Phytoplankton Samples Research Articles

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.

Occurrence and spatial distribution of paralytic shellfish toxins in seawater and marine organisms in the coastal waters of Qinhuangdao, China

In recent years, paralytic shellfish toxins (PSTs) have been prevalent in the coastal waters of Qinhuangdao, the west coast of the Bohai Sea, China. The content of PSTs in shellfish often exceeded the regulatory limit of 800 μg STX equivalent (eq.) kg−1, which poses a serious threat to human health. In this study, two surveys were conducted in May 2021 and May 2022 to investigate the distribution of PSTs in the coastal waters of Qinhuangdao. Seawater, surface sediment, phytoplankton, zooplankton, and other marine organism samples were collected, and the composition and concentration of PSTs were analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results showed that multiple PST components were detected in all seawater samples collected at different depths, mainly including GTX1/4, GTX2/3, dcGTX2, STX and C1/2, and the highest concentration of PSTs reached 244 ng STX eq. L−1. The sediment samples also contained low levels of C1/2 and GTX2/3. Trace amounts of C1/2 and GTX1-4 were detected in phytoplankton and zooplankton. Moreover, all bivalve shellfish samples were found to contain PSTs, and the scallop Azumapecten farreri and the ark clam Anadara kagoshimensis showed relatively high concentrations of 607 and 497 μg STX eq. kg−1, respectively. In addition, low levels of PSTs were also found in some non-traditional PST vectors, including whelk Rapana venosa, octopus Amphioctopus ovulum, goby Ctenotrypauchen chinensis, and greenling Hexagrammos agrammus. Results of this study improve the understanding of the distribution of PSTs in seawater and marine organisms and the potential risk of persistent PSTs in seawater to marine ecosystems and human health.

Preliminary data on the sea-ice algae and phytoplankton in the Arctic Basin (based on the results of the «SP-41» expedition, 2022–2023 years)

During the expedition Severny Polyus-41 in the winter of 2022–2023 112 samples of phytoplankton and sea-ice algae were taken from 16 stations in the central part of the Arctic Ocean. Diatoms dominate in the samples in species number as well as quantitative development. Preliminary data on taxonomic composition and relative role of dominant species are given.

Electron-transfer MALDI MS methodology for microalgae/phytoplankton pigments analysis

The method describes pigment analysis from microalgae/phytoplankton extracts using electron-transfer Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (ET MALDI MS). Current microalgae/phytoplankton pigment analysis requires resource- and time-intensive chromatographic methods due to the broad polarity range of the target analytes. On the other hand, traditional MALDI MS chlorophyll analysis, using proton-transfer matrices such as 2,5-dihydroxybenzoic acid (DHB) or α-cyano-4-hydroxycinnamic acid (CHCA), results in central metal loss and phytol–ester cleavage. ET MALDI MS is an alternative for the rapid screening and detection of pigments in microalgae extracts.•MALDI matrices with ionization energies above 8.0 eV guarantee electron-transfer processes from photosynthetic and photoprotective pigments whose ionization energies lay below 7.5 eV.•ET MALDI MS pigment analysis agrees with data gathered from conventional chromatographic techniques (HPLC) and optical microscopy for pigment extracts from C. vulgaris cultures and freshwater phytoplankton samples.•The ET MALDI MS method allows fast and reliable detection of pigments in microalgae cultures and freshwater phytoplankton samples.

Determinantes locais e regionais da comunidade fitoplanctônica em barragens de água do bioma Cerrado

Abstract Aim Based on a study comprising water reservoirs within the Brazilian Cerrado biome, we seek to answer the following question: how does phytoplankton communities respond to environmental, landscape, and spatial predictors? We expected local predictors to be the main factors structuring the communities. Since phytoplankton has high dispersal capacity, the geographical distance would be of minor importance. Methods: We collected phytoplankton samples from 40 water reservoirs in the rainy season and 37 reservoirs in the dry season. We performed a partial Redundancy Analysis (pRDA) to evaluate the factors influencing the variation in the composition of phytoplankton communities. Results We found that spatially structured environmental factors were controlling phytoplankton communities at the rainy season, whereas landscape was the main predictor in the dry season. On the other hand, phytoplankton morphofunctional groups were influenced only by local predictors. Conclusions We demonstrated that phytoplankton dynamics differs between rainy and dry seasons, and that distinct predictors affect phytoplankton communities over seasons.

