03344 III Congresso Brasileiro de Oceanografia – CBO’2010 Rio Grande (RS), 17 a 21 de maio de 2010 AOCEANO – Associação Brasileira de Oceanografia SURFACE PALYNOLOGY OF THE INTERTIDAL MARSHES FROM CHUÍ (RS, BRAZIL): NON-POLLEN PALYNOMORPH DIVERSITY Medeanic, S. 1 ; Costa, C. S. B. 2 1 Institute of Oceanography, FURG, Av. Itália km 08, Rio Grande, CEP 96.201-900, RS, Brasil, e-mails: svetlana.medeanic@ufrgs.br, docosta@furg.br. ABSTRACT The eight samples from the surface sediments of the salt marshes in the Chui area (extreme southern Brazil were studied by palynological analysis. Besides pollen and spores of vascular plants, non-pollen palynomorphs (NPPs), represented by microalgae of Chlorophyta, cysts of acritarchs and dinoflagellates, microforaminifers and fungal palynomorphs were identified. The diversity of palynomorph taxa, their frequency and abundance from the samples varied, depending on salinity, granulometry of sediments and vegetation cover. Analysis of NPPs discovered various taxa: Botryococcus, Spirogyra, Operculodium, Spiniferites, Micrhystridium, Glomus, and Tetraploa aristata, composing specific palynomorph assemblages, characterized surface sediments of intertidal marshes. Described assemblages of NPPs from the surface sediments of intertidal marshes may be easily recognized from the Quaternary samples of the cores, indicating spreading of intertidal marshes and their taxonomic variety in the past. Keywords: Palynomorphs, salt marshes, Rio Grande do Sul, Brazil INTRODUCTION Intertidal marshes of coastal plains are wide spread whose distribution depends on many factors, along them: frequency of tidal cycles, the weather and topography, the connection with channels, creeks and temporary freshwater influxes (CHAPMAN, 1974). Intertidal marshes divide in: constantly flooded oligohaline, frequently flooded mesohaline, occasionally flooded, and rarely flooded marshes (COSTA, 1992). The expansion of intertidal marshes in the coastal plain of the Rio Grande do Sul State (RS) began after the last post- glacial transgression event occurred at about 4-5 k years BP. To understand better the history of intertidal marshes (spreading and taxonomic diversity) it is important to make palynological study of the samples from the outcrops and performed cores, dated by isotopic elements. The more precise interpretation of palynological results for the past environment reconstruction should be made using data on surface palynology, based on study of palynomorphs from the surface sediments. Palynomorphs include pollen and spores of terrestrial and aquatic vascular plants, algal palynomorphs, microforaminifers, and fungal palynomorphs. Non-pollen palynomorphs (NPPs) of microalgae of Chrophyta are zygospores, coenobiums and colonies which are very useful for reconstructions of freshwater and brackish- water palaeoenvironments (VAN GEEL, 1976). Cysts of dinoflagellate and acritarchs are indicators of marine environments or aquatic environments, subjected by sea water influence (GRILL & GURSHTEIN, 1995). Microforaminifers (microforaminiferal lining) represent very small chitinous inner tests of foraminifera and are indicative for marine palaeoenvironments (STANCLIFFE, 1989). Fungal palynomorphs (ascospores, fruit bodies, and hyphopodia), composed of chitin are widely applied for palaeoreconstructions (VAN GEEL & APTROOT, 2006). The first preliminary data on palynomorph distribution in the surface sediments of intertidal marshes in the estuarine part of the Patos Lagoon were represented by MEDEANIC (2006). Marine indicators - cysts of acritarchs and dinoflagellates, fungal palynomorphs, and microforaminers were registered from the samples, showing difference from palynomorph assemplages, discovered from the surface sediments of freshwater marshes. In this paper, we represent the detail characteristic of NPPs assemblages, established from the surface sediments of actual intertidal marshes in Chui, RS, Brazil. MATERIAL AND METHODS The chosen for study are is located in Chui region (33 o 44´20´´-33 o 44´40´´S – 53 o 24´00´´- 53 o 22´´30´´W). Five transects corresponded to Oligohaline Low marsh (OLM -