Phytoplankton Phyla Research Articles

The phenomenon of Harmful Algae Blooms (HABs) based on literature study in Indonesia Sea Waters from 2005-2021

Phytoplankton plays a vital role as a significant component of the food chain and primary production in the marine environment. However, the blooming of certain phytoplankton can have a detrimental impact on aquatic ecosystems. Toxins produced by these algae can be harmful to humans and animals. This study aims to map the spatial and temporal distribution of harmful phytoplankton in the sea waters of Indonesia. The study uses literature published from 2005 to 2021 about harmful algae blooms in Indonesia. This literature is then analyzed by reviewing existing literature from reputable repositories, with the keyword harmful algae blooms in Indonesia, and visualized using R. The study results show two phyla of phytoplankton most commonly found in the waters of the Indonesian Sea, namely Ochrophyta and Myzozoa. Seventeen genera were identified as potentially harmful phytoplankton (Chaetoceros, Coscinodiscus, Pyrodinium, Nitzschia, Skeletonema, Thalassiosira, Trichodesmium, Alexandrium, Rhizosolenia, Pseudo-Nietzsche, Ceratium, Dinophysis, Noctiluca, Protoperidinium, Prorocentrum, Anabaena, and Oscillatoria), with ten of them known to be potentially toxic (Nitzschia, Cochlodinium, Trichodesmium, Alexandrium, Dinophysis, Pyrodinium, Protoperidinium, Prorocentrum, Oscillatoria, and Anabaena). The most affected areas by harmful algae blooms (HABs) in Indonesia are in western Indonesia, especially the southern part of Sumatra, Lampung, and DKI Jakarta. The analysis of the causes of HABs shows that excess nutrients, as well as domestic and anthropogenic wastes, are the leading causes of the HABs phenomenon in Indonesia.

The physico-chemical variables and phytoplankton of Ufiobodo and Ebonyi Reservoirs, Ebonyi State, Nigeria

The water quality and phytoplankton of Ufiobodo and Ebonyi River reservoirs were studied for nine months from March to November, 2019 to evaluate the suitability of the reservoirs for domestic water supply and habitat for aquatic organisms. Temperature, pH, conductivity, total dissolved solid (TDS), transparency, dissolved oxygen (DO) and depth were measured in situ, while water samples were collected for determination of nitrate, iron, silicate and phosphate in the laboratory. Phytoplankton samples were also collected concurrently using plankton net of mesh size 45μm and mouth diameter (0.26m) and identified in the laboratory using standard keys. The results showed that mean conductivity (32.33μS/cm), TDS (16.00mg/l), nitrate (33.99mg/l), depth (10.36m) and phosphate (4.81mg/l) were higher at Ebonyi than Ufiobodo Reservoir but DO was lower at Ebonyi Reservoir (2.77mg/l) than at Ufiobodo Reservoir (6.67mg/l). Mean DO level was below the permissible limit for drinking water at Ebonyi Reservoir while nitrate, phosphate and iron concentrations exceeded permissible limits in both Reservoirs. Five phytoplankton Phyla were encountered, predominated by Chlorophyta (107 individuals/l, H=2.80 and d=3.85) and Bacillariophyta (81 individuals/l, H=2.39 and d=2.50) at Ufiobodo and Ebonyi Reservoirs, respectively. Principal Component Analysis (PCA) showed that temperature, conductivity, TDS, depth, DO, nitrate and phosphate were the major factors influencing phytoplankton abundance and diversity of the reservoirs. Thus, the reservoirs should be protected to maintain/improve the water quality for domestic use and to support the socio-economic and ecological services they provide.

Biodiversity and Interannual Variation of Harmful Algal Bloom Species in the Coastal Sea of Qinhuangdao, China.

