Microphythobentos: their ecological and geomorphological role

DA RODDA, C; PARODI, E.R

Bahía Blanca

Congreso; ECSA 44; 2008

Estuarine and Coastal Sciences Association

. This study aimed to understand the ecological and geomorphological implications of the microphytobenthos of a muddy salt marsh in the Bahía Blanca Estuary (Argentina). The microphytobenthic assemblage was sampled by scrapping the upper 1 cm of the sediment at low tide, and was analyzed with light microscope and scanning electron microscope, in a temporal sequence. The early assemblage structure was described by characterizing the substrate and by estimating both relative abundance and ecological strategy of each kind and size species. The initial colonizers of deposited sediments would be opportunist diatoms. These constituted biofilms that have been shown to enhance the retention of sediments by production of EPS as they can move through the substrate to the surface. These species that altered the habitat were successively replaced by others diatoms and then by cyanobacterias. The last species that should be incorporated were attached diatoms (i.e. Navicula exigua, Cymbella spp.) and sheathed filamentous cyanobacteria (Microcoleus chthonoplastes), which occurred in mature mats like that which they were originated. Assemblages would develop with increasing sediment layer until a community often recovers, and delay the development of a typical saltmarsh macrophyte community. The resulting differences in the micro-topography possibly also enhance a singular stability on the surface sediment beds of these kind of biological structures. Funded by PGI 24B/145 SGCyT-UNS