ABSTRACT
Polychlorinated biphenyls at concentrations of 1 to 10 micrograms per liter reduced phytoplankton biomass and size in natural estuarine phytoplankton communities grown within dialysis bags in situ in an estuarine marsh. In polychlorinated biphenyls-contaminated waters, these changes could increase the number of trophic levels and divert the flow of biomass from harvestable fish to jellyfish and other gelatinous predators.
Subject(s)
Phytoplankton/drug effects , Plankton/drug effects , Polychlorinated Biphenyls/pharmacology , Water Pollutants, Chemical/toxicity , Water Pollutants/toxicity , Carbon Dioxide/metabolism , Chlorophyll/metabolism , Photosynthesis/drug effects , Phytoplankton/cytology , Phytoplankton/metabolismABSTRACT
Chlordane and heptachlor at 50 microgram/1 reduced cell density, chlorophyll a per unit volume of culture, 14C uptake per cell and carbon fixation per unit of chlorophyll a in the marine dinoflagellate Exuviella baltica Lohmann. The concentration of chlorophyll a per cell was not reduced, however, by treatment with either compound. Chlordane was more toxic than heptachlor at this concentration, and caused the disintegration of many cells, thus affecting particle size distribution in the cultures. In nature, such an inhibition and shift in size class distribution could affect the availability of food for particle-feeding herbivores.
Subject(s)
Chlordan/pharmacology , Dinoflagellida/drug effects , Heptachlor/pharmacology , Dinoflagellida/cytology , Dinoflagellida/growth & development , Humans , Photosynthesis/drug effects , Time FactorsABSTRACT
Polychlorinated biphenyls (PCB) at a concentration of 10 mug/liter substantially but temporarily suppressed the growth rate and photosynthesis of two species of Thalassiosira recently isolated from Long Island Sound and grown in dialysis membrane bags suspended in the tidal channel of an estuarine marsh. Inhibition of carbon fixation was apparently due to reduced levels of chlorophyll a per PCB-treated cell, but no significant loss of function per unit of existing chlorophyll a was observed. Cell concentrations in all size classes (3.2- to 18.6-mum-equivalent spherical diameters) were markedly lower in PCB-treated cultures, with toal biomass equaling only 30% of that in control cultures throughout the experiment.
