Pollen used to reconstruct flora history of the Los Flamencos Sanctuary

The influence of the ocean on mangrove formations at the Los Flamencos Flora and Fauna Sanctuary in the Colombian Province of La Guajira, began more than three centuries ago.

About 610 years ago the northeast area of the sanctuary, adjacent to the Navío lagoon, had at least 42 species of mangroves including Solanum and Conocarpus erectus (approximately 292 years ago).

As explained by Universidad Nacional de Colombia (UNal) Geology student in his thesis project focused on rebuilding the flora history of the above-mentioned sanctuary using palynological records (pollen analyses).

Due to the concentration of carbon or breakdown levels through which scientists may determine life cycles, Díaz established that the inflow of salinity, i.e. the influence of the sea began 292 years ago. During this stage several mangrove species appeared –as Conocarpus- dependent on salinity and Poacea, Fimbristlys or Typha; and at the same time others dependent on minerals and freshwater disappeared, including       -Solanum- such as Montrichordia, Eclipta and Paspalum.

However given that Conocarpus erectus requires low salinity levels, the sea is not totally impacting or dominating the ecosystem. In fact the mangroves most impacted by the saline effect are Avicenia germinans, Laguncularia and Rizhophora mangle, which were not found in the lagoon or lagoon banks.

Los Flamencos has an extension of 548,000 hectares (1,354,100 acres) and is one of 11 sanctuaries of the country and one of five located in the Colombian Caribbean. It may be reached after a 20 minute ride from the city of Riohacha.

Based on the soil records and collections gathered by the biodiversity and conservation group of the UNal Natural Sciences Institute, Díaz analyzed the components of these soil samples from 98 cms (38.5 in.) deep.

The samples were taken in an intermediate area called the littoral line of the Navío lagoon which is actually a linear portion of land which separates the sea from the lagoon.

In a segment between 50 cms (19.6 in.) and 1 mt (3.28 ft.) deep he took samples every 2 cms (0.7 in.) to perform a flotation process which consists of a density assessment. In a density scale when density is greater than 2 they are minerals while if it is less than 1.8 it is organic material. The samples were separated by densities; therefore minerals were on the bottom and organic material on top.

Later he took the organic material of 20 samples and placed them on 5 plates to analyze the existence of mangrove traces with a microscope. Díaz discovered more than 40 types of pollen.

The research project provides clues on the influence of climate change as it has had a bearing on the ocean water levels, which impacts on several species within an ecosystem, in this particular case, mangroves.

According to Díaz one of the goals of his project is to provide knowledge for conservation using geology and also mainly separating it from extractivism, in one of the most historically abandoned areas of the country.

Agencia Noticias UNAL |

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