The anatomy of two species of emergent macrophytes of the genus Polygonum differentially changes in response to water‐level fluctuations

Abstract

Temporal fluctuations in water levels are important ecological driving forces in shallow aquatic ecosystems. Alterations to fluviometric levels are even more conspicuous after the construction of dams, and aquatic macrophytes respond with anatomical and morphological adaptations to such changes. We performed an experiment to analyse the anatomical responses of two common Neotropical species of emergent macrophytes (Polygonum ferrugineum and P. acuminatum) to water-level fluctuations.The experiment simulated three water-level variations: constant low water, constant deep water and fluctuating water levels (0.8-m oscillation/6 days; commonly caused by dam operation). We measured anatomical responses of roots (perimeter and number of the intercellular spaces), stems (perimeter and number of the intercellular spaces and cortical thickness) and leaves (palisade and lacunous parenchyma thickness). Water level affected all anatomical traits we measured and all increased when plants remained submerged (high-depth treatment). Compared with P. ferrugineum, P. acuminatum had higher values of both perimeter of the intercellular space in the roots and number of intercellular spaces in the stems. These results indicate that water-level fluctuations influence the anatomy of both species and that, compared with P. ferrugineum, P. acuminatum has greater plasticity and better tolerates submersion. These responses may be explained by the different survival strategies of each species when growing under submersion. Thus, our results reflect the different selective pressures from water levels experienced by these two species during their evolution.

Indicators of rapid adaptation of an exotic aquatic Poaceae to increased salinity

“…Salinity is considered one of the main factors influencing the distribution and development of aquatic vegetation throughout these ecosystems (Nunes & Camargo, 2016). As mentioned, some species shows adaptations to survive to these different environmental conditions and can exhibit phenotypic plasticity to adapt to these new conditions (dos Santos Machado et al, 2021;Silveira et al, 2016). Studies have demonstrated that the relative amount of intercellular spaces in salinized plants may decrease noticeably, mainly due to the disruption to the arrangement of these tissues (de Villiers et al, 1994).…”

“…Invasion success is often attributed to species with greater tolerances to various environmental conditions (e.g., temperature, nutrients and salinization of water bodies) (Clavero & García‐Berthou, 2005), as well as the adaptive strategies that these species can employ in their new environments to survive (Hayat et al., 2020), for example, rapid growth rate, dispersion (Xie et al., 2010) and adaptation of internal structures (e.g., increase in intercellular spaces; Silveira et al., 2016; dos Santos Machado et al., 2021).…”

Who Wins? Comparison Between Emergent Macrophytes and Pontederia Crassipes (Water Hyacinth) as Nature-Based Solutions for Nutrient Phytoremediation and Cyanobacteria Mitigation

“…philoxeroides is a perennial species with stolons and rhizomes, featuring floating stems due to stem aerenchyma, thriving in aquatic margins, flooded areas, and dry land, reproducing vegetatively (Griseb, 2016) as well as P. ferrugineum that creates floating branches when flooded (de Assis Murillo et al, 2019;dos Santos Machado et al, 2021), whereas L. leptocarpa inhabiting riverbanks, lakes, and flooded areas (De Sousa et al, 2019).…”