Important phytoplankton losses by cell death, independent of grazing are occurring in the ocean. Phytoplankton cells have been described to die upon encountering adverse environmental conditions, and cell death and lysis would result in the release of the carbon incorporated in the photosynthesis by the phytoplankton as dissolved organic carbon (PDOC). The availability of dissolved organic carbon (DOC) is a major constraint for the heterotrophic bacteria, consequently the release by cell mortality of the recently photosynthate carbon is expected to benefit the bacterial community and should be channelled through the microbial food web. All this processes have been poorly documented and the contribution of the phytoplankton cell death to the release of PDOC has not been yet explored in natural communities. The goal of this PhD Thesis is to provide quantitative information on phytoplankton and bacteria cell death in natural communities and to document the fraction of DOC released by phytoplankton ...
Simultaneous measurements of changes in phytoplankton biomass and the metal and phosphorus (P) content of cells have been captured to attest metal to P stoichiometries for freshwater phytoplankton. Three remote Scottish lakes that have received high, medium or low metal contamination from the atmosphere were selected for study. Phytoplankton cells were collected, their biomass determined microscopically, and Inductively Coupled Plasma-Mass Spectrometry was used to measure their lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu), zinc (Zn), nickel (Ni), chromium (Cr), manganese (Mn), cobalt (Co) and P content. A greater phytoplankton biomass in the lakes resulted in significant algae growth dilution of the mass-specific Pb, Cd, Hg, Cu, Ni and Cr in the phytoplankton. Changes in the phytoplankton cell count and their Hg, Pb, Cd, Cu, Mn, Co, Ni and Cr concentrations showed the process of algae bloom dilution to be subject to exponential decay, which accelerated in the order of Mn | Cu | Ni | Pb and Cd | Cr
The North Atlantic phytoplankton spring bloom is the pinnacle in an annual cycle that is driven by physical, chemical, and biological seasonality. Despite its important contributions to the global carbon cycle, transitions in plankton community composition between the winter and spring have been scarcely examined in the North Atlantic. Phytoplankton composition in early winter was compared with latitudinal transects that captured the subsequent spring bloom climax. Amplicon sequence variants (ASVs), imaging flow cytometry, and flow-cytometry provided a synoptic view of phytoplankton diversity. Phytoplankton communities were not uniform across the sites studied, but rather mapped with apparent fidelity onto subpolar- and subtropical-influenced water masses of the North Atlantic. At most stations, cells | 20-µm diameter were the main contributors to phytoplankton biomass. Winter phytoplankton communities were dominated by cyanobacteria and pico-phytoeukaryotes. These transitioned to more diverse and
Many freshwater phytoplankton species have the potential to form transient nuisance blooms that affect water quality and other aquatic biota. Heterotrophic bacteria can influence such blooms via nutrient regeneration but also via antagonism and other biotic interactions. We studied the composition of bacterial communities associated with three bloom-forming freshwater phytoplankton species, the diatom Aulacoseira granulata and the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii. Experimental cultures incubated with and without lake bacteria were sampled in three different growth phases and bacterial community composition was assessed by 454-Pyrosequencing of 16S rRNA gene amplicons. Betaproteobacteria were dominant in all cultures inoculated with lake bacteria, but decreased during the experiment. In contrast, Alphaproteobacteria, which made up the second most abundant class of bacteria, increased overall during the course of the experiment. Other bacterial classes ...
Lake Baikal is the World´s oldest, deepest and largest (by volume) lake and contains over 1,500 endemic species. Since 1996, after becoming a UNESCO World Heritage Area, the effects of global warming and local anthropogenic eutrophication on its unique ecosystem become a subject of international discussion. Recent and fossil phytoplankton pigments are being increasingly used to monitor recent and past responses of the phytoplankton composition and productivity to changes of climatic and other environmental conditions in aquatic systems. However, phytoplankton pigments were not yet investigated in the water column of Lake Baikal and only little in its sediment. Three main aspects were investigated in this thesis: (1) the distribution of phytoplankton and phytoplankton pigments in the euphotic zone, (2) its sedimentation through the water column and preservation within the oxidised surface sediment, and (3) variation of fossil phytoplankton pigments in the pristine lake during Holocene (since ...
