Temperature and salinity effects on Stuckenia pectinata traits and susceptibility to grazing

This research examined the effects of temperature (20, 25, and 30°C) and salinity (0, 6, and 12) on the plant traits of the aquatic macrophyte, Stuckenia pectinata, and how changes in these traits influence herbivory by invertebrate grazers. The highest temperatures showed positive effects (e.g., leaf area and sexual reproduction), counter to my predictions, while the highest salinity tended to have negative effects, as expected. Thus, the coolest temperature (20°C) and highest salinity (12), presumably the most stressful treatment for the plants, tended to lower %C, %N, protein content, and phenolic concentrations, while salinities of 0 at this same temperature tended toward higher phenolics, C:N, and %C. Salinities of 12 at 30°C had the highest %N and %P content; however, this treatment also suffered the highest herbivory from the amphipod, Ampithoe valida. Herbivory in salinity treatments of 12 with increasing temperature was negatively correlated with C:N, and positively correlated with %N, %P, and protein content. These results can inform future management, conservation and restoration efforts.