Temporal changes in the hydrology and nutrient concentrations of a large tropical river: Anthropogenic influence in the Lower Grijalva River, Mexico

Abstract

Dam construction and nutrient loading are among the greatest threats to freshwater ecosystems, altering ecological processes and the provisioning of ecosystem services.Temporal change in hydrology and ambient nitrogen and phosphorus concentrations was studied on the Grijalva, a large tropical river in southern Mexico, where four hydroelectric dams operate and where land conversion has impacted the freshwater environment. Temporal changes in discharge and in river chemistry were examined by analysing long-term discharge and nutrient data using the software Indicators of Hydrologic Alteration and Mann-Kendall tests. Furthermore, additional water chemistry samples were collected to examine seasonal nutrient dynamics in the lower Grijalva. Long-term discharge data indicated dam construction has severely altered temporal patterns in discharge and other hydrological characteristics. The lower Grijalva has also experienced increase in nitrate concentrations through time, which may be attributed to the expansion of agricultural and urban areas in the watershed.In contrast, total phosphorus appeared to decline at the sites influenced by dam construction. Lower nutrient concentrations were recorded upstream from the city of Villahermosa, suggesting that inputs from urban areas may have contributed to nutrient loading. Additionally, higher nitrate and total phosphorus concentrations were detected in tributaries draining intensive agricultural and suburban areas. Collectively, the results from the study suggest that dam construction and land conversion in large, tropical watersheds can produce chemical and hydrological changes, which may negatively impact important ecosystem services-such as fisheries and the provisioning of sources of drinking water-and may compromise the integrity of coastal zones.

Bacterial flora associated with commercial Octopus maya captured in the Yucatan Peninsula, Mexic

“…In the Maluco river-floodplain system, the highest values of TP in time could be better explained by the wide fluctuation of its inputs throughout the rivers, as has been registered for others riverine ecosystems (Jarvie et al, 2005;Guan et al, 2016). In the case of the Gri- jalva floodplain, the TP concentrations increased significantly during the high water level in sites surrounded by extensive suburban areas (Lázaro-Vázquez et al, 2018). They related the increment of TP to the wastewater discharges, which were mainly caused by the expansion of agricultural areas and growth of human populations.…”

“…However, the high variability of the concentrations of nutrients in short times regarding the inter-annual fluctuation of the WL can enhance the eutrophication (carbon, nitrogen, phosphorus), which in turn increase the phytoplankton biomass (Dodds, 2007;Cruz-Ramírez et al, 2019). Additionally, wastewater discharges, diffuse input of agricultural nutrients, runoffs and hydraulic disconnection are other causes associated with the enhancement of nutrients in river-floodplain systems (Cetin 2009;Sharma et al, 2010;Sánchez et al, 2012;Jeppesen et al, 2015;Lázaro-Vázquez et al, 2018).…”

Intraspecific morphological variation in shads, Dorosoma anale and D. petenense (Actinopterygii: Clupeiformes: Clupeidae), in the Mexican Grijalva and Usumacinta river basins

“…Additionally, while the Grijalva and Usumacinta basins share some biological and ecological characteristics, each basin has an independent biogeographical history (Elías et al 2021). Likewise, they have been subjected to different modifications and anthropic activities (Lázaro-Vázquez et al 2018;Sánchez et al 2019). Also, it should be noted that hydrogeomorphological and habitat changes can affect the migratory behavior of these species-especially in the lower regions of both basins (Bloom and Egan 2018).…”

Characterization and improvement of Cannavalia ensiformis meal as balanced feed for Oreochromis niloticus

“…However, the high variability of the concentrations of nutrients in short times regarding the inter-annual fluctuation of the WL can enhance the eutrophication (carbon, nitrogen, phosphorus), which in turn increase the phytoplankton biomass (Dodds, 2007;Cruz-Ramírez et al, 2019). Additionally, wastewater discharges, diffuse input of agricultural nutrients, runoffs and hydraulic disconnection are other causes associated with the enhancement of nutrients in river-floodplain systems (Cetin 2009;Sharma et al, 2010;Sánchez et al, 2012;Jeppesen et al, 2015;Lázaro-Vázquez et al, 2018).…”