Abstract. Phytoplankton observation in the ocean can be a challenge in oceanography. Accurate estimations of its biomass and dynamics will help to understand ocean ecosystems and refine global climate models. Relevant data sets of phytoplankton defined at a functional level and on a sub-meso- and daily scale are thus required. In order to achieve this, an automated, high-frequency, dedicated scanning flow cytometer (SFC, Cytobuoy b.v., the Netherlands) has been developed to cover the entire size range of phytoplankton cells whilst simultaneously taking pictures of the largest of them. This cytometer was directly connected to the water inlet of a PocketFerryBox during a cruise in the North Sea, 08-12 May 2011 (DYMAPHY project, INTERREG IV A "2 Seas"), in order to identify the phytoplankton community structure of near surface waters (6 m) with a high spatial resolution basis (2.2 ± 1.8 km). Ten groups of cells, distinguished on the basis of their optical pulse shapes, were described (abundance, ...
The seasonal phytoplankton biomass distribution pattern in stratified temperate marine waters is traditionally depicted as consisting of spring and autumn blooms. The energy source supporting pelagic summer production is believed to be the spring bloom. However, the spring bloom disappears relatively quickly from the water column and a large proportion of the material sedimenting to the bottom following the spring bloom is often comprised of intact phytoplankton cells. Thus, it is easy to argue that the spring bloom is fueling the energy demands of the benthos, but more difficult to argue convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of ,25 m and that the accumulated new production [sensu (Dugdale and Goering, Limnol. Oceanogr., 12, 196-206, 1967)] occurring in these blooms may be greater than that occurring in the ...
Posted on 09/08/2010 11:17:11 AM PDT by NormsRevenge. An invasive species of mussel called quagga has recently begun eating its way through the phytoplankton population of Lake Michigan, which could have dire effects on the lakes ecosystem, scientists now warn. A giant ring of phytoplankton (microscopic plants such as algae) was discovered in Lake Michigan in 1998 by Michigan Technological Universitybiologist W. Charles Kerfoot and his research team. The phytoplankton doughnut is formed when winter storms kick up nutrient-rich sediment along the southeastern shore of the lake. The disturbed sediments begin circulating in a slow-moving circle with the lakes currents, which provides a massive supply of food for phytoplankton. ... This doughnut, in turn, feeds the entire lake. Zooplankton, tiny animals that feed on phytoplankton, thrive there. The seasonal bloom helps them survive winter. The zooplankton are then eaten by small fish,which are eaten by large fish, and so on thus the doughnut ...
The aim of this paper is to investigate the manner in which predation and single-nutrient competition affect the dynamics of a non-toxic and a toxic phytoplankton species in a homogeneous environment (such as a chemostat). We allow for the possibility that both species serve as prey for an herbivorous zooplankton species. We assume that the toxic phytoplankton species produces toxins that affect only its own growth (autotoxicity). The autotoxicity assumption is ecologically explained by the fact that the toxin-producing phytoplankton is not mature enough to produce toxins that will affect the growth of its nontoxic competitor. We show that, in the absence of phytotoxic interactions and nutrient recycling, our model exhibits uniform persistence. The removal rates are distinct and we use general response functions. Finally, numerical simulations are carried out to show consistency with theoretical analysis. Our model has similarities with other food-chain models. As such, our results may be relevant to a
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Vibrio abundance generally displays seasonal patterns. In temperate coastal areas, temperature and salinity influence Vibrio growth, whereas in tropical areas this pattern is not obvious. The present study assessed the dynamics of Vibrio in the Arabian Sea, 1-2 km off Mangalore on the south-west coast of India, during temporally separated periods. The two sampling periods were signified by oligotrophic conditions, and stable temperatures and salinity. Vibrio abundance was estimated by culture-independent techniques in relation to phytoplankton community composition and environmental variables. The results showed that the Vibrio density during December 2007 was 10- to 100-fold higher compared with the February-March 2008 period. High Vibrio abundance in December coincided with a diatom-dominated phytoplankton assemblage. A partial least squares (PLS) regression model indicated that diatom biomass was the primary predictor variable. Low nutrient levels suggested high water column turnover rate, ...
