Nitrogen content in the brown alga Fucus gardneri and its relation to light, herbivory and wave exposure

Nitrogen is a necessary element for much of seaweed physiology, and is the most common limiting nutrient for marine macroalgae. Therefore, the content of nitrogen in algal tissue is often considered a useful indicator of algal productivity. However, the significance of algal nitrogen content in the field is understudied. We used a factorial manipulation of light and herbivory at three sites in order to evaluate how three factors (light, herbivory, wave exposure) affect the nitrogen content of the brown alga Fucus gardneri. We found that nitrogen content was a function of (1) nitrogen supply via amount of water flow and (2) irradiance, possibly via photoinhibitory effects. This research shows that local effects, by shifting nutrient allocation, can change nitrogen content over spatial scales of centimeters.