Identification Of Phytoplankton Research Articles

The aquatic environmental quality of koi fish (Cyprinus carpio) pond infected by Myxobolus sp. based on the biological status of the phytoplankton

The purpose of this study was to observe the biology of phytoplankton found in the waters pond of C. carpio and the Myxobolus sp. infect C. carpio in Blitar, Indonesia. Analysis of the sample of phytoplankton in water pond, identification of phytoplankton in the targeted fish organs infected with Myxobolus sp. C. carpio samples have a length of 1-3 cm and weight of 5-8 grams. Observation of both phytoplankton and myxobolus samples was done using the Olympus CX31 microscopes and Olympus E330-ADU1.2X cameras. The identification results showed that the phytoplankton was from the Charophyta division, genus Mougeotia, Division of Chlorophyta, genus Pediastrum, and Ulothrix, Division of Cyanobacteria, genus Mycrocystis. In Myxobolus sp. infected koi, the gills, the stomach, and the intestine indicated phytoplankton. The phytoplankton found in water cultured pond of koi fish allegedly biologically became an intermediary for infection in koi fish. The conclusion is the biological phytoplankton from the genus Mougeotia, Pediastrum, Ulothrix, and Mycrocystis, found both in the waters pond and in the target organs of infected fish such as in the gill, the stomach, and the intestines. This finding used to make a decision to treat the waters pond for successfully fish culture.

Combining high-throughput imaging flow cytometry and deep learning for efficient species and life-cycle stage identification of phytoplankton

BackgroundPhytoplankton species identification and counting is a crucial step of water quality assessment. Especially drinking water reservoirs, bathing and ballast water need to be regularly monitored for harmful species. In times of multiple environmental threats like eutrophication, climate warming and introduction of invasive species more intensive monitoring would be helpful to develop adequate measures. However, traditional methods such as microscopic counting by experts or high throughput flow cytometry based on scattering and fluorescence signals are either too time-consuming or inaccurate for species identification tasks. The combination of high qualitative microscopy with high throughput and latest development in machine learning techniques can overcome this hurdle.ResultsIn this study, image based cytometry was used to collect ~ 47,000 images for brightfield and Chl a fluorescence at 60× magnification for nine common freshwater species of nano- and micro-phytoplankton. A deep neuronal network trained on these images was applied to identify the species and the corresponding life cycle stage during the batch cultivation. The results show the high potential of this approach, where species identity and their respective life cycle stage could be predicted with a high accuracy of 97%.ConclusionsThese findings could pave the way for reliable and fast phytoplankton species determination of indicator species as a crucial step in water quality assessment.

Distribution and species diversity of phytoplankton in the inshore waters of Tuticorin in relation to the physicochemical variables

A study was conducted to evaluate the phytoplankton community structure and its relationship with selected physicochemical variables in the inshore waters of Tuticorin during January to December 2008. Water and plankton samples from the surface waters at two depths (5m and 10m) were collected on board the research vessel Cadalmin-IV. Standard methods were followed for phytoplankton identification, enumeration and estimation of physicochemical variables. The present study recorded 69 species of phytoplankton with 85.5% dominance of diatoms followed by 14.5% of dinoflagellates. The overall density of phytoplankton was comparatively higher at 10 m with a mean of 2.14x104 ±0.4x104 cells L-1 and 3.37x104 ±0.9x104 cells L-1 at 5 m and 10 m depth respectively. The analysis indicated that 10 m depth, especially during the monsoon season, is rich in diversity of algal species than at the same depth during post-monsoon. It is confirmed that the population density of phytoplankton is more influenced by seasonal fluctuation of the physicochemical variables especially due to the effect of northeast monsoon in the inshore waters of Tuticorin.

