Analysis Of Phytoplankton Research Articles

Biomonitoring of cyanotoxins in two tropical reservoirs by cladoceran toxicity bioassays

This study evaluates the potential for the use of cladocerans in biomonitoring of cyanobacterial toxins. Two zooplankton species ( Daphnia gessneri and Moina micrura) were cultivated in the laboratory for use in acute (48 h) and chronic (10 days) bioassays. Water samples were collected from two reservoirs and diluted in mineral water at four concentrations. Survivorship in the acute bioassays was used to calculate LC 50, and survivorship and fecundity in chronic bioassays were used to calculate the intrinsic population growth rate ( r) and the EC 50. Analysis of phytoplankton in the water samples from one reservoir revealed that cyanobacteria were the dominant group, represented by the genera Anabaena, Cylindrospermopsis, and Microcystis. Results of bioassays showed adverse effects including death, paralysis, and reduced population growth rate, generally proportional to the reservoir water concentration. These effects may be related to the presence of cyanobacteria toxins (microcystins or saxitoxins) in the water.

Influence of diatoms on copepod reproduction. II. Uncorrelated effects of diatom-derived α,β,γ,δ-unsaturated aldehydes and polyunsaturated fatty acids on Calanus helgolandicus in the field

We set up a survey involving comprehensive chemical analyses of phytoplankton and the simultaneous monitoring of the reproductive response of Calanus helgolandicus. Hatching success and larvae development of C. helgolandicus were monitored weekly with female specimens sampled along with phytoplankton in the coastal waters off Roscoff (Western English Channel) from March/April to October in 2003 and 2004. Polyunsaturated aldehyde (PUA) production and nutritional parameters of phytoplankton [i.e. polyunsaturated fatty acids (PUFAs), particulate organic carbon (POC) and nitrogen (PON)] were measured. The hatching success varied between 0% and 80% during the two spring–summer spawning seasons. Neither the nutritional parameters measured nor polyunsaturated aldehydes could be found responsible for the frequently observed hatching failure. However, egg production and hatching rates were strongly positively correlated, suggesting a functional link between these reproductive parameters. PUA production in phytoplankton was mainly determined by Thalassiosira rotula. The occurrence of this diatom species might be used as a marker of PUAs in the study area. Laboratory feeding experiments showed that single species diets of freshly isolated diatoms ( T. rotula, Guinardia striata, Guinardia delicatula and Rhizosolenia setigera) caused high or low egg viability and naupliar survival of C. helgolandicus independent of PUA production and PUFA content. The impact of PUA on the hatching success of Calanus among different ecosystems is discussed. The combined approach of feeding experiments and chemical analysis supports the idea that parameters other than PUAs and PUFAs have to be taken into account in order to explain the highly variable hatching rates observed in this environment.

Use of fluorescence information for automated phytoplankton investigation by image analysis

Automated identification and quantification of algae in microscopic images is a tool that allows high taxonomic resolution with reasonable technical efforts. However, in samples containing various non-algal objects, this is still not a satisfactorily solved problem. We show that autofluorescence information improves discrimination of algae from non-algal objects as well as phycoerythrin (PE) containing algae from others. We analyse the stability of the autofluorescence to estimate its constraints. Cold and dark storage of glutaraldehyde fixed samples maintains autofluorescence sufficiently for 3 weeks. Under repeated excitations, chlorophyll a (Chl a) or PE autofluorescence show an exponential decrease followed by an intermediate maximum. A peak also occurs in emission wavelength ranges without chlorophyll and PE fluorescence. The unspecific autofluorescence causing the peaks is at least partly identical with the blue-green fluorescence (BGF) in plant cells. BGF interferes with identification of algae, thus correction of pigment autofluorescence with such unspecific fluorescence allows a more reliable algal discrimination procedure. A classification scheme for discrimination of Chl a and PE-containing algae shows a high performance in a test with natural samples. Integration of fluorescence and bright-field image information provides a powerful tool for phytoplankton analysis in complex samples.

