Spatial and seasonal microphytobenthos primary production in a subtropical intertidal flat, Paranaguá Bay, Paraná - Brasil

Abstract

The microphytobenthic primary production and biomass were measured on the intertidal fiat of the Rasa da Cotinga island, eurihaline sector of Paranaguá Bay, during four neap tides of autumn-winter of 1996 and spring-summer of 1996/1997. The eight in situ experiments were carried with benthic chamber and the primary production was measured by dissolved oxygen variation in two light and two dark incubations. The null hypothesis about no significant differences among the periods(season) and the environmental gradient (spatial) in the intertidal fiat was tested byone and two way ANüVAs. Photosynthetic Active Radiation - PAR was measured at each sampling site. The biomass was higher in the autunm-winter than springsummer, while the primary production and PAR were higher in the spring-summer. All variables showed an increase gradient from lower region, above 1 meter isobath, to median and upper region of the intertidal fiat. The importance of this community in the Paranaguá Bay estuarine system was discussed.