Hopkins Marine Station, Pacific Grove, California 93950.
VARIATION IN NITROGEN PHYSIOLOGY AND GROWTH AMONG GEOGRAPHICALLY ISOLATED POPULATIONS OF THE GIANT KELP, MACROCYSTIS PYRIFERA (PHAEOPHYTA)1
Version of Record online: 27 OCT 2004
Journal of Phycology
Volume 27, Issue 2, pages 149–158, April 1991
How to Cite
Kopczak, C. D., Zimmerman, R. C. and Kremer, J. N. (1991), VARIATION IN NITROGEN PHYSIOLOGY AND GROWTH AMONG GEOGRAPHICALLY ISOLATED POPULATIONS OF THE GIANT KELP, MACROCYSTIS PYRIFERA (PHAEOPHYTA). Journal of Phycology, 27: 149–158. doi: 10.1111/j.0022-3646.1991.00149.x
Received 9 July 1990. Accepted 26 November 1990.
We thank V. Anderson, R. Horvath, M. Reeder, D. Robertson, C. Staller, and G. Tellegen for assistance with field collections; J. Watanabe, Director of Research, Monterey Bay Aquarium (MBA), for providing access to facilities of the Monterey Bay Aquarium; C. Dea for assistance with amino acid analyses; and W. North for helpful comments and suggestions. We thank R. C. Dugdale and F. P. Wilkerson for helpful comments on the manuscript. This research was supported by the National Oceanic and Atmospheric Administration's National Sea Grant College Program, Department of Commerce, under grant number NA 86-AA-D-SG119; the State of California Resources Agency, Project No. R/RD-30 from the Sea Grant Institutional Program, University of Southern California; and Contract No. N00014-88-K-0445 from the Office of Naval Research. Funding for C.D.K. was provided by a Sea Grant Traineeship, scholarships from the ARCS Foundation and the Joseph Drown Foundation, and a Sigma Xi Grant-in-Aid-of-Research. This is contribution No. 140 from the Catalina Marine Science Center, University of Southern California.
- Issue online: 27 OCT 2004
- Version of Record online: 27 OCT 2004
- geographic variation;
Three geographically isolated populations of the giant kelp, Macrocystis pyrifera (L.) C. Ag., were examined for responses to nitrate availability in batch culture experiments using juvenile sporophytes reared from spores in the laboratory. Although maximum rates of nitrate-saturated growth were similar among groups, there were significant quantitative differences in the response to nitrate limitation that can be related to natural patterns of nutrient availability at these sites. Plants from Santa Catalina Island (most oligotrophic) achieved maximum growth rates at ambient nitrate concentrations that were lower than those for plants from Monterey Bay, California (most eutrophic), or Refugio State Beach (near Santa Barbara, California). Tissue nitrogen and amino acid concentrations were highest in plants cultured from Santa Catalina Island populations at all external nitrate concentrations, suggesting that differences in nitrate requirements for growth may reflect the efficiency of nitrate uptake and assimilation at subsaturating nitrate concentrations. Given the different physical environments from which these plants came, the data suggest that geographically isolated populations of M. pyrifera have undergone genetic divergence that can be explained by ecotypic adaptation to unique habitat conditions at these sites.