Phytoplankton-linked viable non-culturable Vibrio cholerae O1 (VNC) from rivers in Tucuman, Argentina

Plankton-linked Vibrio cholerae has been detected in aquatic environments since the first decades of the 20th century. Several mechanisms have been proposed to explain the survival of V. cholerae during inter-epidemic periods, one of which is through existence in its viable non-culturable (VNC) form in biological reservoirs. This latent form of V. cholerae (VNC) would explain the seasonal outbreaks and the way the pathogen survives in the environment. The objectives of this study were to assay V. cholerae O1 in its viable non-culturable form in two rivers in Tucuman, Argentina, as well as its possible association to phytoplankton and its relation to four environmental variables (pH, temperature, conductivity and dissolved oxygen), using direct immunofluorescence. Analysis of phytoplankton revealed that diatoms were predominant with percentages between 85 and 100%. Nitzschia palea was the only species found at all three sample sites with percentages between 0 and 38%. Of the 54 samples obtained during the 18 sampling periods, V. cholerae VNC was detected through direct immunofluorescence in 39% of the cases and at all three sampling sites. Positive samples were analysed for association of VNC with phytoplankton and between 1 and 10 bacteria were found adhered to a single algal cell. This confirms for the first time in northwestern Argentina adherence of this microorganism to the genera Stigeoclonium and Nitzschia as environmental reservoirs. No correlation could be found between the latent form of Vibrio and the environmental variables assayed.

Occurrence and toxicity of an Anabaena bloom in a tropical reservoir (Southeast Brazil)

Potentially toxic cyanobacterial blooms are becoming common in the Brazilian reservoirs in all regions of the country. During October 2004, a dense bloom of cyanobacteria occurred in the Monjolinho Reservoir (São Carlos, São Paulo State, Brazil) and a significant amount of cyanobacterial material accumulated on the water surface. Phytoplankton analysis showed that the main species in this bloom were Anabaena circinalis and Anabaena spiroides. Cladoceran ( Ceriodaphnia dubia and Ceriodaphnia silvestrii) and mouse bioassays were performed to detect toxic products in extracts of the natural samples collected at the three different dates during in short period. To prepare the extracts, freeze-dried cells were dispersed in distilled water and subjected to repeated freeze/thaw cycles and sonication and centrifuging processes. Crude extracts were toxic both to cladocerans (LC 50 94–406 mg freeze-dried cells L −1) and mice (indicative LD 50 297–445 mg freeze-dried cells kg −1) and the toxicity of the bloom increased for cladocerans during the occurrence of the bloom. Toxin analysis by ELISA revealed that microcystin (MC) was found in the water of the reservoir (concentrations ranging from 28 to 45 μg L −1). In addition, microcystin was also found in freeze-dried cyanobacteria cells with concentrations ranging from 138 to 223 μg g −1. On the other hand, neurotoxins (saxitoxin and gonyautoxin) were not detected in any of the natural samples by HPLC. Signs of toxicity in mice did not indicate whether the bloom samples were predominantly hepatotoxic or neurotoxic. It is known that natural Anabaena blooms can contain other toxic compounds besides microcystins and neurotoxins such as lipopolysaccharides or other toxins not identified or known. Methods of detecting cyanotoxins used in this study were insufficient to clarify the toxicological features of Anabaena bloom and indicated that other methods should be investigated.

An extensive Cochlodinium bloom along the western coast of Palawan, Philippines

A massive fish kill and water discoloration were reported off the western coast of Puerto Princesa, Palawan, Philippines in March 2005. Phytoplankton analysis revealed a near monospecific bloom of the dinoflagellate, Cochlodinium polykrikoides, with cell concentrations ranging from 2.5 × 10 5 to 3.2 × 10 6 cells per liter. Ground truth data were supplemented by processed satellite images from MODIS Aqua Level 2 data (1 km resolution) from January to April 2005, which revealed high surface chlorophyll- a levels (up to 50 mg/m 3) offshore of west and southwest Palawan as early as February 2005. The bloom extended 310 km in length and 80 km in width at its peak in March off the central coast (Puerto Princesa). By April, the bloom declined in intensity, but was still apparent along the northern coast (El Nido). Fluctuations in chlorophyll levels off the western coast of Sabah, Malaysia and Brunei during this time period suggested that the bloom was not limited to the coast of Palawan. Satellite imagery from Sabah in late January revealed a plume of chl- a that is believed to be the source of the C. polykrikoides bloom in Palawan. This plume drifted offshore, advected northward via the basin-wide counterclockwise gyre, and reached nutrient-rich, upwelled waters near Palawan (due to a positive wind stress curl) where the dinoflagellate bloomed and persisted for 2 months from March to April 2005.

