New Zealand Journal of Marine and Freshwater Research abstracts

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Influence of light and three nitrogen sources on growth of Heterosigma carterae (Raphidophyceae)

F. HOE CHANG
M. PAGE

National Institute of Water & Atmospheric
Research Ltd
P.O. Box 14-901
Kilbirnie
Wellington, New Zealand

Abstract Growth rates of Heterosigma carterae (Hulburt) comb, nov., isolated from the 1989 bloom in Big Glory Bay, New Zealand, were studied in continuous batch cultures, with 48 combinations of light and nitrogen (N) sources: NO₃, NH₄, and urea. Light had more influence on cultures grown with NO₃ than cultures grown with the other N sources. At 160 µmol photons m2 s"1, the growth rate of H. carterae was highest with NO₃, intermediate with NH₄, and lowest with urea. At lower irradiances, growth rates of NO₃-grown H. carterae were lower than those of either form of "recycled" N. For NH₄- and urea-grown cultures, nutrient concentration contributed to a greater variation of growth than did light. H. carterae exhibited signs of toxicity at high concentrations of NH₄ and urea, particularly at low light levels. The implication of the variations in growth rate under different combinations of light and N sources is that maximum growth of H. carterae in the field is probably attained in the well-illuminated, upper water column with NO₃ as the major N source. When either NH₄ or urea is the major N source, a lower maximum growth rate is probably attained over a greater range of illumination deeper in the water column.

Keywords growth rates; light; nitrogen sources; interaction; Heterosigma carterae

 

New Zealand Journal of Marine and Freshwater Research, 1995: Vol. 29: 299-304

0028-8330/95/2902-0299 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (434K); (scanned from paper original: notes about this process)

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