Rock pools provide shelter from desiccation and swell during
low tide, but are habitats of extreme environmental conditions in
terms of salinity and temperature. In addition to providing potentially
extreme environmental conditions, the rock pool at Moyrus
was situated in a very exposed location, with regular heavy swells
disturbing the shallow pool. With its extreme high exposure and
additional pressures characteristic of tide pools this study site was
chosen to provide insights into Sargassum muticum ecology at the
presumed limits of its habitat range. Previously, De Paula and De
Oliveira (1982) found morphological differences between populations
of Sargassum cymosum, a related species, growing in
locations with different degrees of wave exposure. Transplantation
experiments suggested genotypic differentiation and a new species
variety was proposed, but the plants were not examined for
physiological differences. Peckol and Ramus (1985) investigated
differences in the physiological traits of Sargassum filipendula of
near-shore and off-shore populations and reported significant differences in chlorophyll a concentrations and photosynthetic
activity between populations.