EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Use of nitrogen as a tool for the study of the trophic state of vulnerable coastal ecosystems

Karla Camacho-Cruz, Nestor Rey-Villiers, Diana Medina-Contreras, Paula Gonzalez-Jones, Fernando Arenas-Gonzalez, and Alberto Sanchez-Gonzalez
Karla Camacho-Cruz et al.
  • Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, La Paz, México.

Concentration and flux of nitrogen in mangrove wetlands and coral reefs are modified by chemical and hydrodynamic mechanisms determined by natural and anthropic factors. Nearby anthropic activities impact ecosystems making them vulnerable, mainly due to nutrient flow increase which modifies biogeochemical cycles and trophic dynamics. Here, spatial-temporal variability of N in three tropical coastal ecosystems under different levels of anthropic pressure were studied; 1) trophic dynamics of mangroves in the Colombian Pacific using stable isotopes (δ13C, δ15N); 2) quantification of δ15N in octocorals from the northwestern region of Cuba as an indicator of wastewater pollution, and 3) determination of the trophic status of coastal and continental sites in the Mexican Caribbean using Karidy’s index and CE-CCA-001-89. In the mangrove food web, a value of 5 ‰ for δ15N was found, principally in systems with modified trophic structures close to tourist and urban centers. In octocorals, δ15N was significantly higher in reefs close to polluted river basins, evidencing a positive and significant correlation with the concentration of fecal and total coliforms, fecal streptococci, heterotrophic and sulfate-reducing bacteria. The nutrients analyzed in the Mexican Caribbean, exceeded the permissible limit for the protection of marine life, with Karidy’s index suggesting in some sites concentrations of nitrates in a mesotrophic and eutrophic state, principally during the months of highest tourist influx. The results confirm the effect and vulnerability of these ecosystems towards anthropic N, which could result in a reduction of ecosystem services and diversity.

How to cite: Camacho-Cruz, K., Rey-Villiers, N., Medina-Contreras, D., Gonzalez-Jones, P., Arenas-Gonzalez, F., and Sanchez-Gonzalez, A.: Use of nitrogen as a tool for the study of the trophic state of vulnerable coastal ecosystems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6987,, 2021.