Healthy seagrass beds were once found throughout the shallow areas of Narragansett Bay, R.I. but have largely disappeared due to infilling, nutrient pollution, and disease. In Greenwich Bay, a highly developed embayment within Narragansett Bay, the widgeon grass, Ruppia maritima, has colonized an area on the northern shore once dominated by the eelgrass, Zostera marina. This area is sandy, which may allow groundwater seepage. This observation is consistent with our understanding of Ruppia ecology. This genus is extremely salinity tolerant and may be more nutrient tolerant than Zostera. To experimentally explore this phenomena, two, 6-week microcosm experiments were conducted. For both experiments, shoots of sub-aquatic vegetation (SAV; Ruppia or Zostera) were planted in sediment in 10 cm plastic tubes. These tubes were placed in large flow-through water tanks outside on a dock to keep temperature consistent. experiments, shoots of SAV were planted in sediment in 10 cm plastic tubes. These tubes were placed in large flow-through water tanks outside on a dock to keep temperature consistent.