Diatom assemblages (Bacillariophyta) in six tropical reservoirs from southeast Brazil: species composition and spatial and temporal variation patterns

Abstract

Aim Relationships between species composition and variation patterns in diatom assemblages over six tropical reservoirs located in Southeast Brazil were explored. Methods Surface-sediment and phytoplankton diatom assemblages were determined and Canonical Correspondence Analysis was used to verify the set of environmental variables that best explain the species composition variation among sites. Results A total of 28 diatom taxa representing 20 genera were identified using light and scanning electron microscopy. Information on their ecological preferences was also provided. Humidophila biscutella is reported for the first time in Brazil whereas Sellaphora sassiana and Humidophila brekkaensis are reported for the first time in São Paulo State. Three groups of potential water quality indicators were delineated: the first suggests oligotrophic conditions, the second is related to cold waters with low luminosity in a mixing regime, and the third is a small group of tolerant species occurring in water with high conductivity, pH and total phosphorus conditions. Conclusion present study provided the first insight into the general diatom communities over six tropical reservoirs in Southeast Brazil and provided information on their ecology and distribution aiming bioassessment. The potential of water quality indicator diatom groups here outlined are in line with those reported in the literature and reinforce the importance of PEJU for the maintenance of ecological quality of reservoirs and reference conditions for the Metropolitan Region of São Paulo water sources.

Is a rare diatom relevant for Brazilian reservoirs?

“…Birks et al, 1990;Dixit et al, 1992;Weckström et al, 1997). Our study also shows a strongly significant correlation of this environmental parameter during stepwise selection in a CCA of diatom assemblages with environmental variables in the study area (Marquardt et al, 2018), and was considered a relevant variable from our dataset, with a relatively long gradient. We used a training set composed of 40 phytoplankton diatom samples from six reservoirs located in Southwest São Paulo (Brazil).…”

“…Chl-a corrected for phaeophytin was extracted by using 90 % ethanol (Sartory & Grobbelaar, 1984) (Table 1). Details of the study area and further information on the limnological variables are available in Marquardt et al (2017Marquardt et al ( , 2018.…”

“…Lowe. Within the study area, their abundance was correlated with the Secchi disk transparency vector, considered as indicators of oligotrophic conditions (Marquardt et al, 2018). In contrast, Aulacoseira ambigua (AAMB), A. granulata (AUGR) and A. pusila (AUPU) correlated to the total nitrogen (NT) vector and lowest conductivity and Secchi values (Marquardt et al, 2018).…”

Periphytic diatoms from an oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil

“…Humidophila deceptionensis Kopalová, Zidarova & Van de Vijver is similar to H. biscutella, but has wider valves (2.7-3.2 µm) (Kopalová et al 2015). In Brazil, it was previously registered for reservoirs in São Paulo state (Marquardt et al 2018).…”

Sediment diatoms from Upper Paraná River floodplain lakes

“…Material examined: BRAZIL, MATO GROSSO DO SUL: Batayporã, Garças Lake, 21.IX.2017, sediment, D.T. Ruwer (Nupélia UEM -18066, 18071, 18076, 18083-84, 18086-87, 18093 Marra et al (2016) and Marquardt et al (2018). Material examined: BRAZIL, MATO GROSSO DO SUL: Batayporã, Garças Lake, 21.IX.2017, sediment, D.T.…”