Abstract
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 μmol·photons/m2·s, a temperature of 20–25 °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 (μmax) and carrying capacity (Bmax). 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 μmax (1.99 d−1) and highest Bmax (7.01 mg/m2) for Chl-a at the moderate water velocity. For AFDM, we observed the highest μmax (0.57 d−1) and Bmax (1.47 g/m2) 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 × 103 cells/cm2, 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.
Highlights
Periphyton refers to a complex layer composed of algae, cyanobacteria, heterotrophic microbes, and detritus attached to the sediment surface or to aquatic macrophytes in aquatic systems [1].It serves as an important food source for invertebrates and some fish, and it can absorb and immobilize major nutrients and some heavy metal contaminants [2]
Periphyton growth is affected by environmental factors, such as light [9], temperature [10], substrate availability [11,12], Water 2016, 8, 461; doi:10.3390/w8100461
Chl‐a were determined by response surface methodology (RSM) (Equation (6)) and visualized by examining the surface plot presented method (F > 2.0; MATLAB R2014a, MathWorks, Inc., Natick, MA, USA)
Summary
Periphyton refers to a complex layer composed of algae, cyanobacteria, heterotrophic microbes, and detritus attached to the sediment surface or to aquatic macrophytes in aquatic systems [1]. It serves as an important food source for invertebrates and some fish, and it can absorb and immobilize major nutrients and some heavy metal contaminants [2]. Periphyton plays a major role in the metabolic conversion and partial removal of biodegradable materials in rivers and streams [3] It can pose engineering and environmental problems; for instance, it clogs hydraulic devices [4] and is sensitive to eutrophication [5]. Periphyton growth is affected by environmental factors, such as light [9], temperature [10], substrate availability [11,12], Water 2016, 8, 461; doi:10.3390/w8100461 www.mdpi.com/journal/water
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