Cladocera (Crustacea: Branchiopoda) quickly respond to changes in environmental conditions and their remains are usually found in large amounts in lacustrine sediments, which make them an important biological proxy in paleolimnological studies. Variations in species composition have been used to infer paleo-climate and paleo-environmental variables including lake depth, eutrophication, and deforestation. However, despite their advantages as bioindicators in the study of past conditions, they are underutilized in paleolimnological research in Central America due to limited knowledge about their diversity and the morphological differences between the subfossil remains of different taxa. In order to address this issue, we described and analyzed cladoceran remains from 56 waterbodies located in Mexico, Guatemala, El Salvador, and Honduras. Here, we provide a description of the remains from 10 different taxa that belong to the Sididae, Bosminidae, Daphniidae, Macrothricidae, and Ilyocryptidae families.

Lake Maninjau, like many surface water bodies worldwide, faces significant water pollution challenges due to extensive aquaculture activities, making it an ideal site to study the impact of fish farming on water quality, which has contributed to eutrophication and declining water quality. This study investigates the physicochemical parameters and pollution levels in the lake, aiming to provide insights into its environmental health. In August 2022, a comprehensive sampling campaign was undertaken at nine stations within the upper layers of open water and littoral zones of Lake Maninjau. In situ measurements, including temperature, dissolved oxygen, and pH, were conducted, accompanied by water sample collection for laboratory analysis of trace elements and heavy metals. Our study revealed notable variability in water parameters across different sites, with surface water layers exhibiting the greatest differences. While certain parameters such as temperature and conductivity remain relatively stable, pH levels show a decreasing trend with increasing water depth. Dissolved oxygen levels vary widely, while oxidation–reduction potential indicates water pollution, particularly in littoral zones. Potassium dominance within cations likely suggests anthropogenic influences, notably from aquaculture activities, that may also contribute to nutrient enrichment and heavy metal pollution. Elevated levels of total nitrogen and ammonia underscore the lake’s moderate pollution levels, with heavy metals such as mercury exceeding permissible limits, posing risks to aquatic life and human health.

We analysed a 24 cm long sediment sequence (past ~200 years) from an alpine lake (Tatra Mts., Slovakia) for chironomids, cladocerans, and diatoms to reconstruct the effects of a historically documented fish introduction. Our results indicate that fish introduction predated the age of the sequence, and thus, we did not cover the lake’s fishless period. The individual proxies coincide in showing two main lake development stages. The first stage lasted until ~1950 CE and was interpreted as the stage when brown trout and alpine bullhead co-occurred. The extremely low concentration of cladocerans, the dominance of small-bodied chydorids, and the low share of daphnids, together with the low proportion/absence of large-bodied tanypod chironomids, suggest a strong effect of both species. The beginning of the next stage is probably related to the ban on fish manipulations and grazing in the catchment. A significant increase in the total abundance of cladocerans and of daphnids may indicate the extirpation of trout. The steep increase in thermally plastic chironomid taxa since the end of the 20th century indicates climate warming. Generally, while cladocerans primarily indicate fish manipulations, chironomids and diatoms mainly reflect other local and global environmental stressors.

Using a 530-year sediment record from the maar Lake Apastepeque, El Salvador, and based on diverse geochemical and biological (cladocerans, chironomids, diatoms, ostracods, testate amoebae) indicators, we estimated climatic and environmental alterations during the Little Ice Age (LIA) and reconstructed the recent history of the lake. Results demonstrate relatively humid conditions in the mid-elevations (500 m a.s.l.) of El Salvador during most parts of the LIA, resulting in high lake levels. Contrarily, the first part of the LIA was characterized by drier climates comparable to studies from Mexico and Belize, which correlated this phase with the Spörer minimum. Regional comparison with palaeorecords from the northern Neotropics reveals a high heterogeneity in local expressions of the LIA in Central America, likely connected to the high topographic heterogeneity of the region. Since the beginning of the 20^th century, Lake Apastepeque has experienced enhanced human impact expressed as increased nutrient supply. The most recent period was characterized by significant environmental disturbance, which we relate to an upper-crustal earthquake, one of the strongest over the last 500 years, that affected the region on 13^th February 2001 (Mw = 6.6, epicentre at 10 km depth, 30 km from the lake). The release of toxic bottom components such as hydrogen sulphide and high turbidity and turbulence of water caused major species turnover in the lake ecosystem, resulting in a massive fish kill and colonization by large cladocerans. Modern sediments still show slightly altered biota communities compared to pre-earthquake assemblages, indicating that the ecosystem has still not fully recovered.

This article aims to trace in detail the periods of rapid changes during the Late Glacial period based on a subfossil Cladocera analysis and a palynological, geochemical, and statistical analysis. At the end of the Older Dryas, the water level in the reservoir was low, with quite cold waters and inconvenient conditions for developing Cladocera-dominated cold-tolerant species. The beginning of the Alleröd is marked by increasing vegetation density and a rising water temperature, with favorable conditions for developing rare species. At its end, there was a large diversity of species, along with the quite deep and rather mesotrophic nature of the water body. The beginning of the Younger Dryas is a shift back to conditions similar to those noticed during the Older Dryas. The shift to Holocene is manifested by a rapid increase in the number of species and abundance of planktonic forms that appeared before the Holocene onset. The high resolution of the research (1 cm sampling) allowed us to set up more precisely the boundaries between the stadials and interstadials of the Late Glacial and to find some species which were found in the sediment earlier than in previous studies.