[Biochemical study of plankton. 1. Unsaponifiables of marine and lake plankton; sterols of a lake plankton].
Explore the source record for details and available documents.
Cholesterol↗
SEARCH · PubMed Health
Results for “PLANKTON”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Toxin-producing plankton may act as a biological control for planktonic blooms--field study and mathematical modelling.
Termination of planktonic blooms is of great importance to human health, ecosystem, environment, tourism and fisheries. Toxic substances released by plankton play an important role in this context. The effect of toxin-producing plankton (TPP) on zooplankton is observed from the field-collected samples and mathematical modelling. Information from both the studies led us to suggest that TPP may terminate the planktonic blooms by decreasing the grazing pressure of zooplankton and thus acts as a biological control.
Animals↗
Plankton lattices and the role of chaos in plankton patchiness.
Spatiotemporal and interspecies irregularities in planktonic populations have been widely observed. Much research into the drivers of such plankton patches has been initiated over the past few decades but only recently have the dynamics of the interacting patches themselves been considered. We take a coupled lattice approach to model continuous-in-time plankton patch dynamics, as opposed to the more common continuum type reaction-diffusion-advection model, because it potentially offers a broader scope of application and numerical study with relative ease. We show that nonsynchronous plankton patch dynamics (the discrete analog of spatiotemporal irregularity) arise quite naturally for patches whose underlying dynamics are chaotic. However, we also observe that for parameters in a neighborhood of the chaotic regime, smooth generalized synchronization of nonidentical patches is more readily supported which reduces the incidence of distinct patchiness. We demonstrate that simply associating the coupling strength with measurements of (effective) turbulent diffusivity results in a realistic critical length of the order of 100 km, above which one would expect to observe unsynchronized behavior. It is likely that this estimate of critical length may be reduced by a more exact interpretation of coupling in turbulent flows.
Animals↗
Optical plankton analyser: a flow cytometer for plankton analysis, I: Design considerations.
The design criteria for a flow cytometer (FCM) for the analysis of field samples of phytoplankton are described. The criteria are based on the occurrence of a wide variety of particle sizes in field samples, normally at low concentrations. The instrument should be able to analyse cells and colonies from 0.5 to 500 microns diameter and of over 2,000 microns length. A minimum flow rate of 4 microliters.s-1 was calculated from natural plankton concentrations. Commercially available FCMs are not suited to measure this range of sizes at this rate. Further limitations of standard FCMs are uneven illumination or incomplete processing of long signals. In addition, long filamentous colonies can break into small fragments caused by too high acceleration in the standard flow cuvette. Recognition of these limitations is of importance for the flow cytometry of phytoplankton. The new design was developed to avoid these limitations. A dynamic range 5 to 6 decades could be accomplished by a combination of logarithmic amplifiers, a slit-shaped focal spot, and a pulse integration system that can process long pulses. Multilaser capability to identify different phytoplankton species, a low fluid shear cuvette, and a trigger gate-extension for inhomogeneously fluorescent algal filaments were included in the design.
Electronics↗
Optical plankton analyser: a flow cytometer for plankton analysis, II: Specifications.
An analysing flow cytometer, the optical plankton analyser (OPA), is presented. The instrument is designed for phytoplankton analysis, having a sensitivity comparable with commercially available flow cytometers, but a significantly extended particle size range. Particles of 500 microns in width and over 1,000 microns in length can be analysed. Sample flow rates of up to 55 microliters/s can be used. Also, the dynamic range of the instrument is significantly increased for particles larger than about 5 microns. The optics, hydraulics, and electronics of the instrument are described, including the best form for a low fluid shear cuvette. The new pulse quantification technique we call digital integration is presented. This technique is essential for the instrument to handle both short and very long particles with a large dynamic range. Test measurements demonstrating particle size range and dynamic range are presented. Dynamic ranges of 10,000 and 100,000 were typically observed, measuring field samples with Microcystis aeruginosa colonies, whereas one sample showed a dynamic range of 10(6). A simple method for interpretation of time of flight (TOF) data in terms of particle morphology is presented. The specifications of the instrument are given.
Electronic Data Processing↗
[Biochemical study of plankton. II. onsaponifiables and sterols of a plankton marine animal].
Explore the source record for details and available documents.
Animals↗
Distribution of potentially pathogenic bacteria as free living and plankton associated in a marine coastal zone.
