Nonlinear Relationship of Near-Bed Velocity and Growth of Riverbed Periphyton

作者：Ateia Mohamed^*; Nasr Mahmoud; Ikeda Akira; Okada Hisako; Fujii Manabu; Natsuike Masafumi; Yoshimura Chihiro

来源：Water (Switzerland), 2016, 8(10): 461.

DOI：10.3390/w8100461

• periphyton growth
• logistic model
• response surface method
• near-bed water velocity

Artificial streams were set up to test the relationship between near-bed water velocity and periphyton growth. Periphyton community samples collected from a Japanese stream were incubated for 44 days under a light intensity of 252 +/- 72 mu mol.photons/m(2).s, a temperature of 20-25 degrees C, and three near-bed water velocity classes: low (<17.9 cm/s), moderate (17.9-32.8 cm/s), and high (>32.8 cm/s). A logistic model was applied to estimate the maximum net growth rate (mu(max)) and carrying capacity (B-max). A response surface method was also applied to estimate chlorophyll a (Chl-a) and ash-free dry mass (AFDM) with respect to the independent variables (i.e., time and water velocity). We detected both the highest mu(max) (1.99 d(-1)) and highest B-max (7.01 mg/m(2)) for Chl-a at the moderate water velocity. For AFDM, we observed the highest mu(max) (0.57 d(-1)) and B-max (1.47 g/m(2)) at the low and moderate velocity classes, respectively. The total algae density in the region of moderate velocity at the end of the experiment was 6.47 +/- 10(3) cells/cm(2), corresponding to levels 1.7 and 1.3 times higher than those at lower and higher velocities, respectively. Our findings indicated that the moderate near-bed water velocity provided favorable conditions for algal growth and corresponding biomass accumulation.

• 出版日期2016-10