Nitrite Intoxication of Common Carp (Cyprinus carpio L.) at Different Water Temperatures

Abstract

Common carp (Cyprinus carpio L.) were exposed to nitrite (1.45 mmol·l -1 NO 2 -) for 48 hours at 14 °C and 20 °C, in order to investigate the mechanism of nitrite poisoning at these water temperatures. The effect of nitrite exposure on fish was assessed on selected haematological and biochemical indicators of the blood. Moreover, nitrite accumulation in the blood, liver and muscle was measured. Nitrite exposure produced high levels of methaemoglobin (88.2 ± 3.3% and 92.9 ± 6.1%) at both water temperatures compared with controls (0.3 ± 0.6% and 2.6 ± 3.0%). High fish mortality occurred in experimental groups (30% and 51%) compared with controls (0%). Nitrite exposure also resulted in an accumulation of nitrite in the fish body. The highest nitrite levels developed in the blood plasma, followed by the liver and muscle, respectively. Carp concentrated nitrite in the blood plasma and tissues to markedly higher levels at higher temperature (20 °C). The plasma nitrite concentrations (10.5 ± 1.9 mmol·l -1 ) were in this case more than 7 times higher than the environmental one. At lower temperature (14 °C), plasma nitrite concentration reached 5.0 ± 1.5 mmol·l -1 . In either event, plasma K + levels increased and Cl -levels and osmolality remained unchanged. Plasma Na + levels slightly decreased at the higher temperature. Nitriteexposed fish showed lower haematocrit values (PCV) at both experimental temperatures compared with controls. At 20 °C, the blood haematocrit decrease (0.20 ± 0.02 l·l -1 ) was accompanied by a low erythrocyte count (1.05 ± 0.12·10 12 l -1 ) and by a low haemoglobin level (51 ± 11 g·l -1 ). At the lower temperature (14 °C), the haematocrit decrease (0.25 ± 0.02 l·l -1 ) was caused by a low mean corpuscular volume (167 ± 27 fl). No significant changes were observed in the mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), or selected erythrocyte dimensions (major axis, minor axis and aspect ratio).

Nitrite intoxication of Clarias gariepinus at different water temperatures

“…A significant decrease in plasma Na + concentration was observed in group A 2 (35°C) compared with group A 1 (27°C). This result deviated from the observation of Jensen et al (1987) and Kroupova et al (2006), who observed slight decrease between the two groups.…”

“…Adeyemo et al (2003) documented the haemato-logical response of Clarias gariepinus to changes in acclimation temperature. Kroupova et al (2006) worked on nitrite intoxication of common carp (Cyprinus carpio) at different water temperatures but no information is known about the influence of temperature on nitrite toxicity of the most cultured fish species in Nigeria, C. gariepinus.…”

Toxic effects of nitrite on freshwater organisms: a review

“…; Kroupová et al . ). Important internal factors include the fish species, age, size and individual fish sensitivity (Eddy et al .…”

“…; Kroupová et al . ). However, the latter factor may accelerate the process of fish recovery after nitrite poisoning (Huey et al .…”

“…Similarly, negligible is the effect of pH on nitrite toxicity, particularly at levels commonly occurring in natural waters (Lewis & Morris 1986). On the other hand, factors potentially increasing fish sensitivity to nitrites include low oxygen concentrations in water (Bowser et al 1983) and higher water temperature (Huey et al 1984;Kroupov a et al 2006a). However, the latter factor may accelerate the process of fish recovery after nitrite poisoning (Huey et al 1984).…”