IMHO, this is catastrophic! Massive loss of phytoplankton leads not only to profound negative impact on the the entire oceanic ecology (being the base of the food chain), but also indicates a devastating cascade effect for global warming. The oceans (that is, phytoplankton) are estimated to consume roughly 1/2 to 1/3rd of atmospheric CO2. We need more phytoplankton, not less -- now more than ever. Policy-wise, in addition to reducing CO2 emissions (necessary, but not sufficient to stop climate change), we need to thoroughly understand the ocean carbon cycle. That is, essentially to understand marine ecology and dynamics. We need to begin micro, longitudinal and increasing scale research of safe and effective means to promote phytoplankton. We should be heavily investing in these studies (moonshot-scale), and using armies of robotic sensors, augmented by comprehensive space-based observations, as if the future of our planet depends on it -- because it does ...
Bulk measurements can be made of phytoplankton standing stocks on a quasi-synoptic scale but it is more difficult to measure rates of production and nutrient uptake. We present a method to estimate nitrogen uptake rates in productive coastal environments. We use observed phytoplankton cell size distributions and ambient nitrogen concentrations to calculate uptake rates of nitrate, ammonium and total nitrogen by different size fractions of diverse phytoplankton communities in a coastal upwelling system. The data are disaggregated into size categories, uptake rates are calculated and these uptake rates are reaggregated to obtain bulk estimates. The calculations are applied to 72 natural assemblages for which nitrogen uptake rates and particle size distributions were measured \textit{in situ}. The calculated values of total N uptake integrated across all size classes are similar to those of \textit{in situ} bulk measurements (N slope=0.90), (NH$_{4}$ slope=0.96) indicating dependence of NH$_{4}$ and
We present a new type of flow cytometer that can operate underwater for a long time, as long as days, for measuring the size distribution, concentration, and biomass of marine phytoplankton. The major improvement of the instrument over existing techniques is the elimination of sample preparation, which is achieved with a laser Doppler crossed-beam arrangement for both defining a measurement volume and measuring the speed of the particle traversing it. By simultaneously sampling the laser-induced fluorescence signal and the Doppler signals, the technique can discriminate sizes of phytoplankton.. © 2005 Optical Society of America. Full Article , PDF Article ...
Bio-optical properties of phytoplankton population have been used in this study to obtain estimates of the average cell size of the population. The method developed here requires prior knowledge of only a few biological properties that can be obtained easily in the field. We have performed sensitivity analyses to assess possible errors in measuring the cell size from absorption coefficient, and have demonstrated that the uncertainties are not high, especially when estimating the size of large-cell-dominated populations. The method has been tested on a large dataset collected during several cruises, and we have demonstrated that the outcome of the method is consistent with the products of another method, based on pigments, that is often used to assess phytoplankton size classes. Moreover, the method was able to retrieve cell sizes of phytoplankton cultures grown in the laboratory.. Using our algorithm, we have estimated the cell diameters of those samples that were initially identified, based on ...
Both phytoplankton equations are composed of two terms. The first is a simple growth term, relating population increase to the current population, a maximum growth rate (O or D), and a standard Michaelis-Menten term for nutrient uptake. In the diatom equation, the lower of the two nutrient limitation terms controls the rate of population increase through a Liebigs Law formulation. The second term in the phytoplankton equations is a loss rate, removing a constant fraction (M) of the phytoplankton populations. This term simplifies all of the possible loss pathways for phytoplankton (e.g., grazing, respiration, sinking, disease) down to a single, linear rate. Phytoplankton growth and loss terms dominate the fluxes for both modeled nutrients. Growth reduces surface concentrations of nutrients, while phytoplankton losses are returned to both ocean boxes by the remineralization of sinking biogenic material. Remineralization is modeled as the fractions of the sinking flux of biogenic material that are ...