Characterization of Spatiotemporal Variations in Mert Stream Water Quality by Phytoplankton Community and Biological Indices

In order to determine the water quality of the Mert Stream, algal indicators and some biological indices (TDI, IDG, PTI, Palmer, DAIpo) based on phytoplankton species were used. Phytoplankton samples were performed monthly from six different sites at a depth of 0.5 meter using a one-litre water sampler between July 2011 and June 2012. After phytoplankton samples were placed in 250-mL dark bottles and fixed with Lugol’s solution until processed in the laboratory, they were identified and counted in the tubular plankton counting chambers using an inverted microscope according to Utermöhl method. Bacillariophyta members became the dominant division in the phytoplankton with an abundance rate of 83.3% and 71 taxa. Lindavia glomerata, Navicula cryptocephala, Cyclotella planctonica, and Navicula veneta were determined as the most dominant species among phytoplanktonic taxa of Mert Stream. Trophic diatom index (TDI) and Generic diatom index (IDG) based on planktonic diatoms were used to determine the trophic status of the Mert Stream. Pollution tolerance index (PTI), Diatom assemblage index (DAIPo) and Palmer index were also included to assess the organic load-based sabrobity level of the Mert Stream. According to the results of mean TDI and IDG (55 and 13, respectively), the trophic status of the Mert Stream is a mesotrophic structure with moderate nutrients and good water transparency. According to the average PTI result (2.7), Mert Stream is in the β-mesosaprobic class, which corresponds to moderate pollution. Considering DAIpo indice, the saprobity of Mert stream is α-oligosaprobic level and the stream is not exposed to a serious organic-based pollution. However, according to the Palmer index, all stations of the Mert Stream except the 6th station are under the threat of high organic pollution. In present study, it was seen that the best biological index that reflects the station-based trophic structure of the stream is IDG, and the best biological index that reflects the station-based organic pollution of the stream is PTI.

Struktur Komunitas Fitoplankton sebagai Indikator Kualitas Air di Kali Mas Kota Surabaya

Phytoplankton is an aquatic organism that is sensitive to environmental changes. Kali Mas is one of the rivers that passes through the city of Surabaya, and is a source of water needs for various domestic and industrial needs. The purpose of this study was to determine the status of Kali Mas water quality based on the phytoplankton community structure, which includes: diversity, abundance, evenness, dominance, and saprobic index. The method used in this study is purposive sampling. Water and phytoplankton samples were taken from 5 stations along the Kali Mas flow. The identification results of the phytoplankton found consisted of 10 classes, which consisted of: Bacillariophyceae (44.19%); Chlorophyceae (6.33%); Chrysophyceae (0.26%); Cyanophyceae (24.9%); Conjugatophyceae (7.49%); Dinophyceae (2.84%); Fragilariophyceae (1.29%); Trebouxiophyceae (8.14%); Ulvophyceae (3.18%); and ‎Xanthophyceae (0.65%). Diversity index ranged from 2.35-2.96; evenness index 0.72-0.87; and the dominance index is in the range of 0.05-0.148. Meanwhile, based on the saprobic index, Kali Mas is at 1.05. This value indicates the condition of Kali Mas waters is in β - Meso/oligosaprobic conditions with a mild level of pollution.

