Analysis on the Eutrophication and Algae Blooms of Hongfeng Lake Reservoir in Guizhou

[Objective] The research aimed to know the ecological environment pollution characteristics of Hongfeng Lake water area and the evolution rule,which provided the theory basis for improving the water quality condition.[Method] Based on the investigation and research of indoor and outdoor,the water quality,aquatic ecosystem,pollution characteristic of sediment and occurrence law of algae blooms in Hongfeng Lake were comprehensively analyzed by combining with the relevant literatures.[Result] Hongfeng Lake was in moderate-heavy eutrophication situation,and the water quality was V-bad V class.The sediment accumulated a lot of nutrient salt,which was the important pollution source of eutrophication in Hongfeng Lake Reservoir.The aquatic ecosystem degraded,and it was easy to form the algae blooms.[Conclusion] The pollution treatment of Hongfeng Lake was extremely urgent.

Air–water CO2 flux in an algae bloom year for Lake Hongfeng,Southwest China:implications for the carbon cycle of global inland waters

The carbon cycle of global inland waters is quantitatively comparable to other components in the global carbon budget. Among inland waters, a significant part is man-made lakes formed by damming rivers. Manmade lakes are undergoing a rapid increase in number and size. Human impacts and frequent algae blooms lead to it necessary to make a better constraint on their carbon cycles. Here, we make a primary estimation on the air–water CO_2 transfer flux through an algae bloom year for a subtropical man-made lake—Hongfeng Lake, Southwest China. To do this a new type of glass bottles was designed for content and isotopic analysis of DIC and other environmental parameters. At the early stage of algae bloom,CO_2 was transferred from the atmosphere to the lake with a net flux of 1.770 g·C·m^(-2). Later, the partial pressure(pCO_2) of the aqueous CO_2 increased rapidly and the lake outgassed to the atmosphere with a net flux of 95.727 g·C·m^(-2). In the remaining days, the lake again took up CO_2 from the atmosphere with a net flux of 14.804 g·C·m^(-2). As a whole, Lake Hongfeng released 4527 t C to the atmosphere, accounting for one-third of the atmosphere/soil CO_2 sequestered by chemical weathering in the whole drainage. With an empirical mode decomposition method, we found air temperature plays a major role in controlling water temperature, aqueous pCO_2 and hence CO_2 flux. This work indicates a necessity to make detailed and comprehensive carbon budgets in man-made lakes.

Culture observation and molecular phylogenetic analysis on the blooming green alga Chaetomorpha valida (Cladophorales, Chlorophyta) from China

The marine green alga Chaetomorpha valida fouls aquaculture ponds along the coastal cities of Dalian and Rongcheng, China. Unialgal cultures were observed under a microscope to determine the developmental morphological characters of C. valida. Results reveal that gametophytic filaments often produce lateral branches under laboratory culture conditions, suggesting an atypical heteromorphic life cycle of C. valida between unbranched sporophytes and branched gametophytes, which differs from typical isomorphic alternation of Chaetomorpha species. The shape of the basal attachment cell, an important taxonomic character within the genus, was found variable depending on environmental conditions. The 18S rDNA and 28S rDNA regions were used to explore the phylogenetic affinity of the taxa. Inferred trees from 18S rDNA sequences revealed a close relationship between C. valida and Chaetomorpha moniligera. These results would enrich information in general biology and morphological plasticity of C. valida and provided a basis for future identification of green tide forming algae.

Three-dimensional eutrophication model and application to Taihu Lake,China

Taihu Lake, the largest freshwater shallow lake in eastern China, has suffered from severe eutrophication over the past two decades. This research developed a three-dimensional eutrophication model to investigate the eutrophication dynamics. The model fully coupled the biological processes and hydrodynamics, and also took into account the effects of sediment release and the external loads from the tributaries. After sensitivity analyses, the key parameters were defined and then calibrated by the field observation data. The calibrated model was applied to study the seasonal primary productions and its regional differences. The comparisons between model results and field data in year 2000 indicated that the model is able to simulate the eutrophication dynamics in Taihu Lake with a reasonable accuracy. From the simulation experiments, it was found that the meteorological forcing have significant influences on the temporal variations of the eutrophication dynamics. The wind-induced circulation and sediment distribution play an important role in the spatial distribution of the algae blooms.

