Aspectos populacionais de Sargassum vulgare C. Agardh (Ochrophyta, Fucales) na Ponta do Arpoador - Rio de Janeiro

Abstract

Sargasssum vulgare C. AGARDH POPULATION DINAMIC (OCHROPHYTA, FUCALES) FROM PONTA DO ARPOADOR – RIO DE JANEIRO. A population of Sargassum vulgare C. Agardh of the rocky coast of Ponta do Arpoador beach (Rio de Janeiro State, Brazil) was studied during three different periods: November 2001–October 2002, December 2002–November 2003, and June 2006–March 2007. The height, weight and reproductive state of the fronds (if juvenile, fertile, or senescent) of the algae were recorded and compared among the three periods. Ten frond samples of S. vulgare were randomly collected over an imaginary line parallel to water level. In the last studied period the extension of the population coverage was estimated by mapping the fronds. Seasonal variations in the height and weight of the S. vulgare fronds were detected, being the greatest fronds observed during the spring/summer period and the smallest fronds observed in the autumn/winter period. The highest percentage of fertile plants was observed during winter and summer. The senescent phase was observed during spring and autumn. The coverage area of the S. vulgare population varied over the year, being greatest in the summer (72.4%) and gradually decreasing into spring (25%). Keywords: Sargassum, population, phenology, Ponta do Arpoador.