Analysis Of Phytoplankton Research Articles

Primary description of surface water phytoplankton pigment patterns in the Bay of Bengal

Spatial and temporal variations in surface water phytoplankton pigment distribution in the Bay of Bengal were studied during the spring intermonsoon (SpIM, February–April) and the commencement of the summer monsoon (CSM, May–June), using pigment and diagnostic indices. The Prokaryotic pigment index (Prok DP) was dominant at all the oceanic stations whereas the Flagellate pigment index (Flag DP) was dominant at the near coastal stations. However, during the commencement of summer monsoon, an oscillation in the dominance of Prok DP and Flag DP was observed in the central oceanic bay, whereas flagellates and diatoms were dominant at the near coastal stations. This change in pigment pattern is possibly related to the influence of rainfall. Comparison of pigment data with microscopic cell counts indicated a significant relationship between the diatom pigment index (Diat DP) and diatom abundance. However, the relationship between the dinoflagellate pigment index (Dino DP) and dinoflagellate abundance was not significant. Studies coupling pigment composition analysis with microscopic analysis of phytoplankton in natural conditions should thus be a prerequisite in establishing valid biogeochemical and ecosystem models.

Functional analysis and classification of phytoplankton based on data from an automated flow cytometer

Analytical flow cytometry (FCM) is well suited for the analysis of phytoplankton communities in fresh and sea waters. The measurement of light scatter and autofluorescence properties of particles by FCM provides optical fingerprints, which enables different phytoplankton groups to be separated. A submersible version of the CytoSense flow cytometer (the CytoSub) has been designed for in situ autonomous sampling and analysis, making it possible to monitor phytoplankton at a short temporal scale and obtain accurate information about its dynamics. For data analysis, a manual clustering is usually performed a posteriori: data are displayed on histograms and scatterplots, and group discrimination is made by drawing and combining regions (gating). The purpose of this study is to provide greater objectivity in the data analysis by applying a nonmanual and consistent method to automatically discriminate clusters of particles. In other words, we seek for partitioning methods based on the optical fingerprints of each particle. As the CytoSense is able to record the full pulse shape for each variable, it quickly generates a large and complex dataset to analyze. The shape, length, and area of each curve were chosen as descriptors for the analysis. To test the developed method, numerical experiments were performed on simulated curves. Then, the method was applied and validated on phytoplankton cultures data. Promising results have been obtained with a mixture of various species whose optical fingerprints overlapped considerably and could not be accurately separated using manual gating.

The relative importance of autotrophic and heterotrophic microbial communities in the planktonic food web of the Bay of Quinte, Lake Ontario 2000–2007

The structure and function of the microbial and planktonic communities of the Bay of Quinte, Lake Ontario were studied for 8 years from 2000 to 2007. The bay has a long history of eutrophication and has undergone remediation efforts which included reductions in phosphorus loadings and the implementation of a long term research and monitoring program (1972–present) conducted by Fisheries and Oceans Canada along with other federal and provincial agencies. Microbial loop research was added in 2000 to the ongoing monitoring program which included nutrients, phytoplankton, zooplankton, benthos and fish so that a comprehensive picture of food web linkages would emerge. The structure of the microbial-planktonic food web was determined based on microscopic analysis of bacteria, autotrophic picoplankton (APP), heterotrophic nanoflagellates (HNF), ciliates, phytoplankton and zooplankton and was compared to a traditional grazing food chain consisting of phytoplankton and zooplankton. On a seasonal weighted mean basis, HNF biomass (fresh weight) of 1.7–8.4 g m−3 at Belleville and 1.1–6.3 C m−3 at Conway exceeded that of zooplankton in virtually all observations and was often greater than the combination of phytoplankton and zooplankton. Furthermore, the results showed that HNF contributed upwards to 85% of the organic carbon pool on a seasonal weighted mean basis. Various parameters in the upper bay relating trophic status to autotrophic communities were measured including: point source phosphorus loadings (>10 kg d−1); primary production (>300 g C m−2 y−1); chlorophyll a (>12 μg l−1) and phytoplankton biomass (>3 g m−3) which indicated that the upper bay remained eutrophic. This was also confirmed by the “battery of tests” strategy of ecological indicators developed in our laboratory to assess trophic status, health, and potential Beneficial Use Impairments. Based on our observations spanning 8 years, it was concluded that the microbial food web was dominated by heterotrophic communities which are still widely ignored in Great Lakes research and monitoring efforts. Our data clearly demonstrates that future studies and management strategies should include the “microbial loop” to obtain a holistic picture of the structure, function and dynamics of the lower food web.

