Isotopic composition of aquatic and semiaquatic plants from the Mexican Caribbean: A baseline for regional ecological studies

Abstract

Primary producers in the aquatic community structure are fundamental elements because they are the first link in the trophic network as occur in most ecosystems. They produce oxygen and biomass, act as a shelter for several species, and provide food for a wide variety of megaherbivore species like manatees and sea turtles. Physicochemical processes taken place in primary producers can be determined through stable isotope analysis (SIA) as natural tracers from elements like carbon and nitrogen, applied in ecological, and physiological studies. In the Mexican Caribbean ecosystems, SIA has been little applied in aquatic plants, where Thalassia testudinum is the main seagrass species studied. Here, we present the isotopic composition (δ13C and δ15N) from 95 aquatic and semiaquatic plant species of four vegetation types, from three different environments, hydroclimatic seasons, and geographical zones in the Mexican Caribbean. Main statistical differences in δ13C and δ15N were found according to vegetation type and environment. Besides, for δ13C were also found statistical differences among seasons, while for δ15N differences were found among zones (H-Test, p < 0.05). This study provides an isotopic baseline for further ecological studies in the region. This information can contribute to understanding the structure of aquatic food webs and infer the diet and feedings habits of aquatic species, as well as to detect possible changes related to anthropogenic activities that can affect the survival of these plant species, and the fauna depending on them.