Growth and Adaptation of Estuarine Unicellular Algae in Media with Excess Copper, Cadmium or Zinc, and Effects of Metal-Contaminated Algal Food on Crassostrea virginica Larvae

Publisher Website
Google Scholar
Abstract
Responses of the estuarine unicellular algae Monochrysis lutheri, Isochrysis, galbana, Dunaliella euchlora and Phaeodactylum tricornutum to excess CuCl2, CdCl2 and ZnCl2 in growth media were determined. Tolerance to metals in artificial seawater was greater than in enriched natural seawater, because of the higher concentration of metal ligands in the former. Growth differences between species in media containing excess Cu or Cd were observed in both media. Growth of M. lutheri and I. galbana was inhibited more than that of the other test organisms. This difference did not occur in media with excess Zn. After extended periods of subculture in sublethal concentrations of Cu and Cd, algae developed tolerances to metal concentrations that were inhibitory upon initial exposure. Strains of I. galbana adapted to grow in a medium with 10 mg% CuCl2 (47.3 ppm Cu) or 2.5 mg% CdCl2 (15.3 ppm Cd) were fed to laboratory-reared veliger larvae of the oyster C. virginica. These algal foods induced poor growth and high mortalities in grazing larvae. Pollution of estuarine waters with high concentrations of metals decreased primary productivity and altered algal species dominance. With continued exposure to sublethal concentrations, phytoplankters exhibited a limited increase in tolerance and adaptation to the metals. These populations were potentially toxic for grazing species at higher trophic levels.