Kidney activity increases in copper exposed goldfish (Carassius auratus auratus) Sofie Moyson a, ⁎, Hon Jung Liew a,b , Angela Fazio c , Nathalie Van Dooren a , Aline Delcroix a , Caterina Faggio c , Ronny Blust a , Gudrun De Boeck a a Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium b Institute of Tropical Aquaculture, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia c Department of Biological and Environmental Science, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 S.Agata, Messina, Italy abstract article info Article history: Received 18 March 2016 Received in revised form 5 August 2016 Accepted 8 August 2016 Available online 10 August 2016 In the present study, the effect of copper was examined in the common goldfish (Carassius auratus auratus). Fish were fasted and exposed to either a high (0.84 μM), a low (0.34 μM) or a control copper concentration (0.05 μM) for 1 and 7 days. Swimming performance was not affected by either fasting or copper exposure. Food deprivation alone had no effect on ionoregulation, but low plasma osmolality levels and plasma Na + were noticed in fasted fish exposed to Cu for 7 days. Both gill Na + /K + -ATPase and H + -ATPase activities were undisturbed, while both kidney ATPase activities were up-regulated when challenged with the high Cu levels. Up-regulated kidney ATPase activities likely acted as compensatory strategy to enhance Na + reabsorption. However, this up-regulation was not sufficient to restore Na + to control levels in the highest exposure group. © 2016 Elsevier Inc. All rights reserved. Keywords: Shubunkin Ionoregulation Toxicity Swimming performance Osmolality Heavy metal ATPase 1. Introduction Copper is an essential nutrient for all living organisms and has numerous functions in cellular biochemistry (Burke and Handy, 2005). Increased use of heavy metals in anthropogenic activities during the last decades led to increased metal levels in aquatic environments worldwide, especially in mining and industrialised areas (Yang and Rose, 2003). The average copper level in lake and river water is 0.16 μM, but in contaminated water the concentrations can rise above 15.74 μM(ATSDR, 2004). In Flanders, as an example of an industrialised area, the average norm for environmental quality of surface waters is 0.11 μM dissolved copper, or 0.77 μM total copper. The goal to decrease copper concentrations in 2010 with a minimal of 75% compared to 1985, was not reached but between 2000 and 2010, average copper concentrations in surface waters have successfully decreased with 78% (MIRA, 2010). However, due to historic pollution, the norm for ground water quality of 1.57 μM is still occasionally exceeded (VMM, 2013). Besides industry, agriculture and aquaculture can also significantly con- tribute to surface water copper concentrations. Currently, increasing copper concentrations are often seen in aquaculture (Vutukuru et al., 2006) and they potentially can cause problems. Even sublethal concen- trations of toxic substances can induce biochemical, physiological, mor- phological and genetic changes in aquatic organisms, depending on fish size and water composition (Wood, 2001). Furthermore, different fish species suffer in a varying degree from pollution. In the case of copper, gibel carp (Carassius auratus gibelio) appeared considerably less sensi- tive to aqueous Cu than common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss). Based on LC50 values (96 h), Cu was three times more toxic for rainbow trout (LC50: 3.3 μM) than for com- mon carp (LC50: 10.4 μM), and seven times more toxic than for gibel carp (LC50: 22.0 μM) (De Boeck et al., 2004). It was suggested that the genus Carassius has a relative higher tolerance to copper compared to other freshwater species (De Boeck et al., 2004; Schjolden et al., 2007; Eyckmans et al., 2011). Waterborne copper affects the gills of fish, the main location for gas and ion exchange, and causes mucus production, cell swelling and lifting of the epithelium (Wood, 2001). The gills are in continuous contact with the external environment and are thus a primary target for waterborne pollutants (Pandey et al., 2008). Fast copper accumula- tion in this organ precedes accumulation in other organs, such as liver, kidney and muscle (Grosell and Wood, 2002). This accumulation can lead to a number of adverse effects in gill tissue such as a disruption of the active uptake mechanisms for Na + and Cl - (mainly through an in- hibition of Na + /K + -ATPase activity), an increase in gill permeability, and oxidative stress (Eyckmans et al., 2010, 2011). Therefore, it Comparative Biochemistry and Physiology, Part C 190 (2016) 32–37 ⁎ Corresponding author. E-mail address: Sofie.Moyson@uantwerpen.be (S. Moyson). http://dx.doi.org/10.1016/j.cbpc.2016.08.003 1532-0456/© 2016 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Comparative Biochemistry and Physiology, Part C journal homepage: www.elsevier.com/locate/cbpc