Ecosystem Modeling in Cobscook Bay, Maine: A Boreal, Macrotidal Estuary 2004 Northeastern Naturalist 11(Special Issue 2):425–438 Ecosystem Modeling in Cobscook Bay, Maine: A Summary, Perspective, and Look Forward PETER FOSTER LARSEN1,* AND DANIEL E. CAMPBELL2 Abstract - In the mid-1990s, an interdisciplinary, multi-institutional team of scientists was assembled to address basic issues concerning biological productivity and the unique co-occurrence of many unusual ecological features in Cobscook Bay, ME. Cobscook Bay is a geologically complex, macrotidal system located on the international border at the mouth of the Bay of Fundy. The strategy adopted by the scientific team was to synthesize the known information on Cobscook Bay, focus new field research on information needs related to basic forcing functions and biological primary productivity, and organize the information in an energy systems model to evaluate the flows of energy and materials through the ecosystem and relate them to the inflows of physical energy using the accounting quantity, emergy. As a consequence of this process, diverse new and existing data have been combined and analyzed, leading to new ways of thinking about the functioning of Cobscook Bay and macrotidal estuaries. The principal finding is that an extraordinary convergence of natural energies creates ideal conditions for supporting the development of ecological organization found in few, if any, other estuarine systems. In this contribution, we review the finding of the component research exercises, discuss their integration into an energy systems model and emergy analysis, and suggest a number of fruitful avenues for future research. Introduction In the mid-1990s an interdisciplinary, multi-institutional team of scientists was assembled to address basic issues concerning the unique co-occurrence of many unusual ecological features in Cobscook Bay, ME. Cobscook Bay is a geologically complex, macrotidal system (mean tidal range: 6 m) located on the international border at the mouth of the Bay of Fundy (Fig. 1). Cobscook Bay is part of the Quoddy region, along with Passamaquoddy Bay, the St. Croix estuary, Campobello Island, the Deer Island archipelago, and related features,. The strategy adopted by the scientific team was to synthesize the known information on Cobscook Bay, focus new field research on information needs related to basic forcing functions and biological 1Bigelow Laboratory for Ocean Sciences, PO Box 475, West Boothbay Harbor, ME 04575. 2US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, Narragansett, RI 02882. *Corresponding author - plarsen@bigelow.org. 426 Northeastern Naturalist Vol. 11, Special Issue 2 primary productivity, and organize the information in an energy systems model to evaluate the flows of energy and materials through the ecosystem and relate them to the inflows of physical energy. An overview of the project scope is presented in Larsen (2004a). Complete details on the modeling process and the application of the emergy concept (Campbell 2004; Odum 1988, 1996) to synthesize old and new information about the estuary into a unified characterization of primary production within the Cobscook Bay ecosystem are detailed in Campbell (2004). As a consequence of this process, diverse new and existing data have been combined, and analyzed as never before, leading to new ways of thinking about the functioning of macrotidal estuaries. We now recognize Cobscook Bay as a naturally eutrophic system, its high nutrient levels deriving from up-welled, nutrient-rich Gulf of Maine waters, Figure 1. Cobscook Bay, ME, and environs indicating various place names. Head Harbour Passage County Washington 2004 P.F. Larsen and D.E. Campbell 427 rather than from natural or human activities in the watershed (Garside and Garside 2004). The largest part of the organizing energy is supplied by tidal and wave energy. Primary productivity, a third of which is exported, is dominated by brown macroalgae and benthic microphytes. There is an extraordinary convergence of physical energies in the Bay, and as a result, primary production ranges from moderate to large depending on the requirements for the different kinds of vegetation. However, all plants in the Bay transform the available energy into biomass less efficiently than expected, as indicated by emergy measures, because the energy available is in excess. The efficiency of trophic transfers approaches the usual values as energy moves up the food chain, supporting a productive and diverse fauna in the higher trophic levels. The high diversity found in some environments of Cobscook Bay, e.g., the intertidal, can be attributed to the extraordinary convergence of natural energies providing ideal conditions for supporting the development of ecological organization there (Campbell 2004). The purpose of this paper is to highlight some of the major discoveries of our integrated research program. The reader is directed to the individual contributions contained in this special issue of the Northeastern Naturalist for in-depth considerations of the topics. As with all research, answers lead to questions. The present results are only a step in a continuing process. Along the way we have identified and quantified critical environmental processes, uncovered some serious information needs, and raised some suggestions for future investigation. Tidal Circulation and Exchange