sodium hypochlorite (NaClO) solution (0.2, 0.4, 0.6, 0.8, and 1.0%) were used to kill the alga. The measured chlorophyll content, light quantum yield, and photosynthetic oxygen release rate data from the laboratory experiment suggested that the appropriate concentration of NaClO solution should be 0.6–1.0%. To carry out a small-scale field trial, we developed a device that can spray NaClO on Ulva blades and recycle the residual liquid. Results showed that only the 1.0% NaClO solution could quickly kill the Ulva in outdoor experiments. During the treatment, very little NaClO dripped on the tidal flat, which indicated that the recycling device avoided a potential negative impact of residual solution on the marine ecosystem. By the beginning of November 2019, the Pyropia aquaculture area treated by NaClO was about 13,000 ha, covering about one-third of the total area at the coast of Jiangsu Province. Monitoring by an unmanned aerial vehicle showed that very little attached Ulva was present on the ropes after NaClO treatment, which indicated that it was an effective method to control the green tide. Also, the range of residual active chlorine within seawater during the treatment was only from 0.003 to 0.012 mg/L, which complied with Chinese national standards. However, further monitoring of the formation process of green tides should be conducted in future years to evaluate the effect of NaClO treatment.

Ulva linza is one of the causal species that result in the macroalgal blooms around Yellow Sea, China. The blooms have now become the world’s largest green tide, making great disaster for the ecosystem. We analyzed whole genome sequence of chloroplast for the first time (GenBank accession number KX058323). It was found that the annular-shape genome was made up of 86,726 bp, including 67 protein coding genes. We then aligned amino acids of chlorophyta species containing 44 common genes in series as phylogenetic tree, which shows Chlorophyceae and Trebouxiophyceae separately cluster except for Leptosiraterrestri. In the phylogenetic tree of amino acid alignment, Ulvophyceae, Pedinophyceae, Prasinophytes and Chlorophyta incertae sedis are independent cluster respectively, and closer to Trebouxiophyceae in the origin.

Nutrient removal ability of seaweeds on Pyropia yezoensis aquaculture rafts was studied during the P. yezoensis aquaculture season of 2012–2013 at the offshore farm along the radial sandbanks of Jiangsu Province, China. During the P. yezoensis cultivation season, three Ulva species, including Ulva prolifera , Ulva linza , and Ulva flexuosa , were present on the cultivation rafts. These Ulva spp. were then removed from the rafts or floated away when rafts were recycled in April 2013. The quantities of nitrogen and phosphorus removed by the harvest of P. yezoensis were 3688 and 106 tons, respectively. The nitrogen and phosphorus removal of Ulva were 77 and 3 tons, respectively. These results indicate that P. yezoensis can efficiently remove excess nutrients from coastal waters. The Ulva if harvested can also be utilized as an additional nutrient management tool in eutrophic waters. In addition, introduction of high-temperature adapted seaweeds would be a useful way to continue algal bioremediation during the off season of P. yezoensis aquaculture.

In recent years, green tides caused by water eutrophication, has brought serious environmental problems. Enteromorpha prolifera (E. prolifera), an opportunistic macroalgae, is one of the main source contributing to the formation of green tides. It has been estimated that the excessive growth of E. prolifera is closely related to various reproductive ways of germ cells which are at the micrometer scale. Here we report a microfluidic device named Germ Cell Capture Chip (GCChip) to investigate the E. prolifera reproductive mechanism. GCChip integrates the functions of algal growing, and the release, capture and selective culture of germ cells. Automatic separation and capture of germ cells on the chip allows to study germ cells’ response to different stimuli. The novel device greatly facilitates long-term live-cell imaging at cellular resolution and implements the rapid and accurate exchange of growth medium without manual intervention. Results showed that the starting time of germ cell releases were earlier on the chip than that of traditional experiments with more concentrated breakout. Moreover, GCChip can be widely applied on the study of other algae. The study of algae growth process, including the elongation of somatic cell, the generation, and the release of reproductive cells, can all be improved by using this microfluidic platform.

From 2008 to 2016, massive floating green macroalgal blooms occurred annually during the summer months in the Yellow Sea. The original source of these blooms was traced based on the spatio-temporal distribution and species composition of Ulva microscopic propagules and settled Ulva vegetative thalli monthly from December 2012 to May 2013 in the Yellow Sea. High quantities of Ulva microscopic propagules in both the water column and sediments were found in the Pyropia aquaculture area along the Jiangsu coast before a green macroalgal bloom appeared in the Yellow Sea. The abundance of Ulva microscopic propagules was significantly lower in outer areas compared to in Pyropia aquaculture areas. A molecular phylogenetic analysis suggested that Ulva prolifera microscopic propagules were the dominant microscopic propagules present during the study period. The extremely low biomass of settled Ulva vegetative thalli along the coast indicated that somatic cells of settled Ulva vegetative thalli did not provide a propagule bank for the green macroalgal blooms in the Yellow Sea. The results of this study provide further supporting evidence that the floating green macroalgal blooms originate from green macroalgae attached to Pyropia aquaculture rafts along the Jiangsu coastline of the southern Yellow Sea.