Periphytic algal community in lentic environments of the Upper Paraná River floodplain: seasonal and spatial variation

Abstract

Aim: This study aimed to evaluate the influence of seasonal variation in the hydrological regime and of limnological variables on species richness of periphytic algae in lakes of the Upper Paraná River floodplain. Methods The study area is located in the last undammed stretch of the Paraná River in this floodplain, in which three lakes were sampled quarterly (May, August and November 2014, and February and May 2015) for one year. The periphytic material was obtained from petioles of the aquatic macrophyte Eichhornia azurea (Sw.) Kunth. Results We registered 149 taxa of periphytic algae, distributed in 9 classes. Algal richness changed as a function of the seasonal dynamics of the Paraná River’s hydrological regime. Water level fluctuations directly influenced periphytic algae species. During periods of high water level, species richness increased. Limnological variables showed a close relationship with the hydrological regime, and the dissolved nutrients and turbidity were the abiotic factors that most influenced the algal community. The following species were present in all lakes: Fragilaria capucina Desmazières, Gomphonema gracile Ehrenberg and Navicula cryptotenella Lange-Bertalot (Bacillariophyceae) and two species of the genus Oedogonium (Oedogoniophyceae). Conclusions The hydrological regime of the Paraná River played an important role in structuring communities of periphytic algae. Seasonal variation in hydrological regime and in limnological variables together influenced the species richness of these organisms in these floodplain lakes.

On the occurrence of Spirogyra maxima (Zygnematophyceae) in the Upper Paraná River floodplain

“…This study contributes to the addition of a new taxon to the Upper Paraná River floodplain, since Spirogyra species are of great importance in this type of environment, usually reported as abundant or well represented in the periphyton (see Dunck et al 2013, Adame et al 2018. None of the specimens of the genus had previously been reported at a specific level for the ecosystems that comprise this floodplain (Dunck et al 2018).…”

Aquatic insects in plateau streams in Southern Brazil: a functional feeding group analysis

“…This may be due to the strong seasonality present in the sample area, with negative temperatures, reduced luminosity, frost and snow observed during the colder seasons of the year. This leads to variations in different abiotic variables which, in turn, affect in aquatic environments, altering their trophic state (KRUPEK et al, 2012;ADAME et al, 2018;JUNGER et al, 2019).…”

“…The strong recorded association of scraping insects to spring and summer is also environmentally positive, as these insects feed on algae that develop on rocks and are associated with a stable stream substrate (MERRITT et al, 2014). It is possible that these algae are more abundant in the study area during the warm seasons of the year, as the region is characterized by high atmospheric cloudiness during winter and autumn, possibly impairing photosynthetic algae activity, while the warm seasons of the year present higher local rainfall rates (ADAME et al, 2018). Furthermore, this feeding group usually exhibits reduced abundance in degraded environments suffering environmental damage (MERRITT et al, 2014;PEREIRA et al, 2020).…”