Photosynthetic characteristics of nine species of marine macroalgae on the east coast of Scotland in relation to the intertidal position in which they occur.

Upper shore algal species naturally subjected to longer periods of desiccation had higher photosynthetic efficiency (fluorescence characteristics), net photosynthetic rates and dark respiration rates (based on oxygen exchange), whilst hydrated, than those lower down the shore. The possible significance of these physiological differences are discussed within the context of a time use efficiency conceptual framework. There would appear to be a trend towards an increase in time use efficiency in species that have less time available for productivity or nutrient uptake due to increased desiccation, as a result of their position on the shore, compared to those species lower down the shore. Functional differences would appear to be related to position on the shore.