太湖沉水植物附生藻类群落对水盾草入侵能力的影响

为探究冬季乡土沉水植物表面附生藻类群落对水盾草的入侵是否存在抵抗力,在冬季采用透析袋对接种有来自乡土种、入侵种沉水植物及二者混合的附生藻类群落的水盾草断枝进行为期4周的培养,收获后分析不同附生藻类群落对水盾草附生藻类群落密度、组成情况和生长、拓殖再生能力的影响。结果表明,不同处理下,水盾草的附生藻类群落密度与组成有显著区别。入侵沉水植物附生藻类群落处理组中的水盾草断枝生长速率与再生拓殖能力均高于乡土和混合附生藻类群落处理;相较于水盾草表面原生附生藻类群落,乡土附生藻类群落短期内可显著抑制水盾草的生长和拓殖,表现出抵抗作用。但在冬季,随着太湖中乡土沉水植物相继死亡,其附生藻类群落随之消亡,无法继续抵抗水盾草的入侵。这在一定程度上解释了水盾草在冬季太湖入侵并形成单一优势群落的原因,为沉水植物生物入侵的治理提供了理论依据。

Effects of epiphytic algae community on invasion abilities of submerged macrophyte Cabomba caroliniana A. Gray in Taihu Lake

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.