Phytoplankton Species Abundance Research Articles

Community Structure of Phytoplankton in The Waters of Gili Trawangan, North Lombok

Gili Trawangan is one of the popular marine tourism destinations and conservation areas in the West Nusa Tenggara Province. Increased human activity in the Gili Trawangan is associated with increased pressure on aquatic ecosystems. Human activity pressure comes from tourism activities and negative impacts due to various community activities around the waters can reduce water quality. Changes to water quality can be seen from the abundance and composition of phytoplankton. This is because phytoplankton plays an important role in a water body, namely as a primary producer in the food chain and has the ability to respond to the changes of the environment factors. This rearch was conducted to determine the abundance and composition of phytoplankton community structure in Gili Trawangan, North Lombok. Seawater samples were taken using a 20 µm plankton net by filtering 100 L of water. The filtered water samples were then preserved using formalin in 4% concentration. Data were analyzed by calculating the abundance of individuals, diversity (H'), uniformity (E), and dominance (D). The results showed that the average abundance of phytoplankton species was 1026.296 Ind/L and 22 genera of phytoplankton were identified. Species diiversity index (H'=2.58) is classified as medium. Species uniformity index (E=0.88) and species dominance index (C=0.10). Based on the results of this research it can be concluded that the waters of Gili Trawangan North Lombok are classified as oligotrophic waters.

Spatial and temporal variability of phytoplankton dynamics in-relation to essential oceanographic variables in the south east coast of Bangladesh

Phytoplankton form the base of food chain and play a key role in maintaining the global climate system. However, very limited knowledge is available about the phytoplankton ecology of Bangladesh coast which is a representation of sub-tropical coastal ecosystem. Thus, this study aimed to understand the spatial and temporal variability of phytoplankton community in-relation to environmental variables in the South East coast of Bangladesh. Monthly data on essential oceanographic variables (i.e. temperature, salinity, dissolved oxygen, turbidity, silicate, nitrate and phosphate) and phytoplankton species abundance were collected from January 2022 to December 2022. We found a strong spatial and temporal variability in essential oceanographic variables and phytoplankton community compositions in Naf – Saint Martin Peninsula of Bangladesh. Estuarine ecosystem is characterized by high nutrients and low salinity while offshore ecosystem was found with comparatively low nutrients and high salinity. About 154 phytoplankton species were identified from the study area through year round sampling events. In the estuarine ecosystem Skeletonema marino, Coscinodiscus centralis, Coscinodiscus argus and Coscinodiscus traducens were found as the major contributing species at the estuarine ecosystem while Chaetoceros radican, Tripos trichoceros, Cylindrotheca Closterium, Chaetoceros convulutus, Tripos muelleri, and Cyclotella striata were found as the major contributing species at the offshore ecosystem. Our study found that 6 explanatory variables (i.e. temperature, salinity, turbidity, silicate, nitrate and phosphate) jointly explained about 78% variability in phytoplankton community dynamics. Nitrate concentration explained maximum variability (19%) followed by phosphate (17%), salinity (15%), silicate (12%), turbidity (10%) and surface temperature (5%). This study will play a key role in understanding the spatial and temporal variability of phytoplankton dynamics in the sub-tropical coastal ecosystem.

Environmental Controls of phytoplankton in the river dominated sub-tropical coastal ecosystem of Bangladesh

