Water quality, nutrients, and stable isotopic signatures of particulates and vegetation in a mangrove ecosystem exposed to past anthropogenic perturbations

Abstract

Water quality in mangrove estuaries within Caroni Swamp, Trinidad is impaired by a combination of recent increases in nitrogen loads and lingering effects of a series of reclamation efforts that reduced tidal exchanges and fostered low oxygen and high ammonium concentrations, conditions that are relatively unusual for estuaries. Concentrations of available nitrogen diminish down-estuary, with an overall within-estuary interception of about 25% of total dissolved nitrogen. Caroni Swamp remains a productive mangrove environment, and a tourist attraction, in spite of failed and continuing reclamation efforts and increased N loads, a demonstration of remarkable resilience. Developing ecosystem-based management to support that resilience will benefit from improved understanding of processes involved in nitrogen retention and losses, consideration of the consequences in intensifying land use on contributing watersheds and plans to ease tidal water exchanges and diminish extent of shallow and stagnant areas.