For the frequent occurrence of harmful algal blooms (HABs) in the Qinhuangdao coastal sea (QCS) of the Bohai Sea in summer, we tested the hypothesis that high-biodiversity HAB species exist in the area, and a series of censuses of HAB species were conducted in the QCS in the summers of 2014-2019. Through morphological identification, we found 100 algae species representing 42 genera in 3 phytoplankton phyla in this study, among which Bacillariophyta was the most dominant phylum. We also found that the population density of Dinoflagellata increased from 2016 to 2019. In total, 59 HAB species were annotated in this study, including 39 of Bacillariophyta, 18 of Dinoflagellata and 2 of Ochrophyta, of which 13 HAB species were reported in the Bohai Sea for the first time, and most HAB species were widely distributed in the QCS in summer. Notably, four dominant HAB species displayed unique temporal and spatial distribution characteristics, while their distribution ranges and population densities increased from 2014 to 2019. The distributions of five environmental factors were different in the QCS, while the temperature, salinity, and dissolved inorganic nitrogen might be the key environmental factors influencing the distribution of dominant HAB species in the summer. In conclusion, this study provides a detailed evaluation of phytoplankton diversity and interannual variation in the QCS. The existence of a high level of biodiversity of algal bloom species suggests the need for long-term monitoring in order to further study and prevent potential HABs.

Metabolic growth, plankton selectivity, haemato-biochemical and intestinal morphometry of Nile tilapia (Oreochromis niloticus) fed a lysine-deficient diet in earthen ponds

Sustainable aquaculture requires the efficient use of natural pond resources as well as supplements to meet the dietary requirements of fish species. However, aquaculture diets are often produced without considering the lysine content of the natural production in the pond. As such, two plant-based diets, a control diet (L-Con) supplemented with 5.00 g lysine kg−1 diet and a lysine deficient diet (L-Def) without supplementation were fed to Nile tilapia raised in ponds with five replicates ponds for each diet. The aim was to investigate the effect of L-Def diet on plankton selectivity, metabolic growth, haemato-biochemical parameters, gut content and intestinal morphometry. Fish were fed a fixed ration of 18 g kg−0.8 d−1 for 10 weeks. During the experimental period, plankton species in the fish guts were identified and categorised to phylum level: phytoplankton phyla – Euglenophyta, Bacillariophyta, Cyanobacteria, and Chlorophyta; zooplankton phyla - Copepoda, Rotifera, and Cladocera. Fish in ponds receiving the L-Def diet selected positively for all phyto and zooplankton phyla but the selectivity was only significantly higher for Bacillariophyta with fish in ponds receiving the L-Con diet (P < 0.05). The numerical index (N%) of plankton in the gut content of Nile tilapia was higher in the L-Def treatment (48%) than in the L-Con treatment (38%). Fish growth and mortality were not significantly different between the two dietary treatments. The organo-somatic indices and haemato-biochemical parameters were similar between diets. The fish intestinal cross-sections from the L-Con and L-Def treatments showed numerous goblet cells in the proximal, middle, and distal gut, while the distal gut showed a partial serosal surface. Meanwhile, intestine morphometry sections of the distal villi length, submucosal layer, muscular layer and mid villi width, proximal / mid goblet cell counts and proximal lamina propria, were significantly higher in the L-Def treatment than in the L-Con treatment. The adverse impacts of dietary lysine deficiency on growth and fish health were reduced through plankton selectivity by Nile tilapia reared in ponds.

Characteristics of Phytoplankton Community Structure and Indication to Water Quality in the Lake in Agricultural Areas

In recent years, lakes’ water quality and quantity have been affected and damaged by agricultural activities. The sensitivity of phytoplankton to the hydrological environment can effectively indicate the health of the aquatic ecosystem and the change in water quality. Understanding the changes of phytoplankton communities in lakes contaminated by agriculture may contribute to determining the directions of protection of these water bodies and provide reference cases for wider research. It is found that there are 146 species, 63 genera, and 8 phyla of phytoplankton, including 57 species of Bacillariophyta, 46 species of Chlorophyta, 17 species of Cyanobacteria and Euglenophyta. The total abundance was changed successively with Bacillariophyta (75% in June), Cyanobacteria (50% in July–August), and Chlorophyta (75% in September–October). The total biomass decreased continuously over time. The biomass of Chlorophyta is highest in October (67.4%), and diatoms contribute the most biomass in other months (76.5%). The Redundancy analysis indicated that the main environmental factors affecting phytoplankton’s dynamic change are total salt, water temperature, total phosphorus, and 5-day biochemical oxygen demand. The phytoplankton can be divided into 21 functional groups. The MP group has the highest frequency, mainly distributed in the frequently stirred and turbid shallow water. Representative functional groups indicate the high degree of eutrophication and nutrient-rich conditions and the good associated environment for phytoplankton and slow water flow rate. With the seasonal change of agricultural irrigation and drainage, the water quality of Xinmiao Lake began to deteriorate from medium pollution in July and reached serious pollution in October finally. Furthermore, this research discovered that the risk of cyanobacteria bloom is high in summer, primarily when thermal stratification occurs. This study provides necessary information for understanding and predicting the changes of the phytoplankton community caused by the increase of nutrients, human disturbance, and temperature conditions in eutrophic lakes in agricultural areas.

