Radioactive and stable isotopes reveal variations in nearshore submarine groundwater discharge composition and magnitude across low inflow northwestern Gulf of Mexico estuaries

Influence of pelagic sargassum influxes on the δ15N in Thalassia testudinum of the Mexican Caribbean coastal ecosystem

The conservation of Mexican Caribbean Ecosystems (MCE) involves ensuring their capacity to provide resources and ecosystem services to society. Monitoring programs are necessary to establish their management and ensure their sustainability. Thalassia testudinum is the community used to determine anthropogenic influence, in which wastewater is the primary anthropogenic nitrogen source. The extensive amount of pelagic sargassum that enters the area and its decomposition may be additional nitrogen sources in MCE. In the present study, the δ15N in T. testudinum was examined from 2009 to 2019 to infer the nitrogen contribution from pelagic sargassum to MCE. T. testudinum δ15N values showed significant depletion from June/October 2014 to 2019 concerning previous periods. Pelagic sargassum was an alternative nitrogen source, and its leaching reduced T. testudinum δ15N values in MCE.