Phosphorus fuels Cladophora growth and self‑reinforcing adhesion via extracellular polysaccharides on hard substrata

Skip to main content

Abstract

Although high flow velocity, low nutrients, and smooth concrete surfaces typically suppress benthic algae, the filamentous alga Cladophora formed extensive biofilms in a major water transfer canal under conditions typically unfavorable for benthic algal colonization. We quantified Cladophora biomass, extracellular polysaccharides (EPS), and nanoscale adhesion through field surveys along the 1197 km canal and laboratory phosphorus-enrichment experiments. Phosphorus enrichment increased acid-extracted polysaccharides (APS) yield per biomass by 21.6%, and native EPS–sediment adhesion reached 18.6 nN, with polysaccharide backbones contributing approximately 88%. Along the canal, APS and sediment phosphorus were positively associated and both peaked at 30–45 cm depth. These results support a positive feedback mechanism in which APS strengthens adhesion and promotes local retention of phosphorus-bearing particles, potentially increasing phosphorus accessibility at the algal–matrix interface and further stabilizing the biofilm. The same biofilm can detach and cause downstream clogging. This self-reinforcing mechanism explains the spatial persistence of Cladophora blooms and provides a predictive basis for managing risks in large-scale water conveyance systems.

Graphical abstract

Content overview

Effects of phosphorus enrichment and irradiance on Cladophora growth, EPS secretion, and APS accumulation.

Spatial–vertical distributions of EPS, APS, and sediment phosphorus along the canal.

Depth-resolved and spatial distributions of sediment phosphorus and APS along the 1197 km trunk canal.

Macroscopic morphology of attached biofilms and AFM-measured nanoscale adhesion at representative sampling sites.

Citation & Export

@article{du2026phosphorus,
  title = {Phosphorus fuels Cladophora growth and self-reinforcing adhesion via extracellular polysaccharides on hard substrata},
  author = {Yifan Du^#^ and Siguang Yuan^#^ and Jinyi Qin and Siming Jiao and Yufan Ai and Yingjie Li and Nan Li and Xiaonan Chen and Xiaoming Cai and Xinzong Xiao^*^ and Jilong Wang and Min Yang and Ming Su^*^},
  journal = {Water Research},
  pages = {126915},
  year = {2026},
  doi = {10.1016/j.watres.2026.126915},
  issn = {0043-1354}
}