Convolutional Neural Networks for Phytoplankton identification and classification

Phytoplankton form the basis of the marine food web and are an indicator for the overall status of the marine ecosystem. Changes in this community may impact a wide range of species (Capuzzo et al. 2018) ranging from zooplankton and fish to seabirds and marine mammals. Efficient monitoring of the phytoplankton community is therefore essential (Edwards et al. 2002). Traditional monitoring techniques are highly time intensive and involve taxonomists identifying and counting numerous specimens under the light microscope. With the recent development of automated sampling devices, image analysis technologies and learning algorithms, the rate of counting and identification of phytoplankton can be increased significantly (Thyssen et al. 2015). The FlowCAM (Álvarez et al. 2013) is an imaging particle analysis system for the identification and classification of phytoplankton. Within the Belgian Lifewatch observatory, monthly phytoplankton samples are taken at nine stations in the Belgian part of the North Sea. These samples are run through the FlowCAM and each particle is photographed. Next, the particles are identified based on their morphology (and fluorescence) using state-of-the-art Convolutional Neural Networks (CNNs) for computer vision. This procedure requires learning sets of expert validated images. The CNNs are specifically designed to take advantage of the two dimensional structure of these images by finding local patterns, being easier to train and having many fewer parameters than a fully connected network with the same number of hidden units. In this work we present our approach to the use of CNNs for the identification and classification of phytoplankton, testing it on several benchmarks and comparing with previous classification techniques. The network architecture used is ResNet50 (He et al. 2016). The framework is fully written in Python using the TensorFlow (Abadi, M. et al. 2016) module for Deep Learning. Deployment and exploitation of the current framework is supported by the recently started European Union Horizon 2020 programme funded project DEEP-Hybrid-Datacloud (Grant Agreement number 777435), which supports the expensive training of the system needed to develop the application and provides the necessary computational resources to the users.

Phytoplankton Community at Intensive Cultivation System of Whiteleg Shrimp, Litopenaeus vannamei in Probolinggo, East Java

Phytoplankton is a source of natural feed for shrimp cultivation in the pond. Phytoplankton productivity increases by the increasing nutrient content in the pond. Feed and metabolic waste is the sources of nutrient for phytoplankton growth. This study aimed to evaluate productivity and identify phytoplankton at intensive whiteleg shrimp, <em>Litopenaeus vannamei </em>cultivation system. This study was conducted at three intensive whiteleg shrimp located in Probolinggo, East Java. Samples were collected on the early and the late of culture period (day 17 and 87 after stocking). Four environmental parameters including total of ammonia nitrogen (TAN), nitrate, orthophosphate, total of suspended solid (TSS), and chlorophyll-a were measured. Identification and density of phytoplankton were also performed of each pond. The result showed that productivity of three ponds was 22,893.83 kg/ha to 23,600.61 kg/ha with an average size 12.74 g to 14.35 g. During culture period, the concentration of TAN, TSS and chlorophyll-a tended to increase. Meanwhile, the average of both nitrate and orthophosphate tended to decline. Several phytoplankton identified in this study were in the genus of <em>Oocystis, </em><em>Chlorella, Nannochloropsis, Chaetoceros</em>, <em>Stephanodiscus, </em><em>Nitzschia, Coscinodiscus, Cyclotella </em>and <em>Ulothrix. </em>Phytoplankton of the group Chlorophyta is predominance for pond 1 and 2, while pond 3 was dominated by phytoplankton in the group of Diatom/Baccillariophyta. This study indicated that the present of phytoplankton in the pond provide natural feed and good environmental condition for shrimp cultivation.

The taxonomic composition, distribution and abundance of the phytoplankton flora of the Obafemi Awolowo University Teaching and Research Farm Lake, Ile-Ife, Osun State, Nigeria

The study determined the abundance and distribution of phytoplankton flora of an impoundment in the Agricultural Teaching and Research Farm of ObafemiAwolowo University (O.A.U), Ile-Ife, Osun State, Nigeria. The study was carried out over an annual cycle from September 2006- August 2007, Phytoplankton and water samples were collected monthly from three sampling stations by filtering 50 litres of water through a phytoplankton net of 45μm mesh size to a concentrate volume of about 30ml preserved in 5% formalin solution. The phytoplankton were viewed under a compound light microscope at both scanning power (x40) and low power (x100), measured with an ocular micrometer drawn to scale, counted and later identified using various phytoplankton identification keys on Nigerian freshwaters.The results showed that one hundred and fifteen species of phytoplankton belonging to five divisions, seven classes, nineteen orders, forty seven families and eighty three genera were recorded. The predominant genera in terms of occurrence and abundance were members of the green algae (Division Chlorophyta) and included Tetradesmus, Ulotrix, Tetraspora, Protosiphon, Chlorella, Closteriopsis and Pediastrum. Phytoplankton occurrence and abundance were slightly higher in the rainy season (600±350) than in the dry season (533±186) (f= 0.918, p= 0.05). The highest values were recorded at the surface stations of the lake.It was concluded that the water body was comparatively rich in phytoplankton flora. Also the occurrence of some species in the water body such as scenedesmus, stauraastum, Tetradesmus, Ulotrix, Tetraspora and Pediastrum species suggested a high level of primary productivity and a non-polluted lake that was oligotrophic to moderately eutrophic.Keywords: Phytoplankton, composition, distribution, abundance

