The objective of this work was studying the mangrove starting on the coastal plain of Babitonga Bay, southeastern Brazil. A sediment core with 2 m depth was sampled through Russian sampler. Pollen data, sedimentary features, geochemistry data (δ13C, Ntotal e TOC- Total Organic Carbon) were integrated with 14C dating. The deposit started since at least 1.678-1.285 cal yr BP. In this core was possible to distinguish three facies association: i) tidal channel, without mangrove (δ13C = -24,1 a -27,7‰ e C/N 0,59 a 2,24); ii) tidal plain (δ13C = -22,7 a -26,4‰ e C/N = 1,16 a 14,5) which reveals the beginning mangrove development, and 606 cal yr BP until the present: iii) mangrove (δ13C = -22,4 a -25,1‰ e C/N = 13,2 a 47,7) with an apparent expansion of this ecosystem. The data shows that region was marked a climate change during the Late Holocene. The climate change resulted in a mangrove installation/development with first Laguncularia presence. Between 606 cal yr BP until the present was observed a mangrove developing/expansion with biodiversity increasing, due to an Avicennia and Rhizophora presence. The Rhizophora presence is related to the atmospheric temperature increase and/or sea surface temperature. Rhizophora trees show greater sensitivity to low temperatures. In this context, to understanding a mangrove dynamic during Late Holocene becomes a great tool for coastal paleoenvironmental analysis. This ecosystem is a great index of these changes.
|
