Response of benthic algae to environmental conditions in an urban lake recovered from eutrophication, China

Abstract

Benthic algae communities dominate the primary production in littoral zone of shallow lake. To understand the long-term effect of alteration in the composition of benthic algae community assemblage in such as a lake in China, we analyzed the benthic algae developments and indicators in the Donghu Lake in Wuhan, central China in 2004 and 2014. We compared the benthic algae biomass, compositions, and species richness of aquatic macrophytes and the changes of primary physicochemical parameters. The results show that in the 10-year period, chl a and conductivity declined significantly but nutrient level of the whole lake remained largely stable. The benthic algae biomass doubled and the relative proportion of green algae increased, whereas the benthic diatom ratio decreased. The benthic diatom assemblages and taxa differed in a number of ways, showing more epiphytic diatom species, and the relative abundance and species richness changed markedly. The number of aquatic macrophyte species increased from 3 in 2004 to 15 in 2014, presenting a remarkable recovery from previous eutrophication conditions. The changes of water level, chl a, and conductivity played a crucial role in governing aquatic macrophytes re-colonization in the littoral zones in the period. The ecological characteristics of littoral benthic diatoms reflect habitat coupling as indicated by redundancy analysis. Therefore, the close link between benthic algae and macrophyte recovery demonstrates that the benthic algae metrics are much more useful than nutrient levels to quantify the process of restoration in the lake.