Toxicity of a Mixture of Ten Metals to Phytoplankton

Abstract

The effects of a mixture of 10 heavy metals (Cu, Zn, Ni, Cr, Pb, Cd, Hg, As, Sb and Se) were studied on phytoplankton growth in a natural assemblage of diatoms and dinoflagellates from Saanich Inlet, British Columbia (Canada), and in laboratory cultures of the diatom Thalassiosira aestivalis. Growth was not inhibited at metal concentrations expected to occur in a moderately polluted estuary. At 5- or 10-fold higher metal concentrations, phytoplankton growth was inhibited both in natural populations and in laboratory cultures. Inhibition of natural assemblages was due to Cu and Hg; deletion of these elements resulted in growth equivalent to that of control cultures containing no metals. Inhibition of T. aestivalis cultures was due to Cu in the metal mixture. With natural assemblages certain diatoms such as Chaetoceros sp., Rhizosolenia sp. or Nitzschia delicatissima were no longer dominant in cultures containing a metal mixtures 5 times that in controls.