Sub-tropical coastal ecosystems are considered as the hotspot of species diversity. However, due to challenges regarding data collection, these regions are inherently data-limited and thus hindering informed species conservation strategies. Considering this, the present study aimed to assess the ecological characteristics of a river dominated sub-tropical coastal ecosystem of Bangladesh. More specifically, in this study we examined the spatial variability in environmental conditions and phytoplankton in the coastal ecosystems of Bangladesh. We also examined the causal relationship between environmental variables and phytoplankton species abundance. Data on environmental variables, including temperature, salinity, dissolved oxygen, turbidity, and macronutrients, was gathered in the north-east monsoon season between 2020 and 2022. We performed multivariate statistics to identify the variability in phytoplankton community dynamics. Results showed strong spatial variability in environmental conditions. Salinity, turbidity, nutrients concentrations and chlorophyll were found as the major drivers of this spatial heterogeneity. Central coast was characterized by low salinity, and high turbidity and silicate concentration while south-east coast was characterized by high salinity and low nutrient concentrations. In contrast, the south-west coast was characterized by high nitrate and phosphate, and moderate level of turbidity and salinity. Furthermore, our study identified 121 phytoplankton species. Maximum species diversity was observed in the south-west coast followed by central and south-east coast. Whereas 66 species occurred simultaneously in the three coastal zones, Coscinodiscus, Odontella and Nitzchia were the dominant phytoplankton genus in the central coastal zone. Skeletonema, Ditylum and Proboscia were found as dominant species in the south-east coastal zone. Coscinodiscus, Odontella, Nitzchia, Proboscia, Ditylum and Thalassionema were found as the key species in the south-west coastal zone. Seven explanatory variables (i.e. temperature, salinity, turbidity, silicate, nitrite, phosphate and zooplankton abundance) jointly explained about 44% to 73% variability in phytoplankton species abundance. We identified salinity and macronutrients as the major drivers of phytoplankton variability. This study is the first systematic report on phytoplankton community dynamics in-relation to environmental variables considering data from the entire coastal ecosystem of Bangladesh.

Relationship between phytoplankton distribution and salinity in the giant artificial brackish Lake Saemangeum

In 2021, an abundance of phytoplankton species was observed in Lake Saemangeum. We analyzed the relationship between phytoplankton abundance and salinity by comparing the distribution of salinity that changed because of freshwater inflow and drainage sluice gate operation. Thirteen field surveys were conducted: monthly basic surveys from January to November 2021 and additional surveys after rainfall in August and September at seven sites. During the survey period, 46–94 species were recorded. Pearson correlation coefficients were used to analyze the relationship between salinity and abundance of the dominant phytoplankton species. The result showed that Cyclotella atomus, Stephanodiscus hantzschii, Phormidium tenue, and Chaetoceros spp. were correlated with salinity. Chaetoceros spp. was significantly positively correlated (p < 0.001), whereas all other species were negatively correlated. Moreover, the correlation coefficient between seven species and salinity was close to zero. Compared with the general correlation coefficient of salinity and abundance, the point-biserial correlation coefficient showed a higher overall absolute value. Four species (Skeletonema spp., Cyclotella atomus, Phormidium tenue, Chaetoceros spp.) exhibited p < 0.001. Particularly, the correlation coefficient of Cyclotella atomus changed significantly from -0.237 to -0.451, whereas that of Phormidium tenue changed from -0.207 to -0.431. The results imply that salinity can affect the distribution and survival of euryhaline species. Therefore, high salinity may inhibit some freshwater and euryhaline species in the lake. However, further research is required to validate our findings.

Ecological Insights from Phytoplankton Diversity Off Veraval, Gujarat Coast, India