Cobscook Bay lies at the mouth of the Bay of Fundy and is subjected to the large tides created by the near resonance of the semidiurnal tide of the North Atlantic Ocean with the Gulf of Maine/Bay of Fundy basin (Greenberg 1979). The intense tidal mixing in the region, created by the movement of tidal currents over the rugged bottom, insures that source water entering the Bay is cool and rich in nutrients ultimately derived from North Atlantic slope water (Yentsch and Garfield 1981). A massive amount of water, up to half a cubic kilometer, enters and leaves Cobscook Bay on each flood and ebb tide (Brooks 2004, Brooks et al. 1999). This represents about one third of the volume of the Bay. Most of that water passes through Head Harbor Passage, between Deer and Campobello Islands. By contrast, freshwater flow from the small watershed contributes relatively little in terms of the volume of flow and its load of suspended and dissolved materials. Flushing of the Bay is complex. Residence times of neutral particles in the Outer Bay are less than two days while those released in the Inner Bay may never escape. An eddy dipole exists in the Central Bay caused by the collision of the 428 Northeastern Naturalist Vol. 11, Special Issue 2 flood tide current with the constriction between Leighton Point and Denbow Neck (Fig. 1). One consequence is that waterborne substances can become sequestered in the arms of the Bay, especially in South Bay. The result is that the Inner Bay and parts of the Central Bay appear to be unsuitable for aquaculture operations. The forceful tidal currents, that attain velocities of up to 1.8 m sec-1 (Brooks 2004), scour the bottom and remove all but the coarsest sedimentary particles. Up to 70% of the Bay is floored by gravel, cobble, or bedrock (Kelley and Kelley 2004). Finer sediments are introduced by the erosion of glacial sediments of bluffs, as opposed to introduction from the river or seaward ends of the estuary, and deposits of mud and sand are largely limited to sheltered intertidal areas. Mud also accumulates under the gyre-like circulation of the eddy dipoles in the Central Bay. These characteristics emphasize the differences between glaciated, rock-framed embayments of Maine and the Canadian Maritimes and the sediment-rich coastal plain bays of the United States east coast. One of the major ecological constituents distributed by tidal movements is the essential plant nutrient nitrogen in its various forms (Garside and Garside 2004). Plotting nitrate against salinity or mapping its geographic distribution with the hydrodynamic circulation model (Brooks et al. 1999) demonstrates the positive relationship between nitrate and salinity, i.e., the higher the salinity, the higher the nitrate level. Two major conclusions can be drawn from this relationship. The first is that the ultimate source of the nitrate feeding plant productivity in Cobscook Bay is the well-mixed water of the coastal Gulf of Maine. The tidal influx of nitrate in the spring is 70 metric tons per day, by far the largest nitrogen flux in the Bay’s nutrient budget (Garside and Garside 2004). Secondly, these data indicate that the level of nitrate never reaches zero. In other words, in general, nitrogen is not limiting primary production in Cobscook Bay and the Bay may be considered naturally eutrophic. Another remarkable aspect of the Bay’s nitrogen budget is the high level of ammonium throughout the year. This suggests that ammonium is being regenerated within the Bay, most likely by the abundant grazing animals that control the accumulation of plant biomass. Another consequence of the energetic tidal flow is a long tidal excursion. A particle of water and suspended or dissolved materials may be transported 10 km over a flood or ebb tide (Brooks 2004). A management implication is that the tides may facilitate the spread of waterborne pathogens such as the virus that causes infectious salmon anemia. Management strategies must consider this physical reality and be planned on a spatially appropriate scale. This necessitates that in the Quoddy region, aquaculture management and responses to invasive species incursions or oil spills, for instance, must be an international effort to be effective. 2004 P.F. Larsen and D.E. Campbell 429 Primary Production A major thrust of our research into the functioning of the Cobscook Bay ecosystem was the documentation of primary productivity. The principal components investigated were phytoplankton, subtidal benthic microphytes, and four categories of macrophytes grouped as intertidal rockweed, sublittoral fringing kelp, ephemeral red and green algae, and eelgrass (Zostera marina L.). Intertidal benthic microphytes, potentially an important contributor in Cobscook Bay, were not sampled quantitatively. Likewise, the production of the relatively small area of salt marsh (350 ha) was not evaluated. Water column sampling by Phinney et al. (2004) uncovered several unusual features of Cobscook Bay. They were able to characterize the Bay as a high nutrient/low chlorophyll system, i.e., in spite of the high nutrient levels in the water column (Garside and Garside 2004), phytoplankton biomass, and hence chlorophyll concentrations, was low. There was a single peak of productivity in mid- to late summer. Water temperature seemed to be the limiting ecological factor in the spring when phytoplankton growth was inhibited despite high levels