Water quality and spatial and seasonal dynamics in the largest water supply reservoir in Brazil and implications for diatom assemblages

Abstract

Aim in this paper we investigated how spatial factors and seasonal dynamics influenced the diatom community in a tropical deep environment of low productivity waters in Brazil. Methods we used physical and chemical characteristics of the water and planktonic diatoms from 9 sampling stations during dry (austral winter) and wet (austral summer) seasons (N = 18) as the outline to identify water quality, spatial and seasonal patterns. To evaluate spatially and temporally integrated events from the recent past (approximately the last 5 years before sampling), and the species from diverse habitats of the system, we used diatoms from the surface sediment (top 2 cm, N = 9). Since we used the top 2 cm of surface sediment containing the dead diatoms that were deposited over recent past of the reservoir, seasonal sampling of the sediment was not needed. Results during the dry season heavily silicified long colonial planktonic diatom species associated mainly with higher mixing depth, pH, and transparency dominated the plankton, whereas in the wet season the reservoir became stratified, favoring planktonic solitary diatoms with high surface volume ratios. For the sediment, a general pattern emerged where planktonic species dominated in the deep sections of the reservoir, and the abundance of benthic species in shallow areas near the tributaries increased. Conclusions the diatom assemblages was mainly influenced by seasonal variations and mixing regime. Surface sediment samples provided longer-term information, and revealed habitat differentiation shaping diatom assemblages. Overall, the small centric planktonic Aulacoseira tenella (Nygaard) Simonsen stood out as the most abundant species in the entire reservoir in both, the plankton and the sediment, indicating that size and shape serve as adaptive strategies for buoyancy and nutrient uptake stand as a competitive advantage in deep low productivity environments.

Water quality trough the use of bioindicators, climate change and environmental education in the paraense Amazon

“…In the Uraim River, Silva et al (2019), Nascimento et al (2020 and Nascimento et al (2021), analyzed five physical-chemical parameters (pH, Turbidity, Temperature and DO) of water quality at points with higher and lower population agglomeration, and the data obtained were compared with standards already stipulated in Resolution 357 (BRASIL, 2005).…”

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

“…The heavily-silicified diatoms, that is, A. granulata var. granulata, typically require sufficient silica and nutrient levels for their quantitative and dimensional development (Litchman et al, 2007;Nascimento et al, 2021;O'Farrell et al, 2001;Round et al, 1990). Their size and shape are susceptible to various lacustrine parameters such as water level, water-mixing, water transparency, silica concentration, nutrient content, and temperature (Davey, 1986;Genkal and Trifonova, 2020;Gómez et al, 1995;Mohanty et al, 2022;O'Farrell et al, 2001;Turkia and Lepistö, 1999).…”