Poleward mangrove expansion in South America coincides with MCA and CWP: A diatom, pollen, and organic geochemistry study.

The projected warming trend in the 21st century is likely to alter the global distribution of mangroves. However, the migratory pattern of different mangrove species is still unclear, especially in the subtropical Brazilian littoral. This study utilizes pollen, diatom, and organic geochemistry to document the late Holocene morphological and ecological transformation in São Francisco do Sul Bay, the mangrove sub-range limit in south Brazil. This multi-proxy dataset indicates the establishment of saltmarshes and mangroves on muddy tidal flats at ∼1720 and ∼870 cal yr BP, and Laguncularia , Avicennia , and Rhizophora colonized the study area at ∼870, ∼390, and ∼70 cal yr BP, respectively. This stepwise succession of three mangrove species in São Francisco do Sul Bay, and poleward mangrove expansion toward the austral mangrove range limit, indicate that the migratory histories of different mangrove species were not synchronized during the late Holocene, and temperature is the primary climatic factor regulating the mangrove distribution in south Brazil. More importantly, the Medieval Climate Anomaly and the Current Warm Period were clearly registered in the pollen record, suggesting that the two climate anomalies likely facilitated the mangroves colonization into higher latitudes in south Brazil. Overall, our dataset indicates that mangrove expansion into more temperate zones will likely accelerate in South America. [Display omitted] • Temperature is the primary climatic factor regulating the mangrove distribution in South America. • Medieval Climate Anomaly and the Current Warm Period likely facilitated the poleward mangrove migration in south Brazil. • The migratory histories of different mangrove species in South America were not synchronized during the late Holocene. [ABSTRACT FROM AUTHOR]