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High-altitude lakes are sensitive to modern and past climate changes. Given their low-water temperatures, alkalinity, and nutrient levels, small climatic differences can strongly affect their water chemistry, and/or biodiversity. In central Mexico, there are only two high-altitude lakes, and both are within the crater of the Nevado de Toluca volcano. Here, we present a paleolimnological record from one of these lakes: La Luna. Previous paleoenvironmental work showed that it was sensitive to the Little Ice Age (LIA) cooling. Our results show that sediment accumulation began ~6900 to 6100 cal. yr BP under periglacial conditions and that lake conditions were established ~6000 cal. yr BP. One tephra layer was dated to ~5600 cal. yr BP, with no evidence of more recent volcanic activity. The early stages of this lake (6000–4700 cal. yr BP) contained Cladocera and diatom assemblages with different species composition than modern assemblages. This early stage community structure was related to more mesic conditions and cooler winters inferred by the high abundance of planktonic Aulacoseira nivaloides and of Chydorus cf. sphaericus. The establishment of modern limnological conditions after 4700 cal. yr BP is inferred from Cladocera and diatom assemblages similar to recent samples. A reduction in A. nivaloides and low magnetic-susceptibility values suggest lower lakes levels, a trend consistent with lower available moisture in central Mexico after 4000 cal. yr BP. The rest of the sequence shows the impact of two cold periods, the first one around 3000 cal. yr BP, identified by a new increase in Chydorus cf. sphaericus. The second was the larger impact associated with the LIA (AD 1350–1910), and an increase in Cavinula pseudoscutiformis and Pinnularia microstauron suggesting an increase in lake water pH. Also, organic matter and photosynthetic pigments increased during this period showing an increase in nutrient levels and productivity. Finally, the coldest interval during the LIA (AD 1570–1890) is identified by an important reduction in arboreal pollen concentration which points to a wider environmental impact of this cold event.

Subtropical rivers in developing countries often lack adequate monitoring, which makes it difficult to comprehensively determine their water quality when faced with different anthropic impacts. There are no proper protocols in the regulations to incorporate indicators and adapt them to different biogeographic regions, limiting the potential success of conservation and restoration of river ecosystems. This study proposes implementing macroinvertebrates as bioindicators of water quality in river ecosystems, and modifying the calibration of the widely used Biomonitoring Working Party (BMWP) index for its adaptation in a subtropical river. The Duero River, Mexico, was used as an example in this study. Data were explored with multivariate statistics, and the water quality and habitat values were averaged to obtain the families’ bioindication values and the index categories. The BMWP adequately described a deterioration gradient from the origin to the river mouth (from fair to extremely polluted), with some intermediate recovery points related to the presence of springs. Its performance was compared with other biological indices and exhibited a positive relationship with all of them. In addition, how BMWP changed over time was analyzed by examining previous samples, and highlighted increased river deterioration over time. A calibrated BMWP will allow for long-term monitoring at a low cost.