Characterizing seston in the Penobscot River Estuary

The Penobscot River Estuary is an important system for diadromous fish in the Northeast United States of American (USA), in part because it is home to the largest remnant population of Atlantic salmon, Salmo salar, in the country. Little is known about the chemical and biological characteristics of seston in the Penobscot River Estuary. This study used estuarine transects to characterize the seston during the spring when river discharge is high and diadromous fish migration peaks in the Penobscot River Estuary. To characterize the seston, samples were taken in spring 2015 for phytoplankton identification, total suspended matter (TSM), percent organic TSM, chlorophyll a, particle size (2 μm-180 μm), particulate carbon and nitrogen concentrations, and stable carbon and nitrogen isotopes. The estuarine profiles indicate that TSM behaved non-conservatively with a net gain in the estuary. As phytoplankton constituted only 1/1000 of the particles, the non-conservative behavior of TSM observed in the estuary was most likely not attributable to phytoplankton. Particulate carbon and nitrogen ratios and stable isotope signals indicate a strong terrestrial, allochthonous signal. The seston in the Penobscot River Estuary was dominated by non-detrital particles. During a short, two-week time period, Heterosigma akashiwo, a phytoplankton species toxic to finfish, also was detected in the estuary. A limited number of fish samples, taken after the 2015 Penobscot River Estuary bloom of H. akashiwo, indicated frequent pathological gill damage. The composition of seston, along with ichthyotoxic algae, suggest the need for further research into possible effects upon resident and migratory fish in the Penobscot River Estuary.

Identification of Fitoplankton Density on Litoral Zone Lake Kerinci

Research about identification of density phytoplankton had been studied in litoral zone Kerinci Lake. Five stations has been choosen by purposive sampling along litoral zone. The samples were colleted by filtering water through plankton net. The samples has been identified and analyzed in Environmental Boards UPTD Laboratory and laboratory Department of Biology IAIN Kerinci. 53 spesies phytoplankton has been identified consist of three class. Average of individu/liter of Bacillariophyceae (36650), Chlorophyceae (3000) and Cyanophyceae (4000). Highest total of density phytoplankton found in station one are 386 individu and the less density phytoplankton found in station five are 4 individu.. The result of physicochemical properties measuring were temperature ranged from 23 0 C - 25 0 C, pH 5,5-6, BOD 4,8 – 48,96 mg/l, COD 10 – 19 mg/l, nitrit 0,03 – 1,1 mg/l and amoniac 1,9 – 2,7 mg/l. Based on the total density and physicochemical factors of Kerinci Lake refer to oligotrophic condition.

POTENSI PRODUKSI BIOFUEL DARI BIOMASSA FITOPLANKTON LAUT SPESIES Chlorella vulgaris, Dunaliella salina DAN Spirulina sp., YANG DITUMBUHKAN DALAM NUTRIEN UNGGUL “MSSIP” TERINDUKSI ION LOGAM Fe, Co, DAN Ni