Silicon limitation on primary production and its destiny in Jiaozhou Bay, China VI: The ecological variation process of the phytoplankton

The combination effect of light, water temperature and nutrients on phytoplankton growth in Jiaozhou Bay is studied in this paper. The order of importance of the influence on phytoplankton growth is de- termined as nutrients, water temperature, and light. The influence of these factors unveiled the mechanism of the influence, and revealed the variation process of the nutrients limiting phytoplankton primary production, and of the water temperature influencing the phytoplankton reproduction capacity, and hence influencing the structure of phytoplankton assemblage. Temporal and spatial quantification shows different stages of the influence by wa- ter temperature and nutrients on the phytoplankton growth. Moreover, the authors expatiated the ideal state of the phytoplankton growth and the reason of red tide occurrence. People should consider in their activity the input of nutrient Si first, and then the variation of water temperature, advocating sustainable development manner.

The possibility analysis of habitats,origin and reappearance of bloom green alga(Enteromorpha prolifera) on inshore of western Yellow Sea

Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible water area in China producing a large biomass,some reasons for firestorm,and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera.The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons.It was transferred northward by the combination of the flow of rainwater,wind and alongshore marine current.The original region of large biomass produced is possibly located in the southwestern Yellow sea.It will possibly be appearing again in the coming years or in the future.A summary is also given referring to its reproduction,development and distribution worldwide.

Detection of Phaeocystis globosa using sandwich hybridization integrated with nuclease protection assay(NPA-SH)

Phaeocystis globosa Scherffel is one of the common harmful algae species in coastal waters of the southeastern China.In this study,sandwich hybridization integrated with nuclease protection assay(NPA-SH)was used to qualitatively and quantitatively detect P. globosa.Results showed that this method had good applicability and validity in analyzing the samples from laboratory cultures and from fields.The linear regression equation for P.globosa was obtained,and the lowest detection number of cells was 1.8×104 c...

Model study on Bohai ecosystem 2. Annual cycle of nutrient-phytoplankton dynamics

Using the coupled bio-physical model described in the first paper of this series of studies, the annual variations of algae biomass and nutrient concentration in the Bohai Sea are simulated. Modeled results show that the onset of spring bloom is induced by high nutrient stocks stored in winter, though the initial time is earlier in shallow waters than in deep waters, for which the evolution of the vertical stratification in deep waters plays an important role; on the other hand, newly added river-berne nutrients and resuspending sediment-berne nutrients are responsible for the outburst of autumn blooms. On the basis of modeled results, it is also found that the BS ecosystem, as a whole, is limited by nitrogen all the year round, though the phosphorus limitation is apparent in the Laizhou Bay where the ratio of nitrogen concentration to phosphorus concentration is higher than 16 due to the contribution of newly added nutrient species from Huanghe River discharges.

Environmental characteristics of annual pico/nanophytoplankton blooms along the Qinhuangdao Coast

Abstract Blooms of some pico/nanophytoplankton have occurred frequently along the Qinhuangdao coast since 2009, and it is necessary to identify the critical environmental factors inducing them. In this study, variations in the physical and nutrient characteristics of the seawater were analyzed following the development of local blooms in 2013. The local environmental characteristics were also compared with those of the Changjiang River estuary, China, and the Long Island estuaries in the USA, which are also prone to blooms of special algal species. In Qinhuangdao the local water temperature varied seasonally and rose above 15~C in 2013 early summer, coincident with the water discoloration. The salinity was more than 28 with a variation range of 〈3 throughout the year. Our results suggest that the physical conditions of the Qinhuangdao coastal area were suitable for the explosive proliferation of certain pico/nanophytoplankton, e.g. Aureococcus anophagefferens. The water supporting the bloom was not in a condition of serious eutrophication, but there were relatively high concentrations of reduced nitrogen （especially ammonium）, which acted as an important nitrogen source for the pico/nanophytoplankton bloom. There was also a large gap between total nitrogen （TN） and dissolved inorganic nitrogen （DIN）. Although the phosphate concentration was relatively low, there was no evidence of phosphorus limitation to the growth of pico/ nanophytoplankton during bloom events.

