Export of dissolved and particulate carbon and nitrogen from a mangrove-dominated lagoon, Yucatan Peninsula, Mexico

Mangrove ecosystems can significantly influence adjacent coastal areas by acting as either sources or sinks of organic carbon and nutrients. In this study, the total export of carbon and nitrogen from Celestun Lagoon, located on the Yucatan Peninsula, Mexico, was measured during two different seasons. The net export of dissolved and particulate carbon and nitrogen was calculated using measured concentrations within the lagoon coupled with hydrodynamic measurements of lagoon water exchange and published water budgets. The results show that Celestun Lagoon is a source of both organic carbon and nitrogen to the adjacent coastal ocean. Dissolved organic carbon accounted for 92% of the total carbon export, while the particulate form of organic nitrogen accounted for between 65-85% of the total nitrogen export. Groundwater is the major source of dissolved inorganic nitrogen to Celestun Lagoon, but is an insignificant source of both particulate and dissolved organic carbon. The majority of dissolved inorganic nitrogen from the groundwater is recycled within the lagoon, with only a small fraction (approximately 10%) exported to the coastal ocean. Due to the significant export of carbon and nitrogen from the lagoon to the coastal ocean, changes in lagoon functioning or groundwater composition, such as from pollution, will result in changes to the carbon and nitrogen budgets of the adjacent coastal ocean.