Impact of pulp and paper mill effluent on egg hatchability of pike (Esox lucius L.)
Toxicants affect reproduction often at concentrations well below lethal levels. Also, the acidification of fresh waters has been shown to cause extinction of teleost fish populations usually through a failure of recruitment from younger generations. Both field and laboratory studies have documented that the greatest susceptibility to low pH occurs in the early developmental stages (e.g. Lee et al. 1983; Peterson 1984). Also low concetrations of metals (Horning & Neisel 1979; Ozoh 1979, 1980) and environmental accumulation of xenobiotics (Ozoh 1979; yon Westerhagen et al. 1981) diminish egg hatchability. In numerous toxicological studies egg hatchability has been a more sensitive indicator of toxic action than the other parameters studied (e.g. Henderson et al. 1981; DeGraeve et al. 1982; Lewis & Wee 1983). However, only relatively recently have the effects of bleached kraft pulp mill effluent (BKME) on fish reproduction (zebrafish Branchydanio rerio) been studied (Viktor et al. 1980; Viktor 1982) and no recipient species have been used.
Aldrin and dieldrin uptake in insecticide-resistant and susceptible mosquitofish (Gambusia affinis)
Insecticide-resistant and susceptible mosquitofish (Gambusia affinis) were exposed to14C-aldrin and14C-dieldrin for timed intervals. Whole body and tissue levels of the two organochlorine insecticides were compared between the two populations. At the 10 ppb aldrin and dieldrin treatment levels there were no significant insecticide level differences between resistant and susceptible fish. However, at 80 ppb aldrin and 30 ppb dieldrin there were significant differences. There was 8.5 times as much aldrin in whole body samples of susceptible fish as in whole body samples from resistant fish. There was only 1.24 times as much dieldrin in susceptible as in resistant fish, but it was significant (P<0.05). There were significantly higher amounts of both insecticides in tissues (muscle, liver, and brain) examined from susceptible fish, with the exception of the liver in which dieldrin levels were essentially the same for both populations. Insecticide level comparisons were also made on the basis of whether the fish were exhibiting symptoms of poisoning or not exhibiting symptoms of poisoning. Within the susceptible population there was no difference in the aldrin whole body levels between those fish not exhibiting symptoms and those exhibiting symptoms of poisoning. However, there was a higher level of dieldrin in fish exhibiting symptoms as compared to those not exhibiting symptoms. There were no differences in the insecticide levels in tissues. In comparisons between populations there were significantly higher levels in both whole body and tissue samples of susceptible fish as compared to resistant fish. This was true regardless of whether susceptible fish were exhibiting symptoms or not exhibiting symptoms of poisoning.
Hydrazine: Acute Toxicity to Bluegills and Sublethal Effects on Dorsal Light Response and Aggression
Abstract The effects of hydrazine on bluegills, Lepomis macrochirus, were assessed in terms of acute toxicity and by examining the alterations hydrazine induced in the dorsal light response and aggressiveness. The static 96-hour median lethal concentration (LC50) of hydrazine was 1.08 mg/liter and the 96-hour continuous-flow no-lethal-effect concentration was 0.43 mg/liter. The dorsal light response in the presence of an artificial prey was significantly decreased within 15 minutes of exposure to hydrazine concentrations well below the 96-hour static LC50. This was true both in static and in continuous-flow conditions. In addition, aggressiveness, as measured by the number of attacks on the prey, was increased in a dose-related manner. Control fish made no attacks, but attacks increased as the hydrazine concentrations increased. These behavioral measurements offer some promise as monitors of subtle, sublethal effects of hydrazine and possibly other aquatic pollutants on fish.