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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton (〉800 μm) and water samples were collected at night at eleven stations in Parry Channel and adjacent waters, between 28 August and 14 September 1986. Chlorophyll concentrations varied between ≈17 μg l-1 at the surface at one station in Wellington Channel, Canada, and ≈1.5 μg l-1 throughout the top 30 m at one station in Byam Martin Channel, Canada. In tows from 0 to 50 m the zooplankton community at all stations was dominated by varying proportions of three species,Calanus hyperboreus, C. glacialis andMetridia longa. Levels of chlorophyllderived pigments inC. hyperboreus Stages V, IV and III were correlated with the concentration of chlorophyll at the chlorophyll maximum. Defecation rate constants, measured for the different stages where present, were variable but not correlated with ambient chlorophyll concentrations. Ammonia excretion was measured simultaneously for the communities in which defecation was being measured in the invividual species and stages. In these experiments the rate of ammonia accumulation decreased significantly over the period during which the copepods were actively defecating (usually the first 3 h) and then tended to a constant level (over the next 18 to 20 h). The time courses of ammonia accumulation could be described by a model comprised of the sum of a straight line and a saturating curve. For seven experiments the ammonia release given by the asymptote of the saturating component was correlated with the estimate of community defecation, obtained by summing the individual defecations, suggesting that the two processes were closely associated. Weight specific defecation and weight specific “defecation-associated” ammonia excretion were both correlated with ambient chlorophyll concentration. The ratio of initial to basal ammonia excretion rate varied between 2 and 20, so that “defecation-associated” ammonia release may be important in the estimation of in vivo nitrogen excretion or regeneration rates.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Zooplankton and water samples were collected at weekly intervals between April 25 and May 30, 1986 in Barrow Strait, N.W.T. (Canadian Arctic Archipelago). In tows from 0–30 m, the zooplankton community (〉202 μm) was dominated by Pseudocalanus. The population was apparently growing and developing as shown by an increase in the proportion of adults (stage VI) and decreases in the proportion of stages III, IV, and V as the season progressed. Respiration and excretion rates of the Pseudocalanus populations were probably linked, there being an immediate increase in excretion rate, accompanying an increase in feeding rate when chlorophyll concentrations increased, which was followed by a smaller increase in respiration rate after a time lag. Hence, there was a large decrease in the O∶N ratio. Increased metabolism coincided with changes in the population structure, as did protease and bodily protein, but could not be clearly linked to dietary acclimation. Only laminarinase activity could be statistically related to an identifiable fraction of potential nutritional value in the water, particulate soluble carbohydrate, but neither showed overall seasonal change.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of experimental biology and medicine 59 (1965), S. 446-448 
    ISSN: 1573-8221
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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