Numerical simulation of an algal bloom in Dianshan Lake

A hydrodynamic model and an aquatic ecology model of Dianshan Lake,Shanghai,were built using a hydrodynamic simulation module and the water quality simulation module of Delft3D,which is an integrated modelling suite offered by Deltares. The simulated water elevation,current velocity,and direction were validated with observed data to ensure the reliability of hydrodynamic model. The seasonal growth of different algae was analyzed with consideration of observed and historical data,as well as simulated results. In 2008,the dominant algae in Dianshan Lake was Bacillariophyta from February to March,while it was Chlorophyta from April to May,and Cyanophyta from July to August. In summer,the biomass of Cyanophyta grew quickly,reaching levels much higher than the peaks of Bacillariophyta and Chlorophyta. Algae blooms primarily occurred in the stagnation regions. This phenomenon indicates that water residence time can influence algal growth significantly. A longer water residence time was associated with higher algal growth. Two conclusions were drawn from several simulations: reducing the nutrients inflow had little effect on algal blooms in Dianshan Lake; however,increasing the discharge into Dianshan Lake could change the flow field characteristic and narrow the range of stagnation regions,resulting in inhibition of algal aggregation and propagation and a subsequent reduction in areas of high concentration algae.

The study on the effect of NO on the growth of Chaetoceros curvisetus

This article studied nitric oxide (NO) effect on the growth of Chaetoceros curvisetus in chemistry for the first time. Nitric oxide was added into the media with 4 different nutrient concentrations f/2, f/50, f/100, and f/200 when the alga was growing. The growth of C. curvisetus could be obviously promoted or inhibited during the cultivation process in NO enriched media of different concentrations. The growth curve in such media showed a sharp single peak that is the optimal NO concentration for the alga growth, which is consistent with the influence of NO on the growth of high plants. In addition, C. curvisetus can produce NO by itself during the growth. Therefore, using NO could effectively regulate the algae growth, which is important in real tide control and remediation.

Research on Measurable Nonlinear Relationship Between Phytoplankton Biomass and Environmental Factors in Bohai Bay

B ased on the data of phytoplankton and environmental factors in the Bohai Bay, the dependence between the concentration of phytoplankton and environmental factors is analysed by linear correlation coefficient, rank correlation coefficient and Hoeffding test of independence .The result shows that wind-speed, air-pressure, surface temperature, field pH, salinity, DO, silicate and NO3- have a great impact on the concentration of phytoplankton.

Development and Application of a Marine Ecosystem Dynamic Model

A nutrient-phytoplankton-zooplankton-detritus （NPZD） type of marine ecosystem model was developed in this study,and was further coupled to a three-dimensional primitive-equation ocean circulation model with a river discharge model and a solar radiation model to reproduce the dynamics of the low nutrition level in the Bohai Sea （BS）.The simulation results were validated by observations and it was shown that the seasonal variation in the phytoplankton biomass could be characterized by the double-peak structure,corresponding to the spring and summer blooms,respectively.It was also found that both nitrogen and phosphate declined to the lowest level after the onset of the summer bloom,since the large amounts of nutrients were exhausted by phytoplankton for photosynthesis,and the concentrations of nutrients could resume in winter after a series of the biogeochemical-physical processes.By calculating the nitrogen/phosphorus （N/P） ratio,it is easy to see that the phytoplankton dynamics is nitrogen-limited as a whole in BS,though the phosphorus limitation may occur in the Yellow River （YR） Estuary where the input of riverine nitrogen is much more than that of phosphate.

Analysis of a Synechococcus sp. Bloom in the East China Sea and Its Causes

In the spring of 2007,a Synechococcus sp. bloom was monitored in station A1( 30° N,123° E) in the East China Sea. The abundance of Synechococcus sp. was nearly 2×10~6 cells/ml,and the contribution of Synechococcus sp. to chlorophyll a was nearly 90%. According to the abundance of Synechococcus sp. in the East China Sea and adjacent Changjiang River estuary in the past tow decades,the main reasons why Synechococcus sp. could form a bloom are listed below: the rising level of nutrients and the further eutrophication of the water body provided sufficient nutrients for Synechococcus sp.;with the global warming,the sea water temperature in the East China Sea rose continuously;the number of major predator heterotrophic flagellates was at a low level,reducing predation pressure.

Allelopathic inhibition on red tide microalgae Skeletonema costatum by five macroalgal extracts

This study aims to identify effective antialgal allelochemicals from marine macroalgae that inhibit the growth of red tide microalgae.Practically,new algicidal agents were developed to control red tide.The growth inhibitory effects of 5 marine macroalgae Porphyra tenera,Laminaria japonica,Ulva pertusa,Enteromorpha clathrata,and Undaria pinnatifida on Skeletonema costatum were evaluated by adding crude seawater extracts of macroalgal dry tissue into the culture medium containing S.costatum.The half-effective concentrations at 120 h(EC_(50),120 h)of the seawater extracts were 0.6,0.9,1.0,1.0,and 4.7 g/L for the five macroalgae above,respectively.E.clathrata,L.japonica and U.pertusa showed strong allelopathic effect on the growth of S.costatum.There have been no previous reports with regard to the allelopathic effects of the former two macroalgae so far.The possible allelochemicals of 21 compounds of the E.clathrata were detected using Gas chromatography-mass spectrometry(GC-MS)analysis.Unsaturated fatty acids,acrylic acid(C_(3)H_(4)O_(2)),and linolenic acid(C_(18)H_(30)O_(2))were the most likely allelochemicals in E.clathrata.

