PCBs contamination does not alter aerobic metabolism and tolerance to hypoxia of juvenile sole (Solea solea L. 1758)

M Cannas,F Atzori,F Rupsard,P Bustamante,V Loizeau,C Lefrançois

doi:10.1016/j.aquatox.2012.04.017

Abstract

Coastal habitats play a major role as nurseries for many fish species; however, they are also submitted to pollutants and oxygen fluctuations. Fry's concept of metabolic scope for activity was used to evaluate the effect of polychlorinated biphenyls (PCBs) on the aerobic metabolism in juvenile common sole (0–1 year old). Aerobic metabolic scope (AMS) in control and PCB-contaminated fish via food pathway was determined using respirometry techniques. Furthermore, the hypoxia tolerance in control and PCB-contaminated fish was evaluated by assessing their critical oxygen concentration (O2crit). Our results showed that while PCB-contaminated fish were able to maintain a constant AMS and O2crit, PCBs tend to affect their aerobic metabolism by acting on maximal oxygen consumption (MO2max) in hypoxia and standard metabolic rate, but only at the highest PCB concentration between 30 and 60 days of exposure. In conclusion, we can hypothetise that the tested PCB-exposures may not impair the tolerance to hypoxia and the survival of common sole in their natural environment.

Highlights

Coastal areas play a key role as nurseries for juveniles of many species of teleosts
Our results are consistent with a recent study carried out on juvenile of common soles exposed to the same protocol of contamination, and which showed that polychlorinated biphenyls (PCBs)-exposure did not affect growth (Eichinger et al.; 2010)
This is contrary to our initial hypothesis, which stated that an increase in standard metabolic rate (SMR) was expected because of supplementary energy costs induced by PCB-related processes of defence and detoxification

Summary

Introduction

Coastal areas play a key role as nurseries for juveniles of many species of teleosts. AMS is partly driven by the environmental factors that were divided by Fry (1947, 1971) into five classes depending on their effects on aerobic metabolism: controlling, masking, limiting, lethal and directive factors In this classification, oxygen and pollutants are considered as limiting factors as they interfere with metabolic processes and can thereby reduce the maximal metabolic rate sustainable by the organism, defined by Fry as the active metabolic rate (AMR). An associated elevation of the standard metabolic rate (SMR) measured in resting individuals (Fry, 1971) is expected as observed in juvenile of rainbow trout (Oncorhynchus mykiss) exposed to sub-lethal concentrations of aluminium (Wilson et al, 1994) In this context, the aim of our study was to investigate the effects of both sub-lethal concentrations of PCBs and hypoxia on the aerobic metabolism of common sole chronically exposed through the food pathway. This study focus on juvenile sole because 1) common sole is a bottom-dwelling species, which occupies the coastal zone during its juvenile phase; 2) during this phase, soles feed on the invertebrates living in the sediments which are expected to be highly contaminated by PCBs (Cicero, 2000; Chau, 2006) and 3) due to their reduced swimming capacity, soles have to cope with a set of interacting environmental stressors, such as hypoxia

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Conclusion