Stable isotopes used to assess pollution impacts on coastal and marine ecosystems of Cuba and México

Abstract

Stable isotopes of nitrogen (δ15N) have been widely used around the world to evaluate the impactof anthropogenic activities on marine ecosystems; however, in the Caribbean Sea countries, such asMéxico and Cuba, they are rarely used. Inputs of nutrients related to urban development and touristactivities along the coasts of the Caribbean Sea have the potential to deteriorate their fragile marineecosystems. The use of isotopic tools and elemental analysis in sentinel organisms would be usefulto provide evidence of the impact generated by anthropogenic nutrients. Measurements ofδ15N (h),carbon and nitrogen content, and C:N ratios, were conducted in different sentinel groups (macroalgae,seagrasses, gorgonians, and corals) collected in five marine ecosystems with different nearby coastaldevelopment pressure in both countries. The selected ecosystems, ordered according to the level ofcoastal areas development (low to high), were: Jardines de la Reina (JR), Gulf of Ana Maria (GAM),Cayo Coco (CC), and Laguna Larga (LL) in Cuba, and Puerto Morelos (PM) in México. Results evidencedthat the majority of sentinels inhabiting near the most developed coastal areas, in terms of populationand tourism, showed higher N contents, lower C:N ratios and higher values ofδ15N (e.g., PM andLL) than those near less developed coastal ecosystems (e.g., GAM and JR). Land-based nutrients frommunicipal wastewater constitute the primary source of N pollution. Because eutrophication representsasignificantthreattotheintegrityofvaluablecoastalecosystems,thereisanurgentneedtoaccelerateprogress in wastewater treatment systems, in terms of capacity and efficiency, to significantly reducenutrient inputs to coastal ecosystems. Otherwise, more negative changes and deteriorations to thehealth of coastal ecosystems, including coral reefs, are expected along the Mexican Caribbean andnumerous key points of Cuba and other Caribbean countries