Urbanization and coral reefs in Guarajuba Beach, north coast of Bahia, Brazil

Several factors have contributed to the continuing degradation of reefs worldwide. However, local anthropogenic threats are the most serious and lasting causes for the devastation of coral reefs. The ecological relationship between biomes and anthromes provide us an interesting field of current studies. In Guarajuba Beach at the northern coast of Bahia there is a reefs complex which has been studied since the 80s. These reefs are suffering modifications due to the installation and continuous expansion of a tourist residential complex. Therefore it is an interesting study subject of the relation between biomes and anthromes represented here by coral reefs and urban occupation. Our main objective is to initiate the evaluation of urbanization effects on the coral reefs in Guarajuba Beach, based on the study of the urbanization process with the support of historical series of air images and sediment composition analysis, comparing them with results obtained before the occupation process. In these studies the sediment composition does not show big differences from those observed by Nolasco (1987); however there is a displacement towards the front of the reef, which is considered as an urbanization effect, as well as the destruction of dune areas and salt marshes nearby. On account of this process the concentration of organic fragments, which indicates reef origin predominance, appear displaced towards the ocean when compared to that observed in 1987 profiles.

► Changes in beach sediments of Guarajuba in the range of 23 years associated with urban development.
► Comparison of the sedimentary composition of years 1987 and 2010.
► Fall the amount of whole organisms by increasing their fragments.
► Advancement of beach on the reef, with displacement of the carbonate compounds to the front of reef.