Response of aquatic macrophyte biomass to limnological changes under water level fluctuation in tropical reservoirs

Abstract

We evaluated the response of the biomass of aquatic macrophytes under limnological changes after water level fluctuation (WLF) of two tropical reservoirs (R1 and R2), located in northeastern Brazil. Initially we tested the hypothesis that post-WLF limnological conditions and biomass of macrophytes increase or decrease, depending on the variable or species. We monitored a 4 × 50 m permanent plot, in four expeditions per period (pre- or post-WLF), assessing species biomass and 10 limnological variables. We utilized 0.25 × 0.25 m quadrats for biomass. Once the effect of WLF in limnological variables and species biomass was confirmed, we utilized Canonical Correspondence Analysis to understand the relationship between limnological variables and species biomass. The abundant and/or dominant species in pre-WLF of R1 ( Pistia stratiotes, Eichhornia crassipes and Salvinia auriculata) and R2 (Paspalidium geminatum and S. auriculata) reduced their biomass post-WLF and were correlated with temperature, total phosphorous and nitrate. The reduced biomass of P. stratiotes, E. crassipes and S. auriculata in post-WLF widened resource availability, allowing coexistence of species. Therefore, we suggest that the change of limnological conditions in post-WLF in artificial lakes acts only as a moderator factor of the interspecific interaction (especially coexistence), without direct relation between these conditions and species biomass.

The invasive tropical tanner grass decreases diversity of the native aquatic macrophyte community at two scales in a subtropical tidal river

“…This combination is typical in coastal environments of Paraná State. With higher biomass production, impact of dominant macrophytes on biodiversity may be enhanced (see also Moura-Júnior et al 2019).…”

A 1232 bp upstream sequence of glutamine synthetase 1b from Eichhornia crassipes is a root-preferential promoter sequence

“…Currently, the study on E. crassipes mainly focused on anaerobic fermentation, feed resources, fertilizer resources, water remediation and biogas production [ 31 , 32 ]. There was only a little research regarding the physiological and biochemical characteristics of E. crassipes such as the determination of enzyme activities related to N metabolism [ 33 – 36 ]. Moreover, there were few papers that reported on the mechanism of E. crassipes at the molecular level [ 37 , 38 ].…”

Ecology of Aquatic Macrophytes in Brazil: The Legacy of Francisco De Assis Esteves

“…Among the physical disturbances affecting macrophytes, we found numerous investigations addressing water level fluctuations. Macrophyte communities respond to disturbances related to the flood pulse (Camargo & Esteves 1996, Monção et al 2012, Catian et al 2018, bar-opening in coastal lagoons (dos Santos & Esteves 2004), drought-wet seasons in semi-arid ecosystems (Maltchik & Pedro 2001, Pedro et al 2006) and water level drawdown in reservoirs (Thomaz et al 2006, Moura-Júnior et al 2019. These types of studies are important because aquatic ecosystems suffering from severe water level fluctuations are common in Brazil, and they include floodplains, reservoirs and ponds in Northeast and other regions.…”