Anais da Academia Brasileira de Ciências ISSN: 0001-3765 [email protected] Academia Brasileira de Ciências Brasil Barreto, Cintia F.; Vilela, Claudia G.; Baptista-Neto, José A.; Barth, Ortrud M. Spatial distribution of pollen grains and spores in surface sediments of Guanabara Bay, Rio de Janeiro, Brazil Anais da Academia Brasileira de Ciências, vol. 84, núm. 3, septiembre, 2012, pp. 627-643 Academia Brasileira de Ciências Rio de Janeiro, Brasil Available in: http://www.redalyc.org/articulo.oa?id=32723112025 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Anais da Academia Brasileira de Ciências (2012) 84(3): 627-643 (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690 www.scielo.br/aabc Spatial distribution of pollen grains and spores in surface sediments of Guanabara Bay, Rio de Janeiro, Brazil 1 2 3 1,4 CINTIA F. BARRETO , CLAUDIA G. VILELA , JOSÉ A. BAPTISTA-NETO and ORTRUD M. BARTH 1 Laboratório de Palinologia, Departamento de Geologia, Instituto de Geociências, Universidade Federal do Rio de Janeiro, CCMN, Ilha do Fundão, 21941-916 Rio de Janeiro, RJ, Brasil 2 Laboratório de Geologia Marinha, LAGEMAR, Instituto de Geociências, Universidade Federal Fluminense, Avenida Litorânea, s/n, 24210-340 Niterói, RJ, Brasil 3 Laboratório de Análise Micropaleontológica, Departamento de Geologia, Instituto de Geociências, Universidade Federal do Rio de Janeiro, CCMN, Ilha do Fundão, 21941-916 Rio de Janeiro, RJ, Brasil 4 Instituto Oswaldo Cruz, Fiocruz, Avenida Brasil, 4365, 21040-000 Rio de Janeiro, RJ, Brasil Manuscript received on February 25, 2010; accepted for publication on March 1, 2011 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. Key words: palynomorphs, surface sediments, deposition, preservation, Guanabara Bay, Brazil. INTRODUCTION The Palynological analysis of Quaternary sedi- Palynological studies are important tools for ments has provided important information about interpreting the past environments and elucidating the past environment in the coastal region of SE questions related to paleoclimates and paleoecology Brazil. Studies have elucidated questions related (Ybert et al. 1992, Salgado-Labouriau 2001). to sea level oscillation and climate changes as well However, it is neces sary to understand the present as to alterations of the natural vegetation as a result environments and the dynamics that controls the of intensive human activities during the Holocene deposition of pollen grains and spores before one (Toledo et al. 1994, Luz et al. 1999, Barth et al. attempts to interpret the fossil record. 2001, 2004, Coelho et al. 1999, Santos et al. 2000). However, pollen studies on surface sediments in lakes Correspondence to: Cintia Ferreira Barreto E-mail: [email protected] and bays that demonstrate the patterns of modern An Acad Bras Cienc (2012) 84 (3) 628 CINTIA F. BARRETO, CLAUDIA G. VILELA, JOSÉ A. BAPTISTA-NETO and ORTRUD M. BARTH pollen deposition and vegetation of this region have The Guanabara Bay extends in the SO-NE not been undertaken to a significant extent. Barreto direction, reaching a maximal width of 28 km et al. (2006) presented a palynological analysis of and a perimeter of 131 km; it possesses a narrow 27 surface sediment samples of Guanabara Bay entrance of approximately 1.6 km width. The bay and reported that the distribution and accumulation surface area, excluding its islands, currently of palynomorphs in the bay were influenced by measures 372 km2. Its hydrographic basin bathymetry, velocity tide and the intensity of fluvial covers approximately 4,600 km2 and includes the inputs. Studying a lake with tributaries, Luz et al. metropolitan regions of the cities of Rio de Janeiro, (2005) verified that fluvial influx, wind action and Duque de Caxias, Niterói and São Gonçalo. There are lakes bathymetry influenced the spatial distribution 45 rivers that discharge in the bay, the Macacu and of pollen grains, spores and algae; an additional Caceribu being the most important ones (Amador control was palynomorph size. Toledo et al. (1994) 1997, Kjerfve et al. 1997). The Guanabara Bay tides verified that the deposition of palynomorphs was are classified as semidiurnal, with one complete tidal influenced by the bathymetry and wind direction in cycle of about 12.5 hours (Amador 1997). a lagoon without any tributaries in the northeastern The bathymetry of the Guanabara Bay is region of the state of Rio de Janeiro. influen ced mainly by the tides. The narrow entrance It is