salinity effects on osmoregulation and growth of the euryhaline flounder paralichthys orbignyanus
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DESCRIPTIONSalinity effects on osmoregulation and growth of the euryhaline flounder Paralichthys orbignyanus. 鹽度對廣鹽性比目魚 Paralichthys orbignyanus 之 滲透壓調節與成長影響. Introduction. Paralichthys orbignyanus. Family : Paralichthyidae Order : Pleuronectiformes Class : Actinopterygii - PowerPoint PPT Presentation
Salinity effects on osmoregulation and growth of the euryhaline flounder Paralichthys orbignyanusParalichthys orbignyanus
Lui's Andre Sampaioa , Adalto Bianchinib,*
Journal of Experimental Marine Biology and Ecology269(2002) 187-196
Paralichthys orbignyanusFamily : ParalichthyidaeOrder : PleuronectiformesClass : ActinopterygiiMax. size:50.0 cm NG (male/unsexed; Ref. 36453); 38 cm TL (female) Environment:demersal; oceanodromous (Ref. 51243); brackish; marine; depth range 1 45 m Climate: subtropical; 23S - 41S
Distribution: Coastal and estuarine waters of Western South Atlantic Ocean (Brazil , Uruguay and Argentina)High market price. Wide tolerance to environmental factors such as salinity(0-40), pH , and nitrogenous compounds and acid stress.
To evaluate the effect of hypo-(freshwater) and hyperosmotic (seawater) conditions on survival and growth.
Materials and methodsOsmo- and ionoregulatory studiesGrowth studies
Osmo- and ionoregulatory studiesCassino Beach(32S,52W)
530,1020,30and 4015Average weight=176.019.5g
300-lSix fish per tank
1550ppm benzocain()1ml Osmotic analysisIonic analysisAnion (Cl-)titration()Cations(Na+,k+,Ca2+)
X2X214 flounders per group.Water temperature was kept within 221C. 12L/12D4. 30 %.
Specific growth rate (SGR) =[( ln wf - ln wi ) / t x 100]wf = final weight (g)wi = initial weight (g)t = time (days).
0306090EX wf = 38.85 (g)wi = 29.19 (g) t = 30 ()SGR = [( ln 38.85 - ln 29.19 ) / 30 x 100] = 0.953 % ()
BloodOsmolality and ionic composition (Na+ and Cl- ).GillNa+,k+ ATPaseGlass Teflon Potter homogenizer
2 ml (250mM sucrose 20mMEDTA and pH7.4 Tris- HClbuffer)3C 1000 x g for 20minBianchiniand Castilho (1999)Castilho et al.(2001)
ResultsOsmo- and ionoregulatory studiesGrowth studies
Osmo- and ionoregulatory studies
Isosmotic point = 328.6 mOsm kg-1 10.9
Isoionic point =210.8 mEq l-111.6
Isoionic point = 136.8 mEq l-1 8.4
Isoionic point = 5.41 mEq l-1 22.6
Isoionic point = 5.21 mEq l-115.7
Growth studiesNo significant between replicates for both flounder survival and growth over 90-day test.Survival was not significantly affected by salinity, since, at the end of the 90-day test, it was 92.9 % in both freshwater and seawater.
The isosmotic point of P. orbignyanus was estimated as 328.6 mOsm kg-1 H2O and corresponded to 10.9 salinity.
Stenohaline freshwater teleostsStenohaline marine teleosts260 mOsm kg-1H2O330 mOsm kg-1H2O370 mOsm kg-1H2O480 mOsm kg-1H2OP.orbignyanus321 mOsm kg-1H2O( 0 )370 mOsm kg-1H2O( 40 )
It is described that environment stressors such as salinity can effect fish growth (Borski et al.,1994).P.orbingnyanusP.orbingnyanus
Paralichthys. orbignyanus 0 40 Paralichthys. lethostigmaSouthern flounder 0 Paralichthys.dentatusSummer flounder 5 50
P. orbignyanus can be characterized as a marine/estuarine euryhaline teleost capable of carrying hyper/hypo iono- and osmoregulation over the fluctuating salinity regime faced by this species in the environment.Long-term exposure to freshwater induces a reduction in growth rate of P. orbignyanus, possibly due to an increase in energy expenditure associated to the osmo- and ionoregulation under this salinity condition.
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