Bacillariophyceae Distribution and Water Quality in Estuarine-Mangrove Environments: The Commonest Phytoplankton in Musi Estuary, Indonesia

This study reveals the distribution of Bacillariophyceae in estuarine-mangrove which is mainly influenced by the quality of the waters. The main component analysis approach between variables is critical in this study because it determines the environmental characteristics in each estuarine zone. Estuarine-mangrove environments have different physical-chemical dynamics compared to other types of waters, one of which is Musi Estuary, located on the coast of South Sumatra. The aquatic environment of the Musi Estuary is influenced by tidal fluctuations that bring nutrients from inland waters and mangrove litter. This condition is perfect for the phytoplankton habitat, which plays an essential role in the ecological processes of waters as primary producers. This study aims to examine the diversity of Bacillariophyceae phytoplankton in the mangrove estuary environment and its possible role in estuarine ecology. Data were collected at ten observation stations in July, including samples of phytoplankton and water physical-chemical data such as pH, dissolved oxygen, temperature, salinity, water brightness, current speed, nitrates, and phosphates. Quantitative measurement of phytoplankton was performed using an Olympus CX23 light microscope at 100X magnification, while data were analyzed using PCA and Bray-Curtis similarity analysis. Water environment conditions were measured in a stable range in each zone except for salinity and brightness. Furthermore, only Bacillariophyceae were observed in all observation zones dominated by the Skeletonema genus. It is a dominant presence, and its abundance determined its role as a significant primary producer in the estuary outer zone near the sea. This study implicitly revealed the existence of Skeletonema in influencing ecological processes in estuary mangrove waters.

Struktur Komunitas Fitoplakton di Kolam Bekas Tambang Emas sebagai Budidaya Ikan

This study aims to analyze the community structure of phytoplankton in ex-gold mining ponds for fish farming in Nagari Muaro, Sijunjung District, Sijunjung Regency, West Sumatra. The method used is a descriptive survey. Purposive sampling was done by determining the location of the phytoplankton sampling. The results showed that there were three divisions of phytoplankton (Cyanophyta, Chlorophyta and Crysophyta) and 17 genera. The highest relative abundance (KR) was found in the Pediastrum genus of 22.9 with an average diversity index of 3.72, an evenness index of 0.72 and a dominance index of 0.16. The results of the measurement of physical factors, namely the average turbidity of 3.53 NTU, the average water temperature of 32oC and the average water pH of 6. The results of the measurement of the chemical factors of the average water are DO of water of 5.15 ppm, BOD = 1.77 ppm, COD = 26.45 ppm, CO2 = 18.29 ppm and measured levels of mercury (Hg) ranged from 0 – 0.05 ppm. In conclusion, the abundance of phytoplankton is in the low category with a moderate diversity index and the waters are classified as stable.
 Keywords: Used, Phytoplankton, Community, Pond, Mine Structure

Species Richness, Diversity and Distribution of Phytoplankton in Fertilised Ponds of the Western Highlands Agro-Ecological Zone of Cameroon

In developing countries, advanced aquaculture techniques are still at the embryonic stage. This study was carried out from January to December 2021 in the ponds of the West Cameroon Region and at the Ichthyology and Applied Hydrobiology Research Unit of the University of Dschang with the aim of contributing to a better understanding of species richness and distribution of phytoplankton populations in fertilised ponds. For this purpose, a total of fifteen (15) ponds including 03 in Bamendou (fertilised with cow dung), four in Batié (two fertilised with pig manure and two with wheat bran), one in Dschang (fertilised with chicken manure), four in Fokoué (two fertilised with pig manure and two unfertilised), and three in Foumbot (fertilised with cow dung), were assessed. These ponds were chosen based on the availability of fish farmers and the type of fertiliser administered. Together with water physicochemical properties measurement, phytoplankton sampling was done between 6 a.m. and 8 a.m. on a monthly basis. The results showed that phytoplankton species and genera richness was higher in unfertilised ponds in Fokoué ponds and in animal feed enriched ponds in Batié, respectively. However, the highest family richness was obtained in Dschang receiving chicken manure with a percentage of 88.8% of the total family richness. The species Microcystis aeroginosa exhibited the highest species frequency (57%) out of all the species recorded in the ponds of Batié fertilised with pig manure. The lowest Shannon-Weaver diversity indices and Piélou evenness indices were recorded in the Fokoué ponds independent of the type of fertiliser, and in the Dschang ponds receiving chicken manure. The outputs of this work are better proposals for the production of phytophagous or bulldozer fish, such as carp, in relation to the site and the type of fertilisers in the Western highlands agroecological zone of Cameroon in particular and the world in general.