Does digital analysis of micro image data improve understanding of reality?Contradictions–Challenges: Contradictions–Challenges

Understanding of reality means among many others the ability to recognize, to predict reliably behaviours and properties of certain entities, and to describe. Besides verbal, often metaphorical descriptions, models are frequently used to formalize this understanding. In science the validity of models (hypotheses) has to be proven by experiments. Model parameters like start values, constraints and boundary conditions are often extracted from image data. Qualitative terms like shape, surface, structure (density, texture) and arrangement (spatial relationship) are explored and their possible measurements are outlined. They are also related to underlying experimental questions and intuitive understanding. Particular emphasis is given to properties without a commonly accepted quantitative counter part or which pose difficulties in perception and discrimination. Image analysis in methodologies and results from eco- and geobiology are presented and discussed. Namely, measurements of bacteria in biofilm and in the rhizosphere, characterization of biofilm growth, bacterial impact on surfaces, and automated phytoplankton analysis are outlined and iconographically related.

Methodological aspects of phytoplankton analysis in transitional waters

1 - The methodological issues in the analysis of phytoplankton guilds in transitional waters, using inverted microscopy (Utermohl technique), will showing and discuss the four steps (sampling, conservation, sedimentation and counting). 2 - The importance of inter- and intra-laboratory comparison tests to avoid or minimize discrepancies in identification and counting among analysts was also emphasized.

Phytoplankton bloom in commercial shrimp ponds using green-water technology

Phytoplankton community composition, density, and succession were studied in tropical commercial ponds with euryhaline tiger shrimp (Penaeus monodon Fabricius) using green-water technology at two different stocking densities [T1 10 post-larvae (PL) m−2 and T2 15 PL m−2] in one grow-out season (May–October 2005) in Leganes, Iloilo, Philippines. Weekly qualitative and quantitative analyses of phytoplankton were done along with physicochemical analyses of the pond waters. A total of 103 taxa belonging to nine different algal classes were observed. Of these classes, the Chlorophyceae, Cyanophyceae and Bacillariophyceae constituted the great bulk of the phytoplankton population. The two treatments did not show any significant differences in the growth pattern of phytoplankton over time and in their diversity indices. Although T2 had higher values than T1 for algal density and species diversity index, the differences were not significant. The mean Shannon-Wiener diversity index for T2 (1.56) was higher than T1 (1.39) but not significantly different. Both treatment ponds had Chlorophyceae as the dominant algae during the initial culture phase [0–35 days of culture (DOC)], which coincided with high salinity (average = 35.67 ppt) and relatively high N:P ratios (average = 1.95). The chlorophycean bloom was made up mostly of Nannochloropsis sp. The cyanophycean bloom occurred towards the final culture phase (84–112/126 DOC) when there was low salinity (average = 19.5 ppt) and relatively high N:P ratios (average 2.01). A short diatom bloom occurred in T2 at the same time that the N:P ratios rose dramatically to 4.2 at 42 DOC. Among the eight physicochemical parameters examined, positive correlations were noted among alkalinity, ammonium-nitrogen, nitrite-nitrogen and phytoplankton community. High species diversity index and species richness could have enhanced the stability of favorable Nannochloropsis blooms, especially in T2. No differences were noted between the two treatments in terms of the shrimp’s biomass at harvest time (T1 = 28.9 and T2 = 29.4 g fresh wt per shrimp), although a significantly higher survival rate (P < 0.05) was observed in T1 (97%) than in T2 (56%). Both treatments were able to control the occurrence of the luminous bacterium Vibrio harveyi.

Dinoflagellés toxiques et/ou responsables de blooms dans la baie d'Annaba (Algérie)

We present here the first description of harmful and non-toxic red-tide dinoflagellates of the Annaba bay (Algeria), during 2002. The qualitative and quantitative phytoplankton analyses reveal the presence of eleven dinoflagellates; two species, Alexandrium catenella and Gymnodinium catenatum, are responsible for efflorescences and known to be harmful. Seven species, Dinophysis caudata, D. fortii, D. rapa, D. rotundata, D. tripos, Lingulodinium polyedrum, and Protoperidinium crassipes, are considered to produce a toxin. Two others, P. triestinum, and Scrippsiella trochoidea, have sometimes been associated with blooms. Analyses of physical and chemical parameters show that stations 1 and 2 are eutrophic, whereas station 3 is oligotrophic. To cite this article: H. Frehi et al., C. R. Biologies 330 (2007).

