SPATIAL AND TEMPORAL DYNAMICS OF ALGAL BIOMASS ASSOCIATED WITH MANGROVE ROOTS IN BUENAVENTURA BAY, PACIFIC COAST OF COLOMBIA

Abstract

The spatial and temporal variation of biomass of mangroveassociated macroalgae growing on roots of Rhizophora. mangle and pneumatophores of Avicennia. germinans were studied at three sampling stations in Buenaventura bay, Colombia, between November 1999 and September 2003. Eighteen species of algae were collected including nine Rhodophyceae, five Chlorophyceae and four Cyanophyta (Cyanobacteria). Four species dominated the algal flora and collectively contributed with 90 % of the total algal biomass. Bostrychia calliptera was the most dominant with 32 % of the total biomass, followed by Boodleopsis verticillata (26 %), Catenella impudica (18 %), and Caloglossa leprieurii (12 %). Algal biomass between seasons showed significant differences, with higher biomass found during the dry season compared to those of the rainy season. The algal biomass at the mouth of the estuary was significantly higher than that found in the inner areas of the estuary (annual means of 30.7 ± 10.8 vs. 13.8 ± 4.1 g m-2 respectively).Three well-defined vertical zones were observed, based on algal biomass: A narrow upper zone, dominated by B. calliptera; a wide middle zone, with mixed populations of C. impudica and B. calliptera, registering annual mean of 86.8 ± 24.1 g m-2, and a bottom zone, dominated by C. leprieurii and B. verticillata. The results indicated that water level inundation and the vertical position along the roots seem to be the most important factors influencing the algal biomass.