Influence of Grasshopper Herbivory on Nitrogen Cycling in Northern Gulf of Mexico Black Needlerush Salt Marshes

Herbivory is a common process in salt marshes. However, the direct impact of marsh herbivory on nutrient cycling in this ecosystem is poorly understood. Using a 15 N enrichment mesocosm study, we quantified nitrogen (N) cycling in sediment and plants of black needlerush ( Juncus roemerianus ) salt marshes, facilitated by litter decomposition and litter plus grasshopper feces decomposition. We found 15 times more 15 N recovery in sediment with grasshopper herbivory compared to sediment with no grasshopper herbivory. In plants, even though we found three times and a half larger 15 N recovery with grasshopper herbivory, we did not find significant differences. Thus, herbivory can enhance N cycling in black needlerush salt marshes sediments and elevate the role of these salt marshes as nutrient sinks.