Trace Metal Constraints on Carbon, Nitrogen and Phosphorus Acquisition and Assimilation by Phytoplankton

Abstract

Reviews of trace metal interactions with phytoplankton by Sunda (1994, 2000) and Bruland et al. (1991) have critically analyzed the importance of the bioactive trace metals: Mn, Fe, Co, Ni, Cu, and Zn in controlling biological activity of primary producers in the marine environment, and conversely, of the importance of biological processes in the regulation of trace metal chemistry. The availability of bioactive trace metals, so called because of their involvement in photosynthetic electron transport (Raven et al. 1999) and other metabolic processes, can affect the acquisition and assimilation of macronutrients such as C, N and P. Our purpose here is not to provide another discussion of the information presented by these authors, but rather, following the theme of this compendium, we will highlight the aspects of phytoplankton living in stressed environments. These environments are stressed from the point of view of essential nutrient availability including bioactive trace metals. We seek to highlight the instances where potential to achieve maximum productivity based on macronutrient availability is limited by the availability of essential trace metals. Of course, our evaluation of “potential” is frequently based on the provision of adequate nutrient levels or optimal physical growth conditions, as often occur during enrichment bottle assays or during the culture of phytoplankton in the laboratory. Therefore, it is quite possible that in the natural environment, phytoplankton frequently exist under suboptimal conditions, and that in any given natural environment, there exists a range of nutrient limitations based on each organism’s current nutrient requirements.