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.
Responses of fish populations and communities to pulp mill effluents: a holistic assessment.
Fish populations residing in a river receiving bleached kraft mill effluents (BKME) and in an uncontaminated river were investigated to evaluate causal relationships between exposure to BKME and various indicators of fish health. The Index of Biotic Integrity demonstrated that species richness and composition were much lower in the contaminated river with an obvious imbalance in the trophic structure of the fish community. Biomolecular and biochemical responses such as DNA damage and elevated activity of detoxification enzymes indicated that fish in the contaminated river had been exposed to toxicants. The status of various condition indices such as the liver and visceral somatic indices suggested metabolic and nutritional imbalances in sunfish as a result of exposure to pulp mill effluents. Fish populations in the contaminated river also demonstrated an abnormal size distribution and age structure. Female redbreast sunfish from the BKME-impacted river contained a large number of atretic oocytes and had lower serum levels of estradiol than fish from the reference site. These observations plus data from previous developmental toxicity studies suggest that the primary mechanism by which BKME may affect fish populations in this river is through reproductive dysfunction and recruitment failure. Decreased recruitment may have caused a reduction in population size and resulted in decreased competition and increased resource availability. With increased food and habitat availability, more energy may have been available for growth and lipid storage of survivors in the contaminated river.
The qualitative research interview
Background  Interviews are among the most familiar strategies for collecting qualitative data. The different qualitative interviewing strategies in common use emerged from diverse disciplinary perspectives resulting in a wide variation among interviewing approaches. Unlike the highly structured survey interviews and questionnaires used in epidemiology and most health services research, we examine less structured interview strategies in which the person interviewed is more a participant in meaning making than a conduit from which information is retrieved.