Contrasting relationships between genetic diversity and species diversity in conserved and disturbed submerged macrophyte communities of Honghu Lake, a typical freshwater lake of Yangtze River Basin

Abstract

Submerged macrophytes, as the primary producer in lakes, possess fundamental function for the construction of the lake ecosystem. Here, species-genetic diversity correlation (SGDC) was evaluated between the species diversity (SD) of submerged macrophyte communities and the genetic diversity (GD) of dominant submerged macrophyte Myriophyllum spicatum in the conserved and disturbed water areas of the Honghu Lake, China. For communities, higher level of SD was unexpectedly found in the disturbed area, despite the fact that higher biomass was exhibited in the conserved area. For M. spicatum , the two areas showed similar level of GD. Neither the conserved area ( r = 0.092, P = 0.755) nor the disturbed area ( r = 0.377, P = 0.253) showed significant SGDC. This was attributed to the convenient exchanges of species and genes within the Honghu Lake. Additionally, the response for SD of submerged macrophyte communities to disturbance was more rapid than that for GD of M. spicatum , which also led to no SGDC in the disturbed area. Based on the results, a conservation strategy for conserving the two levels of biodiversity (both SD and GD) separately is recommended. The conserved area should be enlarged and serve as stable supplies of species and genes for the disturbed area; reasonable collection should be carried out in the disturbed area; seedlings can be replanted to the lake for GD maintaining. Additionally, government supervision should be strengthened, with controlling pollutant discharge and monitoring aquatic plant diversity regularly.