Continuous-flow toxicity tests were conducted to determine the relative tolerances of newly hatched alevins, swim-up alevins, parr, and smolts of chinook salmon (Oncorhynchus tshawytscha) and steelhead (Salmo gairdneri) to cadmium, copper, and zinc. Newly hatched alevins were much more tolerant to cadmium and, to a lesser extent, to zinc than were later juvenile forms. However, the later progre...

Krogh (1939) first proposed that freshwater organisms extract needed Na+ in exchange for NHJ to maintain near-electroneutrality across the skin or gills. Maetz & Garcia-Romeu (1964) provided an indirect demonstration of Na/NH^" exchange in the goldfish {Carassius auratus) by showing that injected NH4C1 stimulated Na + uptake, but addition of NH4C1 to the freshwater inhibited Na + uptake. They p...