Integrated physiological response of tilapia, Oreochromis mossambicus, to sublethal copper exposure

Abstract

Juvenile and mature tilapia {O reochrom is m ossam bicus) were exposed to a range o f sublethal copper (Cu) concentrations for 6 days to examine the mechanisms underlying the acclimation to the toxic effects o f the metal. The study focuses on the gills, the primary target for waterborne pollutants. To obtain a comprehensive picture o f the branchial acclimation processes operating, multiple biochemical and m orphological parameters were studied. A t all concentrations tested, Cu exposure resulted in the accum ulation o f the metal in mature fish. A t 100 and 200 jug C u I-1 only, chloride cell proliferation was observed, which was accompanied by an increase in aver age cell diameter in these groups. W hole body flux measurements in juvenile fish demonstrated a decrease in N a influx in fish exposed to 200 jug I' 1 Cu, in the absence o f an effect on Ca influx. G ill N a + / K + -ATPase activity was also decreased in the crude branchial homogenates o f the mature fish exposed to the highest C u concentration only, but not in the purified branchial vesicle preparations o f these fish, which may indicate reactivation o f in vivo Cu-inhibited ATPase activity during the isolation process. Plasma pH , Na, Cl, K, glucose and ceruloplasmin concentrations were also affected in the 200 jug Cu l_l group exclusively. In accordance with the gill accum ulation data, plasma C u levels were clearly elevated in all groups exposed to the metal. The results underscore the integrated response o f the gills to Cu, which, however, does not come into play until challenged by relatively high ambient concentrations. These results indicate that, in comparison to the Cu-sensitive rainbow trout, tilapia is more Cu-tolerant. The most sensitive parameters affected by Cu are gill and plasma metal levels, followed by chloride cell num ber and diameter. Pelgrom et al. IA quatic Toxicology 32 (1995) [303][304][305][306][307][308][309][310][311][312][313][314][315][316][317][318][319][320]

Hematological and physiological changes induced by short-term exposure to copper in the freshwater fish, Prochilodus scrofa

“…Copper concentrations as low as 20 µg L -1 decreased the concentration of sodium in the plasma and at a concentration of 29 µg L -1 (96 h LC 50 (Mazon & Fernandes, 1999)), plasma sodium and chloride were significantly lower than the control, with a concomitant increase in plasmatic potassium concentration. Previous investigations have also found ion imbalance in Salvelinius fontinalis (McKim et al, 1970), Ictalurus nebulosus (Christensen et al, 1972), Lepomis macrochirus (Heath, 1991), and O. mossambicus (Nussey et al, 1995a;Pelgrom et al, 1995). Ionregulatory disruption induced by copper is related to inhibition of branchial Na + -K + -ATPase and ion uptake with concomitant stimulation of ion efflux in freshwater fish (Laurén & McDonald, 1985;Pelgrom et al, 1995).…”

Interactions between copper and cadmium modify metal organ distribution in mature tilapia, Oreochromis mossambicus

“…Metal-metal interactions after single metal exposure were shown by Gill et al (1992) who reported an increased Cu concentration in the gills of eels after Cd exposure. Previous experiments with single metal exposed fish have shown effects of sublethal concentrations of Cu or Cd on the number and function of ion transporting cells in the gills (Baker, 1969;Verbost et al, 1987;Reid and McDonald, 1988;Pratap and Wendelaar Bonga, 1993;Pelgrom et al, 1995). Exposure to low Cd concentrations resulted in an unexpectedly high increase in metal concentration in the gills.…”

Copper acclimation in juvenile fathead minnows: Is a cycle of branchial damage and repair necessary?

“…The branchial damage can include: a reduction in Na + influx McDonald, 1985, 1987a) a stimulation of Na + efflux (Laurén and McDonald, 1985) and an inhibition of branchial Na + -K + ATPase activity (Stagg and Shuttleworth, 1982;Laurén and McDonald, 1987b;Pelgrom et al, 1995;Kolok et al, 2002). These branchial changes can lead to an increase in net Na + loss (Croke and McDonald, 2002;Taylor et al, 2004), which can culminate in a significantly reduced concentration of whole-body Na + (Laurén and McDonald, 1987a;McGeer et al, 2000;Kolok et al, 2002).…”