Abstract
With tritiated water (THO), we can follow up the diffusional water flow in fish body. Some pollutants may affect the THO flux, which occurs independently of osmotic gradients. The effects of 25 chemicals were determined on the THO influx in 8 species of marine (longchin goby, girella, red sea bream, etc) and fresh water fish (medaka) of small size (0.2-1.5g) for 15 min exposure. Saponins of 2ppm doubled the THO influx ( ?? 100% increase), digitonin and anionic synthetic surfactants (LAS, SDS, Aerosol-OT) had similar effect. Nonionic surfactant Tween 20 (2-20ppm) was less effective ( ?? 40%) and Triton X-100 was barely effective at 80ppm. Except for these surface active agents, the other 18 chemicals were without effect at the concentrations tested. A gill perfusion test with eels, showed saponin to act on gills, the major site for water exchange, but not the skin or oesophagus.