Assembly rules vary seasonally in stable phytoplankton associations of the Gulf of Naples (Mediterranean Sea)

AbstractCoastal phytoplankton present remarkable variability because of complex patterns and relationships of hydrological parameters at the land–sea interface. We analysed a time series of 917 phytoplankton samples collected in the period 1984–2010 at the coastal station LTER‐MC (Gulf of Naples, Mediterranean Sea) with the aims of determining: (i) whether recurrent species associations are recognizable in this variable coastal environment; (ii) what are their composition and seasonal patterns; (iii) what are the environmental variables driving their distributions, and (iv) to what extent those associations are functionally homogeneous. Using a cluster analysis of a dataset of the 87 more frequent and abundant species in the samples, we identified seven main groups of species. Five of them were recurrent over the years in the same seasons, while two other groups showed a bimodal occurrence or no clear seasonality, respectively. Differences in the occurrence of those assemblages were primarily associated with the season (i.e., temperature), and the coastal nature of the site (mainly salinity). Except for the winter cluster, which included mostly coccolithophores and silicoflagellates, diatoms were present in all associations, along with species belonging to diverse phylogenetic groups. The diversity of morphological features defining ecological traits varied across the different associations, with a maximum divergence in the spring association and a minimum in winter. We conclude that the stability of the associations is related to the marked phenological recurrence of their individual species and their overlap in specific periods of the year, while convergent or divergent trait compositions in the different associations indicate a variable strength of the environmental filtering across the seasonal succession.

IMPACTS OF CLIMATE CHANGE ON PHYTOPLANKTON COMPOSITION AND VARIABILITY IN IKO RIVER, COASTAL WATER OF EASTERN OBOLO, NIGERIA

This study investigated the effects of climate change on phytoplankton composition and diversity in Iko River, coastal water of Eastern Obolo, Akwa Ibom State, South Eastern Nigeria. The study area was greatly influenced by tidal flush from the Atlantic Ocean. Phytoplankton samples were collected monthly from October 2021 to March 2022 at high tide and low tide from 3 stations. Phytoplankton was identified and diversity was calculated using standard indices. Dissolved oxygen (3.3–6.0 mg/L) was above WHO guidelines of <5.0mg/L and BOD (2.40-5.30 mg/L) in this study was above the (4.0 mg/L) limit recommended as suitable for aquatic life by the National Environmental Standards and Regulation Enforcement Agency (NESREA), which could pose a threat to aquatic life. A total number of 65 species of phytoplankton were identified in the study area. Bacillariophyta was the dominant group (69%) throughout the study in species number, occurrence and abundance. The increasing order of dominance values was; Bacillariophyta > Cyanophyta > Chlorophyta > Dinophyta > Euglenophyta . Diversity indices (Margalef, Shanon, Dominance, Simpson Evenness and Equitability) showed spatial variations significant at (P>0.05). Pollution-indicator species such as; Tabellaria fenestrata, Nitzschia. paradoxa, N. filiformis, N. longissima, Cymbella cuspidata, Melosira distans and Anabaena constrica were recorded at either high tide, low tide or at both tides. Concerted efforts have been recommended to Government agencies and individuals to help reduce natural and anthropogenic pollution of the coastal water bodies.