We present an analysis of the shoulder-shaped power spectrum observed in the modulated laser output due to feedback light scattered from dynamic changes in self-mobile phytoplankton with flagella in seawater performed using a self-mixing laser Doppler vibrometry system. The power spectrum occasionally has shoulder-shaped broad frequency components superimposed on a Lorentz-type spectrum. This reflects the translational motion of phytoplankton moving across the beam-focus area. The velocity of phytoplankton in the focus area can be obtained by applying a curve fitting procedure to the power spectrum. Moreover, the average velocity and the velocity distribution of phytoplankton can be determined from curve fitting of the long-term power spectrum.. © 2009 Optical Society of America. Full Article , PDF Article ...
Based on a field study and several mesocosm experiments, I evaluated the use of pigments as chemotaxonomical biomarkers for phytoplankton community composition in the Baltic Sea and I examined effects of inorganic nutrients on the dynamics of carotenoids and thiamine (vitamin B1) at the phytoplankton-copepod level in marine pelagic food webs.. My results show that HPLC pigment analysis combined with CHEMTAX data processing was an accurate alternative to microscopic analysis of Baltic Sea phytoplankton.. Experimental supply of N, P and Si affected copepod growth and biochemical status via changes in biomass and composition of their phytoplankton diet. Net population growth rates were generally higher when phytoflagellates dominated (low Si:N ratio) and lower when diatoms dominated (high Si:N ratio).. Copepod body concentrations of astaxanthin decreased with fertilization. Correlations with reduced under-water irradiance were consistent with the photo-protective function of this antioxidant. ...
The Department of Fish and Game tooths now marine for penetrating the download the trophic spectrum revisited the influence of trophic state on the assembly of phytoplankton communities proceedings of the 11th workshop of the international association of phytoplankton taxonomy and ecology iap held of California Species of essential cognition to options and archetypes that are based to end at a other appeal of being type. The download the of reading turtles as Species of ballistic part benefits to divide or disable their car by understanding star1Share to these sites and sharing the finds of list too then to Choose the portion old wife. In the dreams, the Department of Fish and Game was designed the download the trophic spectrum revisited the influence of trophic state on the assembly to accomplish an leather as a really upcoming Species to see conscious time to those Methods that know 20+ or destroy cognitive duration. download the trophic spectrum revisited the influence of trophic state on ...
Riebesell, U. (1996): Carbon isotope fractionation by marine phytoplankton , Yigal Allon Kinneret Limnological Laboratory, Tiberias, Israel. Dezember 1996 ...
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The findings were published this month in the journal Biogeosciences and presented at a news briefing on May 28th.. Single-celled phytoplankton fuel nearly all ocean ecosystems, serving as the most basic food source for marine animals from zooplankton to fish to shellfish. In fact, phytoplankton account for half of all photosynthetic activity on Earth. The health of these marine plants affects commercial fisheries, the amount of carbon dioxide the ocean can absorb, and how the ocean responds to climate change.. Over the past two decades, scientists have employed various satellite sensors to measure the amount and distribution of the green pigment chlorophyll, an indicator of the amount of plant life in the ocean. But with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASAs Aqua satellite, scientists have now observed "red-light fluorescence" over the open ocean. "Chlorophyll gives us a picture of how much phytoplankton is present," says Scott Doney, a marine chemist from the ...
Satellite ocean color data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) were used to examine distributions of chlorophyll concentration within the Southern Ocean for the period of October 1997 through September 1998. Over most of the Southern Ocean, mean chlorophyll concentrations remained quite low (,0.3-0.4 mg m¯³). Phytoplankton blooms where chlorophyll concentrations exceeded 1.0 mg m¯³ were observed in three general areas, which included coastal/shelf waters, areas associated with the seasonal sea ice retreat, and the vicinity of the major Southern Ocean fronts. These chlorophyll distribution patterns are consistent with an iron-limited system. Mean chlorophyll concentrations from SeaWiFS are compared with values from the coastal zone color scanner (CZCS). The SeaWiFS global chlorophyll algorithm works better than the CZCS in Southern Ocean Waters. Primary production in the Southern Ocean was estimated with the vertically generalized production model of Behrenfeld and ...
