Seston and eutrophication on a tropical karst lake district: Lagunas de Montebello, Chiapas, Mexico

Abstract

Large quantities of seston are among the most important indicators of eutrophication in aquatic ecosystems. The present study aimed to elucidate the role seston plays in the general limnological dynamics of a cluster of eighteen tropical karstic lakes with different anthropic impacts (non-impacted, oligotrophic, clear-water lakes, and impacted, eutrophic, turbid-water lakes) of the “Lagunas de Montebello” National Park lake district. The seston concentration was measured twice, in the warm/rainy and the cold/dry season. Vertical profiles of temperature, dissolved oxygen, electrical conductivity, pH, and photosynthetic active radiation (PAR) were recorded at each lake. Water samples were taken along the water column to evaluate seston and chlorophyll a (Chl-a) concentration. Impacted lakes displayed higher seston (4.1-21.0 mg/L) and Chl-a (8.1-129.8 μg/L) concentrations, reduced euphotic zone (ZEU = 2.6-6.3 m), and superficial thermo- (gradient = 0.8 ± 0.2 °C/m) and oxyclines (gradient = 4.7 ± 2.4 mg DO/m). Non-impacted lakes had lower seston (1.0-2.1 mg/L) and Chl-a (0.4-5.2 μg/L) concentrations, wide ZEU (10.1-33.4 m), and deeper thermo- (gradient = 0.5 ± 0.1 °C/m) and oxyclines (gradient = 0.6 ± 0.4 mg DO/m). The changes reported in impacted lakes linked with the increase in the seston and Chl-a concentrations are most likely related to the eutrophication process asso¬ciated with anthropogenic activities (agriculture, urban development, land-use change) in the NW part of the area. This research highlights the fragility of the tropical karst lake ecosystems worth protecting to preserve the aquatic ecosystem’s health.

Shifts in water column microbial composition associated to lakes with different trophic conditions: “Lagunas de Montebello” National Park, Chiapas, México

“…DCM are characteristic features of oligotrophic waters ( Cullen, 1982 ; Fee, 1976 ). Although research in other study sites has shown that eutrophication increases towards the summer when stratification reaches its maximum, Vargas-Sánchez, Alcocer & Oseguera (2022) found higher Chl-a concentrations in the lakes of the LMNP during the cold/dry season (winter) than in the warm/rainy season (summer). Tropical warm monomictic lakes show characteristic winter phytoplankton blooms associated with the full water column mixing ( Lewis Jr, 1996 ; Sarmento, 2012 ).…”

“…Esmeralda is a “functionally shallow” (warm polymictic) lake, while the other 11 lakes are deep, warm, and monomictic ( Cortés-Guzmán, Alcocer & Oseguera, 2019 ). The trophic classification was designated according to Vargas-Sánchez, Alcocer & Oseguera (2022) .…”

Microcrustacean (Cladocera and Copepoda) Assemblages of a Tropical Karst Lake District

“…The T and DO vertical profiles during the stratification season showed major differences between non-impacted/oligotrophic and impacted/eutrophic lakes despite similar average values. [53] reported shallower (5.3 ± 1.5 m) thermoclines with stronger (0.8 ± 0.2 • C m −1 ) thermal gradients in impacted/eutrophic lakes, comparing with deeper (14.0 ± 7.1 m) and weaker (0.5 ± 0.1 • C m −1 ) thermal gradients in non-impacted/oligotrophic. All lakes' hypolimnia became anoxic and uninhabitable for aerobic organisms during the stratification.…”

“…The anthropogenic impacts supplying agricultural fertilizers and urban wastewater to the lakes since the early 1950s drove the lakes' eutrophication [25,54]. Some authors [24,53] reported high nutrient, Chl-a, seston, and particulate organic carbon concentrations in the impacted/eutrophic lakes. The nuisance cyanobacterial scums in some of the PNLM lakes ratified the advanced state of eutrophication, which negatively impacts tourism and the general economic development of the area [55].…”

Carbon Dioxide Concentration and Emissions along a Trophic Gradient in Tropical Karst Lakes

“…The "Lagunas de Montebello" National Park (LMNP), located in Chiapas State, extends over one of Mexico's main karst lake districts. The LMNP has more than 130 karst water bodies of different morphometric and physicochemical characteristics [33][34][35]. Since these lakes can be found throughout gradients related to groundwater and surface water inputs, contaminated effluents, surrounded by agriculture or pristine forests, provide a unique opportunity to assess CO 2 emissions mechanisms together with eutrophication effects, considering a wide variety of lakes.…”