Spatial distribution of pollen grains and spores in surface sediments of Guanabara Bay, Rio de Janeiro, Brazil

Cintia F Barreto,Claudia G Vilela,Ortrud M Barth,José A Baptista-Neto

doi:10.1590/s0001-37652012005000049

Abstract

Aiming to investigate the deposition of pollen grains and spores in Guanabara Bay, Rio de Janeiro State, 61 surface sediment samples were analyzed. The results showed that the current deposition of palynomorphs in surface sediments of Guanabara Bay represents the regional vegetation of this hydrographic basin. The differential distribution of palynomorphs followed a pattern influenced by bathymetry, tidal currents speed, discharge of numerous rivers, and by human activity. The dominance of representatives of Field Vegetation reflects the changes of the original flora caused by intense human activities in the region. The continued presence and richness of pollen types of rain forest in the samples indicates that their source area might be the vegetation from riparian border of rivers in the western sector of the Bay, where the mangrove vegetation is being preserved. The large amount of damaged palynomorphs may be related to abrasion that occurs during river transport, indicating removal or reworking from their areas of origin.

Highlights

Palynological studies are important tools for interpreting the past environments and elucidating questions related to paleoclimates and paleoecology (Ybert et al 1992, Salgado-Labouriau 2001)
The present study offers a better resolution of environmental questions related to modern ecosystems and characterizes the processes of current dynamics that control the deposition and preservation of palynomorphs in distinct sectors of the Guanabara Bay, indicating the best areas to collect sediment cores for future palynological studies
One hundred thirty-one palynomorph types were identified in the 61 surface sediment samples analyzed

Summary

Introduction

Palynological studies are important tools for interpreting the past environments and elucidating questions related to paleoclimates and paleoecology (Ybert et al 1992, Salgado-Labouriau 2001). It is necessary to understand the present environments and the dynamics that controls the deposition of pollen grains and spores before one attempts to interpret the fossil record. Barreto et al (2006) presented a palynological analysis of 27 surface sediment samples of Guanabara Bay and reported that the distribution and accumulation of palynomorphs in the bay were influenced by bathymetry, velocity tide and the intensity of fluvial inputs. Studying a lake with tributaries, Luz et al (2005) verified that fluvial influx, wind action and lakes bathymetry influenced the spatial distribution of pollen grains, spores and algae; an additional control was palynomorph size. Toledo et al (1994) verified that the deposition of palynomorphs was influenced by the bathymetry and wind direction in a lagoon without any tributaries in the northeastern region of the state of Rio de Janeiro

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Discussion

Conclusion