of light and nutrients in the water column. This is a consequence of tidal mixing that delays the warming of surface waters and prevents vertical stratification. Light was the limiting factor in summer and fall. Productivity decreased with the shortening day length, and the effect seemed to be enhanced by increased turbidity, probably resulting from autumnal winds and dragging operations. Flushing rates played a role in phytoplankton productivity as growth exceeded export in the Inner Bay. Light sufficient to support photosynthesis was able to reach the bottom throughout the Bay in spring and summer (Phinney et al. 2004). This allowed the maintenance of benthic microalgal populations on all suitable bottom types. Subtidal benthic microphyte biomass was perhaps 100 times that of the overlying water column and productivity was up to 10 times the productivity of the phytoplankton. Indeed, subtidal benthic microphytes were one of the most important primary producer groups. Cobscook Bay contains a rich mixture of macrophyte groups. These plants are not only important primary producers, but their size and growth forms make them an important habitat, nursery, and refuge for a diverse assemblage of epiphytes, invertebrates, and fishes. Several aspects of their biomass, growth forms, seasonality, productivity, and relationships to ecological factors were studied at a variety of sites within the Bay. The results of these site-specific investigations were extrapolated to the entire Bay through the use of habitat-area values produced by Larsen et al. (2004). These authors produced a synoptic point-in-time thematic map of Cobscook Bay 430 Northeastern Naturalist Vol. 11, Special Issue 2 using pre-existing Landsat TM satellite images, on-site ground truthing, and a cost effective unsupervised classification scheme. Overall accuracy of the procedure was a high 86%, and habitat-area estimates compared well with existing area estimates produced at different times by more traditional methods. The characteristic boreal rockweed, Ascophyllum nodosum Le Jolis, was investigated as a representative of the perennial intertidal brown algae. Mean biomass was 25 kg wet wt. m-2, which compares to the higher values found at other Northwest Atlantic sites (Vadas et al. 2004a). Productivity of Ascophyllum ranged from 203–894 gC m-2 yr-1 with a mean of 594 gC m-2 yr-1. These values also compare well with other sites in the Northeast. Because of the large area of rockweed in Cobscook Bay, total productivity is very large, 6.3 x 109 gC yr-1. A large proportion of this production is cycled into the detrital food web where it supports a diverse invertebrate community. The kelps of the sublittoral fringe are limited in their areal extent, but important producers nevertheless. These large plants turn over their biomass 3–4 times per year, resulting in a contribution to the ecosystem of 3.34 x 107 gC yr-1 (Vadas et al. 2004b). The role of red and green algae was investigated by studying the red alga Palmaria plamata (Linnaeus) and the green algae Ulva lactuca (Linnaeus) and Enteromorpha spp. Each group played a role as a habitat and as contributors to the grazer and detrital pathways (Vadas et al. 2004c). Densities of green algal beds varied seasonally by two orders of magnitude within the Bay and had a total production of 9.0 x 108 gC yr-1. Red algae contributed 3.6 x 108 gC yr-1. Eelgrass was characterized by a high degree of variability in terms of growth, productivity, and turnover in Cobscook Bay (Beal et al 2004). Consideration was limited to above-ground productivity, yet the leaf turnover rate of 6–7 times per year resulted in a contribution to the Bay of 3.3–5.3 x 108 gC yr-1. For a number of reasons, methods used to study macrophyte productivity tended to yield underestimates, so that the values presented here should be considered conservative. Consumers The richness of the Cobscook Bay ecosystem is exemplified by the biodiversity exhibited by the benthic invertebrates (Larsen 2004b). Although not a primary focus of new research done in support of our ecosystem modeling exercise, three recent efforts give useful insights. First, Trott (2004a) tabulates historical records of invertebrate species occurrences in the interior of Cobscook Bay. Over 800 species are documented in this 162-year record, a rather large number from a relatively small area. Larsen and Gilfillan (2004) report on the only known quantitative subtidal survey: a one-time 1975 effort around the proposed 2004 P.F. Larsen and D.E. Campbell 431 oil refinery site on Shackford Head. These results indicate that macroinvertebrate communities of Cobscook Bay are closely linked to hydrographic and geological attributes. The subtidal areas of the outer Cobscook Bay are characterized by infaunal and tube-dwelling species in the protected sandy coves and a rich epifaunal community in the extensive current-swept channel areas floored by gravel, cobble, and bedrock. The latter areas comprise 70% of the subtidal areas of the Bay (Kelley and Kelley 2004), which is unusual for a Maine estuary. It also suggests that filter-feeding components of this community may play an important role in the nutrient budget of the Bay, one that is characterized by high levels of ammonium in the water column. This conclusion is reached by Garside and Garside (2004), who infer that the high levels of ammonium throughout the year must