Research about composition of superior nutrients, growth parameters, and best method to maximize production of biomass sea phytoplankton, Chlorella vulgaris, Dunaliella salina, and Spirulina sp. has been performed. The nutrients was named as MSSIP which were consist of following compositions: urea fertilizer, Arschat-M nutrient, Fe:Co:Ni metal ions (6 : 3 : 9 : 6 : 3). Methods used were identification and analysis of sea phytoplankton. Determination of optimum growth condition, pure culture, and mass culture were using local raw materials-based engineered nutrients or MSSIP (M. Sjahrul-Syahruddin Kasim-Indah Raya-Paulina Taba). Determination of product density of sea phytoplankton biomass, analyses of carbohydrate content, and lipid biomass were done by using haemocytometer and microscope, Luff Schrol method, and soxhlet method (n-hexane as solvent), respectively. Morphology of phytoplankton was identified by using a digital camera microscope, SZ60/sZ60-61. Furthermore, to understand the effect of metal ions, Fe, Co, and Ni added into MSSIP nutrient, identification of nutrient before and after culturing process were done using XRF-Thermo-Fisher. The results showed that Chlorella vulgaris, Dunaliella salina, and Spirulina sp. were suitable as raw materials to produce biofuel. Those three phytoplankton contained 0,3095 g/L, 0,3782 g/L, and 0,3325 g/L biomass, 32,49%w/w, 31,58%w/w, and 29,81%w/w carbohydrates; and 25,95%w/w, 26,82%w/w and 24,53%w/w lipid, respectively. Best optimum condition of culture were salinity of 30-35%, temperature of 20-30 °C, pH of 8-9, initial density of 2.5 x 104 cell/mL, light exposure of 40 watt, and continuously aerated with CO2. Based on our study, sea phytoplankton, Chlorella vulgaris, Dunaliella salina, and Spirulina sp. have a high potency as source of bioethanol and biodiesel.Keywords: mass culture, superior nutrient MSSIP, sea phytoplankton biomass, Fe, Co, Ni metal ions

Phytoplankton response to the summer 2015 heat wave – a case study from prealpine Lake Mondsee, Austria

Phytoplankton response to a heat wave in deep prealpine Lake Mondsee, Austria, was minor overall, although temperature significantly affected the epilimnetic phytoplankton assemblage at the deepest site of the lake. We detected no significant effect of nutrients. Using 3 complementary optical methods—light microscopy (Utermöhl technique), FlowCAM, and acoustic flow cytometry (AFC)—we found relatively low horizontal variation in the epilimnion but significant changes in phytoplankton community composition integrated over the 0–20 m water layer at the central station of the lake. These changes were mainly caused by a vertical shift in the Planktothrix rubescens peak from 11 to 16 m during the heat wave. Air temperatures reaching or exceeding 30 °C were measured in the area during 6 consecutive days at the end of June to the beginning of July, the first of 3 heat waves recorded during summer 2015; in-shore surface water temperature exceeded 27 °C. We sampled 9 stations across Lake Mondsee on 4 occasions during the heat wave and analysed temperature, nutrient levels, conductivity, pH, and the phytoplankton community. In addition to reporting the implications of increasing water temperatures for the algal assemblage in a deep stratified lake, we discuss the pros and cons of the different optical methods for phytoplankton identification and counting. For future field campaigns similar to the present study, we recommend using light microscopy to assess large or rare species, such as Ceratium hirundinella, and AFC, FlowCAM, or similar semi-automated devices for abundant small- to medium-sized species.

Bloom of Dinophysis spp. dominated by D. sacculus and its related diarrhetic shellfish poisoning (DSP) outbreak in Alfacs Bay (Catalonia, NW Mediterranean Sea): Identification of DSP toxins in phytoplankton, shellfish and passive samplers

We report a comprehensive study of a diarrhetic shellfish poisoning (DSP) outbreak in a Mediterranean coastal embayment, integrating phytoplankton identification and quantification data, with toxin analysis by LC–MS/MS of shellfish samples (mussels and oysters), phytoplankton concentrates, and solid phase adsorbing toxin tracking (SPATT) devices. Alfacs Bay was proposed as a model for the study of semi-enclosed coastal embayments and it is the most important shellfish farming area in Catalonia (Spain, NW Mediterranean Sea). The bay suffered a ban for bivalve harvesting that lasted 78 days, from late winter to the end of the spring of 2012, due to a harmful algae bloom of the toxic dinoflagellate Dinophysis sacculusthat fluctuated in three abundance peaks, reaching maximum abundance of 2200 cell/L. Mussels sampled during the bloom contained okadaic acid (OA, maximum 592 μg/kg, 3.7 times the maximum permitted level (MPL) set by the European Commission), and pectenotoxin-2 (PTX2, maximum 61 μg/kg). Oysters also contained OA and PTX2, but always below the MPL. Toxin content per cell measured from phytoplankton concentrates in filters was most likely overestimated (up to 461 pg OA/cell and 668 pg PTX2/cell), but showed an increase of cell toxicity towards the end of the bloom. OA-diol esters were not detected in phytoplankton aggregates. Concentration of DSP toxins in SPATT devices were up to 94 ng OA/g resin⋅day, 42 ng PTX2/g resin⋅day and 7 ng PTX2-sa/g resin⋅day. The applied monitoring strategy, based on the measurement of Dinophysis cell abundance in the water column, was effective to protect public health and did not extended the regulatory closure unnecessarily. Concentration of DSP in SPATT bags followed Dinophysis abundance dynamics, thus SPATTs were confirmed as a valuable research tool for Dinophysis blooms.