AIMS: To determine the abundance of faecal and nonfaecal bacteria related to human and animal health, as free living or associated with small (>64 microm) and large (>200 microm) plankton, samples were collected monthly from the coastal zone at Messina (Italy). METHODS AND RESULTS: Different enrichment and selective cultural methods were used to determine the abundance of bacteria in sea water and plankton. The bacteria were more frequently isolated from water and large plankton than from small plankton. Vibrio and Aeromonas spp. showed different distribution patterns in water and plankton. Faecal indicators were always present in water and the large size class plankton samples. Enterococci associated with large plankton were more abundant than E. coli in the winter. Vibrio species distributions were different in water and plankton samples. Among arcobacters only A. butzleri was isolated from water and plankton samples. Campylobacter spp. was always absent in small plankton and more frequent in large plankton than in water. CONCLUSIONS: The colonization of zooplankton by potentially pathogenic bacteria is a widespread phenomenon. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of potentially pathogenic bacteria in sea water and associated with plankton can have ecological and epidemiological implications.
Aeromonas↗
Comparison of the fatty acids in Baltic herring and available plankton feed.
Triglycerides and phospholipids dominate in Baltic herring flesh lipids throughout the plankton growth season though at the same time plankton species and their lipids vary considerably. Wax esters and fatty alcohols do not exist in significant amounts in Baltic herring flesh or plankton. Saturated fatty acids exist in equal proportions in herring and plankton lipids whereas monoenoic acids are more dominant in herring and polyunsaturated acids in plankton lipids, respectively. The component alkyl chains are similar in both fish and plankton fatty acids, thus suggesting the planktonic origin. During the period of abundant availability of plankton the changes in the fatty acids of the herring depot fat are related to the changes in the plankton lipid composition.
Animals↗
Two worlds beneath: Distinct microbial strategies of the rock-attached and planktonic subsurface biosphere.
BACKGROUND: Microorganisms in groundwater ecosystems exist either as planktonic cells or as attached communities on aquifer rock surfaces. Attached cells outnumber planktonic ones by at least three orders of magnitude, suggesting a critical role in aquifer ecosystem function. However, particularly in consolidated carbonate aquifers, where research has predominantly focused on planktonic microbes, the metabolic potential and ecological roles of attached communities remain poorly understood. RESULTS: To investigate the differences between attached and planktonic communities, we sampled the attached microbiome from passive samplers filled with crushed carbonate rock exposed to oxic and anoxic groundwater in the Hainich Critical Zone Exploratory and compared it to a previously published, extensive dataset of planktonic communities from the same aquifer ecosystem. Microbial lifestyle (attached vs. planktonic) explained more variance in community composition than redox conditions, prompting us to further investigate its role in shaping functional and activity profiles. Metagenomic analysis revealed a striking taxonomic and functional segregation: the 605 metagenome-assembled genomes (MAGs) from attached communities were dominated by Proteobacteria (358 MAGs) and were enriched in genes for biofilm formation, chemolithoautotrophy, and redox cycling (e.g., iron and sulfur metabolism). In contrast, the 891 MAGs from planktonic communities were dominated by Cand. Patescibacteria (464 MAGs) and Nitrospirota (60 MAGs) and showed lower functional versatility. Only a few genera were shared, and even closely related MAGs (> 90% average nucleotide identity) differed in assembly size and metabolic traits, demonstrating lifestyle-specific functional adaptation. Analysis of active replication indicated that the active fraction of the attached community was primarily represented by the most abundant MAGs. Planktonic communities featured a higher fraction of active MAGs compared to attached communities, but overall with lower relative abundances. CONCLUSIONS: The high abundance, metabolic specialization, and carbon fixation potential of attached microbes suggest that they are key drivers of subsurface biogeochemical processes. Carbonate aquifers may act as much larger inorganic carbon sinks than previously estimated based on CO2 fixation rates of the planktonic communities alone. Our findings underscore the need to incorporate attached microbial communities into models of subsurface ecosystem function. Video Abstract.
Plankton↗
Factors influencing planktonic, post-settlement dispersal of early juvenile blue crabs (Callinectes sapidus Rathbun).
