Effect of copper exposure on growth, condition indices and biomarker response in juvenile sole &lt;i&gt;Solea senegalensis&lt;/i&gt;

Vanessa Fonseca,Henrique Cabral,Rui Company,Ângela Serafim,Maria João Bebianno

doi:10.3989/scimar.2009.73n1051

Abstract

Juvenile Solea senegalensis were exposed to different concentrations of waterborne copper (Cu) for 15 days in static conditions with continuous aerated artificial salt water at 20°C (± 0.8°C) with a normal photoperiod (10 h/14 h light/dark) and daily feeding. Several measures of exposure and effects were determined: 1) biomarkers - metallothioneins and lipid peroxidation level; 2) mass indices - growth rate and morphometric condition indices; and 3) biochemical condition indices - RNA:DNA ratio and lipid and protein content in fish tissues. Copper exposure triggered the response of the biomarkers and resulted in reduced growth and condition (RNA:DNA and lipid content), but the morphometric indices did not vary. The physiological costs of Cu contamination on condition suggested that lipid reserves were allocated as an energy source to enable exposed fish to respond to Cu toxicity as well as to maintain positive growth rates and protein synthesis throughout the experiment, although with lower growth rates than the control fish. This study showed the importance of selecting suitable biomarkers according to contaminant source, fish species and their life-history stage. In addition, the use of several biomarkers of exposure, growth and specific condition indices can improve fish health determination and should be considered in evaluations of the effects of environmental contaminants on fish.

Highlights

Aquatic ecosystems are increasingly threatened by the presence of organic and inorganic anthropogenic pollutants (Daskalakis and O’Connor, 1995)
Cultured juvenile Solea senegalensis (2.3-6.7 g ± 0.01 g wet weight, 5.7-8.0 cm ± 0.1 cm total length) from the same spawning batch were exposed to three sublethal copper treatments at the concentrations of 5, 25 and 100 μg Cu L-1, plus a clean water control group, over a 15-day experiment period
Copper exposure was carried out by the dilution in distilled water of copper sulphate hydrate (Sigma) and Cu concentrations were monitored during the experimental period by atomic absorption spectrophotometry

Summary

Introduction

Aquatic ecosystems are increasingly threatened by the presence of organic and inorganic anthropogenic pollutants (Daskalakis and O’Connor, 1995). Fish behaviour and physiological responses to specific and multiple stressors have been extensively used to determine individual health and population status, and to assess habitat quality Biomarkers are considered, in a broad sense, as measurements of changes in biological responses linked to a potential hazard, which may be chemical, physical or biological (van der Oost et al, 2003). When assessing the adverse effects of environmental contamination, exposure biomarkers are commonly used as early signs or functional measures of toxicity of specific contaminants or suites of contaminants (Shugart et al, 1992; Adams, 2002). A direct relationship between biomarkers’ response to pollutants and further ecological consequences at the individual or higher level is difficult to establish, and still needs further integration of both individual adaptability and the influence of natural attributes (van der Oost et al, 2003)

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