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A multi-disciplinary approach was used to evaluate the health of yellow perch (Perca flavescens) in the St. Lawrence River (Quebec, Canada), which is experiencing a severe population decline in the downstream portion of the river. Physiological parameters, liver alterations, trace metal concentrations, parasite prevalence and abundance, stable isotope composition, and the presence/absence of the viral hemorragic septicemia virus (VHSV) were evaluated in perch collected at six sites along the river: Lake St. François, Lake St. Louis (north and south), Beauregard Island, and Lake St. Pierre (north and south). Trace metal concentrations in surface water were higher in Lake St. Louis and downstream of a major urban wastewater treatment plant discharge, indicating that this effluent was a significant source of Cu, As, Ag, Zn, and Cd. Levels of Pb in surface water exceeded thresholds for the protection of aquatic life in Lake St. Louis and were negatively correlated with body condition index in this lake. In Lake St. Pierre, Cu, Ag, and Cd bioaccumulated significantly in perch liver and lower body condition index and greater liver damage were observed compared to upstream sites. Parasite analyses indicated a higher abundance of metacercariae of the trematodes Apophallus brevis and Diplostomum spp. in Lake St. Louis, and VHSV was not detected in the liver of yellow perch for all studied sites. Overall, results suggested that the global health of yellow perch from Lake St. Pierre is lower compared to upstream studied sites, which could contribute to the documented population collapse at this site.  相似文献   
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Environmental Science and Pollution Research - Multi-biological level assessments have become great tools to evaluate the health of aquatic ecosystems. Using this approach, a complementary study...  相似文献   
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A note on permits, standards, and technological innovation   总被引:1,自引:0,他引:1  
Montero (J. Environ. Econom. Manage. 44 (2002) 23) contrasts the incentives to invest in new abatement technologies under different regulatory instruments and argues that one needs to consider the induced output effects that derive from lower abatement costs. Montero shows that, once one takes into account these effects on output, command-and-control instruments can generate stronger incentives to innovate than market-based instruments. This result rests on strategic output effects under command-and-control. However, he maintains that, under perfectly competitive conditions, market-based instruments will continue to weakly dominate command-and-control regulation. This note clarifies two issues raised by Montero. First, I use Montero's approach to show that in fact performance (concentration) standards will generate greater incentives to innovate than market-based instruments in perfectly competitive markets. One does not require strategic effects to get this result. Second, Montero abstracts from production costs and concentrates solely on abatement costs. He implicitly assumes that marginal production costs are constant. I show that some of Montero's results change once increasing marginal production costs are considered. When marginal costs are increasing, the benefit of additional output is tempered and market-based instruments again look more favorable.  相似文献   
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Inefficient environmental instruments and the gains from trade   总被引:1,自引:0,他引:1  
The primary result from the trade and environment literature is that countries never lose from trade liberalization as long as they implement optimal pollution targets or if they hold emissions constant. These results are derived in models where the regulators use efficient instruments such as tradable permits or emission taxes. Regulators, however, continue to prefer command and control instruments. I show that regulation under these inefficient instruments (such as design standards or concentration standards) can lead to net losses under trade liberalization even if emissions are optimally adjusted for trade. Furthermore, holding the line on emissions need not guarantee welfare improvements either. The problem is that institutional distortions, the excess costs of inefficient instruments, can rise with trade and offset the material gains from trade. Hence the presumption that we can achieve gains from trade by considering only the level of emissions fails to recognize that the mode of regulation also matters.  相似文献   
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