Phytoplankton species are sensitive to environmental and seasonal variability. This property of phytoplankton can be used to predict and study fluctuations in the ecological health of the system. In this study, phytoplankton diversity and its direct interactions with abiotic components of the ecosystem were studied to evaluate the health and stability of the coastal waters of Veraval, Gujarat coast, India. Results showed that diatoms dominated the ecosystem with a strong seasonal pattern of community succession. Waters were well churned and turbidity hindered penetration of light into deeper layers during the fall and winter monsoon season whereas stratification during spring inter-monsoon governed the distribution of different phytoplankton groups in the water column. These seasonal shifts resulted in a sincere pattern of annually re-occurring seasonal succession and formation of bloom events in the region. Apart from general phytoplankton diversity and its seasonal succession, the study intended to understand the forces governing the diversity and ecological system as a whole. To meet this objective, percent light intensities of chlorophyll-a, at various depths and temperatures were studied in relation to phytoplankton density. The correlation did not stand well for stations having active bloom formation showing that chlorophyll-a cannot be used as a proxy of phytoplankton biomass during bloom conditions. Thus excluding the points corresponding to active bloom conditions, second order polynomial equations were developed explaining the changes in chlorophyll-a concentration with variations in phytoplankton cell counts for study seasons. It was observed that most phytoplankton cells preferred upper well-lit layers of the water column with 100% light intensity followed by depths with 50% and 1% light intensities respectively. Study on temporal dynamics of the phytoplankton community in relation to temperature showed that the winter monsoon was characterized by a temperature range of 21.9 °C to 29 °C where Navicula distans was the most abundant phytoplankton species. Skeletonema costatum was the most abundant species at 27.2 °C during fall intermonsoon. Spring inter monsoon had an abundance of Navicula distans at both 28.35 °C and 28.9 °C.

Characterizing a subtropical hypereutrophic lake: From physicochemical variables to shotgun metagenomic data.

Lake Cajititlán is a subtropical and endorheic lake, which is heavily impacted by nutrient pollution. Agricultural runoff and poorly treated wastewater have entered this reservoir at alarming rates during past rainy seasons, causing the cultural eutrophication of this body of water and resulting in several massive fish kill events. In this study, shotgun metagenomic sequencing was used to examine the taxonomic and functional structure of microbial communities in Lake Cajititlán during the rainy season. Several water quality features and their interactions with microbial communities were also assessed to identify the major factors affecting the water quality and biota, specifically fish species. According to current water quality regulations, most of the physicochemical variables analyzed (dissolved oxygen, pH, Secchi disk, NH4 +, NO3 -, blue-green algae, total phosphorus, and chlorophyll-a) were outside of the permissible limits. Planktothrix agardhii and Microcystis aeruginosa were the most abundant phytoplankton species, and the dominant bacterial genera were Pseudomonas, Streptomyces, and Flavobacterium, with Pseudomonas fluorescens, Stenotrophomonas maltophilia, and Aeromonas veronii representing the most abundant bacterial species. All of these microorganisms have been reported to be potentially harmful to fish, and the latter three (P. fluorescens, S. maltophilia, A. veronii) also contain genes associated with pathogenicity in fish mortality (fur, luxS, aer, act, aha, exu, lip, ser). Genetic evidence from the microbial communities analyzed herein reveals that anthropogenic sources of nutrients in the lake altered genes involved in nitrogen, phosphorus, sulfur, and carbon metabolism, mainly at the beginning of the rainy season. These findings suggest that abiotic factors influence the structure of the microbial communities, along with the major biogeochemical cycles of Lake Cajititlán, resulting in temporal variations and an excess of microorganisms that can thrive in high-nutrient and low-oxygen environments. After reviewing the literature, this appears to be the first study that focuses on characterizing the water quality of a subtropical hypereutrophic lake through associations between physicochemical variables and shotgun metagenomic data. In addition, there are few studies that have coupled the metabolism of aquatic ecosystems with nutrient cycles.

The Abundance and Diversity of Plankton in the Waters of the Tasilaha Lagoon Helpano Village, South Banawa, Donggala Regency

Plankton are organisms (animals and plants) that live floating or floating in the water column, their movement is influenced by currents. The role of plankton is very important in aquatic ecosystems, especially phytoplankton which are primary producers. This research is a quantitative descriptive study using purposive sampling method with a field and laboratory survey approach. The purpose of the study was to describe the abundance and diversity of plankton in the waters of the Tasilaha Lagoon. This research was conducted in June – July 2022. The results of the study were 31 types of plankton consisting of 17 types of phytoplankton and 14 types of zooplankton. The abundance of phytoplankton species obtained ranged from 366–5,597 cells/liter and zooplankton 623–5,515 individuals/liter. The value of the phytoplankton diversity index was 2.44–2.55 and the zooplankton ranged from 2.19–2.31.

