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

• Published in: Ecohydrology 2021-12, Vol.14 (8), p.n/a
• Main Authors: Santos Machado, Rafaela, Carvalho Harthman, Vanessa, Murillo, Raytha de Assis, Thomaz, Sidinei Magela, Silveira, Márcio José
• Format: Article
• Language: English
• Subjects: Adaptation; Anatomy; Aquatic ecosystems; Aquatic plants; Dam construction; Deep water; flood pulse; floodplain; Fluctuations; macrophyte anatomy; Macrophytes; Parascyllium ferrugineum; Parenchyma; Polygonum; Roots; Species; Stems; Survival; Thickness; Water level fluctuations; Water levels
• ISSN: 1936-0584; 1936-0592
• DOI: 10.1002/eco.2341

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.