Identification of palynomorphs sampled from a sedimentary profile of the last 5000 years in Lagoa dos Patos, Rio Grande do Sul, southern Brazil.

Abstract Lagoa dos Patos, the largest lagoon in South America, lies on the coastal plain of Rio Grande do Sul state, southern Brazil. This region forms a transition area between the tropical and subtropical zones of South America. Rio Grande do Sul coastal plain extends over 600 km and is affected by climate changes and sea level oscillations. Lagoa dos Patos is limited to the east by the Atlantic Ocean and to the west by terrain containing granitic and metamorphic rocks. The lagoon is 250 km long, with a maximum width of 60 km and an average depth of 6-7 m. We describe and illustrate 23 palynomorph taxa from six fungi, nine algae, two acritarchs, three bryophytes, as well as three other palynomorphs - platyhelminth eggs, mandible fragments, microforaminifera - preserved in a 2.125-m-long Holocene sediment core (T25) sampled from the lagoon (30º50'51"S-50º59'06"W), which corresponds to the last 5,000 years. After acetolysis, the palynomorphs were analyzed by light microscopy. This study presents the first part of a comprehensive description of palynomorphs from this profile, including their photomicrographs and ecological information. Our objective was to provide comparative materials of palynomorphs for paleoenvironmental reconstructions of Quaternary environments on the southern Brazilian coastal plain.