Heavy metal contamination and hepatic toxicological responses in brown trout (Salmo trutta) from the Kerguelen Islands

Figures & data

Fig. 1  The sub-Antarctic Kerguelen Islands and the locations of the study sites.

Table 1 Water physico-chemical characteristics of sampling sites. Values are expressed as mean and extreme values (minimum–maximum). Some values were not determined (nd) or are not available (NA).

Site/morphotype	Château River	Studer Lake	Ferme Pond
Temperature (°C)	4.1 (−0.1–11.9)	5.2 (0.3–8.6)	5.7 (−0.1–19.4)
pH	7.5 (7–8.7)	7.4 (5.6–8.1)	7.6 (5–9)
Dissolved oxygen (mg/l)	12.3 (10.9–14.2)	11.6 (9.2–12.6)	11.9 (8.6–18.4)
Conductivity (µS/cm)	70 (62–97)	71.9 (46–83)	146.4 (96–182)
Cl^− (mg/l)	11.6 (9.6–16.2)	10.8 (9.7–11.8)	21.9 (7.4–26.4)
(mg/l)	0.9 (0–4)	0.9 (0–2)	1.5 (0–5)
(mg/l)	0.021 (0.01–0.06)	0.016 (0–0.03)	0.012 (0–0.09)
(mg/l)	0.004 (0.003–0.007)	0.004 (0.001–0.006)	0.004 (0.0005–0.009)
(mg/l)	0.87 (0.75–1.06)	0.94 (0.74–1.3)	0.72 (0.39–1.44)
NH3–N (mg/l)	0.031 (0–0.13)	0.026 (0–0.06)	0.153 (0–0.36)
K^+ (mg/l)	0.27 (0.2–0.4)	0.26 (0.2–0.4)	0.58 (0.2–0.95)
Total iron (mg/l)	0.1 (0.03–0.47)	0.16 (0.02–0.58)	0.34 (0.03–0.81)
Chemical oxygen demand (mg/l)	37 (0–120)	39.4 (3–103)	42.2 (1–147)
Phenolic compounds (mg/l)	0.022 (0.007–0.072)	0.011 (0.001–0.034)	0.055 (0–0.185)
Cadmium (µg/l)	0.03 (nd–0.09)	0.05 (nd–0.34)	NA^a
Copper (µg/l)	1.11 (nd–2.65)	1.19 (nd–6.84)	NA^a

^aWater sampled in Ferme Pond in 2005 presented metal concentration < 2 µg/L for copper and < 0.1 µg/L for cadmium, but such results were not recorded on a monthly basis (unpublished results).

Fig. 2  (a) Copper and (b) cadmium concentrations in livers of brown trout from the Kerguelen Islands from three Kerguelen morphotypes: river (n=10), lake (n=24) and station (n=54). Bars represent mean±SD of metal concentrations measured in the whole sample, in the livers of females and males in each morphotype. The different letters indicate significant differences in hepatic metal mean measured in the whole sample between the three morphotypes (Kruskal–Wallis test). Asterisks indicate significant differences in mean between females and males in each morphotype (Mann–Whitney U test).

Fig. 3  Photomicrographs of liver sections from brown trout from the Kerguelen Islands illustrating (a, b) normal parenchyma. (c–f) Important numbers of melanomacrophage centres (MMC). The following terms are abbreviated: parenchyma (PAR), vein (V), biliary duct (bd); MMC; fibrosis (F), necrotic hepatocyte (nh); altered nucleus (an); erythrocyte (e), lipidic droplet (ld). The dotted line represents the MMC boundary. The scale bars are 40 µm in length.

Fig. 4  Photomicrographs of liver sections from brown trout from the Kerguelen Islands showing different alterations: (a) fibrosis, (b) fibrosis with melanomacrophage centres (MMC), (c, d) altered nucleus, (e) parenchyma with lipidic droplet and (f) parenchyma with immune cell infiltrations. The following terms are abbreviated: fibrosis (F), necrotic biliary duct (nbd), vein (V), MMC, altered nucleus (an), biliary duct (bd), lipidic droplet (ld), necrotic hepatocyte (nh), immune cell agglomerate (ica). The scale bars are 40 µm in length.

Table 2 Histological alterations observed in male and female Kerguelen brown trout from “river,” “lake” and “station” morphotypes. Values are expressed as mean (minimum–maximum). The different letters indicate significant differences for each alteration (Kruskal–Wallis test, p<0.05), with the number of observations in parentheses.

	River		Lake		Station
	Females (24)	Males (48)	Females (36)	Males (48)	Females (42)	Males (42)
Melanomacrophage centre areas (µm^2/mm^2)	246 (54–531)^a,b	1003 (314–2753)^c	349 (25–746)^a,b.c	854 (0–2395)^a,b,c	184 (47–395)^a	1043 (14–2693)^b,c
Numbers of melanomacrophage centres (/mm^2)	1.6 (0.6–3.5)^a,b	3.5 (2.2–4.9)^b	1.9 (0.4–3)^a,b	4.8 (0–11)^a,b	1.3 (0.2–3.4)^a	6.5 (0.1–15.5)^b
Nuclear alteration scores	4.2 (3.6–5)^b	3.2 (1.5–5)^a,b	3 (2.1–3.8)^a,b	2.8 (1–4.3)^a	3.5 (2.5–5)^a,b	3.8 (2.1–5)^a,b
Vacuolization scores	1.7 (0–4.3)^a,b	0.5 (0–3.1)^a	2.7 (0.3–5)^b	2.7 (1–5)^b	1.5 (0–4.5)^a,b	1.4 (0–4.6)^a,b
Fibrosis scores	2.2 (1.3–3)^a,b,c	2.8 (1.7–4)^c	2.7 (1.1–4.6)^b,c	2.7 (1–3.3)^c	1.8 (1.1–2.8)^a,b	1.6 (1–2.1)^a
Immune cell infiltration scores	1.8 (0.1–2.6)^a	2.6 (1.5–3.8)^a	2.3 (1–3.1)^a	1.7 (0–3.3)^a	1.6 (0.1–3)^a	2.2 (1–3.8)^a
Global scores	2.2 (1.2–3.2)^a	2.3 (1.7–3.1)^a	2.4 (1.5–3.3)^a	2.3 (1.5–3.2)^a	1.9 (1–2.7)^a	2.3 (1.4–3.5)^a

Table 3 Pearson correlation coefficients among hepatic metal concentrations and biomarkers. Values in boldface indicate significant correlations at p<0.05.

	Cd	Cu
Glutathione levels	−0.029	−0.070
Superoxide dismutase activity	−0.115	0.141
Catalase activity	−0.009	0.038
Melanomacrophage centre areas	0.048	0.112
Numbers of melanomacrophage centre	0.017	0.406
Nuclear alteration scores	−0.110	−0.159
Vacuolization scores	0.212	0.054
Fibrosis scores	0.462	0.142
Immune cell infiltration scores	0.127	−0.113
Global scores	0.270	0.017

Fig. 5  (a) Catalase activity (CAT), (b) glutathione levels (GSH) and (c) superoxide dismutase activity (SOD) in the livers of brown trout from three Kerguelen Island morphotypes: river (n=17), lake (n=20) and station (n=21). Bars represent mean±SD of biomarker levels measured in the whole sample, in the liver of females and males in each morphotype. The different letters indicate significant differences in biomarker levels measured in the whole sample between the three morphotypes (Kruskal–Wallis test).