Long-term diatom response to anthropogenic stressors in a Neotropical lake

Abstract

Understanding tropical lake ecosystem responses to anthropogenic disturbance over long timescales is critical for assessing resistance, resilience, and regime shifts; however, such perspectives are rare in the Neotropics. We combined paleolimnological, limnological, and remote-sensing approaches to evaluate the response of a shallow tropical maar lake in the Sierra de Los Tuxtlas (eastern Mexico) to deforestation-driven disturbance over the last ~200 years, with emphasis on ecosystem trajectories following peak impact in the late twentieth century. Forest-cover changes were reconstructed from remote images (1976, 2000, 2024), while lake condition was assessed using limnological measurements and diatom assemblages from the water column (2000–2024) and sediments (~1808–2025). Sedimentary magnetic susceptibility and diatoms documented a major state shift during the 1970s–1980s, coincident with peak deforestation and erosion, characterized by high species turnover and the dominance of disturbance-tolerant taxa ( Achnanthidium minutissimum – Fragilaria capucina ). This transition contrasts with gradual and elastic responses observed during earlier periods. Despite partial reforestation and landscape stabilization since the 1990s, limnological variables indicate persistent eutrophic to hypereutrophic conditions. However, sedimentary and water-column diatoms revealed ongoing ecological changes, marked by declines in disturbance taxa and increasing abundances of baseline planktonic species ( Aulacoseira spp.), indicating an elastic recovery trajectory toward pre-disturbance conditions. Comparisons with an earlier disturbance between AD 100–800 (Classic Mesoamerican period) highlight the importance of disturbance duration and climatic context in determining ecosystem resilience. Our results demonstrate long-term resilience in a tropical lake following intense anthropogenic disturbance, underscoring the value of paleolimnological records for evaluating ecosystem recovery.