Unprecedented differences in phytoplankton community structures in the Amundsen Sea Polynyas, West Antarctica

In the Antarctic coast, ice shelves are rapidly thinning and retreating due to global warming. Basal melt water influences marine life, particularly the phytoplankton, which are directly affected by changes in physicochemical environments. However, there is limited in situ data over large areas in the Amundsen Sea, which is currently a hotspot for rapidly thinning ice shelves in West Antarctica. During the austral summer cruise of 2020, phytoplankton species abundance was investigated along the Amundsen Sea coast using an automated continuous observation instrument, the Imaging FlowCytobot. The phytoplankton community was dominated by Phaeocystis antarctica in most coastal waters of the Amundsen Sea, as previously reported; however, unexpected blooms of diatom Dactyliosolen tenuijunctus were observed throughout the Pine Island Bay region at a high dominance rate (∼90%) and abundance (>107 cells l−1). D. tenuijunctus is a weakly silicified diatom and its massive bloom in the water column has been rarely reported from the Antarctic Ocean. The dramatic difference in phytoplankton compositions between these adjacent polynyas probably indicates an unstable response of phytoplankton to ice melting conditions. They could play a different role in the marine food web and carbon flux compared to other diatoms and P. antarctica. Therefore, further research is warranted to predict the biological and biogeochemical impacts of future melting conditions.

Spatio-temporal variations of phytoplankton assemblage in coastal waters of Maharashtra, north-eastern Arabian Sea

Seasonal variations in phytoplankton species and abundance along the coast of Maharashtra from two different locations (Mumbai and Ratnagiri) and depths were investigated during August 2014-May 2017. A total of 84 species of phytoplankton were recorded from the region out of which 67 were diatoms, 16 dinoflagellates and one blue green alga. Seventy-five and 60 species of phytoplankton were recorded from Ratnagiri and Mumbai respectively. Diatoms dominated the phytoplankton community (81.7-93.3%) followed by dinoflagellates (4.7-7.2%) and blue green algae in both locations. Maximum phytoplankton density was recorded during post-monsoon season followed by pre-monsoon and monsoon seasons at Mumbai and Ratnagiri. Highest average phytoplankton cell density recorded was 9.09 x 104 cells l-1 and 4.06 x 104 cells l-1 during post-monsoon season at Ratnagiri and Mumbai respectively. Maximum cell density was observed at 20 m depth from Mumbai and Ratnagiri. Thalassiosira subtilis, Trieres mobiliensis, Skeletonema costatum, Coscinodiscus centralis and Ditylum brightwelli were the most abundant phytoplankton species recorded at Mumbai, whereas Chaetoceros curvisetus, S. costatum, Trichodesmium erythraeum, Chaetoceros lorenzianus and Ditylum brightwelli were abundant in Ratnagiri waters. The blue green alga, T. erythraeum was abundantly recorded during pre-monsoon season. Species diversity index (H’) ranged from 4.72 to 5.52 and was higher during post-monsoon season compared to pre-monsoon and monsoon. Highest phytoplankton diversity was observed at 20 m depth compared to 40 m depth.Keywords: Arabian Sea, Diversity, Mumbai, Phytoplankton, Ratnagiri

Assessment distribution of the phytoplankton community structure at the fishing ground, Banyuasin estuary, Indonesia