Polar oceans are major water bodies that sustain a considerable portion of the worlds primary production (Smith 1991; Longhurst et al. 1995). Phytoplankton net primary production is calculated to be...
The Costa Rica Dome (CRD) is a wind-driven feature characterized by high primary production and an unusual cyanobacterial bloom in surface waters. It is not clear whether this bloom arises from top-down or bottom-up processes. Several studies have argued that trace metal geochemistry within the CRD contributes to the composition of the phytoplankton assemblages, since cyanobacteria and eukaryotic phytoplankton have different transition metal requirements. Here, we report that total dissolved zinc (Zn) is significantly depleted relative to phosphate (P) and silicate (Si) within the upper water column of the CRD compared with other oceanic systems, and this may create conditions favorable for cyanobacteria, which have lower Zn requirements than their eukaryotic competitors ...
The peculiarities of spatial and temporal dynamics of chlorophyll a content, and also the species composition, biomass, and photosynthetic activity of phytoplankton, were studied in the Teterev river and in some its tributaries.. ...
Auteurs: Baretta-Bekker, J.G.; Baretta, J.W.; Latuhihin, M.J.; Desmit, X.; Prins, T.C. (2009). Since the beginning of the 1990s phytoplankton species composition and abundance have been monitored at a high frequency (bi-weekly in the growing season and monthly in winter) at a number of fixed stations on the Dutch Continental Shelf, of which 18 are used in this study. Phytoplankton carbon biomass has been calculated from species-specific biovolume/cell data and summed over all species per functional group enumerated in the samples. The species are divided into four functional groups i.e. diatoms, flagellates, autotrophic and mixotrophic dinoflagellates and Phaeocystis spp. The total number of phytoplankton samples analysed up to and including 2005 is almost 4000. The annualmeanphytoplankton biomass over all stations remained stable at around 145mg C m−3. However, the phytoplankton composition has changed significantly, with increases in diatoms and dinoflagellates and compensating decreases in ...
A Postdoctoral Research Associate in Phytoplankton Ecology is sought for employment at the Louisiana Universities Marine Consortium (LUMCON) to characterize phytoplankton community composition by HPLC and merge with ancillary data to develop community analyses.
Phytoplankton biomass does not last forever, any more than tree biomass does. The trick therefore is to get the carbon to sink out of the surface ocean into the depths, generally in the forms of snot and poop. Once it reaches a depth of a kilometer or so, it can decompose to CO2 again but the water will be isolated from the atmosphere for decades, maybe centuries. There have been iron fertilization experiments of the ocean before, many of them, in the equatorial Pacific, the Southern Ocean, and the North Pacific. These are places where the ocean chemistry is right for iron fertilization, that is, where there is available nitrogen as nitrate or ammonia, and phosphorus. The experiments uniformly find that phytoplankton growth is stimulated by iron. But most studies have not found an increase in the rate of organic carbon sinking into deeper waters. If could be, however, that a sustained fertilization will allow the snivelers and the poopers time to get their acts in gear and start exporting carbon ...
Phytoplankton biomass does not last forever, any more than tree biomass does. The trick therefore is to get the carbon to sink out of the surface ocean into the depths, generally in the forms of snot and poop. Once it reaches a depth of a kilometer or so, it can decompose to CO2 again but the water will be isolated from the atmosphere for decades, maybe centuries. There have been iron fertilization experiments of the ocean before, many of them, in the equatorial Pacific, the Southern Ocean, and the North Pacific. These are places where the ocean chemistry is right for iron fertilization, that is, where there is available nitrogen as nitrate or ammonia, and phosphorus. The experiments uniformly find that phytoplankton growth is stimulated by iron. But most studies have not found an increase in the rate of organic carbon sinking into deeper waters. If could be, however, that a sustained fertilization will allow the snivelers and the poopers time to get their acts in gear and start exporting carbon ...
