The effects of cadmium and copper on embryonic and

Authors: Malgorzata Witeska Piotr Sarnowski Katarzyna Ługowska Ewelina Kowal

Publish Date: 2013/07/25

Volume: 40, Issue: 1, Pages: 151-163

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Abstract

The effects of Cd and Cu on embryos and larvae of the ide Leuciscus idus were evaluated The ide is an European cyprinid fish natural populations of which tend to decrease The ide is also used as a bioindicator organism to evaluate water quality However sensitivity of ide early developmental stages to heavy metal intoxication is not known Fish were exposed to Cd or Cu 100 μg/L during embryonic larval or both developmental periods Survival of the embryos time of hatching size and quality of newly hatched larvae were evaluated at the end of embryonic period Correctly developed larvae from the control and Cd or Cuexposed groups were transferred to clean water Cd or Cu solutions 100 μg/L immediately after hatching Larval development was observed and the larvae were photographed Time of yolk sac resorption onset of active feeding and swim bladder inflation were evaluated and the measurements were done on body and swim bladder size The results showed that exposure of embryos to Cd and Cu significantly reduced embryonic survival and increased frequency of body malformations and death in newly hatched larvae and delayed hatching Exposure to Cd and Cu during larval period reduced larval survival growth and delayed development yolk utilization beginning of active feeding and swim bladder inflation Cadmium was more toxic to the ide embryos and larvae than copper Exposures to metals during embryonic period alone caused adverse impact on larval performance even when larval development took place in clean water However exposure of embryos to Cu reduced toxic impact of metal on larvae in continuous Cu exposure compared to the nonpreexposed fish but no such an effect occurred in case of Cd exposure The results show that even a shortterm exposure to Cd or Cu during early development of ide may adversely affect recruitment of this species Among the measured endpoints quality of newly hatched larvae frequency of body malformations and larvae dead immediately after hatching and swim bladder size were the most sensitive to intoxication with both metals Embryos were more sensitive to Cu intoxication than larvae while in case of Cd sensitivity of both stages was similarThe ide Leuciscus idus L is a mostly riverine cyprinid fish species inhabiting large and medium size rivers in Europe and Asia They are planktivorous and benthivorous of average body size of 40–50 cm prefer deep clean and cool water and reach sexual maturation at the age of 3–4 years Spawning takes place from April to June at sandy or gravel spawning substrate According to Hamackova et al 2007 in some European countries eg Czech Republic the ide belongs to less frequent and vulnerable species thus it is bred in captivity and reared under controlled conditions Also in Poland natural populations of many rheophilic fish including the ide are dwindling due to environment deterioration and the fish are artificially reproduced and prereared under hatchery conditions Wolnicki and Górny 1995 and cultured in carp farms Cieśla and Wojda 2004 Krejszeff et al 2009 L idus is also used to assess the quality of surface water Allner et al 1999 Fenske et al 2006 and for toxicity tests Braunbeck and Segner 1992 Lenyen et al 1998 However all these studies were performed on juvenile or adult fish while little is known about sensitivity of the early life stages of ide to environmental contaminantsFish embryos and larvae are more sensitive to environmental impacts including toxic substances compared to the juveniles and adults Dave and Xiu 1991 Various embryonic morphological physiological and behavioral endpoints are used to assess toxicity of chemicals Weis et al 2003 Fraysse et al 2006 Fish larvae are also a useful animal model for toxicity evaluation since they are small but developed enough to have almost all functional organs Hernandez and Allende 2008 Sensitivity of various early developmental stages to intoxication is different and so is sensitivity of various endpoints Nguyen and Janssen 2002 Jezierska et al 2009a bCadmium is a xenobiotic while copper is an important essential metal However both are widespread and highly toxic environmental pollutants Copper sulfate is also used in fish culture to control saprolegniosis on eggs Straus et al 2012 and as an antibacterial agent for treatment of larvae Chen et al 2006 Various studies showed that sublethal concentrations of these metals are toxic to fish embryos and larvae and various physiological disturbances were observedIn unpolluted freshwaters the levels of Cd and Cu range from 0 to 13 and 2 to 4 μg/L respectively Contaminated waters often contain much more 40–120 μg/L of Cd and 1–137 μg/L of Cu Dojlido 1995 Cadmium and copper under acidic conditions are leached from the sediments so the concentrations of free Cu2+ and Cd2+ ions may temporarily increase Spring snowmelt often acidifies water thus the risk of contamination coincides with spawning and development of early stages of fish According to Zyśk 2013 sediments of Vistula River contain 2 mg/kg of Cd and 12 mg/kg of Cu while Adamiec and HeliosRybicka 2002 reported 3–21 mg/kg of Cd and 313–298 mg/kg of Cu in sediments of Odra RiverAccording to Paquin et al 2002 acute toxic action of metals involves ionoregulatory disturbances by affecting the activity of Na+/K+ATPase and displacement of calcium from paracellular junctions which results in increased permeability of epithelia and in consequence in sodium loss from the organismThere are many data showing toxicity of cadmium to early life stages of various fish species Shorttime pulseexposure of Melanotaenia fluviatilis embryos and larvae to 3300 μg/L of Cd resulted in embryonic deformities reduced percentage of hatched larvae and larval spinal deformities Williams and Holdway 2000 According to Ismail and Yusof 2011 exposure of fertilized eggs of Oryzias javanicus to low levels of cadmium 10–50 μ/L caused developmental disorders while concentration of 100 μ/L completely inhibited development and resulted in death of all embryos LizardoDaudt and Kennedy 2008 reported disturbances of hatching reduced growth and endocrine disruption in Oncorhynchus mykiss larvae subjected from fertilization to low concentrations of cadmium 005–25 μg/L Developmental defects and mortality were observed in embryos and prolarvae of Silurus soldatovi exposed to various concentrations of cadmium Zhang et al 2012 Cadmium was also observed to induce oxidative stress in Paralichthys olivaceus larvae Cao et al 2010 and directly affected membrane calcium transport in Danio rerio larvae which resulted in reduced Ca2+ uptake Liu et al 2012Toxicity of copper to early developmental stages of fish is also well documented Chen et al 2012 reported that even shortterm pulsed exposure to low levels of copper reduced growth rate of Oreochromis mossambicus larvae Nguyen and Janssen 2002 reported that copper reduced growth and caused morphological anomalies in Clarias gariepinus larvae According to Johnson et al 2007 copper exposure 11–1000 μg/L of D rerio embryos resulted in mortality hatching inhibition impairment of larval development and lateral line dysfunction The latter effect of copper was also reported by Hernandez et al 2006 and Linbo et al 2006 2009

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