Photosynthetic Response of Scandinavian Kelp Forests to Stratospheric Ozone Depletion


Direct quantification of photosynthetic carbon assimilation in seaweeds provides a valuable measure of primary production by these abundant macrophytes. Most photosynthetic studies with macroalgal are based on oxygen evolution. This approach is preferred over traditional C tracer techniques since oxygen electrodes are generally inexpensive and radioactive wastes are not produced. Nevertheless, oxygen techniques do not directly measure carbon assimilation; thus, primary production estimates rely on the conversion of oxygen units to carbon units via a photosynthetic quotient, which may vary depending on physiological state and nutrient status of the alga. Here, I present two methods for measuring photosynthesis in macroalgae, both of which should greatly enhance prospects for photosynthetic research, particularly under field conditions. First, a carbon uptake procedure is described which relies on incorporation of a stable C isotope label. Important advantages of the C method include simplicity of sample processing, avoidance of environmental hazards and restrictions of radioactive C, and ability to be used as a dual tracer with N. Second, I employed a fiber-optic micro-optode system for measurement of dissolved oxygen. The fluorescence-based optodes stabilize quickly (< 15 s), do not consume oxygen, and are simple to set-up and maintain. Oxygen and carbon photosynthesis were assessed concurrently in a light/dark chamber design. Both techniques resolved significant decreases in light-saturated photosynthesis (Pmax)

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@inproceedings{Dunton2002PhotosyntheticRO, title={Photosynthetic Response of Scandinavian Kelp Forests to Stratospheric Ozone Depletion}, author={Kenneth H . Dunton and Jay A. Brandes and Edward J. Buskey and Patrick J. Neale and Tracy A. Villareal and Harlan Laurence Miller and Felicia H. Goulet-Miller}, year={2002} }