Highlights of Previous Findings

Hydrology and Hydrodynamics
Highly variable hydrology and hydrodynamics are major drivers of ecosystem dynamics at PIE, contolling material transport and habitat connections.  Variability is caused by seasonal cycles of fresh water input (spring freshets), dams (human and beaver), human land and water use, and large tidal ranges (3m), as well as climate change drivers such as sea level rise and increased storminess. More ...
 

 
Spatial Patterns and Connectivity
PIE research has shown that the spatial arrangement of  land use features and habitats in the watershed and estuary, and the way they are connected (usually by water) determine material flows and fates.  These systems comprise a complex and dynamic mosaic,  with  land-use patterns and connections continuously changing in response to human and natural forcing. More...




 
Biogeochemical Cycles
Organic matter and its role in supporting production in watersheds and estuaries has been an ongoing interest of PIE-LTER scientists. Understanding the sources and fates of organic matter requires understanding its chemical character as well as the complex array of biogeochemical reactions that tranform it, as well as the microbial communities that facilitate the transformations.  More...



Primary and Secondary Production
Saltmarshes are among the most productive systems in the world, but their survival is uncertain.  They are threatened on the landward side by human activities and on the seaward side by sea level rise.  Scientists at PIE are working to understand what controls the growth of grasses and other primary producers in northern, peat-based marshes, and how this production enters the food web.   This knowledge will increase our ability to predict the capacity of the marshes and their inhabitants to withstand multiple stressors, and help provide strategies for management.   More…

 
Food Webs and Population Dynamics
Understanding food web dynamics is integral to understanding changes in estuaries and watersheds, and for mapping material and energy flows within and between habitats. The study of food webs at PIE was among our initial research efforts, and revealed changes in populations of pivotal species, such as river herring, that could be related to habitat fragmentation. PIE scientists pioneered the use of natural abundance and tracer-level stable isotopes to construct food webs and identify the relative importance of various organic matter sources supporting food webs in different habitats within the PIE domain.  These observation led to the identification of important ‘trophic-linkage’ species that connect the PIE food webs with each other and the coastal ocean. By tracking and modeling the movements of these important mobile species we are learning how they move energy between habitats and across the landscape within PIE as well as between PIE and other coastal systems. More...


Models
Models are principle tools for synthesizing research results, and PIE scientists utilize them in conceptual, predictive, and theoretical approaches. Examples include: a 2D model that reproduces the dynamic, physical environment of PIE estuaries and has been linked to particle transport and used to predict preferred flow fields for striped bass feeding (PIE-FVCOM);  a model  that describes  the growth response of marsh grasses to sea level rise and predicts a “tipping point” beyond which marshes may fail (MEM);  a model used to describe biogeochemical cycles in terms of thermodynamics endeavors to move our understanding beyond case-specific examples to a theoretical and broadly-applicable approach (MEP).   More



Microbial Genomics
Linking microbial community structure and function has long been a research focus at PIE.  Although rapid advancement in molecular techniques has helped us identify a vast array of microbes present in the environment, which of these “species” is active, and when and why, remains a central question in microbial ecology.   By combining genomic approaches with biogeochemical process measurements, PIE scientists are discovering how populations differ along environmental gradients on scales ranging from the estuary to the rhizosphere, and, for example, how these differences relate to nitrogen cycling.  More...