Foraminiferal zonation from a subtropical mangrove in Bertioga Channel (São Paulo, SP, Brazil)

Abstract

This study focus on foraminiferal distribution is from two intertidal mangrove ecosystems is located in the Bertioga Channel (São Paulo, Brazil) and its correlation to environmental gradients. Despite of its vicinity to Sao Paulo and Santos cities, the most populated regions in the country, Bertioga Channel is still partially pristine showing that the balance between fresh water and marine waters still provides natural estuarine variability, which are responsible for the foraminiferal zonation of agglutinated species. The zonation mainly relates to tidal influence, where Haphlophragmoides wilberti inhabits less saline environments than Arenoparrella mexicana. The mangrove located closer to the northern mouth of the Bertioga Channel is a more saline environment with higher numbers of dead calcareous species, evidencing greater tidal influence than the mangrove located near the southern mouth. Distribution of Bolivina striatula and Pararotalia sp, demonstrate a greater marine influence in the Crumaú River than in the Trindade River. Here we show what and why the differences between foraminiferal associations from two mangroves and surroundings are taking place in the recent environment establishing a baseline of understanding paleoclimate alterations and sea level changes.