Effects of mechanical stressors caused by mean flow and turbulence on aquatic plants with different morphologies.

Asaeda, Takashi; Sanjaya, Kelum; Kaneko, Yasuko

Mean flow and turbulence are two significant factors that simultaneously affect aquatic plants. The tension from mean flow is unidirectional, whereas loads from turbulence fluctuate with the forces and pressures of different magnitude and direction. Our aim was to determine which water movement factor was most significant for habitat selection by submerged plants with different morphologies. The effects of mean flow and turbulence were tested with the whorled Elodea nuttallii, Potamogeton crispus, and leafy Vallisneria asiatica, controlling for other factors. A gradually constricted transparent pipe with plants in the middle was used in a recirculating tank to test the effects of the mean flow, and the effects of turbulence were examined by generating different turbulence levels in tanks with vertically oscillating grids. To determine plant response to these stressors, plant morphology, contents of cellulose, lignin, H2O2, pigments, indole acetic acid, and antioxidant activities were measured. Plant tissues were examined using transmission electron microscopy and light microscopy. At high turbulence levels, antioxidant activities and H2O2 concentrations were significantly higher than in plants affected by mean flow or in stagnant water; thus, the physiological stress from turbulence was significantly higher regardless of morphology. V. asiatica benefited from mean flow, whereas whorled E. nuttallii and P. crispus were more stressed than plants in stagnant water. To withstand vigorous motion, accumulations of lignin and cellulose were high and cell ultrastructure was altered in plants exposed to high turbulence levels. Therefore, the physiology of submerged plants was affected more by turbulent motion than by mean flow.

HABITAT selection; EFFECT of turbulence on plants; PLANT morphology; REACTIVE oxygen species; MACROPHYTES

Ecohydrology, 2017, Vol 10, Issue 5, pn/a

1936-0584

Academic Journal

10.1002/eco.1873