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Coastal food webs are subsidized by episodic and seasonal connections to upstream detrital food supplies. However, top coastal estuary predators show great individual variation in their ability to capitalize on this subsidy — a finding that has been applied in comparative cross-site research.  

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…. Read more »

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… Read more »

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.  

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… Read more »

Mobile predators like alligators move between fresh and marine habitats, consume a variety of estuarine prey, and alter the behavior of intermediate predators such as blue crabs. A predator exclusion experiment initiated in 2016 indicated that blue crabs and large fish alter the abundance of marsh invertebrates such as snails and fiddler crabs, which in… Read more »

Contradictory to theoretical models, forest carbon uptake has accelerated over recent decades in maturing forests, a legacy of 19th century land use, and to a lesser degree, modern increases in atmospheric CO2, nitrogen deposition, temperature, and precipitation. This and many other insights into forest ecosystem function have resulted from sustained measurements of biosphere-atmosphere exchanges at… Read more »

Three decades of research on abrupt declines in pre-European hemlock populations, long term regional measurements of hemlock decline from the invasive insect hemlock woolly adelgid, and the long term Hemlock Removal Experiment confirm that hemlocks are a foundation species. They control forest structure, composition, and microclimate, with cascading trophic effects extending from mammals to microbes…. Read more »

Decades of experimental soil warming and nitrogen enrichment have induced adaptive responses in microbial communities, abruptly shifting soil carbon dynamics. The experiments have revealed phased responses to warming, oscillating between multi year periods of significant soil carbon loss and phases of no carbon loss.  

Over the last 30 years, spring phenology has advanced across eastern North America, increasing photosynthesis and net ecosystem carbon storage, with a small negative feedback to climate change. Beginning in 1990 as a biannual pen-and-paper record of bud break and leaf fall, HFR LTER launched the PhenoCam Network in 2008, a continental scale observatory of… Read more »