Organic nitrogen uptake and growth by the chrysophyte Aureococcus anophagefferens during a brown tide event |
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Authors: | G M Berg P M Glibert M W Lomas M A Burford |
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Institution: | (1) Horn Point Environmental Laboratory, University of Maryland, P.O. Box 775, Cambridge, Maryland 21613, USA, US;(2) CSIRO Marine Laboratories, Cleveland, Queensland 4163, Australia, AU |
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Abstract: | The quantitative importance of light-mediated, dissolved organic nitrogen (DON) utilization in relation to overall nitrogen-assimilation
in Aureococcusanophagefferens Hargraves et Sieburth was assessed during a brown tide event in Shinnecock Bay, Long Island, 24 through 26 July 1995. The
growth response of A. anophagefferens was maximal in organic-rich Bay water and decreased proportional to the organic:inorganic nutrient ratio of the water. Short-term
uptake measurements with six nitrogenous substrates revealed that reduced nitrogen could potentially represent 95% of overall
nitrogen uptake of which 70% was due to organic nitrogen alone. Potential uptake of urea by the A. anophagefferens-dominated bloom was substan tially greater than uptake of the other substrates tested during the study, contributing the
largest percentage of total nitrogen uptake (58 to 64%; ρ′
max(urea) 4.4 μg atom N l−1 h−1), followed by NH4
+ (18 to 26%; ρ′max(NH4+) 2 μg atom N l−1 h−1). The combined rates of uptake of algal extract, lysine and glutamic acid contributed between 11 and 16% of total uptake,
whereas NO3
−contributed 5 to 8%. Based on the kinetic determinations from this study we suggest an ecological framework for the events
leading to the dominance and abundance of A. anophagefferens in coastal bays.
Received: 29 March 1997 / Accepted: 24 April 1997 |
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