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NUTRIENT‐LIMITED GROWTH OF AUREOUMBRA LAGUNENSIS (PELAGOPHYCEAE), WITH IMPLICATIONS FOR ITS CAPABILITY TO OUTGROW OTHER PHYTOPLANKTON SPECIES IN PHOSPHATE‐LIMITED ENVIRONMENTS
Author(s) -
Liu Hongbin,
Laws Edward A.,
Villareal Tracy A.,
Buskey Edward J.
Publication year - 2001
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.2001.037004500.x
Subject(s) - biology , phosphate , nutrient , growth rate , phosphorus , ammonium , nitrogen , phytoplankton , zoology , botany , ecology , biochemistry , chemistry , mathematics , geometry , organic chemistry
Growth and chemical compositional characteristics of the brown tide‐forming alga, Aureoumbra lagunensis Stockwell, DeYoe, Hargraves et Johnson, were studied through a series of nitrogen‐limited and phosphate‐limited continuous cultures over a range of growth rates. The specific growth rate of A. lagunensis was hyperbolically related to the cell quota of the limiting nutrient in ammonium‐limited cultures. In phosphate‐limited cultures, the relationship was best described by a straight line. The N cell quota of A. lagunensis ranges from about 20 fmol at zero growth rate under N‐limited conditions to a high of roughly 85 fmol under N‐replete conditions. Similarly, the P cell quota of A. lagunensis ranges from about 0.15 fmol at zero growth rate under P‐limited conditions to a high of 2 fmol under P‐replete conditions. Aureoumbra lagunensis has a very high N:P critical ratio (>100). The high N:P critical ratio, as well as the organism's apparent ability to use forms of phosphorus other than phosphate under severe phosphate deficiency, may partially explain its success in P‐limited environments, such as the Laguna Madre. In addition, a uniqe quadratic relationship between the productivity index (PI) and growth rate was discovered. Such a relationship supports an earlier argument that PI may not be a good indicator of nutritional status.