Original paper
Species composition and ecological traits of the metacommunity of filamentous diatoms in a fragmented river, the North River, China
Zeng, Ru; Zeng, Yanyi; Liu, Qianfu; Xie, Changxin; Hu, Tiehuan; Hu, Caiqin; Sun, Jinhui; Wang, Chao
Fundamental and Applied Limnology Volume 197 Nr. 4 (2025), p. 311 - 328
65 references
published: Aug 27, 2025
published online: Jun 24, 2025
manuscript accepted: Jun 12, 2025
final revised version received: May 8, 2025
manuscript revision requested: Oct 25, 2024
manuscript received: Sep 14, 2024
DOI: 10.1127/fal/1568
ArtNo. ESP141019704005, Price: 29.00 €
Abstract
The North River, one of the tributaries of the Pearl River in southern China, is a main source of water supply for the cities of Shaoguan, Qingyuan, Zhaoqing and Foshan (Guangdong Province). The North River is also largely impacted by the construction of dams. Filamentous diatoms, formed by spiny or protruding structures connected between neighboring cells, are dominant taxa in river phytoplankton communities and crucial to riverine ecosystems. We conducted environmental surveys of the North River in April, August and November 2019 to investigate the species diversity and morphological characteristics of filamentous diatoms in a fragmented river. A total of 17 filamentous diatoms (including varieties) were identified, including 14 species of Aulacoseira and 3 species of Melosira. The highest biomass contribution of Aulacoseira was made by Aulacoseira granulata, followed by Aulacoseira ambigua f. japonica, while Melosira varians had the highest occurrence among Melosira, followed by Melosira juergensii var. bothnica. Spatiotemporal characterization of filamentous diatom biomass and filament length showed that biomass was greater in April than in August and November, mainly related to temperature, runoff, pH and competition with other algae. In general, the biomass and filament length of Aulacoseira were larger than those of Melosira. Spatially, the maximum or minimum biomass often appeared at stations closest to the dams in April. However, this pattern was not observed in August and November. In the three periods of investigation, spatial distribution was characterized by different filament lengths at different dams. At the most downstream dam, there was a tendency for the mean filament length to gradually increase with downstream distance from the dam. This might be related to the long filament lengths of the filamentous diatoms, with longer filament lengths having a greater specific surface area, as a larger specific surface area was more likely to follow the flow in turbulent downstream. Additionally, there was also an increasing trend in the biomass of filamentous diatoms after the last dam. However, unlike the continuous increase in filament length, the biomass showed a discontinuous surge, which might result from the restoration of river connectivity.
Keywords
The North River • cascade dam • phytoplankton • filamentous diatom • spatiotemporal characteristics