An emerging body of literature points to post-settlement, planktonic dispersal as a key determinant of distribution and abundance patterns of aquatic organisms, yet little is known about mechanisms inducing such dispersal. Recent evidence suggests that early juvenile blue crabs (Callinectes sapidus Rathbun) may use planktonic emigration as a means of post-settlement dispersal. The goal of this study was to identify mechanisms inducing post-settlement, planktonic dispersal of early juvenile blue crabs. A combination of field mark-recapture experiments in large seagrass beds within a 2x3 km region near Oregon Inlet, North Carolina, USA, and a series of laboratory flume experiments examined the effects of day vs. night, crab size (first-second juvenile benthic instars: J1-J2 vs. third-fifth juvenile benthic instars: J3-J5), crab density and current speed on planktonic dispersal of early juvenile blue crabs. Transport of dead crabs in the flume experiment identified that planktonic dispersal was an active behavioral response rather than a passive response to increasing current speed. The experimental results demonstrated that planktonic dispersal can range from 4 to 18% under medium to high flow conditions. Planktonic dispersal of juvenile crabs is (1) an active behavioral response, (2) increased significantly with current speeds above 20 cms(-1), and (3) was higher for relatively large (J3-J5) than small (J1-J2) instars. There was a non-significant trend towards greater dispersal at night than during the day in the field experiment, and no effect of crab density on dispersal in the flume experiment. The results from this study highlight the need to consider mechanisms inducing post-settlement, planktonic dispersal when attempting to understand and predict recruitment and population dynamics of aquatic organisms, as well as when linking hydrodynamics, animal behavior and planktonic dispersal.
Journal Article↗
Persister cells, the biofilm matrix and tolerance to metal cations in biofilm and planktonic Pseudomonas aeruginosa.
In this study, we examined Pseudomonas aeruginosa ATCC 27853 biofilm and planktonic cell susceptibility to metal cations. The minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC) required to eradicate 100% of the planktonic population (MBC 100), and the minimum biofilm eradication concentration (MBEC) were determined using the MBEC trade mark-high throughput assay. Six metals - Co(2+), Ni(2+), Cu(2+), Zn(2+), Al(3+) and Pb(2+)- were each tested at 2, 4, 6, 8, 10 and 27 h of exposure to biofilm and planktonic cultures grown in rich or minimal media. With 2 or 4 h of exposure, biofilms were approximately 2-25 times more tolerant to killing by metal cations than the corresponding planktonic cultures. However, by 27 h of exposure, biofilm and planktonic bacteria were eradicated at approximately the same concentration in every instance. Viable cell counts evaluated at 2 and 27 h of exposure revealed that at high concentrations, most of the metals assayed had killed greater than 99.9% of biofilm and planktonic cell populations. The surviving cells were propogated in vitro and gave rise to biofilm and planktonic cultures with normal sensitivity to metals. Further, retention of copper by the biofilm matrix was investigated using the chelator sodium diethlydithiocarbamate. Formation of visible brown metal-chelates in biofilms treated with Cu(2+) suggests that the biofilm matrix may coordinate and sequester metal cations from the aqueous surroundings. Overall, our data suggest that both metal sequestration in the biofilm matrix and the presence of a small population of 'persister' cells may be contributing factors in the time-dependent tolerance of both planktonic cells and biofilms to high concentrations of metal cations.
Animals↗
[Interdependence of plankton spatial distribution and plancton biomass temporal oscillations: mathematical simulation].
The dynamics of aquatic biological communities in a patchy environment is of great interest in respect to interrelations between phenomena at various spatial and time scales. To study the complex plankton dynamics in relation to variations of such a biologically essential parameter as the fish predation rate, we use a simple reaction-diffusion model of trophic interactions between phytoplankton, zooplankton, and fish. We suggest that plankton is distributed between two habitats one of which is fish-free due to hydrological inhomogeneity, while the other is fish-populated. We show that temporal variations in the fish predation rate do not violate the strong correspondence between the character of spatial distribution of plankton and changes of plankton biomass in time: regular temporal oscillations of plankton biomass correspond to large-scale plankton patches, while chaotic oscillations correspond to small-scale plankton patterns. As in the case of the constant fish predation rate, the chaotic plankton dynamics is characterized by coexistence of the chaotic attractor and limit cycle.
Algorithms↗
Cryptic species of planktonic foraminifera: their effect on palaeoceanographic reconstructions.