Water Quality and Phytoplankton Communities in Newly Created Fishponds

During the growing season of the year 2012 and 2013 (April–November) hydrobiological and hydrochemical monitoring of newly created fishponds inhered in Northern Moravia was carried out. Water temperature, dissolved oxygen content, pH, conductivity and water transparency were monitored directly at the sampling place. At the same time, water samples for taxonomical identification of phytoplankton were taken. Chemical parameters stabilization occurred in the second year after flooding. Chemism of fishponds was influenced by higher ration of organic matter in fishponds sediment and by fertilizing and liming. Water saturation by dissolved oxygen, pH, transparency and chlorophyll–a values fluctuated in the wide range due the growth of planktonic communities and composition of the fish stock. Hydrochemical parameters stabilized in the second year after the first flooding. The phytoplanktonic community of fishponds during the much of the growing season was formed by the representatives of green algae. Golden–brown algae were dominant during the spring season, in some cases euglenas as well. Diatoms were present in fishponds from spring to autumn but only to limited degree. The cyanobacteria formed only minor part of phytoplanktonic community, except the fishpond P1 where they formed dominant group.

Algal toxin profiles in Nigerian coastal waters (Gulf of Guinea) using passive sampling and liquid chromatography coupled to mass spectrometry

Algal toxins may accumulate in fish and shellfish and thus cause poisoning in consumers of seafood. Such toxins and the algae producing them are regularly surveyed in many countries, including Europe, North America, Japan and others. However, very little is known regards the occurrence of such algae and their toxins in most African countries. This paper reports on a survey of phytoplankton and algal toxins in Nigerian coastal waters.Seawater samples were obtained from four sites for phytoplankton identification, on three occasions between the middle of October 2014 and the end of February 2015 (Bar Beach and Lekki in Lagos State, Port Harcourt in Rivers State and Uyo in Akwa Ibom State). The phytoplankton community was generally dominated by diatoms and cyanobacteria; however several species of dinoflagellates were also identified: Dinophysis caudata, Lingulodinium polyedrum and two benthic species of Prorocentrum.Passive samplers (containing Diaion® HP-20 resin) were deployed for several 1-week periods on the same four sites to obtain profiles of algal toxins present in the seawater. Quantifiable amounts of okadaic acid (OA) and pectenotoxin 2 (PTX2), as well as traces of dinophysistoxin 1 (DTX1) were detected at several sites. Highest concentrations (60 ng OA g−1 HP-20 resin) were found at Lekki and Bar Beach stations, which also had the highest salinities. Non-targeted analysis using full-scan high resolution mass spectrometry showed that algal metabolites differed from site to site and for different sampling occasions. Screening against a marine natural products database indicated the potential presence of cyanobacterial compounds in the water column, which was also consistent with phytoplankton analysis.During this study, the occurrence of the marine dinoflagellate toxins OA and PTX2 has been demonstrated in coastal waters of Nigeria, despite unfavourable environmental conditions, with regards to the low salinities measured. Hence shellfish samples should be monitored in future to assess the risk for public health through accumulation of such toxins in seafood.

