Pollen and spore palynomorph diversity on Rio Grande do Sul inner continental shelf, Southern Brazil

Abstract

Pollen and spore palynomorph diversity on Rio Grande do Sul inner continental shelf, southern Brazil. The knowledge of modern pollen and spore morphology are very important to consistent palynomorph identifications and robust interpretations on past vegetation and climate change. The objective of this work was to describe pollen and spore palynomorph assemblage over Rio Grande do Sul inner continental shelf, to facilitate and improve palynomorph descriptions and interpretations. The Rio Grande do Sul coastal area is NE/SW oriented, extends for over 600 km, and has two inlets, Patos and Tramandaí lagoons. The water masses that influence this region are Subantarctic Shelf Water, Tropical Water and south Atlantic Central Water, beyond two freshwater sources, from Rio de la Plata estuary and Patos lagoon. The wind circulation there is strongly seasonal, predominantly NE during summer and SW during winter. The surface sediments were sampled in two sites: (i) 48 samples from Balneário Hermenegildo (REMPLAC Project) and (ii) 5 samples from ‘Amazônia Azul’ Project, at Patos lagoon inlet area. We have identified the following families: one family of Bryophyta: Anthocerothaceae; eight families of Pteridophyta: Blechnaceae, Cyatheaceae, Equisetaceae, Lycopodiaceae, Ophioglossaceae, Osmundaceae, Pteridaceae and Polypodiaceae; three families of Monocotyledons: Arecaceae, Cyperaceae and Poaceae; and seven families of Eudicotyledons: Amaranthaceae, Asteraceae, Betulaceae, Fabaceae, Melastomataceae, Typhaceae and Verbenaceae. Almost all registered taxa represent the coastal vegetation from Rio Grande do Sul, except for Betulaceae (Alnus), representing montane forests, with anemophilous pollination and transported for long distances.