Bellamya aeruginosa (Reeve) promote the growth of Elodea nuttallii (Planch.) H. St John in high nutrient environment

Abstract

Elodea nuttallii (Planch.) H. St John is an invasive alien submerged macrophyte, which grows very fast and dominates in many Chinese waters. Bellamya aeruginosa (Reeve) is a widely distributed benthonic organism in China. This snail species rarely grazes submerged macrophytes and may promote their growth by feeding on epiphyte and phytoplankton. The above two species can commonly be found together in nature waters and their interaction may promote the growth of both species, which could disturb the ecological balance. In this paper, effects of different densities of B. aeruginosa at two different nutrient stages on water quality and the growth of E. nuttallii were studied. The results showed that the growth rates (GRs) of E. nuttallii were not significantly affected by different B. aeruginosa densities in the low nutrient (LN) stage. However, in the high nutrient (HN) stage, the GRs of the aboveground parts of E. nuttallii in the high density (HD) groups were considerably higher than the control (CK) and low density (LD) groups. The water chlorophyll (Chl) and nitrate-nitrogen (NO3-N) contents increased substantially with increasing B. aeruginosa density in the LN stage, while the Chl and NO3-N contents in the LD groups were significantly higher than in the HD and CK groups in the HN stage. The results of this paper indicated that B. aeruginosa could promote the growth of E. nuttallii by reducing the Chl contents in the water in high-nutrient environment rather than in low-nutrient environment, which highlighted that B. aeruginosa may strengthen the invisibility of E. nuttallii in eutrophic water caused by human activities.