Quality control of Utermöhl-based phytoplankton counting and biovolume estimates—an easy task or a Gordian knot?

The most suitable way for standardizing biovolume based assemblage analysis using the Utermohl technique for counting combined with biomass conversion has not yet been found even though this method has been successfully used in plankton studies for many years. Due to the complexity of the approach easily applicable steps to initially meet primary standard end point or target counts for intra-laboratory standardization tested here seem promising. Examples from count validation and biometric data from the large datasets of three laboratories are given. The first two examples initially intended to quantify the taxon specific scatter of counts by (A) using identical replica of field samples combined with a half-chamber count (scan of every second transect) and the 30 random field approach, respectively, and (B) the replication of transect counts in one sample. Both examples identified relatively low minimum count thresholds to delimit counting errors for single cell counts. The third example identifies shape variability and allometric relationships of the main axes and shows a way to improve taxon specific biomass estimates with special reference to cell thickness. However improved precision of quantitative phytoplankton analysis requires optimization of combined counting strategy and biovolume assessment methods.

Discrimination and analysis of phytoplankton using a microfluidic cytometer.

Identification and analysis of phytoplankton is important for understanding the environmental parameters that are influenced by the oceans, including pollution and climate change. Phytoplanktons are studied at the single cell level using conventional light-field and fluorescence microscopy, but the technique is labour intensive. Flow cytometry enables rapid and quantitative measurements of single cells and is now used as an analytical tool in phytoplankton analysis. However, it has a number of drawbacks, including high cost and portability. We describe the fabrication of a microfluidic (lab-on-a-chip) device for high-speed analysis of single phytoplankton. The device measures fluorescence (at three wavelength ranges) and the electrical impedance of single particles. The system was tested using a mixture of three algae (Isochrysis Galbana, Rhodosorus m., Synechococcus sp.) and the results compared with predictions from theory and measurements using a commercial flow cytometer (BD FACSAria). It is shown that the microfluidic flow cytometer is able to distinguish and characterise these different taxa and that impedance spectroscopy enables measurement of phytoplankton biophysical properties.

Pre-Bloom Phytoplankton in the Surface Waters of the Celtic Sea and Some Adjacent Waters

Pre-Bloom Phytoplankton in the Surface Waters of the Celtic Sea and Some Adjacent Waters

Seasonal dynamics of phytoplankton in the Gulf of Aqaba, Red Sea

Seawater samples were collected biweekly from the northern Gulf of Aqaba, Red Sea, for Phytoplankton analysis during the period May 1998 to October 1999. Microscopic counts and HPLC methods were employed. Procaryotic and eucaryotic ultraplankton dominated throughout most of the year, with larger nano- and microplankton making up only 5% of the photosynthetic biomass. Moderate seasonal variations in the 0–125 m integrated Chl a contrasted with a pronounced seasonal succession of the major taxonomic groups, reflecting the changes in the density stratification of the water column: Prochlorococcus dominated during the stratified summer period and were almost absent in winter. Chlorophyceae and Cryptophyceae were dominant during winter mixing but scarce or absent during summer. Diatoms and Synechococcus showed sharp and moderate biomass peaks in late winter and spring respectively, but remained at only low Chl a levels for the rest of the year. Chrysophyceae, Prymnesiophyceae and the scarce Dinophyceae showed no clear seasonal distribution pattern. The implications of alternating procaryotic and eucaryote dominated algal communities for the Red Sea pelagic food web are discussed.