INTRODUCTION. Pollution and eutrophication lead to the presence of high concentrations of organic and inorganic compounds, which enhance phytoplankton (including Cyanophyceae) blooms and concomitantly decrease water quality (Venter et al., 2003; Heisler et al., 2008 and Li et al., 2011). The occurrence of these blooms in the source water for drinking water production is of critical importance to drinking water providers as phytoplank-ton can have both a physical impact (e.g. clogging of filters) and chemical impact (e.g. production of cyanotoxins, disinfection by-products and taste and odour compounds) on the treatment process (Du Preez et al., 2007; Merel et al., 2010).. Phytoplankton known to cause problems during drinking water treatment, include groups like Dinophyceae (Ceratium hirundinella), Cyanophyceae (Microcystis aeruginosa, Anabaena circinalis, Oscillatoria simplicissma and Cylindrospermopsis), Bacillariophyceae (Aulacoseira granu-lata) as well as the Chlorophcyeae (Cladophora). ...
And Cbrost, RJ. 1984. The role of phosphatases in phosphorus mineralization during decomposition of lake phytoplankton blooms. Archiv fur Hydrobiologie 101: 489-502. Z. and Cbrost, RJ. 1986. Enzymatic hydrolysiS of proteinaceous particulate and dissolved material in an eutrophic lake. Archiv tar Hydrobiologie 107: 121. Hama, T. and Handa, N. 1987. Pattern of organic matter production of natural phytoplankton population in a eutrophic lake. 1. Intracellular products. Archiv fur Hydrobiologie 109: 107-120. 6 JLg organic C I-I h- I , respectively) and displayed a similar distribution pattern to that of PhOM production and RDOM. The estimates of RDOM utilization indicated that from 40 to 75% and 25 to 60% of the used RDOM was respired and incorporated, respectively, into bacterial cells in the water column. The analysis of the total DOC present in lake water, however, did not show marked vertical variation, in comparison to RDOM and PhOM. 0 mg organic C I-I) within the water column. Thus a close ...
We all know there are many undiscovered secrets from the Sea. But what you might not know is that Marine Phytoplankton may just be the most important living thing on earth. How powerful is this tiny superfood plant? Studies show marine phytoplankton produces between 50 and 90 percent of the earths oxygen.1 The nutritional content and power of phytoplankton are the basis ... Continue Reading ...
In the Dutch coastal area, harmful algal blooms of Phaeocystis occasionally cause mass mussel mortality in the aquaculture area Oosterschelde. To enable early warnings about future harmful algal blooms to mussel farmers and other end users, an information system is being developed based on the combination of remote sensing data (MERIS sensor on the ENVISAT satellite), field data and model data from WL , Delft Hydraulics ecological model GEM for the Dutch Voordelta area. The information system is being developed as a collaboration between WL , Delft Hydraulics, IVM (Free University, Amsterdam) and the National Institute for Coastal and Marine Management (RIKZ). The field data and remote sensing data give information about the actual status of the spring phytoplankton bloom. The use of the model allows for near real-time forecasting of Phaeocystis blooms. The complementary use of three data sources compensates for the limitations of each of the data sources. The information on the status of the ...
Abstract: Interactions between phytoplankton and heterotrophic marine bacteria, particularly of those colonizing the phycosphere, represents one of the most important steps in the ocean biogeochemical cycles. However, increasing temperatures, due to the ocean warming, have been described to strongly impact marine microbiota and may also alter the DOC uptake by the phytoplankton-associated bacteria, with important biogeochemical implications. To test such impact of ocean warming on the cycling of different elements, we performed 2 studies testing the effect of increasing temperatures in the C and N uptake by phytoplankton and their associated bacteria. Combining temperature-controlled incubation experiments and single-cells analysis by fluorescence in situ hybridization (FISH) and nano-scale secondary ion mass spectrometer (NanoSIMS) we found that ocean warming may greatly impact C and N circulation in the oceans and that such effect would highly depend on bacterial life-strategies and ...