Structural Characteristics of Zooplankton and Phytoplankton Communities and Its Relationship with Environmental Factors in a Typical Tributary Reservoir in the Three Gorges Reservoir Region

Based on the data of zooplankton, phytoplankton, and water environmental factors in different seasons in a typical tributary reservoir in the Three Gorges Reservoir Region (Changshou Lake), this study explored the relationships between the structures of the zooplankton and phytoplankton communities and environmental factors using Pearson correlation analysis. The results showed that there were a total of 107 species of 8 phyla of phytoplankton, and cyanobacteria was the most critical constituent with a relative abundance of 61%. The dominant populations included Phormidium tenue, Merismopedia punctata, and Anabaena oscillarioides. A total of 82 species of 4 phyla of zooplankton were identified, and rotifers was the most abundant with a relative abundance of 88%. The dominant populations included six species, such as Keratella cochlearis, Asplanchna priodonta, and Asplanchna girodi. The spatial differences in the abundances, biomass, and biodiversity indexes of zooplankton and phytoplankton were not significant, whereas the seasonal differences in all the other indexes were significant, except for the zooplankton biodiversity indexes. The abundance of phytoplankton was the highest in summer, followed by spring, and it was the lowest in winter. The maximum abundance of zooplankton occurred in spring, and the biomass of zooplankton and phytoplankton in spring was significantly higher than that in winter. The number of phytoplankton species and the Shannon-Wiener index, Pielou's uniformity index, and Margalef richness index in summer were significantly lower than those in winter and spring. The water quality evaluation showed that Changshou Lake was in a clean to oligo-pollution state in winter and spring and a moderate-pollution state in summer, thereby suggesting that Changshou Lake was in an overall eutrophic state. The environmental factors, including Chla, DOC, nutrients (TP, NO2--N, NO3--N, and NH4+-N), DO, Eh, and T, influenced the structures of the zooplankton and phytoplankton communities in Changshou Lake, and there were seasonal differences in the environmental factors.

What drives the dominance and distribution of Cyanobacteria and Dinoflagellata in reservoirs of Sri Lanka?

Frequent records and health concerns in recent times have directed more attention on freshwater cyanobacterial and dinoflagellate blooms in Sri Lanka. Physico-chemical factors influencing phytoplankton growth are still under debate. This necessitates understanding environmental trends governing the dominance and distribution of algal blooms. Hence this study aimed to assess the dominance of Cyanobacteria and Dinoflagellata in reservoirs of Sri Lanka covering the three major climatic regions of the country, the Wet, Intermediate and Dry Zones. Plankton samples were collected using open type 20 µm plankton net and identified using standard phytoplankton keys. Ninety-one species belonging to three phyla of phytoplankton were identified. Phylum Chlorophyta represented the highest species number followed by Bacillariophyta and Cyanophyta. Fourteen genera of Cyanobacteria were recorded and eleven of them were potentially toxigenic. The widest distribution was shown by Chroococcus and Merismopedia. Cylindrospermopsis raciborskii with the highest mean relative abundance was recorded in Intermediate and Dry Zone reservoirs. Peridinium aciculiferum was the only dinoflagellate species recorded during the study with the highest abundance in the Isinbessagala rocky pond. Except sixteen reservoirs which were mesoeutrophic, all the other studied reservoirs were found to be either eutrophic or hypereutrophic. Iranamadu tank recorded the highest TP concentration (236 µg L-1) value. NO3-:TP ratio revealed the phosphate limited conditions in Wet and Dry Zone reservoirs whereas N was a limited factor in Intermediate Zone. Canonical Correspondence Analysis (CCA) results revealed that Secchi depth and area of water spread are important in determining both site and species variations in reservoirs of Sri Lanka.