Spatial variability in Florida Bay particulate organic matter composition: combining flow cytometry with stable isotope analyses

Long-term management plans for restoration of natural flow conditions through the Everglades increase the importance of understanding potential nutrient impacts of increased freshwater delivery on Florida Bay biogeochemistry. Planktonic communities respond quickly to changes in water quality, thus spatial variability in community composition and relationships to nutrient parameters must be understood in order to evaluate future downstream impacts of modifications to Everglades hydrology. Here we present initial results combining flow cytometry analyses of phytoplankton and bacterial populations (0.1–50 lm size fraction) with measurements of d 13 Ca ndd 15 N composition and dissolved inorganic nutrient concentrations to explore proxies for planktonic species assemblage compositions and nutrient cycling. Particulate organic material in the 0.1–50 lm size fraction was collected from five stations in Northeastern and Western Florida Bay to characterize spatial variability in species assemblage and stable isotopic composition. A dense bloom of the picocyanobacterium, Synechococcus elongatus, was observed at Western Florida Bay sites. Smaller Synechococcus sp. were present at Northeast sites in much lower abundance. Bacteria and detrital particles were also more abundant at Western Florida Bay stations than in the northeast region. The highest abundance of detritus occurred at Trout Creek, which receives freshwater discharge from the Everglades through Taylor Slough. In terms of nutrient availability and stable isotopic values, the S. elongatus population in the Western bay corresponded to low DIN (0.5 l MN H 4 ; 0.2 l MN O 3 ) concentrations and depleted d 15 N signatures ranging from +0.3 to +0.8&, suggesting that the bloom supported high productivity levels through N2-fixation. d 15 N values from the Northeast bay were more enriched (+2.0 to +3.0&), characteristic of N-recycling. d 13 C values were similar for all marine Florida Bay stations, ranging from )17.6 to )14.4&, however were more depleted at the mangrove ecotone station ()25.5 to )22.3&). The difference in the isotopic values reflects differences in carbon sources. These findings imply that variations in resource availability and nutrient sources exert significant control over planktonic community composition, which is reflected by stable isotopic signatures.

Diatom assemblages from a turbid coastal plain estuary: Río de la Plata (South America)

The Río de la Plata is located on the East coast of South America and is a shallow, large-scale, turbid coastal plain estuary that covers an approximate area of 35,000 km 2. Despite the socio-economic importance of the Río de la Plata, studies related to the biological aspects of this ecosystem are scarce, particularly in the freshwater tidal zone. The objective of this study was to explore the diatom composition and distribution of density, biomass and empty frustules along the fluvial–mixohaline axis. Furthermore it was to analyze the spatial succession of diatom assemblages and the environmental variables during an extensive sampling carried out during spring 2001. Two replicate sub-surface water samples were collected at 29 sites for quantitative analysis of phytoplankton. The greatest number of species, mainly pennate taxa, were observed in the freshwater tidal zone. The average density of the diatoms was 59 cells ml − 1 . Chains or filaments of centric diatoms were frequent and dominant in the samples along the fluvial–mixohaline axis. The carbon content of the diatoms increased downstream, with an average value of 2.5 μg C l − 1 in the freshwater tidal zone and 4.4 μg C l − 1 in the mixohaline zone. Diatoms supplied 65% of the total phytoplankton carbon content in the freshwater tidal zone and reached 17% in the mixohaline zone. Canonical Correspondence Analysis (CCA) allowed us to identify two species assemblages in the Río de la Plata differentiated mainly by salinity, pH and silicate gradients. In our study species exclusive to brackish waters were not identified, but some freshwater and marine taxa with wide ranges of salinity tolerance were observed.

Induced growth of phytoplankton using two fertilizers (NPK and agrolyser) under laboratory conditions

An investigation was carried out on the ability of two types of fertilizer; agrolyser-micronutrient and NPK (nitrogen, phosphorus, potassium)-macronutrient in inducing phytoplankton growth for sixteen days under laboratory conditions. The parameters studied were abundance, species diversity and occurrence of the phytoplankton. Twelve 14 L plastics tanks labeled A, B, C and D was used. Each letter represented a fertilizer treatment (three replicates): A, 0.27 g agrolyser; B, 200 g NPK; C, 200 g agrolyser + 0.27 g NPK; and D which is the control. Before the application of these fertilizers, water samples were taken for phytoplankton analyses using 250 ml wide mouth plastic containers. All the tanks were allowed to be naturally inoculated for 3 days. Samples were collected for phytoplankton and physicochemical parameters at an interval of 3 days except temperature which was measured twice daily (morning and evening). A total of 1244 phytoplankton made up of 20 species, belonging to three families: Bacillariophyceae (diatoms), Cyanophyceae (blue-green algae) and Euglenophyceae (euglenophytes) were observed. Out of these algae, tanks C had 51.7%, B 33.2%, A 10.6% and D 4.5% phytoplankters. In the various groups of tanks, the orders of abundance, species diversity and percentage distribution of species of algae were C>B>A>D, C>B>A=D and C>B>D>A, respectively. This paper intends to provide preliminary information to fish farmers that agrolyser should be combined with a macronutrient fertilizer for better fertilization of pond. Key words: Induced growth, phytoplankton, fertilizer, NPK, agrolyser.