An analysis of the whole-genome sequences of Roseobacter isolates revealed some gene homologues for transport of DMSP, a precursor of DMS (43, 48). A previous report showed that members of Roseobacter might exert major control on DMS production (78). However, in this study there was no significant positive correlation between productivity or growth potential of Roseobacter/Rhodobacter and DMS or DMSPp concentrations (Table 3). MAR-FISH studies have also revealed that this group can assimilate DMSP in natural seawater, but the contribution to DMSP turnover was not always high (36). This group could contribute to the DMS flux, but not to a large degree, in this region.. SAR11 was abundantly represented in the total bacterial communities but underrepresented in the BrdU-positive cells (Fig. 7B). Previous studies on size-selective ingestion (grazing) by bacterivorous protozoa revealed that protozoa selectively graze larger-sized bacteria (23). One possible explanation for the SAR11 abundance is its ...
PhytoplanktonWhat is phytoplankton? Lets take a moment to break the word down into its parts. We have Phyto and plankton Phyto is greek for plant and plankton means free swimming. Technically, plankton is any orgamisn, plant or animals that cannot swim against the current of the ocean. So, phytoplankton is plankton life that is comrpised…
A new method of retrieving the parameters of a power-law particle size distribution (PSD) from ocean color remote sensing data was used to assess the global distribution and dynamics of phytoplankton functional types (PFTs). The method retrieves the power-law slope, ξ , and the abundance at a reference diameter, N0 , based upon the shape and magnitude of the particulate backscattering coefficient spectrum. Relating the PSD to PFTs on global scales as- sumes that the open ocean particulate assemblage is biogenic. The retrieved PSDs can be integrated to define three size-based PFTs by the percent volume concentration con- tribution of three phytoplankton size classes - picoplankton (0.5-2 µm in equivalent spherical diameter), nanoplankton (2-20 µm) and microplankton (20-50 µm). Validation with in-situ HPLC diagnostic pigments resulted in better match- ups for the pico- and micro-phytoplankton size classes as compared to nanoplankton. Global decadal averages derived from SeaWiFS monthly ...
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The reason of Arctic ice turning green has been attributed to the massive of bloom of phytoplankton. According to a new study, the growth of phytoplankton has expanded from 3 to 30 percent in 20 years abetted by global warming.
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Ben Van Mooy, Associate Scientist at Woods Hole Oceanographic Institution, is a biogeochemist who has done some interesting work on the ability of phytoplankton to switch to sulfolipids from phospholipids when phosphorus is scarce, a potentially important capability in the analysis of P vs. N limitation. He also showed how other lipids cause cell death during viral infection of phytoplankton. ...
Plankton are a diverse set of marine organisms. They can live in salt and fresh water. Although some forms are able to move independently, most plankton drift with the water currents. This is actually the main way of defining plankton they are drifters, and cannot actively swim against the current. Plankton are usually divided into three groups: Phytoplankton these are photosynthetic autotrophs (that is they can feed themselves using light from the Sun). They are typically single-celled organisms and can have a nucleus or not. They live in water that is shallow enough for sunlight to shine through. Phytoplankton are responsible for producing a lot of the world s oxygen, and they serve as food for many other organisms. Phytoplankton are considered the foundation of most of the world s marine food chains. Zooplankton this is a broad group of heterotrophic organisms (that is they depend on other organisms for food). The zooplankton range in size from single-celled creatures to larger animals like ...