The influence of land use-impacted tributaries on water quality and phytoplankton in the Mooi River, North West Province, South Africa

Background: Effluents from agricultural activities, metal and peat mining, urban and industrial areas, informal settlements and wastewater treatment plants all influence tributaries feeding the Mooi River. All these land uses ultimately result in a deterioration of water quality in the Mooi River.Objectives: The main objective was to relate the effects of inflowing tributaries to water quality and phytoplankton assemblages in the Mooi River.Method: Physico-chemical environmental variables were compared with water quality objectives and known limits to assess general water quality in the Mooi River over a one-year period. Water quality and phytoplankton in tributarieswere compared to that at sites upstream and downstream from their inflows to determine the extent to which the tributaries affected the Mooi River. Multivariate analysis assisted in the interpretation of phytoplankton and physico-chemical data at the different sites.Results: Seven phytoplankton phyla were identified in the Mooi River. Diatoms and green algae were most dense and diverse. Cyanobacteria were responsible for various problems, especially in the Wasgoedspruit where they dominated and reached high densities. Lowest phytoplankton density and diversity were found in the upstream and downstream sections of the river, while maximum density and diversity were found during summer in the middle reaches. The inflow of tributaries, especially the Wasgoedspruit, had a pronounced effect on water quality downstream. Phytoplankton density and diversity were less affected than chemical variables, especially nutrient concentrations.Conclusion: Various land use activities surrounding the Mooi River’s tributaries contributed to a deterioration of water quality in the main stream of the Mooi River.

Characteristics of Eukaryotic Plankton Communities in the Cold Water Masses and Nearshore Waters of the South Yellow Sea

Eukaryotic plankton are important parts of the marine biome and play an important role in maintaining the stability of marine ecosystems. In order to characterize the eukaryotic plankton communities in the South Yellow Sea Cold Water Mass (CWM) and the South Yellow Sea nearshore waters (NW) in October 2019, Illumina high–throughput sequencing was performed using the 18S rDNA V9 region as the target gene. Environmental factors (depth, pH, salinity, temperature, Chl a, nitrate, nitrite, ammonium, silicate, phosphate) in two sea areas were measured, and their correlations with abundance and diversity of eukaryotic plankton were analyzed. A total of 807 species of plankton were identified, of which 663 species in 24 categories were from the CWM area, and 614 species in 26 categories were from NW. The total phytoplankton abundance in CWM waters was higher than that in NW. Dinophyta and Bacillariophyta were the most abundant phyla of phytoplankton in the two areas. Arthropoda and Cnidaria were the major zooplankton taxa. The dominant fungal population was mainly Basidiomycota. Both the CWM and NW have effects on dissolved inorganic nutrient concentrations and plankton abundance. Environmental factor correlation analysis showed that the concentration of dissolved inorganic nutrients within the CWM increased with water depth and the abundance of plankton gradually increased. Ammonium salts, nitrates, phosphates, silicates and water depth were important factors affecting phytoplankton growth. Phytoplankton abundance increased with increasing concentrations of inorganic nutrients. Bacillariophyta showed a strong positive correlation with silicates and depth. Depth and microscopic phytoplankton abundance were important factors influencing the structure of the zooplankton community.

Spatial Distribution of Plankton in Citanduy River, Cisayong Region, Tasikmalaya, West Java

The Cisayong area of ​​Tasikmalaya Regency is an area that is passed by the Citanduy River. The condition of the waters in the Citanduy River in Cisayong area, has received various waste inputs which will affect the quality of the river waters and cause a decrease in water fertility. Plankton can be used as an indicator of water fertility. This study aims to determine the spatial distribution of plankton in the Citanduy River, Cisayong Tasikmalaya Region, West Java. This research was conducted from January 2020 to February 2020. The research stations are located in four locations which are determined based on environmental and land use factors with a sampling period span of once every seven days. This research was conducted using a survey method and the data were analyzed descriptively and comparatively. The results showed that there were 67 genera of plankton from 5 phytoplankton phyla and 4 zooplankton phyla with most of the phytoplankton groups found from the Bacillariophyceae class and the zooplankton group from the Tubulinea class. The total average abundance of phytoplankton was 11,534 ind / L and the total average abundance of zooplankton was 295 ind / L. The biological index values ​​of the average diversity and dominance of phytoplankton were 2.72 and 0.11, while the average values ​​of diversity and dominance of zooplankton were 0.92 and 0.47. The results of the plankton spatial distribution show that the fertility of the waters in Citanduy River is classified as oligotrophic for station 1 and mesotrophic waters for stations 2,3, and 4.

