Research Product

A flow-through system for exposure of seagrass to pollutants is described. Sea water with dissolved atrazine for PCP (pentachlorophenol) was pumped through a sealed 2-liter volume glass exposure vessel that contained wither whole plants or leaves of Thallassia testudinum. Effects of the compounds on oxygen evolution and uptake by leaves were measured after exposure for 40 and 88 h. Rate of oxygen evolution was depressed strongly after 40 h by 1 ppm of atrazine or PCP. The rate of oxygen uptake was slightly depressed by atrazine but strongly depressed by PCP. Photosynthesis/respiration ratios were depressed to less than one by 1 ppm of atrazine or PCP and by 0.5 ppm atrazine. EC50 values based upon depression of oxygen evolution after 40 hrs exposure were: atrazine, 0.32 ppm; PCP, 0.74 ppm. The data suggest that leaves may recover from or adapt to the presence of either toxicant.