Automatic analysis of aqueous specimens for phytoplankton structure recognition and population estimation

An automatic microscope image acquisition, evaluation, and recognition system was developed for the analysis of Utermöhl plankton chambers in terms of taxonomic algae recognition. The system called PLASA (Plankton Structure Analysis) comprises (1) fully automatic archiving (optical fixation) of aqueous specimens as digital bright field and fluorescence images, (2) phytoplankton analysis and recognition, and (3) training facilities for new taxa. It enables characterization of aqueous specimens by their populations. The system is described in detail with emphasis on image analytical aspects. Plankton chambers are scanned by sizable grids, divers objective(s), and up to four fluorescence spectral bands. Acquisition positions are focused and digitized by a TV camera and archived on disk. The image data sets are evaluated by a large set of quantitative features. Automatic classifications for a number of organisms are developed and embedded in the program. Interactive programs for the design of training sets were additionally implemented. A long-term sampling period of 23 weeks from two ponds at two different locations each was performed to generate a reliable data set for training and testing purposes. These data were used to present this system's results for phytoplankton structure characterization. PLASA represents an automatic system, comprising all steps from specimen processing to algae identification up to species level and quantification.

APPLICATION OF PIXE FOR A MULTI-ELEMENT ANALYSIS OF MARINE PHYTOPLANKTON TOWARDS THE DEVELOPMENT OF A NEW BIOLOGICAL ASSESSMENT METHOD FOR HEAVY METAL POLLUTION

Particle-induced X-ray emission (PIXE) was applied for the determination of heavy metals accumulated in natural phytoplankton. We selected four Japanese marine sites to collect phytoplankton: Toni Bay and Kamaishi Bay (Kamaishi, Iwate) as non-polluted areas; and Shimotsu port (Shimotsu, Wakayama) and Toyama new port (Shinminato, Toyama) as polluted areas. After removing the zooplankton and visible dust by passing the seawater through an NXX13 plankton net (95-μm mesh aperture), the phytoplankton were collected on a polycarbonate filter (25 mm diameter, 1.0 μm pore size) by suction filtration. The filter was dried and subjected to scanning electron microscopy (SEM) and a PIXE analysis. The phytoplankton consisted of diatoms, dinoflagellates and coccolithophores were observed by SEM analysis on the filter prepared from 100 ml of Toni Bay seawater. Heavy metals ( Pb , Ni , Cu , Cr , Zn , Mn , Hg and As ) could be detected by the PIXE analysis in almost all the cases tested, in which 50-200 ml each of respective seawater sample was filtered. There was a linear relationship between the amount of heavy metals on the polycarbonate filter (ng cm-2) and the volume of seawater (25-200 ml) filtered (i.e. the amount of phytoplankton collected on the filter). Likewise, the PIXE analysis revealed that significant differences in heavy metal contamination between the polluted and non-polluted areas, and also among sampling sites in a polluted area depending on the location and seawater movement. These results indicate that a multi-element analysis of marine phytoplankton by PIXE would be a promising technique for biologically assessing and monitoring heavy metal pollution in the first link of the aquatic food chain.

대청호의 식물플랑크톤 군집 변화

Temporal variability in lake phytoplankton is controlled by a complex between hydrological and chemical factors, and biological interactions. We explored annual change of phytoplankton in Lake Daecheong, using phytoplankton analysis data from 1997 to 2002 (except 2000). The standing crop of phytoplankton was ranged from 3.5 x 10 to 1.5 x 106 cells mL and the highest mean value was at site 1. The class composition ratios of phytoplankton standing crop were divided into three classes. From January to March, diatoms showed a dominance (68.1-77.7%). From April to June, diatoms were mixed with cryptomonad etc. or blue-green algae. From July to October, blue-green algae showed a dominance (54.7-84.0%). In the case of green algae, the class composition ratios were below 10%. But green algae appeared all the year round.