J. M. Lawrence

The Effects Of Heated Water On Warmwater Fish In Earthen Raceways

Two-year studies were conducted in 3 earthen raceways (160 m x 6 m x 2 m). One raceway was maintained at ambient water temperature, I had a heated floating plume over 60% of the surface, and 1 was maintained at near heated water discharge temperature. Average water temperatures ranging up to 36.7 C were not lethal for any fish species tested. With the possible exception of threadfin shad (Dorosoma petenense) 110 difference in long-term survival of any species was detected, but when the entire population was considered as a whole, survival of fishes confined to the highest temperatures was...


The Status Of Diquat And Paraquat As Aquatic Herbicides

The chemical and physical properties and phytocidal activity of diquat (1:1'-ethylene- 2 :2'-bipyridylium cation) and paraquat (1 :l'-dimethyl-4 :4'-bipyridylium cation) are discussed. Data are presented on the evaluation of herbicidal activity of the various salts of these 2 chemicals under controlled laboratory conditions, in plastic pools, and in earthen ponds. Research indicates that a majority of common submersed and many emergent aquatic weeds may be killed by concentrations of 0.2 to 0.5 ppm cation of these 2 chemicals. Fish toxicity studies indicate a threshold toxic concentration...