G: Principles and Methods

It has been suggested that naturally occurring copper and zinc concentrations in deep seawater are toxic to marine organisms when the free ion forms are overabundant. The effects of micronutrients on the growth of gametophytes of the ecologically and commercially significant giant kelp Macrocystis pyrifera were studied in defined media. The results indicate that toxic copper and zinc ion concentrations as well as cobalt and manganese deficiencies may be among the factors controlling the growth of marine organisms in nature. A least squares fit of gametophytic growth data in the defined medium generated the expression (1) where Y is mean gametophytic length in micrometers. The fit of the experimental data to Eq. (1) was considered excellent. Here, several variables are important for predicting growth. 18xCo 6xCux 2 Zn 6xCux 2 Mn 7xZnxCu 15x 2 Zn 27x 2 Mn 12x 2 Cu Y 136 8xMn 5xCu 7xCo Source: J. S. Kuwabara, “Micronutrients and Kelp Cultures: Evidence for Cobalt and Manganese Deficiency in Southern California Deep Sea Waters,” Science, 216 (June 11, 1982), pp. 1219–1221. Copyright © 1982 by AAAS. © David Hall/Photo Researchers, Inc. c12.qxd 10/15/09 11:18 AM Page 486