Shells of planktonic foraminifera recovered from marine sediments provide a multitude of important palaeoproxies. Most of these proxies are based on the assumption that each morphospecies of planktonic foraminifera represents a genetically continuous species with a unique habitat. Recent discovery of hitherto hidden genetic diversity among modern planktonic foraminifera has significant repercussions on palaeoproxies derived from their fossil shells. We have compiled all available data on this genetic diversity. To date, 33 cryptic genetic types were found in 9 out of the 22 sequenced morphospecies of modern planktonic foraminifera. An examination of this database suggests that cryptic genetic diversity may be a prevalent pattern among modern planktonic foraminifera, but that the total number of cryptic genetic types per morphospecies is not large and that most genetic types show a non-random pattern of distribution in the oceans. Using modern distribution data from the Atlantic Ocean as constraints, the relationship between abundances of three genetic types of Globigerina bulloides and sea-surface temperature has been modelled and this model has been applied to a database of species counts in Atlantic coretops (761 samples). Trials with artificial neural networks (ANNs), the modern analogue technique and Imbrie-Kipp transfer functions showed that the splitting of G. bulloides into three genetic types resulted in substantial reduction in the prediction error rate (by 5 to 34%) and that this improvement was by far greatest in ANN trials (on average more than 20%). We conclude that such a large reduction in error rate occurred because the models resonated with a real pattern in the original data. This study indicates that genetic diversity among planktonic foraminifera may become more of a gift than malaise to palaeoproxies. If it becomes possible to distinguish these genetic types in the fossil record, the accuracy of proxies based on planktonic foraminifera will indeed substantially increase.
Animals↗
Interrelationships between colonies, biofilms, and planktonic cells of Pseudomonas aeruginosa.
Pseudomonas aeruginosa is a gram-negative bacterium and an opportunistic human pathogen that causes chronic infections in immunocompromised individuals. These infections are hard to treat, partly due to the high intrinsic resistance of the bacterium to clinically used antibiotics and partly due to the formation of antibiotic-tolerant biofilms. The three most common ways of growing bacteria in vitro are as planktonic cultures, colonies on agar plates, and biofilms in continuous-flow systems. Biofilms are known to express genes different from those of planktonic cells, and biofilm cells are generally believed to closely resemble planktonic cells in stationary phase. However, few, if any, studies have examined global gene expression in colonies. We used a proteomic approach to investigate the interrelationships between planktonic cells, colonies, and biofilms under comparable conditions. Our results show that protein profiles in colonies resemble those of planktonic cells. Furthermore, contrary to what has been reported previously, the protein profiles of biofilms were found to more closely resemble those of exponentially growing planktonic cells than those of planktonic cells in the stationary phase. These findings raise some intriguing questions about the true nature of biofilms.
Agar↗
Studies on the efficacy of Chloramine T trihydrate (N-chloro-p-toluene sulfonamide) against planktonic and sessile populations of different Legionella pneumophila strains.
Effectiveness of Chloramine T trihydrate (N-chloro-p-toluene sulfonamide) on both planktonic and sessile populations of different Legionella pneumophila strains was assessed. Although Chloramine T is a recommended commercial formulation for disinfecting cooling towers, there is a lack of published data about the efficacy of this compound against both planktonic and sessile populations of L. pneumophila. Planktonic L. pneumophila strains were suspended in tap water and sessile L. pneumophila strains were grown on stainless steel which is used in the construction of cooling towers, followed by exposure to the biocide. The sensitivity of both planktonic and sessile populations of L. pneumophila strains was different. The biocide was found effective below recommended dosages (0.1-0.3%) against planktonic populations of L. pneumophila, whereas it was determined that higher dosages than those recommended were required for sessile populations of L. pneumophila. The results indicated that studying only the planktonic populations of L. pneumophila for biocide tests might not be sufficient to provide information about the optimum dosage and contact time. Therefore, efficacy has to be tested on both planktonic and sessile bacteria.
Air Conditioning↗
Phylogeny and rates of molecular evolution of planktonic foraminifera: SSU rDNA sequences compared to the fossil record.
