Taylor J C., Miller J M.
Department of Zoology, Campus Box 7617, North Carolina State University, 27695, Raleigh, NC, USA
J Exp Mar Biol Ecol. 2001 Apr 15;258(2):195-214. doi: 10.1016/s0022-0981(01)00215-5.
Dissolved oxygen (DO) is proving to be one of the most important abiotic factors determining growth and survival of juvenile estuarine fish. In shallow, throughout estuarine systems, low DO can occur in two broad categories: a diel oscillating pattern resulting in repeated nocturnal hypoxia due to the photosynthesis-respiration cycle of algal populations, or as prolonged bottom water hypoxia or anoxia caused by stratification. A series of laboratory experiments was conducted to characterize the physiological performance of juvenile southern flounder, Paralichthys lethostigma, (55-65 mm TL) exposed to four treatments of DO: (1) constant normoxia (6.50+/-0.50 mg O(2) l(-1)), (2) constant hypoxia (2.79+/-0.19 mg O(2) l(-1)), (3) constant intermediate hypoxia (4.74+/-0.18 mg O(2) l(-1)), and (4) an oscillating oxygen environment cycling dielly between the normoxic and hypoxic levels (2.8-6.2 mg O(2) l(-1), daily mean=4.40 mg O(2) l(-1)). Routine respiration was positively correlated with DO level and increased significantly during the day in the oscillating treatment in response to increasing DO. Ventilation rates were negatively correlated with the DO level in the constant treatments and increased significantly at night in the oscillating treatment in response to nocturnal hypoxia. Similarly, hematocrit levels were negatively related to DO levels in the constant treatments after 5 and 26 days of exposure to the treatments. Hematocrit levels also increased significantly the oscillating treatment, apparently in response to the episodic nocturnal hypoxia. Growth was significantly reduced in the 2.8 mg O(2) l(-1) treatment and the oscillating treatment but not in the 4.7 mg O(2) l(-1) treatment. Acclimation was evident by an increase in growth rates from week 2 to week 3 and a decrease in hematocrit levels between 5 and 26 days of exposure in the 2.7 and 4.5 mg O(2) l(-1) treatments but was not evident in the normoxic or oscillating treatments. These results suggest that a juvenile fish must remain in even moderately low DO in order for acclimation to occur. The research presented demonstrates that correctly assessing habitat quality in terms of DO requires knowledge of a fish's physiological and environmental history.
溶解氧（DO）已被证明是决定河口幼鱼生长和生存的最重要非生物因素之一。在整个河口系统的浅水区，低溶解氧可分为两大类：一类是由于藻类种群的光合作用 - 呼吸循环导致的昼夜振荡模式，从而造成夜间反复缺氧；另一类是由分层导致的长时间底层水缺氧或无氧。进行了一系列实验室实验，以描述暴露于四种溶解氧处理条件下的南方鲆幼鱼（Paralichthys lethostigma，全长55 - 65毫米）的生理性能：（1）恒定常氧（6.50±0.50毫克O₂/升），（2）恒定低氧（2.79±0.19毫克O₂/升），（3）恒定中度低氧（4.74±0.18毫克O₂/升），以及（4）在常氧和低氧水平之间昼夜循环振荡的氧环境（2.8 - 6.2毫克O₂/升，日均值 = 4.40毫克O₂/升）。常规呼吸与溶解氧水平呈正相关，并且在振荡处理的白天，随着溶解氧增加而显著增加。在恒定处理中，通气率与溶解氧水平呈负相关，而在振荡处理的夜间，由于夜间缺氧，通气率显著增加。同样，在暴露于处理5天和26天后，恒定处理中的血细胞比容水平与溶解氧水平呈负相关。在振荡处理中，血细胞比容水平也显著增加，显然是对夜间间歇性缺氧的反应。在2.8毫克O₂/升处理和振荡处理中生长显著降低，但在4.7毫克O₂/升处理中未降低。在2.7和4.5毫克O₂/升处理中，从第2周到第3周生长速率增加以及在暴露5天至26天期间血细胞比容水平降低表明存在适应现象，但在常氧或振荡处理中不明显。这些结果表明，幼鱼必须处于即使是适度低的溶解氧环境中才能发生适应。所呈现的研究表明，要根据溶解氧正确评估栖息地质量，需要了解鱼类的生理和环境历史。
