Effects of water regime on the growth of the submerged macrophyte Ceratophyllum demersum at different densities

Abstract

ABSTRACTTo successfully restore deteriorated lake ecosystems, it is vital to identify influencing environmental factors that impact submerged macrophytes. Planting density and water regime are important factors for submerged macrophytes’ growth. While many experimental studies have examined effects of water regime on the growth of some aquatic plant species, very few have tested both planting density and water regime on population, individual, and internode growth of a submerged population. We constructed Ceratophyllum demersum populations at two density levels (four and 16 shoot fragments per pot, responding to 96 and 384 plants m−2), subjected to two static water depths (30 and 150 cm) and to low, medium, and high water level fluctuation frequencies (24, 12, and 6 days per fluctuation cycle of water depth change between 30 and 150 cm). Initial density had no significant effect on individuals of C. demersum; however, it had a positive effect on population performance. Fluctuation frequency did not affect the growth of C. demersum, whereas increasing water depth significantly decreased both individual and internode biomass, and also increased shoot length regardless of comparison level. We therefore conclude that managing water depth and establishing populations with higher plant density may be helpful for the restoration of submerged macrophytes in degraded wetlands.