Palynological and microfossil-based environmental reconstruction at 7,147–6,435 cal yr BP of the Lagoa Comprida coastal lagoon in the restinga de Jurubatiba National Park, Rio de Janeiro, Brazil

Abstract

The restinga vegetation and environment dynamics during the Mid-Holocene have been reconstructed through microfossil analysis of a 153 cm-long core from the Lagoa Comprida coastal lagoon of the Parque Nacional Restinga de Jurubatiba (Restinga de Jurubatiba National Park), in the State of Rio de Janeiro, Brazil. The analysis was supported by core stratigraphy, 14C dating, and evaluation of microfossil frequency and concentration. Core sediments were dated from ∼7,147 to 6,435 cal yr BP. Four zones of environmental changes were characterized. A high concentration of marine diatoms was recorded in the basal portion of the core, suggesting possible sea-water influence, corroborating a Holocene Marine Transgression event. The marine diatoms disappeared from the record before ∼7,005 cal yr BP when a major inflow of freshwater began. Palynoforaminifers remained until ca. 6,470 cal yr BP, revealing a mixohaline environment. The restinga vegetation was present in the surroundings from the beginning of the record. The open-scrub plant community was predominant, mainly characterized by Solanum, Borreria, Euphorbia, Pteridium, Garcinia, Guapira and Protium. This plant formation is the most representative vegetation physiognomy in the area nowadays. Clusia lanceolata was well established during the period studied but has since changed its distribution limit to being dominant further south, in the municipality of Maricá.