Dinámica poblacional de Eisenia arborea (Laminariales, Ochrophyta) en el intermareal de Punta Eugenia, Baja California Sur, México

Abstract

The population dynamics of Eisenia arborea from the intertidal zone of Punta Eugenia, Baja California Sur, was studied. Eisenia arborea is one of the critical species for the community assemblage in the study area. Sampling was carried out from December 2003 to August 2004. We measured the plant density, growth rate, reproductive season, recruitment and morphometric correlations in the population. Average density was 23 plants m-2, with a significantly maximum in July 2004. The growth rate is seasonal and, in contrast to the finding for other species from Laminariales, the growth rate for E. arborea was much lower. The average was always lower than 0.20 mm d-1. Nevertheless, younger plants showed significant higher growth rates. We found a significant seasonal variation for sori presence. The highest percentage of plants with reproductive fronds was obtained during autumn-winter. The highest number of recruits in the study site was in February 2004. Morphometric correlations between maximum stipe length and perimeter showed a positive trend. This study focuses on the most accessible portion of E. arborea populations. Such marginal parts would be the first ones to be affected by the commercial exploitation, activity that already started.