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  • 1
    Electronic Resource
    Electronic Resource
    Nocturnal synthesis and diurnal degradation of phytoplankton biomass in surface waters (1989)
    Springer
    Marine biology 101 (1989), S. 457-462 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural populations of phytoplankton were collected near the Bay of Bourgneuf, France, in spring 1982, and were subjected to natural surface irradiance outdoors. They exhibited exponential growth on time scales of a week, but significant decreases in biomass indicators such as chlorophyll a and particulate nitrogen were observed during daytime. At night, these decreases were more than compensated by increases in the same biomass variables, which could double over 12 h of darkness. These features are characteristic of phytoplankton populations in surface waters which cannot escape high irradiances, and may be representative of situations in incubation bottles held at fixed depths near the surface. Under such conditions, a decrease in biomass during daytime should not necessarily be interpreted as irreversible damage unless growth measurements are carried out over the following night hours to check for possible recovery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541647
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  • 2
    Electronic Resource
    Electronic Resource
    Automated procedure for determination of dissolved organic nitrogen and phosphorus in aquatic environments (1993)
    Springer
    Marine biology 116 (1993), S. 685-688 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method is described for estimating dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in aquatic environments. The method is based on ultraviolet oxidation under successive acid and alkaline conditions, and uses continuous-flow techniques. A number of pure organic nitrogen compounds were tested in the concentration range 2 to 40 μg-at Nl-1. At the 10 μg-at Nl-1 level, recovery ranged from 60 to 100% in deionized water, and from 40 to 80% in seawater (30‰ S). In general, recovery decreased with increasing nitrogen concentration. For pure organic phosphorus compounds, recovery ranged from 73 to 100% at the 5 μg-at Pl-1 level. An application of the method to the surface water of a clay pond along the Atlantic coast of France for a period of 72 h under natural irradiance revealed very strong diel variations of dissolved organic nitrogen, but no significant trends for dissolved organic phosphorus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00355485
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon and nitrogen dynamics during growth and degradation of phytoplankton under natural surface irradiance (1992)
    Springer
    Marine biology 112 (1992), S. 491-496 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Under conditions of natural irradiance, the development and decline of a flagellate-dominated phytoplankton population was followed in a coastal North Atlantic pond over a 3 d period in summer 1986. Irradiance negatively affected phytoplankton biomass estimated as chlorophyll a, which decreased during the day at photosynthetically available radiation (PAR) levels above 600 to 1000 μmol m-2s-1; chlorophyll a increased at PAR values below this threshold. In addition, an inverse relationship was found between changes in chlorophyll a and changes in dissolved inorganic nitrogen, indicating synthesis of nitrogenous biomass mainly at night and degradation mainly during the day, with intense exchanges of material between the particulate and dissolved nitrogen fractions. The natural abundance of 13C in particulate matter increased initially, and then remained constant, and was controlled mainly by the ratio β-carboxylases activity: ribulose biphosphate carboxylase activity. The hypothesis that the latter enzyme is broken down under high irradiance and is partly responsible for increases in external dissolved nitrogen was rejected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00356295
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  • 4
    Electronic Resource
    Electronic Resource
    Blooms of surf-zone diatoms along the coast of the Olympic Peninsula, Washington. IV. Nitrate reductase activity in natural populations and laboratory cultures of Chaetoceros armatum and Asterionella socialis (1974)
    Springer
    Marine biology 25 (1974), S. 213-221 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrate reductase (NR) activity in the surf-zone diatom Chaetoceros armatum T. West was studied in its natural habitat at Copalis Beach, Olympic Peninsula, Washington (USA) over a period of 18 months. Variations of enzyme activity were found, depending on the season and the time of day. General seasonal trends in NR activity were correlated with nitrate concentrations in the surf-zone. The results also indicated that several factors may limit the activity of the enzyme. This is one of the reasons why NR activity could not be correlated with environmental nitrate concentration on the basis of individual measurements at a given point in time. Enzyme inhibition due to the presence of ammonium occurred on several occasions throughout the study period, and could be detected by the NR assay. This phenomenon for the most part masked any pattern of diel periodicity in NR activity that might have been expected to exist in cells in the natural environment. Cultures of C. armatum and Asterionella socialis Lewin and Norris were also studied in the laboratory. A diel fluctuation in NR activity corresponding to the pattern shown in natural phytoplankton by other authors was exhibited in C. armatum under a light-dark regime of 8 h light – 16 h dark and a light intensity of 400 lux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394967
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  • 5
    Electronic Resource
    Electronic Resource
    An automated assay for the determination of nitrate reductase in marine phytoplankton (1976)
    Springer
    Marine biology 34 (1976), S. 23-26 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrate reductase activity in marine phytoplankton has been assayed on a Technicon AutoAnalyzer®. A description of the automation is given with details of the apparatus and procedure. Twenty samples an hour can be processed. The automated method has been compared with the manual method. The results are in good agreement; a correlation coefficient of 0.96 has been calculated from the data. The results of a study on the diurnal variation of nitrate reductase activity in a phytoplankton shipboard culture are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390783
