Living benthic foraminiferal assemblages monitored monthly in a tide-dominated estuary, Bertioga Channel, Brazil

Abstract

Monitoring studies to characterize coastal environments and/or describe the direct impact of pollutants on foraminiferal fauna must be based on the living assemblages. The aim of this study is to review a benthic foraminifera dataset of a bio-monitoring work performed in Bertioga Channel region (Sao Paulo State) from April of 1999 until March of 2000 by following some of the FOBIMO recommendations. The Bertioga Channel is an estuarine system dominated by tide which may influence the foraminifera fauna. Six distinct stations were selected and sampled monthly during a year. To the faunal analysis, a fixed volume of sediment (50 cm3) was washed through a sieve with 63 µm openings. The foraminifer specimens were picked up and identified. The living fauna showed that Ammonia tepida and Cribroelphidium spp. were the most frequent taxa in almost all stations and during all the monitoring study. Agglutinated species such as Arenoparrella mexicana and Haplophragmoides wilberti were found mainly in the inner portions of the channel. Typical species of marine and paralic environments such as Pararotalia cananeiaensis and Pseudononion japonicumj were found in both entrances of the channel. The living foraminifera abundance and species richness are related to the circulation patterns in this estuarine system with occurrence of opportunistic species near the its entrance closer to impacted areas (Santos Channel), eurihaline in the eastern entrance and mixohaline species in the inner portions of it.