Influence of Spartina alterniflora on structure and temporal variability of macrobenthic associations in a tidal flat of Paranagua Bay (southeastern Brazil)

Abstract

The vegetated site was characterized by significantly higher numbers of species, mean densities and faunal dominance. Presence of plant cover affects epifaunal grazers, eg the gastropods Neritina virginea, Littorina flava and the isopod Sphaeromopsis mourei, besides a number of infaunal dominants associated with the root-rhizome mat, eg the polychaetes Isolda pulchella and Nereis oligohalina. Seasonal patterns of change were evident at both sites, with higher macrofaunal densities coinciding seasonally with higher availability of plant litter and lower predation pressure. Macrobenthic populations were generally more persistent at the vegetated site, despite short-term or seasonal variations. At the unvegetated site, intense and unpredictable population shifts were exhibited by the numerical dominants Kalliapseudes schubarti and Corophium acherusicum. Differences in trophic organization were also evident, with a marked dominance of suspension-feeders at the unvegetated sites. -from Authors