The research objective was to describe the distribution of phytoplankton community structure and corelated to the physic-chemical parameters at fishing ground, Banyuasin estuarine waters. The methodology of research was phytoplankton sampling; physicochemical waters parameters data collected such as; dissolved oxygen, pH, temperature, brightness, salinity, current speed, nitrate, and phosphate. Identifications and calculations phytoplankton are based on photography under a light microscope. Data were analyzed by calculated abundance, diversity (H′ index) and dominance (C index), and Principal Component Analysis (PCA). There were 24 species of phytoplankton on the all-observation station grouped in three classes, Bacillariophyceae 91.3%, Dinophyceae 9%, and Cyanophyceae 0.1%. The abundance of phytoplankton species obtained in the range of 666.48 to 184,592.68 cells L−1, were mostly found in high Chaetoceros affinis and Bacteriastrum furcatum. The distribution of phytoplankton abundance in these waters was found to be more influenced by seawater mass than freshwater. Phytoplankton diversity is considered a moderate category (1.37 < H′ < 2.57), and there were no species of phytoplankton that dominates (C < 0.5). Principal component analyzes showed that waters can be classified based on their physical-chemical characteristics, which were temperature, salinity, pH, transparency, current speed in the south coast around river estuaries, while DO and nutrients on the north coast of the waters. Based on the distribution of phytoplankton abundance is illustrated that the northern part is more potential for fishing area than the southern part with an abundance of phytoplankton >90,000 cells L−1 and more stable water dynamics.

Phytoplankton composition of the mangrove ecosystem in Khanh Hoa province, Vietnam

The objective of this study was to clarify the structureof phytoplankton in the natural mangroves of Nha Phu lagoon in Khanh Hoa province, Vietnam, and their correlation with other environmental factors. The outcome of the surveys in the area showed that there was a high diversity of phytoplankton species with about 139 ones, particularly Silic algae dominance. The biomass of phytoplankton here is not high, ranging from 25 260 to 58686 cells/liter. The environmental parameters show that the area has a favorable environment for the growth of phytoplankton. The salinity of water was from 18 %o to 35 %o the temperature was between 29.4 °C and 30.1 °C, and the pH index varied from 7.03 to 7.98. Analysis of the relationship between the abundance of phytoplankton species and environmental factors pointed out that the number of phytoplankton species has an inverse linear proportion to the content of Chlorophyll-a but a direct one to the salinity and the total content of Phosphorus in seawater. Also, the biomass of phytoplankton has an inverse linear proportion to salinity and pH but follows the opposite one to the environmental temperature and the content of Chlorophyll-a.

Phytoplankton dynamics in relation to Red tide appearance in Qarun Lake, Egypt

Qarun Lake is a unique saline basin. Its phytoplankton species abundance and dynamics in relation to the Red Tide phenomenon is the focus of this study. Samples were collected from May 2015 to April 2016 in twelve successive cruises. Phytoplankton productivity attained the highest level on July with the bloom of Dinophyceae, while showing negative correlation with water transparency (r = −0.72) and positive correlation with DO (r = 0.84). The causative species was Gymnodinium lantzschii. Another incident of Dinophyceae bloom was observed in March when chlorophyll a recorded 158.4 mgm−3, chl. b was (92.7 mgm−3 and chl. c was 160 mgm−3. The causative species were Prorocentrum aporum and Prorocentrum micans and the lake’s water turned to red color; the “Red Tide phenomenon”. Chlorellavulgaris bloom was recorded for the first time in the lake on August at site (4) with green water discoloration.The water temperature of the lake was one of the main phytoplankton bloom’s drivers as the dominant species grew and flourished within a narrow range of temperature (30.4–34.9 °C). The results showed that there were strong correlations between carbonate, bicarbonate, DO and nutrients indicating that the dinoflagellate bloom was due to the high eutrophication of the lake. Finally, the Red tide phenomenon may influence the lake fisheries causing significant economic loss.

