Structure and species composition of diatom community during the wet season in three floodplain lakes of Brazilian Pantanal

Abstract

In order to access environmental conditions, the use of bioindicators that have a close relationship with environmental stressors is a largely common practice, but when evaluating environmental inferences, the individual dominant taxa need to be interpreted. Humid regions such as the marshlands are fragile ecosystems and sustain communities of microalgae, often used as bioindicators, of which diatoms are a good example. Although they provide an excellent response to chemical and physical changes in water, diatom studies in surface sediments in wetlands are scarce worldwide. To determine whether diatom species have the potential to provide unambiguous inferences in the influence of environmental factors, we have evaluated diatom abundance in surface sediment, from three Pantanal lakes, against a set of environmental gradients: pH, dissolved oxygen, turbidity, conductivity, total dissolved solids, water temperature, index of trophic water status, total phosphorus and total nitrogen. The Ferradura lake presented an oligotrophic state and both Burro and Caracará lakes presented mesotrophic state. Diatoms were more abundant in the a mesotrophic conditions, but with higher species richness in the oligotrophic conditions. Depending on the N:P ratio, the nutrients nitrogen and phosphorus can also play the role of pollutants and may have negative and unpredictable effects in the environment, such as biotic homogenization. Despite the spatial variation in species, there was a greater richness of Eunotia Ehrenberg species, with the highest relative density of Eunotia formica Ehrenberg and E. pantropica Glushchenko, Kulikovskiy & Kociolek, due to the environmental acidic conditions, a determining characteristic of this genus. It was also observed that a small increase in the level of phosphorus generated an increase in the abundance of Aulacoseira Thwaites with the highest relative density of A. pusilla (Meister) Tuji & Houki and A. veraluciae Tremarin, Torgan & T.Ludwig. However, A. italica dominated in the moderately acidic environment. The results can help with decisions in impacted areas to solve socioeconomic problems, environmental management and biodiversity.

Diatom Stratigraphy as a Flood Record in the Lower Tuntang River, Demak, Central Java

“…The relative abundance of planktonic diatoms (A. granulata, C. invisitatus, C. pseudostelligera) increased in the wetland (USA) during high-magnitude floods. Meanwhile, other species, such as A. italica and M. varians, were found to be abundant during the rainy season in Lake Broa, Brazil 91) . The genus Aulacoseira is an indicator of storms and swift water currents, as evidenced by the abundance of this species in waters with mixed water, such as Huguang Maar Lake 92) , Rocky Mountain Lakes 93) , Hidden Lake 94) , and Alpine Lakes 95 ).…”

Diatom-based indications of an environmental regime shift and droughts associated with seasonal monsoons during the Holocene in Biển Hồ maar lake, the Central Highlands, Vietnam

“…Thus, A. veraluciae requires a more vigorous water circulation for its suspension. Moreover, this species has been found in a wide range of environments, from oligotrophic to eutrophic (Nardelli et al, 2021; Nogueira et al, 2006; Pagioro et al, 2005). We suppose that the observed high abundance of A. veraluciae in Biển Hồ lake during the Early Holocene was driven by strong water-mixing primarily occurring during winter seasons along with intense monsoonal winds and rainfalls, which contributed to the influx of silica-rich nutrients into the lake.…”

“…A direct relationship between D. stelligera and nitrogen concentration has also been suggested by a positive response to additional nitrogen inputs into its living environment when phosphorus levels remain relatively limited (Rühland et al, 2015; Saros and Anderson, 2015). However, because the high diversity of the diatom community and the frequent occurrence of Aulacoseira taxa imply a high level of trophic state (Nardelli et al, 2021), the phosphorus levels in the Biển Hồ water were probably unlimited during this time. Hence, we suppose that during the Early Holocene, the lake experienced summer seasons with prolonged insolation and reduced rainfall, supplying less silica and nutrients into the lake and promoting thermal stratification.…”

Epipelic Diatoms to Determine Ecological Status Based on Diatom Index in Mangrove Ecosystem of Morosari Village, Indonesia

“…Station 2 is in the middle of a mangrove ecosystem that has a slow flow of sea water. Eunotia formica species have been found, these species can survive in wetlands and slow waters such as mesotrophic to oligotrophic water areas with a water pH of 5.6-7.4 [Nardelli et al, 2021;Sari et al, 2018]. Meso-eutrophic or mesotrophic waters are waters that have a moderate level of fertility.…”