necessary to understand the processes that of the bay is occupied by a big sandy bank that control the preservation, transport and deposition extends upwards from the bay floor to a height of 12 of pollen grains and spores in aquatic environment m. This bank promotes the channelization of water in order to obtain an accurate interpretation of flow and is also an obstacle to the tidal circulation. pollen occurrence. The present study offers a better The central channel of the bay has a S-N orientation resolution of environmental questions related to starting at the bay entrance until the Governador modern ecosystems and characterizes the processes Island and accounts for the deep depths in the bay of current dynamics that control the deposition and (around 30 and 40 m deep). The dominant sediments preservation of palynomorphs in distinct sectors of in the channel are medium to very fine sands. The the Guanabara Bay, indicating the best areas to collect innermost part of the bay (i.e., the north region) sediment cores for future palynological studies. has smooth, flat bathymetry (less than 10 m) and a high sedimentation rate. Its sediments are primarily STUDY AREA silt/clay (Amador 1992, 1997, Dias and Quaresma 1996, V.S. Quaresma, unpublished data, Kjerfve et The Guanabara Bay is located in the coastal area al. 1997, L.F. Catanzaro unpublished data). of Rio de Janeiro State – Southeast Brazil, between The climate of the Guanabara Bay region is 22°40’ - 23°00’S of latitude and 043°00’ - 043°20’W tropical humid with a well - defined rainy season of longitude (Figure 1). It lies within a depressed and between December and April, and a dry season elongated tectonic band of Tertiary age known as between June and August (Denemet 1992). The “Baixada Fluminense” or Guanabara Rift, of the half- mean annual air temperature is 23.7°C, and the graben type (Ruellan 1974, Ferrari 1990, Amador mean annual relative humidity is 78%, with an 1997). Its origin is also related to climatic and sea annual average precipitation higher than 2,000 mm level changes that occurred during the Quaternary over the Serra do Mar hills, and 1,000 to 1,500 and that resulted in the drowning of a Pleistocene mm in the lowlands (Baixada Fluminense region) fluvial valley (Amador and Ponzi 1974, Ireland (Amador 1997). The winds most frequently blow 1987, Amador 1992, 1997, Martin et al. 1997). from the east (21% of the time), south (17%) and An Acad Bras Cienc (2012) 84 (3) POLLEN DISTRIBUTION SEDIMENTS OF GUANABARA BAY 629 Figure 1 - Map of the study area showing the location of the surface sediment samples and the different sectors of the Guanabara Bay (Vilela et al. 2003). north (14%), with a mean velocity of 3 m/s in the recognized in the area. A phytosociological survey Santos Dumont Airport area (Kjerfve et al. 1997). conducted by Guedes (1988) in the Magé municipality, A Tropical Rain Forest (Mata Atlântica) is 15 km away from the Guanabara Bay, recorded considered as one of the richest ecosystems. This the following predominant plant associations: an vegetation is preserved mainly in forest reserves and herbaceous stratum of Aphelandra (Acanthaceae), on the mountain slopes (Radambrasil 1983, Veloso et Dorstenia (Moraceae), Heliconia (Heliconiaceae), al. 1991). According to Veloso et al. (1991) vegetation Olyra (Poaceae), Pfaffia (Amaranthaceae) and types such as Ombrophilous Forest (“Floresta Polygala (Polygalaceae); a shrub stratum of Eugenia Ombrófila”), Mountain Forest (“Floresta Montana”) (Myrtaceae), Faramea (Rubiaceae), Miconia and Field Vegetation (“Vegetação Campestre”) were (Melastomataceae), Myrcia (Myrtaceae), Ouratea An Acad Bras Cienc (2012) 84 (3) 630 CINTIA F. BARRETO, CLAUDIA G. VILELA, JOSÉ A. BAPTISTA-NETO and ORTRUD M. BARTH (Ochnaceae), Psychotria (Rubiaceae) and Rudgea LABORATORY ANALYSIS (Rubiaceae); and an arboreal stratum of Aniba The samples were chemically treated according to (Lauraceae), Aparisthimium (Euphorbiaceae), Euterpe the standard methodology for Quaternary sediments (Arecaceae), Guapira (Nyctaginaceae), Guarea proposed by Ybert et al. (1992). This includes the (Meliaceae), Newtonia (Leguminosae-Mimosoidea), use of 10% of HCl for the elimination of carbonates, Pera (Euphorbiaceae), Sebastiania (Euphorbiaceae) followed by 40% HF for elimination of silicates, then and Tapirira (Anacardiaceae). the acetolysis and heavy liquid separation using a The Mangrove vegetation occurs in the inner- ZnCL2 (density = 2).