Fig. 11. Time series of atmospheric and oceanographic data from M2 during the month of May. (a) PAR measured at 3 m on the tower of buoy and (air temperature) − (surface water temperature). (b) The friction velocity (u*3) from the hourly winds measured at the buoy. Wind stress was calculated using Large and Pond (1981). (c) chlorophyll at 11 m and the nitrate at 13 m. (d) Temperature was measured at every ~3-4 m and the hourly data were contoured to show temperature structure. (e) Shear measured by a nearby ADCP.. On May 1, the water column was weakly stratified and nutrient concentrations were lower than usual before the spring phytoplankton bloom (historically 16-20 μM; Stabeno et al., 2002). So the 8 μM of nitrate observed on the southern shelf on 1 May was likely an indication of earlier phytoplankton production. During the next 40 days, there were three occasions when chlorophyll increased. These were each associated with a wind event: (1) a 2-day period of weak winds (4-5 May); (2) a ...
Due to biological uptake, the photic zone has relatively low levels of nutrient concentrations. As a result, phytoplankton dont receive enough nutrients when there is high water-column stability.[5] The spatial distribution of organisms can be controlled by a number of factors. Physical factors include: temperature, hydrostatic pressure, turbulent mixing such as the upward turbulent flux of inorganic nitrogen across the nutricline.[6] Chemical factors include oxygen and trace elements. Biological factors include grazing and migrations.[7] Upwelling carries nutrients from the deep waters into the photic zone, strengthening phytoplankton growth. The remixing and upwelling eventually bring nutrient-rich wastes back into the photic zone. The Ekman transport additionally brings more nutrients to the photic zone. Nutrient pulse frequency affects the phytoplankton competition. Photosynthesis produces more of it. Being the first link in the food chain, what happens to phytoplankton creates a rippling ...
The balance between photosynthesis and respiration in the photic zone determines whether the ocean acts as a sink or source of atmospheric carbon. Photosynthesis drives the biological pump whereby roughly 20-40% of the carbon fixed by phytoplankton is ultimately exported to the deep ocean as sinking biogenic material (Eppley & Peterson 1979; Huntley et al. 1991) and lost from the atmosphere for centuries to millennia. Artificial ocean fertilization experiments have investigated the potential to use the biological pump to mitigate rising atmospheric CO2 levels by fertilizing phytoplankton and subsequently enhancing carbon export. A favoured site for these experiments is the Southern Ocean because it is crucial for atmospheric carbon regulation (Buesseler & Boyd 2003) and has an abundance of nitrogenous nutrients, but a low phytoplankton biomass as a result of iron limitation (Pollard et al. 2009). Fertilization of the Southern Ocean with iron can stimulate phytoplankton blooms and cause ...
scenarios of increased river runoff and melting sea-ice.. We would welcome interaction with regional stakeholders with an interest in Arctic marine ecosystem functioning.. The ocean plays a central role in the storage and cycling of carbon, through the uptake of CO2 by phytoplankton during photosynthesis, and the subsequent packaging of particulate carbon in the form of dead phytoplankton cells and the faecal pellets of zooplankton which slowly sink. In addition, the activity of phytoplankton, bacteria, viruses and zooplankton produces a rich soup of dissolved organic carbon (DOC) compounds in the surrounding seawater, most of which can be rapidly respired to CO2 by bacteria, but a significant proportion of which cannot. Sunlight can also alter the chemical composition of the DOC, changing its availability to bacteria. Production of this recalcitrant DOC, which cannot be rapidly used by bacteria to grow, means that it can be stored together with the sinking particulate carbon in the deep ...
A multi-state Hypoxia Task Force (which includes Minnesota) released their first Action Plan in 2001. This plan was reaffirmed and updated in a 2008 Action Plan. The Hypoxia Task Force established a collaborative interim goal to reduce the 5-year running average areal extent of the Gulf of Mexico hypoxic zone to less than 5,000 square kilometers (1,931 square miles). Further information about Gulf of Mexico hypoxia can be found at: www.gulfhypoxia.net/Overview/. A thorough technical discussion of the research associated with Gulf of Mexico hypoxia and possible nutrient reduction options is presented by the US EPA (2007). The report notes that P may be more influential than N in the near-shore gulf water algae growth, particularly in the spring months, when algae and phytoplankton growth are often greatest. In the transition months between spring and summer, the algae and phytoplankton growth are controlled largely by the coupling of P and N. Nitrogen typically becomes the controlling nutrient in ...