SEAWEED DISTRIBUTION AND BIOMASS IN A MANGROVE OF BAÍA DA BABITONGA, SC: PRELIMINARY RESULTS

Abstract

This work aims to assess distribution and biomass of epiphyte macroalgae of mangrove roots in the Babitonga Bay. The macroalgae were collected monthly in three topographyc levels into the mangrove (Places A, B and C). In each place the collect was stratified in the trees (0 to 10 cm high, 10 to 20 cm , etc). The observed Rhodophyta, from higher to smaller biomass, were: Bostrychia calliptera, Bostrychia pinnata, Bostrychia radicans f. radicans, Bostrychia montagnei, Catenella caespitosa, Caloglossa leprieurii, Bostrychia tenella, Caloglossa ogazawaraensis, Bostrychia radicans f. moniliforme, Bostrychia moritziana, Polysiphonia howei, Bostrychia binderi, Gelidium spp., Polysiphonia tepida. The observed Chlorophyta were: Bloodleopsis pusilla, Cladophoropsis membranacea, Rhizoclonium spp., Ulvaria oxysperma, Enteromorpha spp. There are strong variation on horizontal and vertical biomass and on contribution of each species to total biomass. In the mangrove fringe (place A) the algae occur from 0 to 60 cm high in the trees, the mean biomass along this high varies 30 and 45 g m-2 of substrate. Higher values of biomass occur between 10 and 30 cm high, rising to 75 g m-2. On place B (intermediate tidal flooding) the algae occur from 0 to 30 cm high in the trees, the mean biomass along this high varies 20 and 30 g m-2 of substrate. Higher values of biomass occur between 0 and 10 cm high (50 g m-2 of substrate), but high values may also occur between 10 and 20 cm high. In the inner mangrove (place C) the algae occur from 0 to 20 cm high in the trees, the mean biomass along this high varies 10 and 20 g m-2 of substrate. Like place B, higher values of biomass occur between 0 and 10 cm high (35 g m-2 of substrate), but high values may also occur between 10 and 20 cm high. The green algae, Bloodleopsis pusilla, Cladophoropsis membranacea, Rhizoclonium, and the red algae, Bostrychia montagnei, Caloglossa leprieurii and Caloglossa ogazawaraensis were mainly present from 0 to 10 cm high, and rarely occur above 20 cm. Bostrychia radicans f. radicans presents the most broad distribution, has the higher frequency of occurrence in all places and all strata, and it is the main algae in the upper strata. The higher values of biomass, specially on place A, are due to Bostrychia calliptera and Bostrychia pinnata. This two algae also have a broad vertical and horizontal distribution, but they have higher values from 10 to 30 cm high. The results found until now suggest that macroalgae may be an important component of mangrove primary production. Meanwhile, to evaluate the mangrove magroalgae biomass, we need to include algae epiphytic on pneumatophores. And to evaluate the contribution of these algae to the total primary production of the mangrove, it will be necessary to complement biomass data with ecophysiological experiments, including the responses of growth and photosynthetic rates to environmental factors.