GCE-LTER Key Findings

Since the GCE-LTER project began in 2000, our research has contributed significantly to understanding patterns and processes that shape estuarine and marsh environments. Key site-based findings from the last decade are listed below. For a complete list and more recent findings click here.

Estuaries play an outsized role in the global carbon budget

Estuaries are net sources of CO2 to the atmosphere and coastal ocean, and net sinks for oceanic and atmospheric O2. This finding challenges the simplistic treatment of estuaries in global carbon models, and suggests that interactions between river discharge, changes in marsh area, and increasing atmospheric CO2 will alter shelf-ocean carbon exchange in the future. (more information)






Ammonia oxidizers transform the nitrogen cycle

Ammonia-oxidizing archaea (AOA) convert ammonium into nitrite, but little is known about the population dynamics of this relatively new addition to the nitrogen cycle. Research from GCE LTER found that mid-summer blooms of AOA coincide with a peak in nitrite concentration. Field data from 29 estuaries showed similar summer peaks in nitrite, suggesting that summer blooms of AOA are widespread and play a previously unrecognized role in driving estuarine nitrogen cycling. (more information)






Sea level rise alters wetland function

Sea level rise is expected to cause salt marshes to extend upstream at the expense of freshwater wetlands, dramatically altering the intertidal landscape. Experimental salinization reduces primary production, reduces plant species diversity, decreases respiration, and leads to loss of marsh elevation. (more information)






River flow supports marsh production

Long term monitoring, remote sensing, and field experiments showed that dominant estuarine plants grow up to 3 times better in years with low salinities, and that salinity is driven most strongly by river discharge. A high frequency of drought in 1998-2012 led to declines in plant biomass relative to the 28-year period of record for Landsat 8. (more information)






Mobile predators structure communities

The density of marine organisms varies tremendously among and within habitats, leading to very different communities. GCE scientists combined ecological approaches with modern genetic analyses to reveal how abundance and genetic diversity of larvae vary from inland to offshore, with important implications for populations of snails, barnacles, and other organisms. (more information)






For a complete list and more recent findings click here