Ecological Decline over a Decade in the Albufera of Valencia Coastal Lagoon (Spain): A Growing Environmental Hazard in a Hypertrophic System

Overview

The Albufera of Valencia is a shallow, hypertrophic Mediterranean coastal lagoon that has experienced substantial ecological deterioration since the 1970s, characterized by macrophyte bed decline and phytoplankton predominance. This study monitored key water quality variables across a decade to assess the persistence of eutrophication and current ecological status of the lagoon system.

Methods and approach

Remote sensing data from the Sentinel-2 constellation were applied in conjunction with algorithms calibrated using in situ field data spanning 2016-2025. The remote sensing approach was used to estimate chlorophyll-a concentration as an indicator of phytoplankton biomass, suspended solids, and Secchi disk depth. Temporal trend analysis was conducted over the 2017-2025 period to evaluate changes in water quality and trophic status.

Results

Temporal trend analysis from 2017 to 2025 revealed progressive system deterioration. Chlorophyll-a concentration and suspended solids exhibited statistically significant increasing trends (p < 0.01). Water transparency, measured as Secchi disk depth, decreased significantly (p < 0.001). These findings indicate progressive deterioration in trophic status and ecological quality of the lagoon over the analysis period, despite implementation of prior management interventions.

Implications

The documented persistence of eutrophication and progressive decline in ecological quality indicate that existing management approaches require enhancement. Implementation of more effective conservation strategies is warranted, including regulation of nutrient inputs and increased water renewal time in the lagoon system. The progressive nature of degradation despite prior interventions underscores the need for improved management efficacy in addressing the lagoon's hypertrophic conditions.