Middle to late Holocene relative sea level rise, climate variability and environmental change along the Colombian Caribbean coast

Abstract

We analyzed diatoms, lithology, and stable isotopes in a sediment core from the Ciénaga Grande de Santa Marta lagoon to reveal the history of late Holocene relative sea level rise and the ontogeny of the lagoon on the Caribbean coast of Colombia. At ~5300 cal. yr BP, the area was characterized by shallow, freshwater ponds that were prone to seasonal flooding. From ~4250 to ~2060 cal. yr BP, these ponds became brackish as relative sea level began to rise, and since ~2060 cal. yr BP, marine conditions have prevailed. In addition to tracking relative sea level rise, we also investigated periods of greater and lesser precipitation during times of brackish and marine conditions, respectively, as indicated by diatom-inferred changes in water salinity and shifts in the source of sediment organic matter. Comparisons with other regional paleoenvironmental records suggest that humid climate conditions prevailed in the Caribbean until about 4000 cal. yr BP. After that time, climate became more variable, with drier conditions registered from ~ 4000 to 2000 cal. yr BP. Wetter conditions returned after ~2000 cal. yr BP.

Understanding climate-human interactions in Small Island Developing States (SIDS)

“…3.3 Case Study 3: responses to recent sea-level rise Within the past 200 years or so, sea level has been rising around most oceanic islands (Church et al, 2006;Velez et al, 2014)[6]. The best-available projections for the future show that sea-level rise is likely to accelerate for the rest of this century (Church et al, 2013)[7] and will continue rising thereafter for at least a few hundred years (Jevrejeva et al, 2012).…”

Tamaños de la diatomea céntrica Actinocyclus normanii en función de la salinidad, una nueva herramienta aplicada a la interpretación de paleoambientes

“…Actinocyclus normanii cells from BL205 to BL165 samples have diameters above the limit of 40 µm, which indicates that a transgression was already affecting the lagoon by 1,870 years BP (Van der Hammen & Noldus, 1984;Vélez, et al, 2014). Then, a transition state has been identified from 1,058 to 912 years BP (samples BL145 and BL135) as indicated by average cell diameters of 40 μm.…”

“…Samples BL265 and BL 245 had diameters under 40 µm ( Figure 6) which indicates fresh water conditions. Cohen & Wiedemann (1973) found remains of the marine indicator Rhizophora mangle 2 km north of the coring site (Vélez, et al, 2014) at a 200 cm depth. At this depth and at 4 km south of the coring site , Cohen & Wiedemann (1973) found Laguncularia recemosa and the fern Acrosticum aureum, both indicators of freshwater conditions.…”

“…In the second part of this work, we measured A. normanii cell diameters from 15 permanent plates prepared for a diatom count as part of a published paleoenvironmental reconstruction for the CGSM lagoon (Vélez, et al, 2014). Each of these plates contained two aliquots of 0.6 ml prepared from specific depths within a sedimentary core extracted in the lagoon (Figure 1).…”

“…The code of the 15 samples indicates the core name (Bocas López -BL) followed by the core depth in cm: BL05, BL15, BL35, BL55, BL95, BL115, BL125, BL135, BL154, BL165, BL175, BL195, BL205, BL245, BL265. The age of the samples was recalculated from those presented in Vélez, et al (2014). For the present study, 14 C dates were calibrated using the Bacon software (Blaauw & Christiansen, 2011).…”