| 论文摘要： |
Aquatic plants are vital components of shallow aquatic ecosystems, and they can substantially contribute to food webs. However, the large spatial and temporal variations of delta C-13 and delta N-15 signatures of aquatic plants have hindered the interpretation of their trophic interactions with organisms at higher trophic levels, and the effects of temperature on plant isotopic signatures remain to be fully elucidated. Herein, we cultured three common submerged macrophytes [Elodea nuttallii (Planch.) St. John, Vallisneria spiralis L., and Potamogeton lucens L.] at four temperatures (10, 15, 20 and 25 degrees C) for 16 weeks and analyzed their delta C-13 and delta N-15 signatures. Results showed that temperature altered the isotopic signatures of all three plant species. delta C-13 and delta N-15 varied by 16.06 parts per thousand and 11.68 parts per thousand in P. lucens at different temperatures, respectively. Plant delta N-15 significantly decreased with rising temperature in all three plant species and was correlated with plant growth, N content, and pore water dissolved inorganic N (DIN) concentrations. Conversely, delta C-13 responded non-linearly with temperature: a hump-shaped response of delta C-13 with temperature was observed for P. lucens. Plant delta C-13 was not correlated with any of the measured parameters. Temperature can alter plant metabolism and photosynthesis and the compositions and concentrations of C and N sources, thereby influencing plant delta C-13 and delta N-15 signatures, respectively. Temperature plays a key role in altering plant C and N isotopic signatures. Therefore, we recommend future studies to carefully consider the effects of temperature on plant stable isotopic signatures when interpreting the food contribution of aquatic plants in food webs and long-term environmental changes via historical isotopic signatures of plants exposed to different temperatures, particularly in light of changing climate conditions. |
