Bacterial Dynamics and Their Influence on the Biogeochemical Cycles in a Subtropical Hypereutrophic Lake During the Rainy Season

Abstract

Lakes in subtropical regions are highly susceptible to eutrophication due to the heavy rainfall, which causes significant runoff of pollutants (e.g., nutrients) to reach surface waters, altering the water quality and influencing the microbial communities that regulate the biogeochemical cycles within these ecosystems. Lake Cajititlán is a shallow, subtropical, and endorheic lake in western Mexico. Nutrient pollution from agricultural activity and wastewater discharge have affected the lake’s water quality, leading the reservoir to a hypereutrophic state, resulting in episodes of fish mortality during the rainy season. This study investigated the temporal dynamics of bacterial communities within Lake Cajititlán and their genes associated with the nitrogen, phosphorus, sulfur, and carbon biogeochemical cycles during the rainy season, as well as the influences of physicochemical and environmental variables on such dynamics. Significant temporal variations were observed in the composition of bacterial communities, of which Flavobacterium and Pseudomonas were the dominant genera. The climatological parameters that were most correlated with the bacterial communities and their functional profiles were pH, DO, ORP, turbidity, TN, EC, NH4+, and NO3–. The bacterial communities displayed variations in their functional composition for nitrogen, phosphorus, and sulfur metabolisms during the sampling months. The bacterial communities within the lake are highly susceptible to nutrient loads and low DO levels during the rainy season. Bacterial communities had a higher relative abundance of genes associated with denitrification, nitrogen fixation, assimilatory sulfate reduction, cysteine, SOX system, and all phosphorus metabolic pathways. The results obtained here enrich our understanding of the bidirectional interactions between bacterial communities and major biogeochemical processes in eutrophic subtropical lakes.

Spatiotemporal variations, assembly processes, and co-occurrence patterns of particle-attached and free-living bacteria in a large drinking water reservoir in China

“…NH 4 + is generally of great importance in determining the distribution of bacterial communities. Large amounts of nitrogen are required for bacteria to synthesize their primary cellular components, including amino sugars, purines, pyrimidines, and amino acids ( Diaz-Torres et al, 2022 ). In addition, Chl- a is widely used as an indicator of phytoplankton biomass ( Buchan et al, 2014 ), and the metabolic interaction between bacteria and phytoplankton can lead to either mutual suppression or stimulation of their respective growth.…”

Indirect Impact of Eutrophication on Occurrence, Air–Water Exchange, and Vertical Sinking Fluxes of Antibiotics in a Subtropical River

“…The F sinking of SMZ, CFX, OFX, OTC, and ETM was examined as the examples aforementioned in the F air−water . The sinking fluxes were 19 S9). The highest sinking fluxes observed in spring are primarily due to the high usage of antibiotics and significant phytoplankton blooms, driven by increased sunlight, favorable temperatures, and nutrient availability, leading to an increase in biomass and enhanced production of organic matter that sinks.…”

“…Eutrophication, caused by nutrient enrichment, is a primary anthropogenic influence on water ecosystems, resulting in spatiotemporal variations of phytoplankton biomass and the occurrence of severe phytoplankton bloom events, and represents a significant problem in the sustainability of freshwater resources management. − Contamination of pharmaceuticals such as antibiotics (ABs) is another widespread environmental concern caused by anthropogenic emissions. − Eutrophication has been found to directly promote phytoplankton biomass, depleting the dissolved persistent organic pollutants (POPs) in the water column and increasing exchange fluxes between atmosphere and water (net absorption), vertical sinking, and surface sediments sequestration. − The investigations have elucidated significant vertical transport of perfluoroalkylated substances (PFASs) driven by the biological pump, with residence times varying widely depending on the pollutants and sampling site. , Air–water interactions assume a significant role in facilitating the transportation of organophosphate esters (OPEs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) to remote oceans and polar regions. − Properties and environmental fate of semivolatile aromatic hydrocarbons are modulated by the biogeochemical mechanism such as biodegradation and sinking of particle-bound chemicals in the water column . Eutrophication is primarily caused by excessive nutrient concentrations, leading to changes in aquatic plant growth and potentially affecting the entire ecosystem’s biomass and biological diversity . Eutrophication affects the biogeochemical cycle of ABs by altering key environmental factors such as the pH, dissolved organic matter, and nutrient concentrations.…”

Salinity-Linked Denitrification Potential in Endorheic Lake Bosten (China) and Its Sensitivity to Climate Change

“…High degrees of continentality and isolation make endorheic lakes particularly susceptible and vulnerable to climate and environmental change (Yapiyev et al, 2017 ; Huang et al, 2020 ). Due to the discharge of agricultural, industrial, and urban wastewaters, endorheic waters have been increasingly threatened by eutrophication in recent decades (Arce et al, 2013 ; Menberu et al, 2021 ; Sun et al, 2021 ; Diaz-Torres et al, 2022 ). More importantly, endorheic lakes are land-locked drainage networks where water does not drain into other water bodies (Yapiyev et al, 2017 ).…”