Diversity of sandy beach macrobenthos as indicators of the climate at the Ecuadorian coast using GIS
Van, N.T.H. (2002). Diversity of sandy beach macrobenthos as indicators of the climate at the Ecuadorian coast using GIS. MSc Thesis. Vrije Universiteit Brussel: Brussel. VII, 96 pp.
The objectives of this study are to bring together a number of tools for the study of biodiversity in relation to climatic variation. The tools include relational database, statistical analysis and GIS. A second objective is to demonstrate the usefulness of this system using a preliminary analysis of macrobenthos density and biodiversity data from selected sandy beaches of Ecuador. Geographically located in the equatorial tropical climate region, the Ecuadorian coast is strongly influenced by anomalous El Niño and La Niña events every 3-7 years. This has indeed led to fluctuating climatic conditions, which can have an effect on several sensitive marine living organisms. Intertidal macrobenthos at ten sandy beaches along the Ecuadorian coast were surveyed during 29 months (August 1999-June 2002). This period had undergone a strong El Niño in 1997-1998, then faced a moderate La Niña in 1999-2000 and is expected to have another El Niño in 2002. Spatial and temporal contexts for the effect of anomalous oceanographic conditions on the sandy beach macrobenthos were investigated. Special references for the monthly anomalies of the Sea Surface Temperature (SST) were correlated with the diversities of the macrobenthos community. Building a relational database, then integrating the extracted information into GIS and some compatible statistical applications for the later analysis of data were used for the approach. The statistical significant differences among ten stations in both biotic and abiotic factors were detected in all stations, especially in Salinas 2 and Posoda. Salinas 2 showed the lowest diversity, with high percentage of gravel on the steepest beach. Posorja showed the high diversity, lowest salinity, most influenced by the activities from the Estuary of Guayas. In those of the ten stations, the correlation of the diversity appeared to be best defined with three recorded environmental variables: sediment granulometric characteristics, salinity and water temperature. Therefore, macrobenthos diversity seemed to be most influenced by the environmental conditions. Statistical significant differences mostly found in temporal variations of diversity in the two stations Posorja and Cenaim. The unevenness of the macrobenthos diversity in different months and years was supposed to be corresponding to the anomalies of SST, or related to the unstable climatic factor during the research.
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