Autoecology of Ceratium furca and Chaetoceros didymus as potential harmful algal blooms in tourism and aquaculture sites at Teluk Pandan Bay, Lampung, Indonesia

Abstract. Hasani Q, Yusup MW, Caesario R, Julian D, Muhtadi A. 2022. Autoecology of Ceratium furca and Chaetoceros didymus as potential harmful algal blooms in tourism and aquaculture sites at Teluk Pandan Bay, Lampung, Indonesia. Biodiversitas 23: 5670-5680. Harmful algal blooms (HABs) phenomenon has been observed around tourism and aquaculture sites in Teluk Pandan Waters, Lampung Bay. The dominant potential HABs found in Teluk Pandan waters were Ceratium furca and Chaetoceros didymus. This study aimed to analyze the relationship between the environmental physicochemical factors and the abundance of C. furca and C. didymus as potential HABs. Phytoplankton samples were collected from four stations (Hurun Bay, Sidodadi Coastal Waters, Sari Ringgung Beach and Cikunyinyi Bay) during May-August 2022. Physical parameters (temperature, depth, brightness, current velocity and salinity), as well as chemical parameters (dissolved oxygen, pH, phosphate, nitrite, nitrate and ammonia) were all measured in conjunction with phytoplankton sampling. Canonical correlation analysis and multiple regression were used to predict the effect of environmental parameters on phytoplankton density. Blooms of C. furca were found with the highest density at 5.417×106 cells/L in Cikunyiyi Bay, while C. didymus predominated in Hurun Bay (2.890×104 cells/L), Sidodadi Coastal Waters (3.923×104 cells/L) and Sari Ringgung Beach (3.531×104 cells/L). The main factors influencing the increase in C. furca population at Cikunyinyi Bay were pH, phosphate and nitrate. The increase in C. didymus population at Sidodadi Coastal Waters was affected by phosphate, nitrate and nitrite, while phosphate and nitrate influenced the increase in C. didymus population at Sari Ringgung Beach. Potentially HABs density was found to be higher near intensive shrimp farming sites. The use of fertilizer and artificial feed in high quantities is thought to be responsible for increased water eutrophication. Periodic monitoring and consistent determination of environmental carrying capacity for intensive shrimp farming activities are required to control HABs and ensure the sustainability of aquaculture and tourism activities in Teluk Pandan Waters.

Recommendations for the preservation of environmental samples in diatom metabarcoding studies

Implementation of DNA metabarcoding for diatoms for environmental monitoring is now moving from a research to an operational phase, requiring rigorous guidelines and standards. In particular, the first steps of the diatom metabarcoding process, which consist of sampling and storage, have been addressed in various ways in scientific and pilot studies and now need to be rationalised. The objective of this study was to compare three currently applied preservation protocols through different storage durations (ranging from one day to one year) for phytobenthos and phytoplankton samples intended for diatom DNA metabarcoding analysis. The experimental design used samples from four freshwater and two marine sites of diverse ecological characteristics. The impact of the sample preservation and storage duration was assessed through diatom metabarcoding endpoints: DNA quality and quantity, diversity and richness, diatom assemblage composition and ecological index values (for freshwater samples). The yield and quality of extracted DNA only decreased for freshwater phytobenthos samples preserved with ethanol. Diatom diversity was not affected and their taxonomic composition predominantly reflected the site origin. Only rare taxa (< 100 reads) differed among preservation methods and storage durations. For biomonitoring purposes, freshwater ecological index values were not affected by the preservation method and storage duration tested (including ethanol preservation), all treatments returning the same ecological status for a site. This study contributes to consolidating diatom metabarcoding. Thus, accompanied by operational standards, the method will be ready to be confidently deployed and prescribed in future regulatory monitoring.