Phytoplankton community characteristics in rice paddy fields under different nitrogen fertiliser applications

Community characteristics of phytoplankton in the surface water of paddy fields under four nitrogen fertiliser (NF) treatments were studied in the Yangtze River Delta, China. The results were as follows: (1) in total, 65 species, belonging to six phytoplankton phyla and 50 genera were detected; their average total density was 1.25 × 106/L. Number of species and diversity of phytoplankton were higher in the control treatment (0 kg N/ha; CK) than in the NF treatments at later experimental times; (2) there was a significant positive correlation between phytoplankton density and total N; however, total density of phytoplankton was higher in CK than in NF treatments; (3) during the transplanting and rehabilitation stage, under high N treatments, phytoplankton mainly comprised Chlorophyta, among which the dominant species was Volvox aureus, while under low N treatments, the main phyla were Chlorophyta and Cryptophyta, with Chlamydomonas reinhardtii and Chroomonas acuta forming the dominant species. During the rice tillering stage, the dominance of Chlorophyta was partially replaced by Cryptophyta and Bacillariophyta in all NF treatments, while the proportion of Cyanobacteria in CK increased significantly; (4) species and density of Cyanobacteria were higher in CK than in NF treatments, accompanied by the dominance of nitrogen-fixing species such as Anabaena spp. at later experimental times. The results indicate that NF application changed the phytoplankton community. Low N conditions can promote competition for photosynthesis and nutrients among phytoplankton in paddy fields, while low N application rates can induce growth of some algae with nitrogen-fixing abilities.

Water Quality Status of Tono and Vea Reservoirs for Aquaculture Development in the Upper East Region of Ghana

Understanding aquatic ecosystem dynamics is fundamental to sustainable development of aquaculture. This study explores the water quality characteristics over temporal and spatial scale in Tono and Vea Reservoirs in the Upper East Region of Ghana for aquaculture development. Water samples and in-situ measurements were taken for fifteen months, from February 2015 to March 2016. Monthly water quality monitoring were based on stratified sampling from upstream, midstream and downstream zones of these reservoirs. Standard analytical methods for examination of water were employed during sampling and laboratory analysis of reservoir water quality. Phytoplankton analysis was done using light microscopy to obtain phylum abundance. Multivariate statistical methods were used to investigate water quality dataset obtained. Cluster analysis grouped fifteen months of water quality changes into three seasonality regimes (periods) based on temporal variation. Principal component analysis (PCA) reduced eighteen water quality variables into five and three factors with total variance of 88.26 % and 79.30% for Tono and Vea reservoirs, respectively. With pH &gt; 7 and alkalinity &gt; 20 but &lt; 100 mg L-1 CaCO3, both reservoirs have alkaline water. Dissolved oxygen was &gt; 5 mg L-1. Three phyla of phytoplankton were identified with dominant (in abundance) phylum as Chlorophyta (72%) occurring in Tono reservoir. To understand the spatial relationship using correspondence analysis (CA), the first axis of CA explained 84.2% and 64.3% of total variation in relative abundance of phytoplankton phyla for Tono and Vea reservoirs, respectively. Thus, Cyanophyta showed strong positive association with conductivity, total hardness, nitrate, sulphate, turbidity, water depth and dissolved oxygen which were responsive to the midstream and upstream zones of Tono reservoir. Whiles in Vea reservoir, Chlorophyta under same water quality variable showed responsiveness to the midstream and downstream zones. Reservoir water quality studied were within acceptable limits for fish culture but changes could be linked to anthropogenic activities on reservoir catchment area and seasonality regime. Results from this provide a baseline to enable information to enable assessment of aquaculture impact in Tono and Vea reservoirs. The use of multivariate analysis could be a reliable statistical method for assessing water quality on a spatio-temporal scale.

