Nitrogen resource analysis and modelling of an eelgrass (Zostera marina L.) meadow in Izembek Lagoon, Alaska

Abstract

Nitrogen limitation in beds of eelgrass, Zostera marina L., was examined by correlating plant standing stock and sediment nitrogen supplies, by measurement of nitrogen uptake in eelgrass roots and leaves, and by experimental manipulation of plant-nitrogen interaction. Eelgrass standing stock and sediment nitrogen across an eelgrass meadow were analyzed. Correlation was found between the integrated interstitial ammonium pool and shoot density and other morphological characteristics. A model of eelgrass growth predicted the effect of nitrogen utilization on biomass production and growth rates; nitrogen limitation controlled growth throughout the summer in ammonium-poor eelgrass beds but only at the peak growth periods in ammonium-rich areas. Prediction of nitrogen enrichment effects similar to literature findings confirmed the impact of nitrogen limitation. Simulation of the spatial and seasonal influences of nitrogen and light as controls on eelgrass growth demonstrated the recurrent effects of dominant environmental limitations within an eelgrass meadow.