Dinâmica dos manguezais do litoral de Natal-RN de acordo com as mudanças no clima e nível do mar desde o Holoceno médio

Abstract

The factors behind the Holocene mangrove dynamics have long been a theme of great interest for research. Among all hypotheses, the establishment, expansion, and contraction of mangrove areas have been mainly attributed to sea level and climate changes. However, other driving forces of limited occurrence in time may be significantly affecting this system. Along the valley of the Ceará Mirim river, near the Natal city, Rio Grande do Norte littoral, northeastern Brazilian the integrate geomorphological, sedimentological, and palynological data with radiocarbon dating, as well as δ13C, δ15N and C/N from sedimentary organic matter from four sediment cores reveal an estuarine influence with mangrove development since 6950 cal yr BP after the post-glacial sea level rise, and it has been stable during the middle and late Holocene. The mangrove expansion along this fluvial valley since the middle Holocene was caused by the sea-level stabilization. The multi-proxies indicate a wetland dynamic was mainly controlled by autogenic factors, relating to tidal channel migrations on the muddy tidal flats formed after the channel abandonment provide suitable conditions for expansion of vegetation surrounding, instead of allogenic process, associated to sea level and/or climate change. Probably, some influence of sea-level and climate changes on mangrove dynamics along in this valley of the Ceará Mirim river have been weakened by the intense tidal channels activities since middle Holoceno.