Co-occurrence of pectenotoxins and Dinophysis miles in an Indonesian semi-enclosed bay

The study aims to unravel the variability of Dinophysis spp. and their alleged toxins in conjunction with environmental drivers in Ambon Bay. Phytoplankton samples, lipophilic toxins and physiochemical water properties were analysed during a 1.5-year period. Three Dinophysis species (D. miles, D. caudata, and D. acuminata) were found in plankton samples, of which D. miles was the most abundant and persistently occurring species. Pectenotoxin-2 (PTX2) and its secoacid (PTX2sa) were detected throughout, and PTX2sa levels strongly correlated with D. miles cell abundance. The toxin showed a positive correlation with temperature, which may suggest that D. miles cells contain rather constant PTX2sa during warmer months. Dissolved nitrate concentrations were found to play a major role in regulating cell abundances and toxin levels. This study adds adequate information regarding marine biotoxins and potentially toxic species for future Harmful Algal Bloom management in Ambon and Indonesia at large.

Phytoplankton Community Structure Dynamics in Relation to Water Environmental Factors in Zhalong Wetland.

Phytoplankton, as the primary producer of the wetland water ecosystem's food chain, are very sensitive to environmental changes. In order to explore the significance of phytoplankton in protecting ecosystem integrity, the wetland ecosystem in Zhalong wetland, one of the most important international wetlands, was selected as the research area. For the study, 81 sampling sites were set up in the whole wetland, and phytoplankton samples and water quality environmental factors were measured in spring, summer, and autumn of 2019. The phytoplankton community structure and water environmental factors were evaluated by canonical correspondence analysis (CCA). The main research findings are as follows: a total of 292 species and variants of phytoplankton belonging to 8 phyla and 110 genera were identified within Zhalong wetland in spring, summer, and autumn 2019. The total phytoplankton abundance and biomass in summer were higher than in spring and autumn, and Cyclotella meneghiniana was the most dominant species in three seasons and three areas. The results of random forest are generally consistent with the results of CCA in spring, when the main environmental factors affecting phytoplankton were NTU and WT; the result in summer and autumn agreed with those of CCA, which awaits further study. In addition, the phytoplankton is mainly affected by WT, depth, and DO in the lake area, TP, DO, and NTU in the river area, and WT in the wetland area.

Concentration and distribution of phytoplankton nitrogen and carbon in the Northwest Atlantic and Indian Ocean: A simple model with applications in satellite remote sensing

Despite the critical role phytoplankton play in marine biogeochemical cycles, direct methods for determining the content of two key elements in natural phytoplankton samples, nitrogen (N) and carbon (C), remain difficult, and such observations are sparse. Here, we extend an existing approach to derive phytoplankton N and C indirectly from a large dataset of in-situ particulate N and C, and Turner fluorometric chlorophyll-a (Chl-a), gathered in the off-shore waters of the Northwest Atlantic and the Arabian Sea. This method uses quantile regression (QR) to partition particulate C and N into autotrophic and non-autotrophic fractions. Both the phytoplankton C and N estimates were combined to compute the C:N ratio. The algal contributions to total N and C increased with increasing Chl-a, whilst the C:N ratio decreased with increasing Chl-a. However, the C:N ratio remained close to the Redfield ratio over the entire Chl-a range. Five different phytoplankton taxa within the samples were identified using data from high-performance liquid chromatography pigment analysis. All algal groups had a C:N ratio higher than Redfield, but for diatoms, the ratio was closer to the Redfield ratio, whereas for Prochlorococcus, other cyanobacteria and green algae, the ratio was significantly higher. The model was applied to remotely-sensed estimates of Chl-a to map the geographical distribution of phytoplankton C, N, and C:N in the two regions from where the data were acquired. Estimates of phytoplankton C and N were found to be consistent with literature values, indirectly validating the approach. The work illustrates how a simple model can be used to derive information on the phytoplankton elemental composition, and be applied to remote sensing data, to map pools of elements like nitrogen, not currently provided by satellite services.

