Naturalization of Elodea canadensis Mich. in Lake Baikal

Abstract

The spatial distribution of Elodea canadensis Mich. was studied in the southern and central basins of Lake Baikal in 2006–2009. E. canadensis has naturalized successfully in the lake ecosystem. It coexists here with the indigenous submerged macrophytes under its canopy or forms either rarefied undergrowth or separate monomorphic spots. The invasion of this species into the Lake Baikal ecosystems has led to the structure reorganization of indigenous phytocenoses in several bays of the Maloye More. Currently, E. canadensis dominates in phytocenoses of Khuzhir-Nugo Bay; and Myriophyllum spicatum L., in Kurkutskaya Bay. The trend of the population dynamics in these two species was observed, common to the Lake Baikal and other fresh-water ecosystems, where a decrease in E. canadensis abundance is followed by an increase in M. spicatum abundance. The abundance and distribution of the associated biota of submerged macrophytes was studied. It was found that the phytoepiphytone community of E. canadensis differed significantly compared to the indigenous submerged macrophytes inhabiting the same biotope. Low values of Shannon-Weaver index, high abundance of one species (Cocconeis placentula var. placentula), and low evenness are evidence of community vulnerability and unfavorable conditions of its habitat on E. canadensis. That is why, when E. canadensis forms thickets, a decrease in biodiversity of phytoepiphytone and dominance of Cocconeis species are usually observed. Structural changes of phytocenoses influence on the abundance of invertebrates. Epibiota of Elodea canadensis differs significantly from that on Myriophyllum spicatum and bottom fauna, which the results of principal component analysis and ANOVA confirm.