Interactive Effects of Rising Temperature, Elevated CO2 and Herbivory on the Growth and Stoichiometry of a Submerged Macrophyte Vallisneria natans

Global climate changes are affecting organisms and their interactions in terrestrial and aquatic ecosystems, such as the increase in temperature and CO2 concentration. Herbivory interaction is a very important part of nutrient cycle and energy flow in freshwater ecosystem, and climate changes may directly or indirectly affect aquatic plants, aquatic herbivores and their interactions. In this study, we explored the effects of the rising temperature, elevated CO2 concentrations and herbivory by an herbivorous snail (Radix auricularia L.) on a submerged plant (Vallisneria natans L.). Our results showed that herbivory, temperature, and CO2 had specific effects on snail and plant growth, statistically there was only one interaction-a reduction in leaf number. Under different experimental conditions, snail herbivory always has negative effects on biomass accumulation and growth of V. natans. Moreover, the increases in temperature also inhibited its growth. Snail herbivory reduced the content of total carbon and total nitrogen of V. natans in all treatments, while the total phenols content increased. Our findings indicate that the rising temperature, elevated CO2 concentrations and herbivory have interactive effects on the growth and stoichiometry of submerged macrophytes, but further research is needed between aquatic plants and aquatic herbivores to aid prediction the impact of climate change on freshwater ecosystems.