Phytoplankton community changes during wetland restoration in Jinghe Estuary, Lake Ebinur, Xinjiang

精河入湖口湿地是新疆艾比湖湿地的重要组成部分.本文通过空间序列代替时间序列的方法,对艾比湖精河入湖口退化湿地不同恢复期的浮游植物群落特征进行分析,结果表明,恢复早期和中期硅藻种类最多,绿藻在密度上占明显优势,恢复近期硅藻为主要优势类群.恢复早期及自然区浮游植物群落结构较为稳定,中期和近期群落结构不够稳定,易受外界环境的影响.艾比湖精河入湖口退化湿地各恢复时期浮游植物群落结构尚不完善,仍需进一步改善.在季节变化上,浮游植物种类和密度以夏季最多,春季次之,秋季最低;春、秋季以硅藻为主要优势类群,夏季绿藻为主要优势类群,蓝藻在夏季密度高于其它各季节.对各恢复期浮游植物和环境因子进行相关性分析表明,温度、盐度和总磷是影响浮游植物种类和数量的主要因素.;The Jinghe Estuary wetland is one of the main proportions in wetlands of Lake Ebinur, Xinjiang. By using the method of spacial investigation, phytoplankton community was analysed in the wetland of Jinghe Estuary under different restoration stages. The results indicated that in the restoration process, species number of Bacillariophyta was the most diversified in the early and middle stage of the restoration, while Chlorophyta was abundant. Bacillariophyta was dominated in the late stage of the restoration. The structure of phytoplankton community was steady in natural site and in the early stage of restoration, but that was not steady in the middle and late stage of restoration. The species composition and abundance in summer were higher than in spring and autumn. In spring and autumn, Bacillariophyta was the first dominant group in the phytoplankton community. In summer, Chlorophyta became the main dominant group. Cyanophyta in summer had a higher abundance than in spring and autumn. Canonical Correspondence Analysis of phytoplankton and environmental data for all sites showed that temperature, total phosphorus and salinity influenced on the phytoplankton community composition and abundance.

Local factors control the community composition of cyanobacteria in lakes while heterotrophic bacteria follow a neutral model

Summary1. Neutral community models are derived from the proposition that basic probabilities of species loss (extinction, emigration) and gain (immigration, speciation) explain biological community structure, such that species with many individuals are very likely to be widespread. Niche models on the other hand assume that interactions between species and differential resource use mediate species coexistence, thus invoking environmental factors to explain community patterns.2. In this study, we compared neutral and niche models to test how much of the spatial variability of assemblages of heterotrophic bacteria and phytoplankton in 13 lakes they could explain. Analysis of phytoplankton was restricted to cyanobacteria, so that they could be studied with the same molecular fingerprinting method, automated ribosomal intergenic spaces analysis (ARISA), as heterotrophic bacteria. We determined local biotic and abiotic lake variables as well as lake age, glacial history and distance between sites.3. The neutral community model had a good fit to the community composition of heterotrophic bacteria (R2 = 0.69), whereas it could not produce a significant model for the community composition of cyanobacteria.4. The community composition of cyanobacteria was instead correlated to environmental variables. The best model, a combination of total organic carbon, biomass of eukaryotic phytoplankton, pH and conductivity, could explain 8% of the variation. In contrast, variation in the community composition of heterotrophic bacteria was not predicted by any of the environmental variables. Historical and spatial variables were not correlated to the community composition of either group.5. The pattern found for heterotrophic bacteria suggests that stochastic processes are important. The correlation of cyanobacteria with local environmental variables alone is consistent with the niche model. We suggest that cyanobacteria, a group of organisms containing bloom‐forming species, may be less likely to fit a neutral community model, since these blooms are usually triggered by a particular combination of environmental conditions.

