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Author Reuter, John E. ♦ Loeb, Stanford L. ♦ Goldman, Charles R.
Source CiteSeerX
Content type Text
File Format PDF
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Epilithic Periphyton ♦ N-deficient Lake ♦ Inorganic Nitrogen ♦ Pg Liter-l ♦ Daily Inorganic Nitrogen Utilization ♦ Relative Unimportance ♦ Dissolved Inorganic Nitrogen ♦ Biomass Dominant ♦ Blue-green Algal Community ♦ Nitrogenase Activity ♦ Sublittoral Epilithic Periphyton Community ♦ Ambient Concentration ♦ Oligotrophic Lake Tahoe ♦ Low Physiological Affinity ♦ Seasonal Rate ♦ Inorganic Carbon Uptake ♦ Dark Uptake ♦ Considerable Variation ♦ Important Source ♦ Seasonal Pattern ♦ Yearly Budget ♦ Distinct Summer Maximum ♦ Benthic Community ♦ Winter Minimum ♦ Low Ambient Substrate Concentration ♦ Blue-green Algae ♦ Efficient Use ♦ N-deficient Environment ♦ Michaelis-menten Kinetics ♦ Ambient Level
Abstract Seasonal patterns of dissolved inorganic nitrogen and inorganic carbon uptake by the sublittoral epilithic periphyton community in N-deficient, oligotrophic Lake Tahoe were examined. The biomass dominants of this community, N,-fixing blue-green algae (e.g. Calothrix, Tolypothrix, and Nostoc) were persistent and retained their nitrogenase activity throughout the year. Seasonal rates of N, fixation exhibited considerable variation, with a distinct summer maximum and winter minimum. Uptake of both N03- and NH4+ followed Michaelis-Menten kinetics. K, values were typically extremely high (> 100 pg N liter-l) compared to the ambient concentrations of these forms of nitrogen (< 10 pg N liter-l). N, fixation was the most important source of inorganic N to the yearly N budget of this benthic community. Low ambient substrate concentrations coupled with a low physiological affinity for these substrates at ambient levels were responsible for the relative unimportance of N03- and NH,+ uptake. Dark uptake of N03-, NH4+, and N, fixation were all significant and could not be neglected in determining rates of daily inorganic nitrogen utilization. This blue-green algal community is not adapted for efficient use of N03- or NH,+ and can survive in the N-deficient environment because of its ability to use N,. In striking contrast,
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Publisher Date 1986-01-01