Phytoplankton species abundance in Tokyo Bay (Japan) from 1998 to 2019

AbstractTokyo Bay is a semienclosed coastal system located in the center of Japan. Eutrophication has progressed since 1950, resulting in red tides and blue tides appearing frequently. This Data Paper reports the abundance of phytoplankton species sampled monthly from April 1998 to March 2019 at 17 stations in Tokyo Bay. Monitoring has been carried out by Chiba Prefectural Government. Phytoplankters were enumerated by microscopy as numbers of cells or colonies. The abundance of each species was expressed as cells per milliliter of seawater. The total cell density ranged from 102 to 106 cells·ml−1. The dominant taxa were diatoms, such as Chaetoceros spp., Skeletonema spp., and Thalassiosira spp. in most of the months. The dominant diatom species reached concentrations of 106 cells·ml−1. Microflagellates or Cryptomonadaceae were also abundant, especially in winter, reaching 106 cells·ml−1. These data can be used to appreciate how anthropogenic disturbances such as eutrophication and global warming affect the density and community composition of phytoplankton. The detailed Metadata for this abstract published in the Data Paper section of the journal is available in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2021-03.1/jalter-en.

Impact of flood regime on phytoplankton communities in the large African reservoir, Lake Nasser, Egypt

Lake Nasser is a reservoir of freshwater for drinking and irrigation in Egypt and it constitutes an important share in the fisheries sector. This study aims to acquire a better understanding of the status of phytoplankton distribution in Lake Nasser under the current flood regime and before the construction of the Grand Ethiopian Renaissance Dam (GERD). Samples were collected from fifteen sites representing different lake sectors along the main channel of the lake during 2016−2017. Approximately 103 species were recorded, belonging to six different classes, dominated by Cyanobacteria, Bacillariophyceae, Chlorophyceae, whereas Euglenophyceae, Dinophyceae and Chrysophyceae were rare. Based on the abundance of phytoplankton species, the pre-flood and post-flood seasons were very well discriminated. A major blooming of Cyanobacteria in the Tushka sector was detected during the pre-flood season, whereas this phenomenon diminished in the post-flood period when Bacillariophyceae and Chlorophyceae appeared. The results of this study indicated that the most important factors affecting phytoplankton species distribution during pre-flood and post-flood seasons are temperature, nutrients and total dissolved solids. The study confirms that flood regime substantially affects the phytoplankton abundance and distribution in Lake Nasser.

Projected Effects of Climate-Induced Changes in Hydrodynamics on the Biogeochemistry of the Mediterranean Sea Under the RCP 8.5 Regional Climate Scenario

The Mediterranean region has been shown to be particularly exposed to climate change, with observed trends that are more pronounced than the global tendency. In forecast studies based on a RCP 8.5 scenario, there seems to be a consensus that, along with an increase in temperature and salinity over the next century, a reduction in the intensity of deep-water formation and a shallowing of the mixed layer (especially in the North-Western Mediterranean Sea (MS)) are expected. By contrast, only a few studies have investigated the effects of climate change on the biogeochemistry of the MS using a 3D physical/biogeochemical model. In this study, our aim was to explore the impact of the variations in hydrodynamic forcing induced by climate change on the biogeochemistry of the MS over the next century. For this purpose, high-resolution simulations under the RCP 8.5 emission scenario have been run using the regional climate system model CNRM-RCSM4 including the NEMO-MED8 marine component, coupled (off-line) with the biogeochemical model Eco3M-Med. The results of this scenario first highlight that most of the changes in the biogeochemistry of the MS will occur (under the RCP 8.5 scenario) after 2050. They suggest that the MS will become increasingly oligotrophic, and therefore less and less productive (14 % decrease in integrated primary production in the Western Basin and in the Eastern Basin). Significant changes would also occur in the planktonic food web, with a reduction (22 % in the Western Basin and 38 % in the Eastern Basin) of large phytoplankton species abundance in favour of small organisms. Organisms will also be more and more N-limited in the future since NO3 concentrations are expected to decline more than those of PO4 in the surface layer. All these changes would mainly concern the Western Basin, while the Eastern Basin would be less impacted.

