On the Differential Sensitivity of Estuarine and Open-Ocean Diatoms to Exotic Chemical Stress

Abstract

Different clones of phytoplankton isolated from the Sargasso Sea and from temperate-zone estuaries were grown in culture and exposed to several toxic chemicals which, presumably, they have never experienced in their evolutionary histories. Intraspecific differences in sensitivity were noted; the growth of the estuarine clones was always less affected by these novel chemical stresses than was the growth of the oceanic clones. The data indicate that phytoplankton and other organisms which have evolved in and adapted to physically variable environments would, because of their adaptations, be better able to tolerate any toxic compound (and possibly any perturbation) than would morphologically similar organisms adapted to stable environments. Further experimental evidence suggests the degree of sensitivity of phytoplankton to pollutants may be correlated with certain adaptations of their membrane systems; open-ocean cells, whose membrane systems permit nutrient exploitation and maximal growth at low ambient concentrations, have lower resistance to perturbation than estuarine algae, whose membranes are capable of tolerating rapidly fluctuating environmental conditions.