This work compares the vegetation and morphological changes occurred along the littoral of
the Marajó Island, Amazonian littoral, and the coastal plain of the Rio Doce, southeastern
Brazil, during the Holocene and late Pleistocene/Holocene, respectively, focused specifically
on the response of mangroves to sea-level fluctuations and climate change, which have been
identified in several studies along the Brazilian coast. This integrated approach combined
radiocarbon dating, description of sedimentary features, pollen data, and organic geochemical
indicators (δ13C, δ1₵N and C/N). On coastal plain of the Doce River between ~47,500 and
~29,400 cal yr BP, a deltaic system was developed in response mainly to sea-level fall. The
post-glacial sea-level rise caused a marine incursion with invasion of embayed coast and
broad valleys, and it favored the evolution of a lagoonal/estuary system with wide tidal mud
flats occupied by mangroves between at least ~7400 and ~5100 cal yr BP. Considering the
Marajó Island during the early and middle Holocene (~7500 and ~3200 cal yr BP) mangrove
area increased over tidal mud flats with accumulation of estuarine/marine organic matter. It
was a consequence of the marine incursion caused by post-glacial sea-level rise, further
driven by tectonic subsidence. Dry conditions in the Amazon region during this time led to a
rise is tidal water salinity and contributed to mangrove expansion. Therefore the effect of
relative sea-level (RSL) rise was determinant to the mangrove establishment in the
southeastern and northern region. During the late Holocene (~3050 – 1880 cal yr BP) the
mangroves in both regions were retracted to a small area, with some areas replaced by
freshwater vegetation. This was caused by the increase in river discharge associated to a wet
period recorded in the Amazon region, and considering the coastal plain of the Doce River
(southeastern Brazil), the mangroves shrank in response to an increase in fluvial sediment
input associated to a sea-level fall.
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