result from long-lived benthic filter feeders. The information presented by Trott (2004a) and Larsen and Gilfillan (2004) must be considered historical as it is decades old and does not address the issue of contemporary biodiversity levels. Trott (2004b) attempted to do this by comparing qualitative data on intertidal communities collected by Maine’s Critical Areas Program in the 1970s with present-day surveys. Results suggest that a faunal shift has occurred, characterized by a simplification of community composition with a move towards dominance by mussel beds. He speculates that an increase in siltation, perhaps from increased dragging for scallops and urchins, may have triggered a cascade of faunal changes in the intertidal zone. Certainly this is an area ripe for further investigation. Information on other groups of consumers, including zooplankton, fish, birds, and marine mammals, was gleaned from historical studies in the Quoddy region (see Campbell 2004, Larsen and Webb 1997). Energy Systems Model and Emergy Analysis The results of the ecological characterization of Cobscook Bay fall into two categories: (1) an evaluation and characterization of material and energy flows within the ecosystem network, and (2) the calculation of emergy indicators to synthesize knowledge about the structure and function of the estuarine ecosystem. A layman’s definition of emergy follows: Emergy is the memory or sum of all the energy of different kinds that has gone into making a product or service in nature or in the economy. Before summing, each different kind of energy used in the production process (e.g., a calorie of oil or a calorie of plant biomass) is converted to units of one kind of energy, in this case solar joules. Emergy provides scientists with a comprehensive accounting tool based on the 2nd law of thermodynamics that allows the comparison of different energy and material quantities and fluxes on the same basis. 432 Northeastern Naturalist Vol. 11, Special Issue 2 The following aspects of the ecosystem were documented using existing information and the results of our field studies to determine the carbon and nitrogen flows in the system: (1) new nitrogen inflows, (2) nitrogen required by primary producers, (3) primary production and its fate, and (4) the import-export balance of chemical constituents and phytoplankton. Seventy-five percent of the annual supply of new nitrogen comes from the sea. Summer nitrate concentrations in Cobscook Bay (≈ 2 micromoles l-1) are comparable to those found in the summer in culturally eutrophic estuaries such as Narragansett Bay, RI (Nixon 1986). Thus, we have said that Cobscook Bay is a naturally eutrophic estuarine ecosystem. Nonetheless, the nitrogen required to support the primary production exceeds the net flux of new nitrogen to the Bay. Therefore, some of the annual primary production in the Bay must depend on remineralized nitrogen in the form of ammonium. Emergy synthesis of the Cobscook Bay ecosystem network consisted of three elements: (1) documentation of the Bay’s energy and emergy signatures (the convergence of energy and emergy within the estuary), (2) tracing the emergy basis for primary and secondary productivity within the ecosystem network, and (3) comparing the results to data from other estuarine ecosystems. The energy signature of Cobscook Bay is dominated by solar energy and shows two distinct peaks, one for tidal and wave energy and a second showing the chemical potential energy of fresh water inflow. The emergy signature of the Bay shows the relative ability of each energy source to do work in the system. The emergy signature contains the two previously mentioned peaks and a third peak corresponding to the nitrogen received in seawater moving back and forth each day with the tide. The emergy base for the Cobscook Bay ecosystem (7.64 x 1020 sej y-1) is comprised of the emergy inputs in the tides, waves, and the emergy of the cross boundary flows, i.e., chemical potential energy in fresh water and the new nitrogen entering the estuary from the sea, salmon culture, rivers, and the atmosphere. Emergy analysis of the Cobscook Bay ecosystem network indicated that primary producers are unable to use the estuary’s emergy sources as efficiently as in other estuaries. The additional emergy goes into creating rare and unusual physical, geological, and biological structures in the environment. Many of these unique features of the Bay are derived from processes using the available energy in its large tides. For example, tidal mixing cools the surface waters in summer resulting in an extremely foggy environment that protects intertidal creatures from desiccation and may support the development of a diverse and sometimes giant intertidal fauna; swift tidal currents account for rare hydrologic features such as reversing falls and whirlpools, and scour has produced an unusually large expanse of hard bottom in the central channels of the estuary (Kelly and Kelly 2004); and a large tidal 2004 P.F. Larsen and D.E. Campbell 433 exchange volume and strong vertical mixing result in high nitrate concentrations in the estuary for most of the year. The renewable empower density in Cobscook Bay (7.4 E12 sej m –2) is one of the highest we have measured and is equivalent to that required for intensive Tilapia culture in Mexico. It is three times the minimum estimate for salmon culture made by H.T. Odum (2000) for