Submarine Springs and Sewage
This poster presents data from the lagoons along the Caribbean coast of the Yucatan Peninsula, Mexico, a region undergoing appreciable growth. The region is characterized by karst limestone without appreciable surface drainage or rivers. However, there are various submarine springs and fissures that deliver runoff to coastal waters. The tropical seagrass Thalassia testudinum was sampled near the developed regions of Cancun as well as in the Puerto Morelos lagoon to the south. Both tissue nutrient concentrations and stable isotope ratios (δ15N) were analyzed in seagrass tissue. A strong sewage signal was inferred for regions adjacent to Cancun, with a much lower signal detected in regions distant from these nutrient sources. Interpretation of this bioindicator data leads to the conclusion that submarine springs that release groundwater into the lagoons appear to be an important source of nutrients to the nutrient-poor coastal lagoons of Mexico.