Investigating filamentous algae attachment by rhizoidal differentiation to promote algae establishment on filamentous algae nutrient scrubbers
摘要
Filamentous Algae Nutrient Scrubbers (FANS) are a promising approach for agricultural drainage treatment. FANS use attached filamentous algae to recover nutrients from drainage, while generating algal biomass for beneficial reuse. Natural attachment of filamentous algae can take a minimum of three weeks. Hence, this research provides a better understanding of how different filamentous algal species attach. Rhizoid formation is a mechanism by which algal filaments attach to substrates, providing stable anchorage in aquatic environments. Laboratory-scale batch experiments were conducted using four New Zealand filamentous algal species. The effects of chopped filament length, water velocity, and biofilm presence on rhizoidal development and attachment were studied. Species-specific rhizoidal attachment responses were observed. Spirogyra sp.-initiated attachment within 96 h and was the only species reaching 92.4 ± 1.1% attachment after 7 days. No attachment was observed in Klebsormidium sp., Oedogonium sp. and Rhizoclonium sp. Chopping of Spirogyra sp. filaments to a smaller length further improved rhizoidal attachment (99.4 ± 0.3% for ~ 1.0 cm filaments compared with 91.0 ± 1.8% and 52.6 ± 7.5% in ~ 2.5 cm and ~ 7.5 cm filaments, respectively). Attachment declined with increasing water velocity (76 ± 0.7% at a water velocity of ~ 0.63 cm s−1 compared to no attachment at ~ 1.46 cm s−1). Presence of a biofilm promoted rhizoid formation in Rhizoclonium sp. filaments, achieving 26% attachment after 7 days. This research developed a novel technique to quantify filament attachment, essential for optimizing FANS performance as a sustainable water treatment and management technology in New Zealand and worldwide.