Microphytobenthos biomass assessment in mangrove forests in the Santos Estuarine System (SP, Brazil) Claudio Parreira Almada Rezende, João Marcos Miragaia Schmiegelow

Abstract

The microphytobenthos forms an important primary producers community in shallow and intertidal areas, being formed by photosynthetic eukaryotes and cyanobacteria algae that live in the substrate. They are poorly studied in Brazil – in Santos estuarine system there is very few information about this group. The biomass of this community was assessed in seven fringe mangrove forests, where were also obtained data of interstitial salinity, soil compaction degree, organic matter content and soil moisture. Other environmental data were used from another study in the region as the phytosociology, litter production and particle size of the substrate of the mangrove forests. The average value of chlorophyll-a for all sites studied was equal to 13.52 ± 6.14 μgCl-ag-¹ showing no statistical difference between studied areas. The phaeopigments average value was 57.22 ± 30.19 μgFeo-ag-¹ showing some statistical differences between the studied areas. The highest average value for chlorophyll-a and phaeopigments ratio was 1.07 ± 1.50, while the lowest average value was equal to 0.13 ± 0.01, with no significant statistical difference between the areas. The only correlation (Spearman) between chlorophyll-a and phaeopigments with phytosociology and litter production of mangrove forests and environmental descriptors was the chlorophyll-a/ phaeopigments ratio with the soil moisture, being negative. This study contributes to a better understanding of the microphytobenthos community in Brazilian estuarine areas.