Phytoplankton Community Structure and Its Relationship with Environmental Factors in Nanhai Lake

In order to determine the characteristics of phytoplankton community structure in Nanhai Lake in Baotou City and its relationship with environmental factors, water and phytoplankton samples were collected and composition and biomass were investigated at six sites in the spring, summer, and autumn of 2021. This article used correlation analysis and redundancy analysis (RDA) combined with the community turnover index (BC) to analyze the phytoplankton functional groups. The results showed that 7 phyla and 68 genera of phytoplankton were identified in the water body, of which Chlorophyta, Bacillariophyta, Cyanobacteria, Chrysophyta, Euglenophyta, Cryptophyta, and Pyrrophyta accounted for 34%, 32%, 16%, 6%, 4%, 4%, and 3%, respectively. The phytoplankton in the water body was classified into 23 functional groups, of which MP and D functional groups were the long−term dominant functional groups, indicating that the habitat is a turbid water body. The ecological state index (Q) value ranged from 1.94 to 3.13, with an average value of 2.74. The comprehensive nutritional index (TSIM(∑)) was between 49.32 and 52.11, with an average value of 51.72, indicating that Nanhai Lake was in a mesotrophic state. Correlation analysis and redundancy analysis (RDA) showed that multiple nutrients, transparency (SD), chemical oxygen demand (COD), water temperature (WT), and Chlorophyll a (Chl−a) were the main environmental factors affecting the biomass of dominant functional groups in the water body. The study showed the characteristics of the functional groups of algae in a precious urban lake in arid and semi−arid areas of China and their relationship with environmental factors (physical and chemical indicators, anions and cation ions, and heavy metal ions), and provided a scientific basis for its water quality evaluation.

Influence of an industrial discharge on long-term dynamics of abiotic and biotic resources in Lavaca Bay, Texas, USA

The current study seeks to identify possible anthropogenic and/or natural environmental stressors that may account for the long-term decline of ecosystem health in Lavaca Bay, Texas, USA. The Formosa Plastics Corporation instituted monitoring of an industrial discharge into the bay with 16 fixed point stations and quarterly sampling from 1993 to 2020. Comprehensive measurements included organic and inorganic solutes in surface water, porewater and sediment, sediment content, plankton, nekton, and infaunal benthos. All parameter trends changed over time due to climate, freshwater inflow events, and/or seasonal changes. Biological community structure and sediment changed with distance from the discharge site. Dominance characterized community structure because three to four taxa comprised > 70% of individuals for nekton (trawl and gill net), phytoplankton, zooplankton, and ichthyoplankton samples. Sediment became sandier over time (48 to 75%) and away from the discharge. Surface water and porewater at reference (R) stations and stations near the discharge site had similar hydrographical and biological trends over time, indicating no long-term impact due to the discharge. However, 99.9% of 424,671 measurements of organic contaminants were non-detectable because the methods were insensitive to ambient concentrations. Thus, it is still not known if contaminants play a role in the long-term decline of ecosystem health in Lavaca Bay. Furthermore, only four R stations were sampled and were all 3810 m from the discharge site, so it is possible that trends in R stations do not represent the natural background. Future studies should include more R stations and lower detection limits for contaminants.

THE CURRENT STATE OF HYDROBIONTS OF THE AYDAR-ARNASAY SYSTEMS OF LAKES

The material for this article was the results of many years of comprehensive studies of the current state of the biodiversity of aquatic biocenoses (phyto- and zooplankton, periphyton communities and macrophyte associations, zoobenthic organisms and ichthyofauna), the taxonomic structure and species composition of hydrobions in the Aydar-Arnasay system of lakes. During the growing season (winter-autumn) of 2019-2020, from 186 to 224 species and forms of algae were found in phytoplankton samples, where the dominant complex is diatoms, blue-green and green algae. Zooplankton is represented by 67 species, of which Rotifera - 37 species, Copepoda - 17 species, Cladocera - 13 species. Periphyton is represented by three main groups: producers (308 species of forms and varieties of algae), consumers (21 species) and decomposers (8 species), a total of 337 organisms were noted. The ichthyofauna of the lakes is represented by 18 species and subspecies of fish, of which there are 18 species in the East Arnasay Lake, 16 species in the Tuzkan Lake and 14 species in the Aydarkul Lake.