Population biology of Durvillaea antarctica and Lessonia nigrescens (Phaeophyta) on the rocky shores of southern Chile

Abstract

The Lessonia nigrescens-Durvdlaea antarctica belt is a characteristic feature of the lower intertidal zone along the Chilean coast. This study describes the dynamics of the Lessonja-Durvillaea assemblage in an exposed locality of southern Chile. Abundance, spatial and ten~poral distribution, reproductive penods and response to experimental pruning were quantified. The results revealed differences in population dynamics between species. L. nigrescens had low recruitment, but a longer life expectancy. In contrast, D. antarctica had great temporal fluctuations in abundance, which were associated to massive recruitment during the warmer seasons. It occupied zones where old L. nigrescens individuals were dislodged by wave action. Replacement of D. antarctica by L. nigrescens was not seen. Regeneration from pruned plants of the 2 species was evident during the first months, but subsequently, deterioration of the regenerated parts was seen, leading to the degeneration and detachment of the whole plant. Thus, for management plans, the total removal of old individuals would be preferable.