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Salinity effects on osmoregulation and growth of the euryhaline flounder Paralichthys orbignyanus

Salinity 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

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Salinity effects on osmoregulation and growth of the euryhaline flounder Paralichthys orbignyanus

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  1. Salinity 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

  2. Introduction

  3. Paralichthys orbignyanus • Family : Paralichthyidae • Order : Pleuronectiformes • Class : Actinopterygii • Max. 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; 23°S - 41°S

  4. 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.

  5. Materials and methods • Osmo- and ionoregulatory studies • Growth studies

  6. Isosmotic point(等滲點): 血漿中滲透壓與外界滲透壓相等的點。 • Isoionic point(等離子點): 血漿中離子濃度與外界離子濃度相同時的點。 如果魚生活在水中的鹽度,可以達到等滲點鹽度或是 等離子點鹽度,魚就不用在耗費太多的能量調節滲透 壓與離子濃度,也可以達到比較高的成長率。

  7. Osmo- and ionoregulatory studies Cassino Beach(32∘S,52∘W)

  8. 馴養5天 馴養3天適應鹽度分 別為0‰,10‰20‰, 30‰and 40‰ 實驗飼養15天 Average weight=176.0±19.5g 取出樣本 上升到50℃加速曝氣 自來水(0‰) 濃縮海水(50‰) 1000-l 鹽度維持在33‰ 22±1°C海水 12L/12D 餵食活的鯔科仔稚魚 300-l Six fish per tank 餵食活的鯔科仔稚魚 每天以虹吸的方 式抽出排泄物, 更換50%的水。

  9. 在不同鹽度中馴養15天後的魚,以50ppm benzocain (苯坐卡因)麻醉,抽出1ml 的血,離心後,將血漿保存 在液態氮中。 Osmotic analysis Ionic analysis Anion (Cl-)利用 titration (滴定法) Cations(Na+,k+,Ca2+)

  10. Growth studies 500-l 鹽度維持在30‰ 500-l 鹽度維持在30‰ 放置一星期使比目魚適應鹽度 定量餵食 X2 500-l 在一星期內逐漸適應 鹽度降到0‰ • 14 flounders per group. • Water temperature was kept within • 22±1°C. • 12L/12D • 一天餵食4次. • 排泄物以虹吸方式抽出,每日換水 • 30 %. X2

  11. (天) 90 0 30 60 麻醉,測量 體長、重量, 取出腮及血 麻醉,測量 體長、重量 麻醉,測量 體長、重量 麻醉,測量 體長、重量 Specific growth rate (SGR) =[( ln wf - ln wi ) / t x 100] wf = final weight (g) wi = initial weight (g) t = time (days). EX : wf = 38.85 (g) wi = 29.19 (g) t = 30 (天) SGR = [( ln38.85 - ln 29.19 ) / 30 x 100] = 0.953 %

  12. 2 ml (250mM sucrose 20mM EDTA and pH 7.4 Tris- HCl buffer) • Blood:Osmolality and ionic composition (Na+ and Cl- ). • Gill:Na+,k+ ATPase Bianchini and Castilho (1999) Castilho et al. (2001) 腮絲 3°C 1000 x g for 20min Glass Teflon Potter homogenizer

  13. Results • Osmo- and ionoregulatory studies • Growth studies

  14. Osmo- and ionoregulatory studies 增加

  15. Isosmotic point = 328.6 mOsm kg-1相當於10.9 ‰

  16. Isoionic point =210.8 mEq l-1 相當於11.6 ‰

  17. Isoionic point = 136.8 mEq l-1 相當於8.4 ‰

  18. Isoionic point = 5.41 mEq l-1 相當於22.6 ‰

  19. Isoionic point = 5.21 mEq l-1 相當於15.7 ‰

  20. 可推估Paralichthys orbignyanus是廣鹽性的魚類。

  21. Growth studies • No 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.

  22. Discussion

  23. Stenohaline freshwater teleosts Stenohaline marine teleosts • The isosmotic point of P. orbignyanus was estimated as 328.6 mOsm kg-1 H2O and corresponded to 10.9‰ salinity. 260 mOsm kg-1H2O 330 mOsm kg-1H2O 370 mOsm kg-1H2O 480 mOsm kg-1H2O P.orbignyanus 321 mOsm kg-1H2O ( 0 ‰ ) 370 mOsm kg-1H2O ( 40 ‰ )

  24. It is described that environment stressors such as salinity can effect fish growth (Borski et al.,1994). 淡水中P.orbingnyanus的成長率比海水中P.orbingnyanus的成長率小。

  25. Conclusions

  26. 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.

  27. ~The end~ Thank you for your attention

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