Growth and photosynthesis responses of Phaeodactylum tricornutum to dissolved organic matter from salt marsh plant and sediment

The effects of allochthonous dissolved organic matter (DOM) on the growth and photosynthesis of Phaeodactylum tricornutum were investigated. P. tricornutum incubated in f/2 medium was exposed to DOM additives, which were extracted from the plant and sediment samples of a salt marsh in North Branch of the Yangtze estuary, China. During 12 days incubation, the chlorophyll fluorescence parameters of P. tricornutum were measured by a Phyto-PAM phytoplankton analyzer. Spectral properties of DOM in algae filtrates were also observed. The concentrations of chlorophyll a, active chlorophyll a, and the maximum quantum yield of photosystem II significantly decreased after four days of incubation, suggesting that the growth and photosynthetic efficiency of P. tricornutum were inhibited. After adding sediment-DOM extract, both a 250/ a 365 (the ratio of the absorption coefficients at 250 and 365 nm) and S values (spectral slope coefficients) of algae filtrates declined in the first two days, which demonstrated a loss of low molecular weight DOM. Parallel factor analysis of fluorescence spectra of DOM in algae filtrates revealed that DOM could be classified into two humic-like and two protein-like components. The fluorescence intensity of tyrosine-like component originating from algae increased significantly during incubation. This study supports the hypothesis that allochthonous DOM derived from salt marsh plant and sediment have a strong influence on the adjacent aquatic ecosystems.

Biological responses to liming in boreal lakes: an assessment using plankton, macroinvertebrate and fish communities

1. Biological responses to liming of acidified surface waters are equivocal and limit the overall assessment of food web responses. In this study, we analysed community structure in limed, acidified and circumneutral lakes, based on the analyses of phytoplankton, zooplankton, macroinvertebrates (littoral, sublittoral, profundal) and fish between 2000 and 2004. We also studied associations between functional feeding groups in food webs. 2. Most univariate metrics of structure and function revealed similar community attributes among lake types, suggesting that community responses to natural recovery from acidification and liming management converge with those observed in circumneutral lakes. These trends were less clear in the multivariate analyses which showed significant community differences among lake types. For phytoplankton, these patterns were partly mediated by the invasive raphidophycean flagellate Gonyostomum semen. 3. The associations between functional feeding groups indicated less connectivity and food web complexity in limed lakes relative to the other lake types. We speculate that repeated lime applications comprise frequent pulse disturbances which offset the establishment of stable trophic relationships in the food webs of limed lakes. 4. Synthesis and applications. The limited structural and functional food web similarity among lake types supports the argument that liming constitutes an ecosystem-level disturbance. Managers should be aware of the ecosystem impacts of altered disturbance regimes when designing their management schemes because this can influence the success of restoration programmes. Furthermore, the lack of recovery, mediated in part by species invasions, suggests that impacts derived from global change are likely to lead to novel environmental situations. This calls for adaptive management strategies where managers are challenged to tackle multiple forms of anthropogenic stress simultaneously.

Phytoplankton and eutrophication development in the water supply reservoirs Garaši and Bukulja (Serbia)

This paper presents the results of physico-chemical analysis of the water, qualitative and quantitative analysis of phytoplankton and trophic state of the water supply reservoirs Garaši and Bukulja. The water samples were collected on water supply site, on different depths and in various seasons. The presence of six algal divisions with 194 taxa was established for both reservoirs. From the total number of taxa found, there were 162 taxa present in Garaši reservoir, and 134 in Bukulja. The highest number of taxa was established within divisions Bacillariophyta, Cyanobacteria and Chlorophyta. The results of physico-chemical testing of water, phytoplankton density and biomass, as well as chlorophyll- a concentration showed increased eutrophication in both reservoirs. Dominating blue-green algae are: Planktothrix agardhii, Aphanizomenon flos-aquae, Microcystis aeruginosa and Anabaena affinis. Detected large biomass of blue-green algae that can produce toxins dangerous for water lifeforms, requires appropriate environmental protection of these reservoirs. Based on the calculated trophic index (TSI), the Garaši reservoir could be considered as mesotrophic, while the Bukulja reservoir as mesotrophic–eutrophic model.