Phytoplankton species composition of four ecological provinces in Yellow Sea, China

The ecological province based on phytoplankton species composition is important to understanding the interplay between environmental parameters and phytoplankton species composition. The aim of this study was to establish phytoplankton species composition ecological pattern thus elucidate the relationship between environmental factors and the phytoplankton species composition in the ecological provinces. Phytoplankton samples were collected from 31 stations in Yellow Sea (121.00°–125.00°E, 32.00°–39.22°N) in November 2014. The samples were enumerated and identified with the Utermohl method under an optical inverted microscope-AE2000 with magnifications of 200 × or 400 ×. In the present study, a total of 141 taxa belonging to 60 genera of 4 phyla of phytoplankton were identified, among them 101 species of 45 genera were Bacillariophyta, 36 species of 11 genera were Dinophyta, 3 species of 3 genera were Chrysophyta and 1 species of 1 genera was Chlorophyta. The study area was divided into 4 ecological provinces according to an unsupervised cluster algorithm applied to the phytoplankton biomass. A T-S (Temperature-Salinity) scatter diagram depicted with data of water temperature and salinity defined by environmental provinces matched well with the ecological provinces. The results of Canonical Correspondence Analysis (CCA) indicated that the phytoplankton species composition was mainly correlated with temperature, salinity and silicate concentration in the studied area. A method of establishing ecological provinces is useful to further understanding the environmental effects on the marine phytoplankton species composition and the consequent marine biogeochemistry.

Phytoplankton community structure and water quality assessment of Hejiang River, a branch of Xijiang River, Pearl River drainage basin

为了解珠江流域西江支流贺江浮游藻类的分布并评价其水质情况,于2013年丰水期和枯水期对贺江的浮游藻类群落结构进行调查和分析,结果表明:调查期间共检出浮游藻类7门130种,其中丰水期7门63种,枯水期5门103种,浮游藻类群落组成以绿藻门、硅藻门和蓝藻门为主,丰水期绿藻门居多,硅藻门次之,藻细胞丰度平均值为2.13×10⁶cells/L;枯水期硅藻门最多,藻细胞丰度平均值为3.71×10⁶cells/L;优势种主要有水华微囊藻、卷曲鱼腥藻、小颤藻、啮蚀隐藻、短小舟形藻、变异直链藻、颗粒直链藻、四尾栅藻、集星藻、小球衣藻和小球藻.RDA分析表明,影响贺江浮游藻类群落分布的主要环境因子是氮、磷营养盐,综合营养状态指数显示贺江处于中营养水平.;To study the distribution of phytoplankton and evaluate water quality of Hejiang River, a branch of Xijiang River, Pearl River drainage basin, the community structure of phytoplankton was investigated and analyzed in wet and dry seasons in 2013.The results showed that a total of 130 species belonging to seven phyla of phytoplankton was identified.Including 63 species of seven phyla in wet season and 103 species of five phyla in dry season, phytoplankton community structure in Hejiang River was represented by Chlorophyta, Bacillariophyta and Cyanophyta.Chlorophyta was dominant in wet season, followed by Bacillariophyta.The mean value of phytoplankton density was 2.13×10⁶ cells/L.Bacillariophyta dominated the phytoplankton in dry season, and the mean value of phytoplankton density was 3.71×10⁶cells/L.The dominant species were Microcystis flos-aquae, Anabaena circinalis, Oscillatoria tenuis, Cryptomonas erosa, Navicula exigua, Melosira varians, Melosira granulata, Scenedesmus quadricauda, Actinastrum hantzschii, Chlamydomonas microsphaera and Chlorella valgaris.Based on RDA analysis, nitrogen and phosphorus were important environmental factors that affected the distribution of phytoplankton in Hejiang River.The river was classified as mesotrophic according to comprehensive trophic state index.

