Humans are altering the ecosystems of the world at rates not previously experienced. Understanding and predicting how multiple stresses affect the sustainability of ecosystems is one of the most crucial challenges in environmental biology. The PIE LTER focuses on how several aspects of global change influence organic matter and inorganic nutrient biogeochemistry and estuarine foodwebs. The inputs of organic matter and nutrients from land, ocean and marshes interact with the external drivers (climate, land use, river discharge, sea level) to dictate the extent and degree of nutrient and organic matter processing and determine the spatial patterns of estuarine productivity and trophic structure. The overarching question is: How will trophic structure and primary and secondary productivity in estuaries be affected by changes in organic matter and nutrient loading and hydrodynamics caused by changing land use, climate and sea level? The project uses a combination of approaches to address research questions and hypotheses: 1) short- and long-term “core” measurements 2) short and long-term experiments, 3) comparative ecosystem studies and 4) modeling. The research integrates estuarine biogeochemistry with studies of food webs and population biology of all trophic levels. The PIE LTER data and information system provides a centralized network of information and data related to the Plum Island Sound Estuarine Ecosystem and its watersheds. The centralized network provides researchers associated with PIE-LTER access to common information and data in addition to centralized long-term storage. Data and information are easily accessible to PIE-LTER scientists, local, regional, state partners and the broader scientific community. Researchers associated with PIE-LTER are committed to the integrity of the information and databases resulting from the research. Broader Impacts: PIE-LTER has developed links with local teachers and students, citizens, conservation organizations, and local, state and federal agencies. What started out as a “minimalist” program has grown to be a broad, well-rounded suite of activities. The education/outreach program is expected to further expand during LTER2, as additional support is obtained from other federal agencies, the Commonwealth of Massachusetts, and private foundations. The long-term goal is to establish a ‘Coastal Outreach” office at the PIE-LTER study site that will serve to integrate and promote interactions with interested parties throughout New England. During the next funding cycle, the LTER will expand its schoolyard program to provide on-going professional development for teachers; support the expansion of this project into nearby urban areas including Salem, Boston, and Revere; and facilitate the transfer of this program to New Hampshire and Maine via the Gulf of Maine Institute. There will have greater involvement with undergraduate and graduate education with the addition of PIs Mather and Pontius from UMass and Clark University. PIE-LTER has a very active outreach program in which the goal is to communicate research findings to individuals, organizations, and agencies that will use PIE-LTER research results to better manage local and regional coastal resources. The project has established partnerships on three major issues: intertidal marshes, coastal eutrophication and watershed resource management. The issues of sea level rise, marsh survival and wetland restoration will be the next outreach focal points of the project. Biogeographical Perspective: Marine biologists have long realized the presence of distinct regional distributions of the coastal flora and fauna. On the basis of diversity and general faunal and floral distributions, 9 geographic provinces have been described for coastal waters of North America. The provinces are generally related to the 4 climatic regions of the Atlantic and Pacific Oceans: arctic, cold-temperate, warm-temperate and tropical (Hayden and Dolan 1976). Coastal and land-margin LTERs are situated in 5 of these 9 provinces. The Plum Island Sound System is located in the cold-temperate Acadian Province. Cape Cod represents a very significant boundary between waters to the south, which experience extreme seasonal temperature fluctuations (Virginian Province) and waters to the north, which are cold year round (Acadian Province). In general the species diversity is low in the Acadian Province. For example, we have found 18 and 28 fish species in Wells and Plum Island estuaries compared to >52 in Waquoit Bay (Virginian Province) (Ayvazian et al. 1992, Buchsbaum 1996). In contrast to the Virginian and Carolinean Province where endemism is extremely low (1% for fish, <10% for mollusks), endemism is high in the Acadian Province (25% for fishes and 30-40% for mollusks)(Briggs 1974). A number of molluscan and algal species found in the Acadian region are arctic or boreal. Fish families common in the Virginian Province and further south such as the Sciaenids (spot, croaker, seatrouts, drum) are replaced by a boreal family, the Gadiformes - hake, cod and haddock, in the Acadian Province. Bay anchovies which are common south of Cape Cod are absent to the North. The Plum Island Ecosystems LTER site lies at the interface of a thinly soiled, formerly glaciated New England land mass and the highly productive Gulf of Maine (Carlozzi et al. 1975). Three watersheds comprise the estuarine drainage basin: Parker (155 km2), Rowley (26 km2) and Ipswich (404 km2). The Ipswich River watershed is highly urbanized with Boston "bedroom" communities encroaching in the headwater region while the Parker is less urbanized and retains a higher proportion of forest. Site Integrity: While the watersheds of the Plum Island Ecosystems LTER site are experiencing rapid change in population, economic activity and land use, wetlands both in the watershed and the estuary are well protected by state and federal regulations. Approximately 25% of the Ipswich River watershed has been set aside as conservation land. In addition, most of the estuarine ecosystem is included in the Parker River National Wildlife Refuge. Thus the integrity of the system is high and will serve as a valuable laboratory well into the next millennium. .