Seasonal abundance and distribution of phytoplankton in Tanintharyi coastal waters, southern Myanmar

The seasonal abundance and distribution of phytoplankton along the Tanintharyi coastal waters were investigated for 24 months from June 2013 to June 2015. A wide fluctuation in cell abundance 72,450-714,396 cells/l at Kawthaung, 47,416-947,501 cells/l at Myeik, 8,930-28,439 cells/l at Kampani, 8,976-17,888 cells/l at Ye and 5,162-16,986 cells/l at Setse were noted during the study period. Amongst, Kawthaung and Myeik stations had the highest phytoplankton abundance, whereas Ye and Setse stations showed remarkably lower abundance. It was noted that Ye and Setse stations were much influenced by freshwater discharge from the Thanlwin River, which deposited huge tons of sediments. The water clarity was lower at these stations compare with others. Therefore, turbidity may affect the occurrence and species abundance of phytoplankton. A clear seasonal trend was found at all five stations with a sharp increase in the pre-monsoon months and a gradual decrease in the monsoon and post-monsoon periods. Keywords: phytoplankton, Tanintharyi, water clarity, turbidity,

A survey of phytoplankton and zooplankton communities in the newly created Tugwi-Mukosi reservoir, Zimbabwe, during the filling phase

The plankton assemblages of Tugwi-Mukosi reservoir in south-eastern Zimbabwe were assessed seven months after impoundment to form a baseline for future monitoring and tracking of changes linked to the reservoir’s ontogenetic development processes. While cyanobacteria were the dominant group at all sites (50−70%), relative abundances of Bacillariophyceae and Chlorophyceae was considerable. The most abundant phytoplankton species were Microcystis aeruginosa and Aulacoseira granulata, whose abundances ranged from 3 200−28 800 ind. l−1 and 1 640−3 146 ind. l−1, respectively. Phytoplankton species richness in the reservoir ranged from 9 to 20, with the highest species richness in the north-eastern region of the reservoir. Zooplankton density was <1 ind. l−1 and after seven months since impoundment, the zooplankton community had not fully established. Twenty zooplankton species comprising of Rotifera, Copepoda and Cladocera were recorded. Cladocera, mainly Diaphanosoma excisum and Ceriodaphnia cornuta, were the most abundant followed by copepods, mainly Thermoclops sp. and Eodiaptomus japonicas. The dominance of Microcystis aeruginosa presents potential future challenges to water quality management, because increased nutrient loading can favour it, resulting in similar challenges being experienced in Lake Chivero. The establishment of an Integrated Lake Basin Management is strongly recommended to avert this.

THE IMPACT OF SEAWEED FARMING ON THE PHYTOPLANKTON COMMUNITY STRUCTURE

This study was aimed to analyze the impact of seaweed farming on changes in the structure of phytoplankton communities on various ecosystems and their relationship with environmental factors. The study was conducted in May-October 2017 in the waters of Karampuang Island, Mamuju Regency. Plankton samples were collectedfromthreecultivationareas, namely areas with sandy bottom (control), seagrass beds, and coral reefs. In each area, three media were placed with a longline system, size 40 x 30 m2 (as replication). Sampling was carried out at the beginning before initiation of the cultivation and every two weeks after cultivation was started for 42 days. Phytoplankton sampling and measurement of environmental factors were carried out at fivesamplingpoints representing the cultivation areas. In sandy areas, sampling was also applied in areas outside the cultivation at a distance of 25m and 50m. Variance analysis was used to analyze differences in the species number and abundance of phytoplankton. Ecological indices was used to test phytoplankton biodiversity. PCA was used to analyze its relationship with environmental factors. Differences in the species number and abundance of phytoplankton between farming areas according to temporal scale were found. The high number and speciesabundance of phytoplankton were found in seagrass areas and significantly different from coral reefs and sandy area. Seaweed farming at the beginning of the farming period showed a positive impact by increasing the number of species and abundance of phytoplankton, but then decreased after entering Week 4-Week 6, along with the occurrence of ice-ice disease on the seaweed. Diversity index value was classified as medium with high equality without the dominance of particular species. The high number of species and abundance of phytoplankton occured at second weeks in all cultivation areas which are characterized by abundance of zooplankton with environmental characteristics, i.e. high DO and low PO4, NO3, andDOM.