Absorption spectroscopy of microalgae, cyanobacteria, and dissolved organic matter: Measurements in an integrating sphere cavity

A device for integrating cavity absorption measurements (ICAM) with an internal diameter of 80 mm suitable for field research is described. The spectral features of the light absorption by some cyanobacteria, green algae, and diatoms in the integrating sphere were studied and the dependences of the absorption on the cell concentration were determined in comparison with the conventional measurements in a 1-cm cuvette. The sensitivity of the chlorophyll estimation with the ICAM reached 0.2–0.5 mg m−3. The results of the ICAM application for the direct analysis of the natural phytoplankton and dissolved organic (“yellow“) matter in the Black Sea and the Sea of Japan are described.

Environmental changes in the eastern shelf of the Laptev Sea in the late-glacial time

Data on the interaction of the land-sea system have been obtained based on complex palynological analysis (pollen and spores of terrestrial plants and cysts of dinoflagellates and green algae) and the SEM analysis of sediments from boreholes drilled on the Laptev Sea’s eastern shelf and dated by the radiocarbon method. The spore and pollen ensemble revealed for the first time in late-glacial sediments of the boreholes indicates that warming which started within the time interval 15.6–10.7 ka ago was accompanied by short-term cooling events. Sedge and herb phytocoenosis predominated in the vegetation cover of East Arctic Siberia during the cooling. The climate warming favored the distribution of shrub birch tundra. The results of the analysis of organic-walled phytoplankton and the low value of the AH criterion indicate cold-water conditions with a longstanding ice sheet at sea. After the interval that ended 10.7 ka ago, thermophilic species of dinocysts appeared on the outer shelf, and the AH-criterion value increased, which suggests an active inflow of relatively warm North-Atlantic water to the shelf. Based on the comparison of the obtained results, an inference has been made about frequent changes of the climate in the region and the environment in the eastern part of the Laptev Sea during the deglaciation epoch.

FLORAÇÕES DE CIANOBACTÉRIAS TÓXICAS NO RESERVATÓRIO DO FUNIL: DINÂMICA SAZONAL E CONSEQÜÊNCIAS PARA O ZOOPLÂNCTON

The Funil water reservoir, located in the Paraiba do Sul River Valley in the municipality of Resende (Rio de Janeiro State, Brazil), has become eutrophic during the last two decades and undergone recurrent blooms of cyanobacteria. This study presents temporal series of physical, chemical and biological data from the reservoir encompassing an overall period of four years (from June/02 to March/06). Monthly, measurements of conductivity, transparency, temperature, pH, dissolved oxygen, and water samples for the analyses of nutrients (N and P), chlorophyll-a, phytoplankton and zooplankton composition and cyanotoxins in seston and in net plankton were performed. Toxicity tests with native and temperate cladocerans species were also performed. The results showed that the high input of N and P favored the persistent dominance of cyanobacteria. A temporal pattern was observed mainly related to changes in water temperature, characterizing two distinct periods: a warm-wet period with cyanobacterial bloom, and a cold-dry period with general reduced biomass. Cyanobacteria included potential hepatotoxins (microcystins) producers like Microcystis spp., and potential neurotoxins (saxitoxins) producers like Anabaena circinalis and Cylindrospermopsis raciborskii. In fact, elevated concentrations of microcystins and saxitoxins were found in the phytoplankton, and high levels of microcystins in the zooplankton, suggesting that these toxins may be transferred through the food chain. The toxicity tests revealed that the cyanobacterial blooms had toxic effects on cladocerans, causing death, reduction in the rate of population increase (r), and paralysis, in agreement with the mechanism of action of the cyanotoxins present.