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  • 6
    Electronic Resource
    Electronic Resource
    Significance of cellular nitrate content in natural populations of marine phytoplankton growing in shipboard cultures (1976)
    Springer
    Marine biology 34 (1976), S. 27-32 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytoplankton intracellular nitrate concentrations have been monitored in a 56-h experiment on a shipboard culture of surface sea water from an upwelling region. These measurements were related to parameters of biomass (particulate nitrogen) and nitrate assimilation using the 15N isotope technique and the nitrate reducase (NR) assay. The procedure for measuring cellular nitrate concentrations is described. This parameter exhibited diurnal variations, ranging from 3.1 to 20.6 ng-at nitrate per μg-at particulate nitrogen, and could be correlated positively with NR activity. Nitrogen budgets show that NR activity represents only 12% of nitrate incorporation in organic phytoplankton material when nitrate is available in the sea water. However, upon depletion of the environmental nitrate (zero uptake), NR activity can fully account for the decrease of internal nitrate. From the results, it seems that internal nitrate content is a better index of nitrate consumption by marine phytoplankton than the external concentration of nitrate-nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390784
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrobiological parameters during an annual cycle in the Arcachon Basin (1987)
    Springer
    Marine biology 95 (1987), S. 631-640 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Temperature, salinity, nutrients and phytoplankton biomass were monitored on a weekly to bimonthly frequency at six stations in the Bay of Arcachon from July 1984 to July 1985. This particular period appears to have differed from the last ten years in displaying higher amplitudes of both temperature and salinity (1.5° to 24.5°C and 20 to 34.5‰) at high tide. However, although in spring both temperature and salinity were normal (14°C, 28‰), an important phytoplankton spring bloom occurred, with maximum chlorophyll levels reaching 15 μg l-1 in April. Utilization of nutrients was high, particularly for nitrate and silicate, the concentrations of which decreased, respectively, from 10–15 to 0.1–2 μM and 10–20 to 0.25–3 μM from February to May. Exhaustion of nitrate was observed in May, except in areas subjected to river input. In contrast, silicate increased throughout the study area from May to July.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393107
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  • 8
    Electronic Resource
    Electronic Resource
    Calculations of ^1^5N uptake rates by phytoplankton assimilating one or several nitrogen sources
    Amsterdam : Elsevier
    International Journal of Radiation Applications & Instrumentation. Part 38 (1987), S. 275-282 
    Details
    ISSN: 0883-2889
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0883-2889(87)90038-4
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  • 9
    Electronic Resource
    Electronic Resource
    An optical method for the rapid measurement of micromolar concentrations of nitrate in marine phytoplankton cultures (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 179-184 
    Details
    ISSN: 1573-5176
    Keywords: optical nitrate measurement ; seawater ; microalgal cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This method of nitrate determination by ultraviolet absorption spectrometry is based on the measurement of sample absorbance at a single wavelength (220 nm), which was chosen on the basis of the absorption spectra of the main components of artificial seawater in the ultraviolet domain. No reagents are used and no sophisticated instruments are necessary. For standards prepared in artificial seawater, the relationship between absorbance and nitrate concentration is linear up to 500 μmol N L−1 and the detection limit is 1 μmol N L−1. Precision is 1.5%. Urea and amino acids did not interfere at concentrations typical of seawater. The method also measures nitrite, but this interference only becomes important for species which excrete large amounts of nitrite. The method is extremely rapid, simple to implement and does not require the use of toxic chemicals such as cadmium. It should prove useful for monitoring quickly the nitrate concentrations in laboratory cultures of marine phytoplankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008046023487
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  • 10
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    Influence of temperature, salinity and irradiance on the growth and cell yield of the harmful red tide dinoflagellate Alexandrium catenella colonizing Mediterranean waters (2011)
    Oxford University Press
    Details
    Publication Date: 2011-11-24
    Description: In a laboratory study, we determined the influence of temperature, salinity and irradiance on the growth of the paralytic shellfish poisoning (PSP) toxin producer Alexandrium catenella , which can form toxic blooms in the Thau lagoon (western Mediterranean Sea). The strain studied, ACT03, was grown in an artificial seawater medium. The influence of temperature and that of salinity were analysed using 48 different combinations of 6 salinities (10–40 psu) and 8 temperatures (9–30°C) under saturating irradiance (100 µmol photons m –2 s –1 ). ACT03 appeared to be an euryhaline strain that can survive at salinities as low as 10 psu and can grow at salinities up to 40 psu. This strain can grow between 15 and 30°C. The highest growth rates (〉0.4 day –1 ) were observed between 35 and 40 psu and 15 and 27°C. The influence of irradiance on growth and cell pigment content was tested between 10 and 260 µmol photons m –2 s –1 at 20°C and 38 psu. The results revealed both a low compensation irradiance and that light saturation was reached at 90 µmol photons m –2 s –1 . Temperature had the greatest influence on growth. The ecophysiological characteristics reported here are consistent with the environmental conditions encountered in the Thau lagoon. A. catenella exhibited important adaptive capacities over the large range of tested physical factors. This flexibility helps us to explain its ability to bloom seasonally on the Mediterranean coast, where the physico-chemical environmental conditions are characterized by high seasonal variations.
    Print ISSN: 0142-7873
    Electronic ISSN: 1464-3774
    Topics: Biology
    Published by Oxford University Press
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