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The influence of elevated CO2 on Vallisneria spiralis, Radix auricularia, and their plant–herbivore interaction

Lv, Chaochao, Wang, Hui, Wang, Jiaan, Ma, Xufa, Xia, Chengxing
Aquatic ecology 2019 v.53 no.1 pp. 137-150
Lymnaeidae, Pulmonata, Vallisneria spiralis, air, carbon dioxide, carbon dioxide enrichment, climate change, food webs, herbivores, inland waters, leaves, macrophytes, phytomass, resource allocation, snails, total nitrogen
Aquatic plants and associated herbivores are expected to perform better under the rising atmospheric CO₂ concentration brought about by climate change. However, it is not clear how increasing CO₂ affects herbivory on aquatic macrophytes. In this research, we set four treatments (A group: ambient air without snails; AS group: ambient air with snails; E group: elevated CO₂ without snails; and ES group: elevated CO₂ with snails) and studied the effects of low (0–0.5 mg/L) and high (4–8 mg/L) CO₂ concentration on the growth, morphology, and chemical traits of the macrophyte Vallisneria spiralis (Angiosperms: Hydrocharitaceae) and the snail Radix auricularia (Pulmonata: Lymnaeidae), and the relationships between them in the laboratory. We found that herbivory decreased the total biomass of V. spiralis by 28.6% and 25.3% under low and high CO₂ conditions, respectively. Compared with A group, ES group reduced the total plant biomass by 43.3%. Elevated CO₂ and herbivory both affected the growth of V. spiralis and change its resource allocation patterns. Total nitrogen content in V. spiralis leaves decreased under herbivory condition, and total phenols increased under the interactions condition between elevated CO₂ and herbivory. However, total C content of R. auricularia increased under elevated CO₂ condition. These results could provide valuable insights into how climate change affects plant–herbivore interactions and food web structure in shallow inland waters.