aquaculture systems in British Columbia; therefore, salmon aquaculture may be a good human use of the Bay’s rich emergy signature. Analysis of energy transfer and productivity in the trophic network of the Bay compared to an analysis of a similar system in Alaska indicates that the ecosystem is productive and healthy overall. However, problems were observed in a number of areas. The negative effects of human activities should be quantified in emergy terms so that the environmental liabilities (Campbell in press) incurred as a result of the loss of empower in the natural ecosystem can be compared to the concomitant empower gains in the economy. Such comparisons should be made in the future as an aid to planning and decision making for Cobscook Bay, the eastern Gulf of Maine, and the Bay of Fundy as a whole. Future Questions The thorough field investigations of the physical and biological characteristics of the Bay combined with hydrodynamic modeling, the compilation of existing and new information into an energy systems model, and the characterization of the ecosystem network using emergy synthesis, provides an integrated understanding of the functioning of Cobscook Bay that is replicated for few coastal systems elsewhere. Nevertheless, an integrated field and modeling exercise like this is a beginning, not an end, to the drive to obtain a meaningful appreciation of the functioning of Cobscook Bay and, by extension, other estuarine systems. The physical, chemical, geological, and biological complexity of Cobscook Bay is high. The energy system model orders many of the interconnected components of the ecosystem and makes maximum use of present knowledge. This same exercise highlights the more poorly understood ecosystem elements and interactions and defines the most promising areas for future research. One obvious requirement for future research is the accumulation of multiyear data. Most of our fieldwork was done in a single year. In the next few paragraphs, we will propose some avenues of investigation that will help quantify ecological network components for which additional information would be useful for ecological understanding and addressing management issues. The tidal circulation in Cobscook Bay is even more complex than originally thought. The eddy structures identified by the hydrodynamic model and satellite imagery, together with unresolved residual flow 434 Northeastern Naturalist Vol. 11, Special Issue 2 patterns in the inner arms of the Bay, need to be further investigated to assess the distribution and long-term impacts of suspended sediments, contaminants, nutrients, larvae, and disease vectors. Our results make it clear that the circulation patterns of Cobscook and Passamaquoddy Bays are intimately linked. The introduction of a Gulf of Maine Ocean Observing buoy in Cobscook Bay will now provide near real-time information to managers, regulators, scientists, and educators. This information can be used to sharpen the hydrodynamic model and provide practical information needed to evaluate future development in aquaculture, scallop and urchin dragging, tidal power, and other energy projects such as a current proposal for a liquid natural gas terminal. Cobscook Bay is a particularly good laboratory in which to evaluate the effects of rising sea level. This is because the high tide level in the region is rising more rapidly than in most coastal areas due to sea level and tidal changes independent of climate change (Greenberg 2001). A hydrodynamic model corrected for the frictional effects of the large intertidal flats would allow for detailed predictions of changes in temperature, salinity, and nutrient distributions. Higher sea levels would also increase bluff erosion and change the sedimentation patterns with concomitant influences on the biological communities. Several components of the ecological network can be further elucidated to provide better estimates of the energy basis for biological production in Cobscook Bay. For instance, the energy systems model did not include components for the microbial or meiofaunal energy loops, nor did it include production estimates for the small amount of salt marsh in the Bay. Because of its small aerial extent, the latter may be more significant as a habitat as opposed to a productive element. No direct information was available on the contribution, potentially quite significant, of intertidal benthic diatoms to the Bay’s overall productivity. A detailed investigation of both subtidal and intertidal microphyte assemblages, their specific composition, vertical distribution in the sediments, and photosynthetic potentials would strengthen an important element of the systems model. Investigations of macroalgal productivity were limited to certain surrogate species and thus resulted in underestimates of the total productivity of these groups. Studies of all the component species would provide a more precise productivity estimate and give a feel for any seasonal or interannual dampening effect of these species suites, as the component species would not necessarily co-vary. Estimates of the contribution of eelgrass are also conservative as below-ground productivity was not determined. The photosynthetic potential of all the primary producer groups could be documented using carbon 14 uptake measurements. A question of both practical and scientific import involves the temporal and spatial distribution of the ephemeral green macroalgae. 