Humans are extremely effective ecosystem engineers but the consequence of our actions warrant study. Multiple anthropogenic stressors including sea level rise, development, and nutrient loading currently threaten coastal systems. Significant alterations to coastal habitats affect their function and potentially causing irreparable damage. This study focused on understanding the function of the estuarine land-water interface, particularly the base of the food web, or primary producers and factors that may alter their distribution, abundance, speciation, and quality as a food source. These experiments were conducted along the coast of North Carolina, but are largely applicable to similar systems worldwide. Nitrogen is typically the limiting nutrient in estuarine systems, and eutrophication is a critical concern due to excessive supplies of nitrogen accelerating primary production to unsustainable levels. I have found that nitrogen processing in the coastal land-water interface can mitigate loading through denitrification, but quality is also important. Since different denitrifying microbes produce different end products, the distribution of these microbes is of critical concern, particularly because of the production of greenhouse gases. Data presented here show that different primary producers in estuarine marshes have staggered growing seasons as a functional means of resource partitioning. However, shifts in global temperatures are altering growing seasons and could potentially intensify competition between species. In some cases, facilitation between primary producers may mitigate temperature effects. This research provides a baseline for future comparison of ecosystem health and function and offers projections of foreboding scenarios of changes to the land-water interface without a concerted effort to adapt our coastal development approaches and to acknowledge and plan for rising water levels and warming temperatures.