Effects of waterborne Fe(II) on juvenile turbot Scophthalmus maximus: analysis of respiratory rate, hematology and gill histology

Abstract

The concentration of Fe(II) is high in some groundwater supplies used in turbot culture, and the toxicity of waterborne Fe(II) is unknown. We investigated the stress responses of juvenile turbot, Scophthalmus maximus, exposed to Fe(II) of different concentrations (0.01, 0.05, 0.1, 0.5, 1, and 2 mg/L) for 1, 7, 14, and 28 d, under the same ambient conditions of other parameters. Changes in respiratory rate, hematological parameters, and gill structure were determined. The results show that waterborne Fe(II) did not cause severe hematological perturbation to turbot. A low-medium Fe(II) concentration (lower than 0.1 mg/L) could boost the respiratory rate, and caused no or very limited damage to fish. A high Fe(II) concentration (0.1 mg/L or higher), however, caused gill damage, such as vacuoles in branchial lamellae, epithelial necrosis, and hypertrophy of epithelial cells, and even death after extended exposure time. Therefore, excess waterborne Fe(II) and long-term exposure to Fe(II) could be responsible for poor growth and high mortality of turbot in culture. The concentration of waterborne Fe(II) in turbot culture should be kept below 0.1 mg/L.

Gill Reaction to Pollutants from the Tamiš River in Three Freshwater Fish Species,Esox luciusL. 1758,Sander lucioperca(L. 1758) andSilurus glanisL. 1758: A Comparative Study

“…Although the observed alterations are not pollutant‐specific, they could be related to previously published results concerning gill alterations caused by experimental exposure to certain pollutants. Iron concentrations close to the values observed in the Tamiš River, in experimental conditions, induced gill damage in the form of hypertrophy, hyperplasia of epithelium, fusions, lifting and rupture of epithelium, haemorrhages and necrosis (Peuranen et al., ; Dalzell and Macfarlane, ; Pandey et al., ; Wu et al., ). Epithelial lifting and swelling, hyperplasia with lamellar fusions, hyperaemia, telangiectasia and alterations in chloride cells were common lesions of gills from fish experimentally exposed to copper (Karan et al., ; Arellano et al., ; Liu et al., ).…”

“…Furthermore, trace metals induce oxidative stress, hence activating the antioxidant systems, in which depletion in activity of superoxide dismutase, catalase, glutathione S ‐transferase and glutathione in gills is usually noticed (Farombi et al., ). It has been observed that some regressive alterations in the form of rupture of epithelium and epithelial necrosis may be attributed to depletion in activity of these enzymes (Wu et al., ). Coutinho and Gokhale () report distinct differences in gill reactions between common carp ( Cyprinus carpio L., 1758) and Mozambique tilapia [ Oreochromis mossambicus (Peters, 1852)] exposed to secondary sewage effluents.…”

“…Histopathological analyses of gills indicate that this organ may react non‐specifically, and therefore, various pollutants can cause similar reactions and alterations of the gill tissue (Evans, ; Heath, ; Ferguson, ). Current literature predominantly deals with papers describing and quantifying fish reaction to specific pollutants or water pollution in general (Peuranen et al., ; Karan et al., ; Camarago and Martinez, ; Pandey et al., ; Liu et al., ; Wu et al., ; Barja‐Fernández et al., ). However, only a few studies have involved comparative analysis of reaction of different fish species to waterborne pollutants (Coutinho and Gokhale, ; Nascimento et al., ).…”