Light-Dependent Oxygen Cycling in Marine Systems Measured by 18o Tracer Techniques

Kana博士将讨论海水中“轻呼吸”的一般问题。相当多的直接和间接证据表明，光线可以显著影响氧气消耗：在某些情况下，将氧气消耗率提高到暗呼吸率的10倍。从有机循环的角度来看，这种氧气消耗的刺激意味着什么，由于测量通量和同时发生的至少5种可区分的氧气摄取过程的历史困难，人们知之甚少。Kana博士的实验室最近开发了两种同位素（180）方法，能够测量光照下的氧循环，为解决这一问题提供了基础。该研究协调了河口栖息地光依赖性氧摄取和进化的实地测量，以及从研究地点分离的浮游植物物种的氧循环的受控实验室研究。我们感兴趣的主要变量是浮游植物的组成，由季节周期和光照强度决定。野外实验主要围绕季节和事件尺度现象对氧循环的影响进行，特别是浮游植物对氧循环的影响。实验室实验的中心是确定负责光依赖性氧摄取的生理过程。在一项相关研究中，Kana博士将继续与dr。卡彭特和卡彭在trichodesium中氧循环的研究。

Dr. Kana will address the general question of "light respiration" in marine waters. Considerable direct and indirect evidence indicates that light can significantly affect oxygen consumption: in some cases elevating the rate up to 10 times the rate of dark respiration. What this stimulation of oxygen consumption means in terms of organic cycling is very poorly understood due to the historical difficulty in measuring the fluxes and the simultaneous occurance of at least 5 distinguishable oxygen uptake processes. Recent development in Dr. Kana's laboratory of two isotope (180) methods capable of measuring oxygen cycling in the light provide the basis for tackling this problem. The research coordinates field measurements of light-dependent oxygen uptake and evolution in an estuarine habitat with controlled laboratory studies of oxygen cycling in phytoplankton species isolated from the study site. The major variables of interest are phytoplankton composition, defined by seasonal cycles, and light intensity. Field experiments center around characterizing the effects of seasonal and event scale phenomena on oxygen cycling, especially as mediated by the phytoplankton. Laboratory experiments center around the identification of the physiological processes responsible for light-dependent oxygen uptake. In a related study, Dr. Kana will continue collaboration with Drs. Carpenter and Capone in the study of oxygen cycling in Trichodesmium.