Ecological relationships, thresholds and time-lags determining phytoplankton community dynamics of Lake Kinneret, Israel elucidated by evolutionary computation and wavelets

The hybrid evolutionary algorithm (HEA) was implemented to model and analyze population dynamics of the different phytoplankton phyla (chlorophyta, bacillariophyta, cyanophyta and dinophyta) in relation to physical, chemical, and biological determinants and their combinations in a large lake. Biweekly measurements over a 12-year period were used as input. The validation of models obtained with HEA showed the best results for bacillariophyta and dinophyta resulting in coefficients of determination (r2) between the modeled and measured data of 0.54–0.79 and 0.29–0.76 for these phyla, respectively, suggesting good predictability of their dynamics. The lowest adequacy of HEA models was found for cyanophyta (r2 of 0.28–0.46). Models that combined physical, chemical and biological inputs scored highest, whilst zooplankton-based models scored lowest in all experiments and indicated that top-down control of algal biomass could have only secondary effect. The input sensitivity analysis was used for testing the best phytoplankton models with threshold values determining high or low algal biomass and inhibitory–excitatory effects of specific parameters. Wavelets were tested to analyze two extreme cases of dinophyta dynamics in years of its exceptionally high and low developments to gain insights into lag times between the exert of key factor and algae response. Lag times extracted from daily interpolated data of highly correlated inputs of dinophyta in 1998 varied between 2 and 4 days.

Understanding the patterns and mechanisms of urban water ecosystem degradation: phytoplankton community structure and water quality in the Qinhuai River, Nanjing City, China

The temporal and spatial distribution characteristics of environmental parameters and the phytoplankton community were investigated in October 2010 and January 2011 in the Qinhuai River, Nanjing, China. Results showed that the water quality in the study area was generally poor, and the main parameters exceeding standards (level V) were nitrogen and phosphorus. The observed average concentrations of the total nitrogen (TN) were 4.90 mg L(-1) in autumn and 9.29 mg L(-1) in winter, and those of the total phosphorus (TP) were 0.24 mg L(-1) in autumn and 0.88 mg L(-1) in winter, respectively. Thirty-seven species, 30 genera, and four phyla of phytoplankton were detected in the river. Cyanophyta and Bacillariophyta were the dominant phyla in autumn, with average abundance and biomass of 221.5 × 10(4) cells L(-1) and 4.41 mg L(-1), respectively. The dominant population in winter was Bacillariophyta, and the average abundance and biomass were 153.4 × 10(4) cells L(-1) and 6.58 mg L(-1), respectively. The results of canonical correspondence analysis (CCA) between environmental parameters and phytoplankton communities showed that Chlorophyta could tolerate the higher concentrations of the permanganate index, nitrogen, and phosphorus in eutrophic water; Bacillariophyta could adapt well to changing water environments; and the TN/TP ratio had obvious impacts on the distributions of Cyanophyta, Euglenophyta, and some species of Chlorophyta. CCA analyses for autumn and winter data revealed that the main environmental parameters influencing phytoplankton distribution were water temperature, conductivity, and total nitrogen, and the secondary factors were dissolved oxygen, NH4(+)-N, NO3-N, TN, CODMn, TN/TP ratio, and oxidation-reduction potential.

The discrimination of the response pattern of inter-phylum phytoplankton diversity to long-term eutrophication trends in Lake Kasumigaura, Japan

To study the response pattern of phytoplankton to eutrophication, the long-term water chemistry and biological data spanning three phytoplankton phyla and 19 genera were investigated in Lake Kasumigaura, a eutrophic lake in Japan. Fisher' s linear discrimination functions in combination with ecological indexes and a similarity index were used to analyze the relationship between the eutrophic levels (representing with dissolved inorganic nitrogen and total dissolved phosphorus) and the response of the inter-phylum phytoplankton diversity. The algal similarity index was found to characterize the change of eutrophication levels well. Almost 80 percent of eutrophic lake water samples can be correctly discriminated based on the logarithmic cells of phytoplankton genera. However, the ecological indices (number of genera, Margalef' s index, Menhinick' s index, McNaughton' s index, as well as the Shannon' s index and evenness index) failed to predict the change of eutrophic state.

A differential-difference equations model of a dynamic aquatic ecosystem†

This paper presents a differential-difference equations model of a dynamic aquatic ecosystem. This paper departs from other models by considering : (a) specific phyla of phytoplankton, zooplankton and nekton ; (b) their prey—predation relationships ; (c) both allelochemic and antotoxic effects of algae upon zooplankton and other algae ; (d) inter-phyla competition for nutrients. Other factors included are : limiting effects of phosphates, nitrates, silicates, photoperiod, turbidity, temperature, and time lag, as they affect growth and reproduction of the biota. The model uses the western basin of Lake Erie as a test example, but any shallow basin that does not experience thermoclines could be used.