Abstract: This study explored whether the biotic resistance exists in winter between epiphytic algae from native submerged macrophytes and invasive submerged macrophyte Cabomba caroliniana A. Gray, as well as effects of epiphytic algae communities on the growth of C. caroliniana in winter Taihu Lake. Fragments of C. caroliniana were cultured in dialysis bags with epiphytic algae from native submerged macrophyte, invasive submerged macrophyte and both macrophytes for 4 weeks. Then the fragments were harvested, and the final epiphytic algae density, community composition and growth attributes were measured. The final epiphytic algae density and community composition were significantly affected by epiphytic algae treatment and showed diverse density levels. Fragments in epiphytic algae from invasive submerged macrophyte treatment showed higher growth rate, regeneration and colonization ability than native and mixed epiphytic algae treatments. Epiphytic algae community from native submerged macrophytes performed biotic resistance against C. caroliniana in short time period. It significantly depressed the growth, colonization and regeneration abilities of C. caroliniana comparing with invasive epiphytic algae. However, with the native submerged macrophytes gradually dying in winter Taihu Lake, their epiphytic algae community could perish and lose the resistance ability against the invasion of C. caroliniana. Such, this partly explained the reason for invasion and superiority community of C. caroliniana in Taihu Lake in winter and provided theoretical basis for the management of invasive submerged macrophytes.

Key words: submerged macrophyte, epiphytic algae community, biotic resistance, biological invasion, Cabomba caroliniana