Trace Metal-Phytoplankton Interactions in Aquatic Systems

Abstract

This chapter examines the effects of trace metals on the growth, composition, and trophic dynamics of phytoplankton communities. To do this, metal interactions are considered at several levels, including the molecular, cellular, community, and ecosystem levels, of organization. The effect of phytoplankton communities on the concentration, complexation, and redox cycling of metals is also need to be considered, which results in feedback relationships between plankton dynamics and trace metal chemistry. The chapter emphasizes interactions in marine systems due to the recent discovery of iron limitation in the ocean as well as the growing body of knowledge about trace metal chemistry, biogeochemical cycling, and controls on phytoplankton dynamics in these systems. Trace metal concentrations vary widely in aquatic systems due to differences in rates of input, loss, and internal cycling. Both complexation and redox cycling affect the behavior of these metals in aquatic systems because of the large differences in the reactivity, kinetic lability, and solubility of different metal oxidation states and coordination species. A number of trace metals (Fe, Zn, Mn, Co, Cu, Mo, and Ni) are essential micronutrients and thus exert important controls on algal growth and metabolism. To fully understand the effects of trace metals on phytoplankton communities, it is necessary to take into account numerous complex interactions, ranging from those at the molecular level to those involving whole ecosystems.