Growth characteristics of algae during early stages of phytoplankton bloom in Lake Taihu,China

Three treatments, sediment plus lake water （S＋W）, sterilized sediment plus lake water （SS＋W）, and sediment plus filtered lake water （S＋FW）, were recruited to investigate the growth characteristics of algae during pre-bloom and the importance of algal inocula in the water column and sediment. The results showed that in the water column, biomass of all algae increased in all treatments when recruitment was initiated, whereas this tendency differed among treatments with further increment of temperature. The process of algal growth consisted of two stages： Stage I, the onset of recruitment and Stage II, the subsequent growth of algae. Compared with S＋W, in Stage I, SS＋W significantly increased the biomass of cyanophytes by 178.70%, and decreased the biomass of non-cyanophytes by 43.40%; In Stage II, SS＋W notably stimulated the growth of all algae, thus incurring the occurrence of phytoplankton bloom. Further analyses revealed that both metabolic activity and photochemical activity of algae were enhanced in SS＋W, which resulted from the releasing of nutrients from sediment. These results suggest that algal growth in Stage II and algal inocula in the water column can be important factors for the formation of phytoplankton bloom. In addition, possible mechanisms promoting algal recruitment and subsequent growth of algae were explored.

Analysis of the Causes of Cyanobacteria Bloom:A Review

Among water blooms,cyanobacteria bloom occurs over the widest range and is much more harmful than other blooms.Its occurrence in inland water bodies is affected by many factors,such as meteorology,hydrology,and human activities.Therefore,the study of the causes of cyanobacterial bloom has become a major focus of scholars.The China Knowledge Network Journal Database contains 143 papers from China and abroad from the years 2004 to 2019 that are relevant to the study of cyanobacteria bloom.We begin by analyzing keywords in these studies and creating a keyword distribution map which indicates the factors related to the blooms.Based on parameters such as the frequency of words appearing in the text,the full text of each of the 143 papers is analyzed to form a word cloud created by a program written in Python language.After irrelevant terms are eliminated,the word cloud map can reveal potential factors that were not identified by keywords alone.After completing this macro analysis,we examined approximately 100 related papers from the China Knowledge Network Journal Database and Web of Science Database published from 2014 to 2019.Finally,we summarize the main reasons for the outbreak of water blooms.The factors causing blooms can be divided into natural factors and human factors.Among the natural factors are illumination,water temperature and nutrient salt conditions.The human factors are generally related to large-scale water conservancy projects.This paper analyzes and summarizes these factors,and provides a reference to aid in the prevention and treatment of algal blooms.The information in the paper has a certain practical significance for the protection of water environments.

Risk associated with toxic blooms of marine phytoplankton functional groups on Artemia franciscana

Objective:To study mortality of copepod Artemia franciscana against the occurrence of harmful marine algae and possible toxicological changes exhibited by binary and tertiary combinations of these harmful algae toxins.Methods:Tweenty four hours acute toxicity assays were performed with selected concentrations of Alexandrium minutum,Prorocentrum lima and Nitzschia N1c1 living cells.Additionally,the results were analyzed using the median-effect/combination index(CI)-isobologram equation to assess possible changes in the toxic effect induced by phytoplankton functional groups.Results:Biotoxin equivalent values obtained by immunodetection were(2.12±0.10),(8.60±1.30)and(4.32±1.67)pg/cell for saxitoxin,okadaic acid and domoic acid,respectively.The 24-h LC_(50) values estimated to saxitoxin and okadaic acid equivalents were 4.06 and 6.27μg/L,significantly below the value obtained for Nitzschia N1c1,which was established at 467.33μg/L.CI analysis applied on phytoplankton assemblages showed that both ternary mixture as the binary combinations exhibited antagonic action on toxic effects in Artemia nauplii,which were significantly lower than the toxic effect exhibited by each species studied.Conclusions:These results show that,although these harmful algae represent a serious risk to estuarine zooplankton community,the presence of phytoplankton functional groups within the same bloom can reduce the potential risk compared to the expected risk when each of the phytoplankton groups are evaluated individually.