Comparative Effects of Water-Column Nitrate Enrichment on Eelgrass, Shoal Grass, and Widgeon Grass

摘要

The objectives of this study were to work toward determining the threshold range of water-column nitrate enrichment that promotes destruction of eelgrass (Zostera marina L.), and to examine whether nitrate enrichment is toxic to two other submersed aquatic marine/estuarine plants, shoal grass (the seagrass Halodule wrightii Ascher) and widgeon grass (Ruppia maritima L.). These species are of interest for potential use in re-establishing beds of submersed aquatic vegetation within areas where eelgrass habitat loss has been correlated with nutrient enrichment or other factors associated with cultural eutrophication and coastal development. This research indicates that Halodule wrightii or Ruppia maritima could be established by transplanting efforts as a management strategy in nitrate-enriched waters where eelgrass meadows have disappeared. Unlike Zostera marina, these plants apparently have physiological mechanisms to more efficiently process and control consumed nitrate; indeed, R. maritima seems to have derived a competitive advantage in nitrate-enriched conditions.