Environmental control of the dominant phytoplankton in Aras Reservoir (Iran): A multivariate approach

This study was undertaken to determine the phytoplankton structure and the environmental variables comprising the driving factors leading to cyanobacterial blooms in Aras Reservoir. Sampling was carried out seasonally at five sampling sites along the main body of the reservoir. Samples were collected for phytoplankton identification and enumeration, chemical analyses and chlorophyll-a (Chl-a) concentrations at each sampling site. Principal component analysis (PCA) and two-way unweighted pair group method with arithmetic mean (UPGMA) were performed to determine the environmental variables affecting phytoplankton community dynamics. Seventy-two species belonging to five divisions were determined during this study. Cyanobacteria contained the highest density (74%) during the study period, with Pseudanabaena limnetica being the most abundant species. The Shannon diversity index was low (0.44–1.87), indicating a high level of cyanobacteria dominance and eutrophic water status. Principal component analysis indicated that total phosphorus and temperature were significantly associated with cyanobacteria growth. Two-way clustering by UPGMA indicated a close relationship among sampling sites during the same season from the perspective of the phytoplankton density. The findings of this study suggested Aras Reservoir could be highly affected by agricultural runoff and untreated sewage loadings. Thus, the proper use of fertilizers and sewage treatment should be taken into account in considering effective conservation and management plans.

행암만 해양환경요인과 플랑크톤 군집구조의 변동

We analyzed with HPLC (High Performance Liquid Chromatography) analysis photosynthetic pigments and environmental factors, microscopic observations of the phytoplankton and zooplankton in the seawater every month from February 2009 to November 2010 in Haengam Bay. The level of dissolved inorganic nutrients was the highest between July and September, when freshwater influx was at its peak, whereas chlorophyll a levels were the highest in April and August. Also, phytoplankton pigment concentration increased when dissolved inorganic nutrients are carried into nearshore waters by rainfall runoff. Based on identification of phytoplankton and photosynthetic pigments results, diatoms were mainly dominant while dinoflagellate populations increased at July and August 2009, May 2010. The zooplankton communities are dominated in terms of Noctiluca scintillans. The contribution of Noctiluca scintillans in 2010 accounts for approximately 77.3% of the total zooplankton. Distribution patterns over time of zooplankton in the seasonal distribution of phytoplankton showed a different pattern.

A Comparative Study on Phytoplankton Diversity in River Tamiraparani and a Man-Made Fresh Water Body

A comparative study on Phytoplankton diversity between River Tamiraparani (Vannarpettai site) and a man made freshwater body was carried out. River Tamiraparani is a perennial river in Tirunelveli District, Tamilnadu. It is the irreplaceable source of freshwater for Tirunelveli district and neighbouring districts. The man made freshwater body is situated in a village namely Tharapuram, Tirunelveli District. It is the main source of water for domestic use and irrigation. The study has been carried out on identification and comparison of the fresh water Phytoplankton in two different kinds of water bodies. The field trip was carried during January 2012 to June 2012 in the two selected sites. The identification of Phytoplankton was done by standard and reputed manuals. The Phytoplankton composition was constituted by members of Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae. Phytoplankton diversity was quantified by Shannon Wiener index.

Using lower taxonomic resolution and ecological approaches as a surrogate for plankton species

The use of lower taxonomic resolutions and ecological classifications can function as a strategy to minimize difficulties in plankton identification. To assess this issue, we evaluated the concordance of the spatial ordering of lakes in a floodplain using phytoplankton and zooplankton densities scaled at three taxonomic levels (species, genus, and family) and two exclusive ecological classifications for phytoplankton [Reynolds functional groups (RFGs) and morphology-based functional groups]. Furthermore, we evaluated the concordance of environmental variables with each taxonomic resolution/ecological classification. Procrustes and Mantel tests (simple and partial) were used for the concordance analysis. The correlations between species and higher taxonomic levels were found for phytoplankton and zooplankton. For the ecological classifications, significant r values, greater than 0.70, were obtained only for the Mantel test between species and RFGs. The relationship between species and genus and between species and family for phytoplankton can be explained by the environmental structure. For zooplankton, only species were related to environmental variables. These results indicate that it is possible to adopt a lower taxonomic resolution for identification of phytoplankton and zooplankton without a significant loss of information. However, the use of ecological classifications for phytoplankton is not recommended for this purpose.

