Dynamics of Bacterial Diversity in Fish Farming Lagoons: Implications for the Ecosystem Trophic Status

Custodio M.; Peñaloza R. · Biology (2025) · DOI: 10.3390/biology14111563

Resumen

Bacterial communities in lake sediments are key to ecosystem health and fish productivity, yet little is known about their composition in the high-altitude Andean lagoons of central Peru. In aquaculture systems, these microbial assemblages regulate nutrient recycling, organic matter degradation and oxygen availability, forming a key component of the microbial loop. Intensive trout farming introduces a continuous nutrient load through uneaten feed and metabolic byproducts, which fuels eutrophication and reshapes benthic microbial structure. This study evaluated the bacterial diversity and community structure in sediments from four fish farming lagoons (Pomacocha, Habascocha, Tipicocha, and Trancagrande). Environmental variables, including dissolved oxygen (DO), inorganic nitrogen, inorganic phosphorus, and chlorophyll-a, were measured to determine trophic status. Sediment bacterial composition was analyzed using Illumina sequencing of 16S rRNA gene amplicons, and community structure differences were assessed with diversity indices and SIMPER analysis. Microbial patterns were assessed at phylum and class levels to capture changes across taxonomic scales. Pseudomonadota, Actinobacteria, Cyanobacteria and Bacteroidetes dominated across lagoons, with significant among-site variation. Richness was similar, but Tipicocha showed the highest evenness (Shannon H′ = 2.769; Simpson 1-D = 0.8969). SIMPER identified Deltaproteobacteria, Alphaproteobacteria, Actinobacteria and Gammaproteobacteria as major contributors to dissimilarity. The presence of Methanomicrobia and Bacilli in Tipicocha and Trancagrande indicated micro-oxic to anoxic conditions, characteristic of systems with high organic load and redox heterogeneity. These results show that aquaculture alters trophic status and reshapes sediment bacterial communities in high-Andean lagoons. Understanding these patterns is essential to design monitoring and management strategies that balance aquaculture productivity with the conservation of sensitive ecosystems.

Instituciones: Universidad Nacional del Centro del Perú