The Alignment of Shallow Water Carbonate Assemblages Along an Oceanographic Gradient in the Galapagos

It has been well established that a connection exists between oceanographic controls and shallow water carbonate production. To date, however, no investigations into these bio-trophic interactions have been performed for the Galápagos Archipelago. In this study, carbonate sediment samples, collected form a host of settings along the geographical extent of the Galápagos are compared with remotely sensed temperature and chlorophyll-a data for each collection site. The Galápagos Archipelago is a volcanic island chain which emerges between 1º40’N-1 °25’S and 89 °15’W-92 º00’W, off the west coast of Ecuador. Though the archipelago lies in proximity to the equator, a unique interaction of environmental conditions results in the Galápagos being situated at the convergence point of 26-29°C currents from the north, 20-22°C currents from the south and nutrient rich and cool upwelling water from the west. This puts the Galápagos in a warm-temperate environment more typical for higher latitudinal settings. In the current study, by comparing sediments from varying environments to the available oceanographic parameter data, a preliminary assessment of the response of carbonate producing organism of the Galápagos Archipelago to their local oceanographic controls was ascertained. The findings from this study add to growing evidence, which stresses the importance that variations in oceanographic parameters play in determining the biogenic makeup of shallow water carbonates (on latitudinal gradients). Furthermore, the results buttress the argument that detailed catalogues of the biogenic components of shallow water carbonates, as well as a cross reference of these sediments with their oceanographic controls, should be compiled if we are going to have a more complete understanding of the complex interactions between these physical and biological realms