Planktonic foraminifera are marine protists, whose calcareous shells form oceanic sediments and are widely used for stratigraphic and paleoenvironmental analyses. The fossil record of planktonic foraminifera is compared here to their molecular phylogeny inferred from ribosomal DNA sequences. Eighteen partial SSU rDNA sequences from species representing all modern planktonic families (Globigerinidae, Hastigerinidae, Globorotaliidae, Candeinidae) were obtained and compared to seven sequences representing the major groups of benthic foraminifera. The phylogenetic analyses indicate a polyphyletic origin for the planktonic foraminifera. The Candeinidae, the Globorotaliidae, and the clade Globigerinidae + Hastigerinidae seem to have originated independently, at different epochs in the evolution of foraminifera. Inference of their relationships, however, is limited by substitution rates of heterogeneity. Rates of SSU rDNA evolution vary from 4.0 x 10(-9) substitutions/site/year in the Globigerinidae to less than 1.0 x 10(-9) substitutions/site/year in the Globorotaliidae. These variations may be related to different levels of adaptation to the planktonic mode of life. A clock-like evolution is observed among the Globigerinidae, for which molecular and paleontological data are congruent. Phylogeny of the Globorotaliidae is clearly biased by rapid rates of substitution in two species (G. truncatulinoides and G. menardii). Our study reveals differences in absolute rates of evolution at all taxonomic levels in planktonic foraminifera and demonstrates their effect on phylogenetic reconstructions.
Animals↗
Plankton diversity in the Bay of Fundy as measured by morphological and molecular methods.
Phytoplankton have traditionally been identified based on morphological characteristics. However, identifications based on morphology are time-consuming, require expertise in taxonomy, and often fail to distinguish differences among the multitudes of minute, nondescript planktonic organisms. Molecular techniques, which have revealed new insights into bacterial and picoplankton communities, may also enhance our knowledge of the diversity among communities of larger plankton. We compared plankton identifications and community assessments based on the two types of techniques (morphological vs molecular) for surface seawater samples collected on 2 May, 31 July and 25 September 2000 from several sampling stations in the Bay of Fundy. Phytoplankton captured in surface bucket samples were quantified and identified based on morphology. DNA was extracted from plankton communities (5-100 microm in diameter) collected by filtration, and 18S rRNA gene fragments were amplified with primers specific for eukaryotes. Denaturing gradient gel electrophoresis (DGGE) was used to develop DNA profiles of eukaryotic phylogenetic diversity and to select cloned 18S rDNA fragments for sequencing. Both morphological and molecular methods showed great community diversity. However, the communities identified with the two different types of techniques were starkly different. Morphological abundances and taxon richness were lowest in the May samples, whereas the number of DGGE bands was highest in May and July. Morphological identifications showed a succession of dominant organisms through time. Whereas neither diatoms nor dinoflagellates were dominant in May, diatoms and a few dinoflagellates were dominant in July and September. In contrast, few 18S rDNA sequences were related to rDNA sequences of known identity, and furthermore, few diatoms were identified in the molecular analyses. Molecular phylogenetic analysis indicated the presence of many novel organisms, several of which were most closely related to other unidentified sequences from diverse marine environments representing new lineages. Our results support the ideas that we are just beginning to uncover the diversity of eukaryotic marine organisms and that there may be many more ubiquitous, microeukaryotic plankton than previously realized. Our results suggest that both types of methods capture only a portion of the community. Morphological methods may be more adept at capturing the phototrophic organisms within the community. However, just as for bacteria and picoplankton, molecular techniques can enhance our understanding of plankton diversity, particularly by detecting previously unidentified organisms.
Atlantic Ocean↗
The effect of the "Prestige" oil spill on the plankton of the N-NW Spanish coast.
Chlorophyll, primary production, zooplankton biomass and the species composition of phytoplankton and zooplankton were studied in 2003, after the Prestige shipwreck. The information obtained was compared to previous data series available for the area affected by the spill. A large data series on plankton variables for the N-NW Spanish coast existed, and therefore a realistic evaluation of the effects by comparison with the range of natural variability could be carried out. We emphasized the evaluation of impact during the spring bloom, the first important biological event after the spill. Some minor changes were observed occasionally, but they did not show any clear pattern and were more related to the natural variability of the ecosystem than to effect of the spill. Plankton community structure did not undergo any changes. Only a few species were more abundant during spring 2003 than in previous years. No significant changes were detected in the planktonic community during productive periods, such as the spring bloom and the summer blooms related to intrusions of East North Atlantic Central Waters. The lack of evidence of the effects of the spill on planktonic communities is discussed in terms of the characteristics of the fuel, the high dynamics of the water masses, the biological mechanisms through which the fuel from the surface waters is transferred to the sea floor and, particularly, the influence of the natural variability by means of large and meso-scale hydrographic processes in the area under study. At the present time it is not possible to determine any minor effects the spill may have had on the plankton owing to the great variability of the planktonic cycles and the short-term impact of the oil from the Prestige on the pelagic system.
Animals↗