Multi-Instrument Assessment of Phytoplankton Abundance and Cell Sizes in Mono-Specific Laboratory Cultures and Whole Plankton Community Composition in the North Atlantic

The abundance and size distribution of plankton in the surface ocean are key metrics to understanding primary and export production, food web dynamics, and the optical properties of the water column. Here we quantified cell size and abundance of phytoplankton species from mono-specific laboratory cultures, using optical, electrical, and image-based benchtop instrumentation. Moreover, we combined particle size distribution and size fractionated chlorophyll a (Chl a) analysis with image analysis to estimate phytoplankton community composition and abundance comparing a high and low biomass station in the North Atlantic during springtime. In laboratory cultures, we found generally good agreement in estimates of both particle concentration and particle size among instruments. Image-based approaches (e.g. microscopy, FlowCam) delivered somewhat lower cell abundance estimates, because image-based instruments distinguish cells from non-living objects. Image-based approaches also measured 10-20% greater cell sizes, because measurements were based only on in-focus images of the target species. Particle counters delivered indistinguishable estimates of size and abundance with much lower effort and technical expertise required. Maximum coefficient of variation for cell abundance and size did not exceed 10 and 15% respectively. Measurement precision was consistent across instrument type and across the size spectrum from 3 to >40 µm equivalent spherical diameter. For whole plankton community analysis from the North Atlantic, combined estimation of Chl a concentration and image-based diversity assessments resolved the dominant contributing phytoplankton species and spatial differences in the size structure of the plankton community. These results provide strong support for using particle counters, that can rapidly process large volumes of samples, to quantify particle size and abundance, including rarer, larger particles. Species identities and community composition can be revealed by supplemental, image-based approaches. Application of this coupled approach can help identify fundamental ecosystem characteristics such as particle size spectra that affect primary production, trophic transfer and export. Ultimately, the tremendous species diversity of plankton can be leveraged as particle tracking and identification keys, such as near-real time identification of coherent water masses.

Temporal and seasonal variations in phytoplankton community structure in Uzuncayir Dam Lake (Tunceli, Turkey).

Seasonal variations in species composition and growth dynamics of phytoplankton in Uzuncayir Dam Lake (Tunceli, Turkey) were studied in relation to ecological factors by collecting horizontal water and phytoplankton samples for over a year. A total of 46 phytoplankton taxa were recorded, where Bacillariophyta was the most abundant in species number representing 24 taxa. Diatoms were the most conspicuous phytoplankton in terms of abundance as well as occurrence frequency. Charophyta, Chlorophyta, Cyanobacteria, Ochrophyta, Miozoa, and Euglenozoa were the least abundant. However, some Diatoms (Gyrosigma attenuatum, Hippodonta hungarica, Meridion circulare, Nitzschia clausii, Nitzschia frustulum, Pantocsekiella ocellata, Rhoicosphenia abbreviata), Charophytes (Cosmarium granatum, Mougeotiopsis calospora), Cyanobacteria (Leiblenia epiphytica, Planktothrix agardhii); Dinoflagellates (Ceratium hirundinella, Parvodinium africanum, Parvodinium inconspicuum, Peridinium cinctum), and Ochrophyta (Dinobryon pediforme) were also noticeable, with their occurrence in all seasons. Canonical correspondence analysis (CCA) and principal component analysis (PCA) were employed to analyze the relationship between occurrence and abundance of phytoplankton species as well as the ecological factors. The results showed that pH and the concentrations of NH4, NO3, and PO4 influenced seasonal occurrence and abundance of phytoplankton species in the lake. Uzuncayir Dam Lake may be classified as an oligotrophic lake with the mean value of nitrate 2.62mgL-1 and phosphate 0.23mgL-1 as supported by the occurrence of various phytoplankton groups. Findings related to pollution indices yielded that Uzuncayir Dam Lake is on the edge of the moderate state of organic pollution.