Environmental changes during the last 1800 years in the Neguanje mangrove, Tayrona National Natural Park, Colombian Caribbean

Abstract

We reconstructed changes in vegetation and climate conditions during the last 1800 years in a column of sediment 4 m deep (Playa Pozo sector, Neguanje Bay, Tayrona National Natural Park, department of Magdalena, Colombia). We characterized the main components (mineral elements, organic matter), micro-stratigraphy (types of organic matter), humidity variations (%), organic and inorganic carbon, and palynological associations (specifically pollen grains), and counted spores of fungi, algae, ferns, plant debris, and insects. The palynological associations (dominant elements) were defined and related to the current types of vegetation. The definition of the dominant groups in the palynological spectrum and their relationship with the current vegetation types was associated with the stratigraphic conditions of the sediments to detect the changes that occurred during this period. In the reconstruction of the paleoenvironments, we determined the relationship between the defined palynological associations and the stratigraphy of the sediments, the humidity (precipitation), and the covered area. For this purpose, we used the temperature calibration curves of the last 2000 years proposed by various authors. We did not recover enough palynomorphs at the base of the column between 400 and 380 cm deep (2000-1693 years BP), but organic components of marine origin predominated in the sediment, a condition associated with a warm period in the central and eastern Colombian Caribbean coastal environments. In zone I (1693-1294 years B.P.), the mangrove was consolidated and in zone II (1294-1078 years A.P.), it expanded with the vegetation of flooded areas. In zone III (1078-654 years B.P.), we detected the occurrence of the greatest mangrove development, especially by the dominant species Rhizophora mangle. In zones IV and V (654 years A.P.-present), the mangrove cover decreased. This period was less warm than the previous ones, similar to the prevailing conditions in the Ciénaga Grande de Santa Marta and its surroundings.

Keywords

• Mangroves
• Late Holocene
• Paleoecology
• Coastal environments
• Colombian Caribbean