The role of hydrographic parameters, measured from a ship of opportunity, in bloom formation of Karenia mikimotoi in the English Channel

Unusually high chlorophyll values (~14mgChlm−3 at 5m depth), recorded on a ship of opportunity (SOO) in July 2010, indicated the occurrence of a potential Harmful Algal Bloom (HAB) in the Western approaches of the English Channel. This bloom, located at 49.7°N, 3.2°W was observed via complementary datasets. These included data from samples collected for microscopic phytoplankton identification, information from satellite maps to follow geographical bloom development and in situ data to identify hydrographic factors related to bloom initiation. The relationships between chlorophyll-fluorescence, temperature, salinity and wind speed were examined. The intense summer bloom predominantly consisted of the dinoflagellate Karenia mikimotoi and followed an increase in sea surface temperature (to 18.5°C). A mid-channel bloom of this magnitude along the SOO route was last seen in 2003. In both years the peak biomass was associated with K. mikimotoi blooms, which occurred at the same location and coincided with the least saline, warmest water and lowest wind speeds. This study demonstrates that ships of opportunity are a useful tool to identify and track HAB events through continuous in situ measurements and for the frequent sampling opportunities that they provide.

Some aspects of the ecology of freshwater algae in the Densu River and two tributaries in Southern Ghana

Studies on the composition and abundance of the phytoplankton in River Densu and two of its tributaries, Rivers Adeiso and Nsakir were carried out at ten sampling sites, including seven from different regions of the river basin namely Afuaman, Akwadum, Densuso, Manhean, Machigeni, Nsawam and Weija, as well as Adeisoand Pokuase. Sampling was done monthly at each sampling site from January to December, 2006. Physical and chemical parameters of river water were studied. The parameters of the river water varied with the sampling sites and the time of the year. Water samples for phytoplankton identification and enumeration were collected at each sampling site. Physico-chemical conditions of the river were assessed during sample collection or in the laboratory. Correlation analysis showed that there was a positive correlation between algal genera and the measured physical and chemical parameters of the river water. DOI: http://dx.doi.org/10.3126/ije.v3i2.10637 International Journal of the Environment Vol.3(2) 2014: 246-257

A physical and biological context for Karenia brevis seed populations on the northwest Florida shelf during July 2009

The current effort focuses on characterizing physical and biological conditions across the northwest Florida shelf during summer as they influence Karenia brevis distributions and phytoplankton/microphytobenthos community associations. Phytoplankton and benthic algal communities were examined in the context of cross-shelf hydrography and sediment conditions during July 2009 between the 20 and 65m isobaths off Panama City, FL. A towed undulating profiler (SeaSciences Acrobat) mapped water column characteristics between near-surface and ∼1m above the sediment. A CTD/rosette provided hydrographic profiles and collected water samples at 17 cross-shelf locations at selected depths for nutrient concentration, phytoplankton biomass determination, and chemotaxonomic and taxonomic phytoplankton identification. In addition, a CTD/rosette time series sample set was collected following a holey sock drogue set at ∼34m along the ∼50m isobath, and cores were collected at eight stations approximately along the 30, 40 and 55m isobaths. Cross-shelf, a pycnocline existed at ∼10m depth, the 1% light level penetrated to ∼45m depth, and nitrate–nitrite (NO3−+NO2−) concentrations increased in the lower 10m of the water column to the 50m isobath and then below 40-m depth to the 65m isobath. A chlorophyll a peak occurred near-bottom between the 25 and 35m isobaths. Gyroxanthin dinoflagellates (GD) representing K. brevis occurred across the shelf in near-surface and near-bottom waters. Near-surface GD co-occurred with cyanophytes at low density in the upper 20m of the water column where NO3−+NO2− concentrations were low. Above sediments in the euphotic zone, near-bottom GD were most abundant between the 25 and 35m isobaths where the NO3−+NO2− concentrations were 1–4µM and where microphytobenthos competed for nutrient sources. Below the euphotic zone, GD were present near-bottom to the 60m isobath where NO3−+NO2− concentrations approached 6µM. A pattern consistent with dinoflagellate diel vertical migration was inferred at the 50-m isobath time-series station. The results provide insight into offshore K. brevis seed populations and their associations with other phytoplankton and microphytobenthos. Under summer light and nutrient conditions along the northwest Florida shelf, K. brevis coastal blooms may be seeded by diffuse near-surface populations during occasional downwelling conditions and by more concentrated near-bottom populations during more prevalent upwelling conditions.