Flow cytometry sorting of freshwater phytoplankton

We used the flow sorting capacities of a benchtop FACSCalibur flow cytometer to analyze the phytoplankton community of four different aquatic ecosystems. We show that despite the high optical, mechanistic, and hydrodynamic stress for the cells while sorted, most of the targeted populations could be isolated and grew in mixed culture media subsequent to sorting. Forty-five phytoplankton taxa were isolated, including green algae (29 species), cyanobacteria (eight), diatoms (seven), and cryptomonads (one). The isolation success average was high since 80% of the total sorted populations grew successfully and 47% constituted monocultures. It is noteworthy, however, that some groups could not be isolated, as for example colonial cyanobacteria, chrysophytes, euglenophytes, desmids, or dinoflagellates, and some species such as Cryptomonas sp. were very sensitive to the sorting process. It is proposed that flow cytometric analysis of freshwater phytoplankton might be a relevant tool for water managers and could be applied in some specific cases, such as early monitoring of blooming taxa or basic bio-monitorings of key species. The higher isolation average obtained from the flow sorting can also be powerful for the physiological or molecular study of some taxa after their cultivation.

Phytoplankton community: indicator of water quality in the Armando Ribeiro Gonçalves Reservoir and Pataxó Channel, Rio Grande do Norte, Brazil

The current study analysed spatial-temporal modifications of the phytoplankton community and water quality, during dry and wet seasons. The phytoplankton community was studied in three areas: Armando Ribeiro Gonçalves Reservoir (ARG), which is an important public use reservoir in RN, Pataxó Channel (PC-before water treatment), Itajá, RN, and after the water treatment (WTP). Water samples from the reservoir were collected during both dry (January, February and November, 2006) and wet seasons (March to June, 2006). Quali-quantitative analyses of phytoplankton were carried out. Results indicated a qualitative similarity of the phytoplankton community in the three areas. However, significant differences were registered in these areas in relation to species relative abundance, with dominance of potentially toxic cyanobacteria, such as Planktothrix agardhii Gomont (dry season) and Microcystis aeruginosa Kutz (wet season). Ecological indexes obtained higher values before water treatment. Nevertheless, densities of cyanobacteria (organisms/mL) gradually reduced in the waters of the reservoir and of the Pataxó Channel before and after water treatment. After the treatment, density values of cyanobacteria were adequate for human consumption, according to the values established by the Health Ministry.

Changes in the phytoplankton community of a lake restored with phosphorus inactivation (Lake Głęboczek, northern Poland)

Abstract The study applied qualitative and quantitative phytoplankton analysis as a tool for determining algal community characteristics and identifying the directions and general trends of changes caused by the restoration of Lake Głęboczek through phosphorous inactivation before and during its application. The method applied in the studied lake aimed at reducing phosphorous availability through the chemical precipitation of its excess mineral forms in the water body and limiting their mobility in the bottom sediments. Restoration efforts led to shifts in the phytoplankton domination structure followed by the inhibition of blue-green algae development. In consequence, a significant decrease was recorded in the growth rate of the phytoplankton community.

Advanced mass spectrometry techniques for identification, characterisation and structural elucidation of natural products

Mass-based structural identification of natural products frequently employs combinations of different mass spectrometers, including triple quadrupole and ion trap instruments. These methods often provide adequate information for tentatively identifying structures of analogues of previously characterized compounds. For completely unknown compound, tentatively identified structures are often further examined by high-resolution MS, from which elemental compositions can be obtained. Here it is required to measure the mass-to-charge ratios with the smallest mass uncertainties possible. Ideally, routines with sufficient resolution and mass accuracy yield single empirical formulae for every compound analysed. In the absence of a unique empirical formula, analysis can be highly ambiguous. In most studies, quadrupole TOF and Fourier-transform MS (orbitrap, ICR) instruments are used. This presentation illustrates state-of-the-art techniques for screening and identifying natural products. (1) Characterization of hyperforin in extracts of St. John's wort (Hypericum perforatum) is illustrated. The strategy used was a combination of MS2 and MS3 experiments, performed on QqLIT and high-resolution FTICR instruments. This combination allowed fragmentation schemes and chemical structures to be proposed. (2) Analysis of Boswellia from the Boswellia serrata tree is demonstrated. Specific active anti-inflammatory ingredients in this herb have been identified, boswellic acids. In animal studies, these acids have been shown to significantly reduce inflammation. We are interested in the metabolism, as the clinical efficiency appears high despite the low observed plasma levels, possibly involving unknown metabolites. (3) Characterization of active species in marine toxin extracts is shown. Analysis of phytoplankton allowed for detection of several previously characterized toxins as well as new unexpected compounds. Purification of crude extracts into several fractions using mass-triggered preparative chromatography permitted enrichment of different species, resulting in high quality mass spectra for all known and unknown species

