Evidence that siltation aggravated by climate change can shift the dominance of two globally invasive freshwater macrophytes

Abstract

Siltation has been aggravated by climate changes due more frequent and intense rain events, resulting in greater amounts of sediment in water bodies. These changes have impacted drastically submerged macrophytes growth by light limitations. Despite biological invasions are among the major threats to freshwater biodiversity and invasive submerged aquatic plants also has been impacted by these changes. The main aim of this study was to investigate through an experimental study as two globally invasive freshwater macrophytes, Hydrilla verticillata and Egeria densa, respond to the changes in water transparency caused by siltation. We performed a factorial experiment to test the effect of turbidity increase caused by siltation on growth of these two species. For this, we included sand or mud sediment in containers to obtain without and with siltation treatments. Then both species were planted at the two treatments and grown for 30 days. The main results of our study were that there was a shift in the dominance at the performance of some biological traits between the species, where H. verticillata showed better development of these biological traits than E. densa at treatment with siltation, and the reverse was also true, where E. densa had better performance in without siltation treatment. In summary, our results demonstrated that if the increase in water siltation continues at the current rate, a greater performance of H. verticillata can also be expected and, consequently, the impacts on aquatic biodiversity will also increased. These results may be helpful in predicting the effects of siltation on the development of two globally invasive freshwater submerged macrophytes. Moreover, could increase the ability of managers environmental to predict the future development of ecosystems in relation to invasions by non-native species.