Dissolved oxygen regimen (PO₂) may affect osmo respiratory compromise in European sea bass (Dicentrarchus labrax, L.)

Figures & data

Figure 1 TRIAL 1: Cumulative Na⁺ efflux from sea bass exposed to a hypotonic environment plus manipulation stress for 60 min. Comparison between groups acclimatized to different PO₂ regimens.

Figure 2 TRIAL 2: Rate of Na⁺ efflux determined for different time intervals in sea bass exposed to hypotonic environment plus manipulation stress. Comparison between groups acclimatized to different PO₂ regimens.

Table 1 TRIAL 2: Na⁺ and Cl⁻ release in water by sea bass acclimatized at two different PO2 conditions, during a 60-min osmotic challenge. Ion concentrations in water are reported at the beginning of the test and after 60 min; water jar volumes were initially 2 L.

	Hyperoxia		Hyperoxia
	Na^+	Cl^-	Na^+	Cl^-
Ion concentration in water at “t0”, mg.L^-1	0.16±0.04	0.22±0.13^b	0.22±0.05^a	0.19±0.05
Ion concentration in water at “;t60”, mg.L^-1	7.00±1.12^c	8.74±1.47^d	15.67±2.79^e	21.09±3.78^f
Fish weight (n=10), g	64.5±13.8		62.4±12.4
Ion release rate, nmol.g^-1.min^-1	76.86±12.79^i	62.02±11.16^l	179.28±32.44^m	157.28± 8.54^n

All the data represent the average of 10 replicates. Comparing boxes reporting for the same ion in water, as well as for ions release, different letters indicate significant differences (P<0.001).

Table 2 TRIAL 2: Trend on concerning blood parameters in D. labrax, previously acclimatized at two different PO₂ conditions, after A 60-min osmotic challenge.

		Hypoxia				Hypoxia
Fish	1	2	3	mean ±SD	11	22	33	mean ±SD
Na+	128.8	116.5	124.3	123.2±1.9	113.5	121.3	112.5	115.7±4.8
K^+	1.59	2.58	1.6	1.92±0.6	2.07	2.39	3.13	2.53±0.5
Cl^-	104.5	99.1	100.5	101.36±2.8	92.3	100.9	78.6	90.6±11.2
pH	7.65	7.46	7.71	7.62+0.1/-0.14	7.52	7.4	7.42	7.45+0.06/-0.07
PO2	15.8	11.4	13.6	13.60±2.2	13.6	23.1	27.7	21.4±7.2
PCO2	10.4	11.8	10.4	10.86±0.8	12.4	19	14.7	15.3±3.3
TCO2	13.9	10.9	15.9	13.56±2.5	12.6	15.3	12.3	13.4±1.6
HCO3	13.2	10.1	15.2	12.83±2.5	11.8	14.2	11.4	12.4±1.5
Tot Hb	10.8	11.2	10.2	10.73±0.5	8.5	10	10.7	9.7±1.1
% Htc	36	37.4	34	35.8±1.7	29.3	33.2	35.7	32.7±3.2