Temporal and spatial variability in the phytoplankton community of Myall Lakes, Australia, and influences of salinity

The variability in the phytoplankton communities of the Myall Lakes, a series of four interconnected coastal lakes on the lower north coast of New South Wales, was studied between 1999 and 2002. There was considerable spatial variability across the lake system. Bombah Broadwater experienced blooms of Anabaena in 1999 and early 2000, but these were replaced from late 2000 onwards by Chroococcus and a variety of eukaryotic taxa, particularly flagellates and diatoms. In comparison, the phytoplankton community of Myall Lake was dominated for much of the study period by Chroococcus, Merismopedia and chlorophyte taxa. The sites located midway between these two main lakes represent an ecotone, with elements of the phytoplanktonic flora of both main lakes being present. Changes in phytoplankton community composition in Bombah Broadwater occurred fairly frequently. In contrast, the phytoplankton community in Myall Lake changed little during the course of the study and can be considered as being at long-term equilibrium. The reasons for this lie in the morphology and hydrology of the lake system, which in turn create gradients in a number of physico-chemical water quality attributes. Bombah Broadwater is influenced by episodic and stochastic freshwater inflows from the upper Myall River catchment, and in times of drought by saline marine incursions via the lower Myall River. Myall Lake however represents a cul-de-sac, with only a small hydraulic connection to the remainder of the lake system. As it has little input from its small catchment, the limnological conditions within this lake remain relatively constant for long periods of time. Although no patterns of seasonal succession were discernable in any of the lakes, some longer-term (annual) changes did occur, and certain taxa displayed enhanced growth in summer. Salinity was found to be an important factor in determining phytoplankton community composition and abundance. Canonical Correspondence Analysis of phytoplankton and environmental data for all sites combined, showed ammonia, total nitrogen and salinity (measured as electrical conductivity) to have the most influence on the phytoplankton community composition and abundance. Anabaena growth was positively related to ammonia concentration and negatively related to conductivity.

Dinâmica da comunidade fitoplanctônica e aspectos sanitários de um lago urbano eutrófico em São Paulo, SP

Algas fitoplanctônicas são importantes na avaliação da qualidade da água, refletindo a dinâmica do ecossistema. O objetivo principal foi verificar a variação sazonal do fitoplâncton, relacionando-a com parâmetros físicos e químicos da água e coliformes do Lago das Garças (Instituto de Botânica, São Paulo, SP, Brasil). Amostras de água para análise das variáveis físicas e químicas e do fitoplâncton foram coletadas mensalmente (janeiro/97 a março/98) em três profundidades (superfície 2 metros e fundo). A comunidade fitoplanctônica foi analisada através da sua biomassa (clorofila-a), da sua densidade e dos índices biológicos. Foram identificados 214 táxons distribuídos em nove classes taxonômicas. As variáveis químicas tiveram variação vertical e temporal enquanto que o fitoplâncton apresentou padrão sazonal; quatro espécies de Cyanobacteria (Cylindrospermopsis raciborskii (Woloszynska) Seenayya & Subba Raju, Sphaerocavum brasiliense M.T.P. Azevedo & C.L. Sant'Anna, Merismopedia glauca (Ehrenberg) Kützing e Merismopedia tenuissima Lemmermann) dominaram, principalmente nos meses mais quentes.

Book review: Flow cytometry with plant cells: Analysis of genes, chromosomes and genomes

Book review: Flow cytometry with plant cells: Analysis of genes, chromosomes and genomes

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.