Colonization of Ulothrix flacca, Urospora penicilliformis and Blidingia minima (Chlorophyta) in Comodoro Rivadavia harbor (Chubut, Argentina)

Abstract

Coverage of the green algae Ulothrix flacca, Urospora penicilliformis and Blidingia minima was studied on rocky substrata immersed in Comodoro Rivadavia harbor. Colonization was clearly influenced by the level at which stones were immersed. These green algae grew almost exclusively in the intertidal zone, with only traces of B. minima and U. flacca found on subtidal samples. B. minima and U. flacca showed no level preferences within the intertidal. U. penicilliformis had significantly higher coverage at upper than at middle intertidal levels, but this trend varied seasonally. Colonization was also strongly influenced by the season during which substrata were immersed: U. penicilliformis and U. flacca reached maximum coverage during spring and B. minima during winter. Interactions between intertidal level and season were also highly significant for all three species, meaning that the seasonal cycle of colonization showed different trends at different intertidal levels.