Allogenic and autogenic effects on mangrove dynamics from the Ceará Mirim River, north‐eastern Brazil, during the middle and late Holocene

It is possible that climate changes and sea level fluctuations (allogenic processes) are and will cause major changes in mangrove dynamics. However, other driving forces may be significantly affecting this system. Distinguishing allogenic and autogenic influence on mangroves is a challenging questio...

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Bibliographic Details
Published in:Earth surface processes and landforms 2018-06, Vol.43 (8), p.1622-1635
Main Authors: Ribeiro, Samuel Rodrigues, Batista, Edson José Louzada, Cohen, Marcelo C.L., França, Marlon Carlos, Pessenda, Luiz C.R., Fontes, Neuza A., Alves, Igor C.C., Bendassolli, José A.
Format: Article
Language:English
Subjects:
Accretion
Brackishwater environment
carbon and nitrogen isotopes
Climate
Climate change
Contraction
Deposition
Dynamics
Erosion
Estuaries
Estuarine dynamics
Estuarine environments
Forces (mechanics)
Geomorphology
Holocene
Influence
Mangroves
Organic matter
Palynology
Radiocarbon dating
Radiometric dating
Rivers
Sea level
Sea level changes
Sea level fluctuations
Sea level rise
sea‐level and climate change
Sedimentary environments
Substrates
tidal channel
Tidal inlets
Vegetation mapping
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Summary:It is possible that climate changes and sea level fluctuations (allogenic processes) are and will cause major changes in mangrove dynamics. However, other driving forces may be significantly affecting this system. Distinguishing allogenic and autogenic influence on mangroves is a challenging question, because mechanisms related to the natural dynamics of depositional environments (autogenic processes) have strong influences on the establishment and degradation of mangroves. Thus, impacts on mangroves caused by autogenic processes may be erroneously attributed to allogenic mechanisms. Therefore, it is imperative to identify the ‘fingerprint’ of global changes in modern mangrove dynamics. In order to characterize the influence of these forces on mangroves, this work has used geomorphology and vegetation maps integrated with sedimentological and palynological data, radiocarbon dating, as well as δ13C, δ15N and C/N from sedimentary organic matter. The inter‐proxy analyses reveal an estuarine influence with mangrove development along the Ceará Mirim River, north‐eastern Brazil, since ~6920 cal yr bp, after the post‐glacial sea level rise. Relative sea level (RSL) has been stable during the middle and late Holocene. Mangrove establishment along this fluvial valley begins at about 6920 cal yr bp, caused by the sea‐level stabilization, an allogenic influence. However, after its establishment, wetland dynamics were mainly controlled by autogenic factors, related to channel migrations, instead of allogenic process. Some influence of sea‐level and climate changes on mangrove dynamics in this estuarine channel have been weakened by more intense tidal channels activities. Therefore, the expansion and contraction of mangrove areas along the estuary of the Ceará Mirim River since 6920 cal yr bp has been mainly influenced by channel dynamics that regulate the accretion and erosion of mangrove substrates. Copyright © 2018 John Wiley & Sons, Ltd. Schematic representation of successive phases of mangrove establishment according to sea‐level change and lateral migration of channels.
ISSN:0197-9337
1096-9837
DOI:10.1002/esp.4342