2004 P.F. Larsen and D.E. Campbell 435 They are important primary producers, but perhaps also harbingers of environmental degradation. Their relationships to natural and anthropogenic nutrient distributions needs to be studied further. The success of our one-time thematic mapping effort using satellite imagery demonstrates a cost effective avenue for addressing this issue. Multi-year archives of images exist and images continue to be collected on a biweekly basis. Analyses of these images would provide seasonal and interannual distributional patterns of the green algae as well as several other ecosystem components. Several aspects of the linkages between primary productivity and higher trophic levels need to be investigated. What portion of the productivity is directly grazed? What portion enters the detrital food chain and how much is exported? What invertebrate species are involved in these processes and which ones are responsible for the production of the unusual high level of ammonium that provides a feedback link to the primary producers? Reliable estimates of grazing rates on phytoplankton would allow a balance to be established for the loss of phytoplankton biomass to grazing versus advection and sinking. The high level of invertebrate biodiversity needs to be documented quantitatively in the various habitats of the Bay. This diversity has been recognized as a hallmark of Cobscook Bay (Verrill 1871), although basic questions, such as the degree to which within-habitat or betweenhabitat diversity contributes to the total, have not been addressed. In addition, intriguing questions remain on the causes of giantism and other unusual biological features. Most historical work in Cobscook Bay has emphasized the intertidal zone. Quantitative and qualitative studies are needed in the subtidal areas to determine whether or not these communities also exhibit unusual ecological features. The link between physical energies (emergy signature) and benthic biodiversity needs to be investigated. This would be particularly useful in predicting the carrying capacities of other estuaries and their susceptibilities to environmental insults. Our research implicated dragging for urchins and scallops as possible causes of increased far-field sedimentation in the Bay and the observed degradation of intertidal benthic communities. No information is available on possible far-field effects on subtidal communities or on the direct effects of dragging on bottom sediments and biological assemblages. The effects of dragging on sedimentation, nutrient fluxes, and available light should be investigated in a future study. Related questions include how serious and widespread the degradation of invertebrate communities may be, and whether these changes have had an expression in higher trophic levels including fishes, birds, and marine mammals. The connections between the Cobscook Bay ecosystem, with its abundant marine resources, and the economy of Washington County 436 Northeastern Naturalist Vol. 11, Special Issue 2 should be quantitatively documented and analyzed in a future study. Environmental accounting using emergy can be used to address several important questions for the region: (1) Are human uses and activities in the estuary and in the region sustainable? (2) Are economic exchanges between the region and others equitable? and (3) What is the intensity of loading on the environment from all sources compared to other systems?” Concluding Thoughts The multi-institutional research team has been successful in synthesizing a wealth of scientific information into a coherent model that can be used to evaluate a number of ecological hypotheses in Cobscook Bay and beyond. This success is due, in large part, to the willingness of individuals to share their knowledge across disciplinary boundaries to achieve a higher understanding of the system. Underlying this success, however, is the concept that environmental research is done best when input is received from stakeholders, the general public, and governmental and non-governmental environmental organizations. Input from these sources received during planning, execution, and analysis of the research was invaluable. The modeling effort highlighted an abundance of further research needs. The ideas mentioned above are far from exhaustive. Much progress can be made through traditional disciplinary investigations and these should be encouraged. Our positive experiences over the last few years, however, indicate that the most efficient way forward may lie with interdisciplinary teams of scientists melding their skills with a guiding influence from the local community. Acknowledgments This work was conducted as part of a research program, “Developing an Ecological Model of a Boreal, Macrotidal Estuary: Cobscook Bay, Maine,” funded by a grant from the A.W. Mellon Foundation to The Nature Conservancy, with matching funds and services provided by Bigelow Laboratory for Ocean Sciences, University of Maine at Orono and Machias, Texas A&M University, US Fish and Wildlife Service Gulf of Maine Program, Suffolk University (Friedman Field Station), Maine Department of Marine Resources, and The Nature Conservancy. Principal investigators heading various aspects of this interdisciplinary, multi-institutional research were (alphabetical order): Brian Beal, University of Maine-Machias; David Brooks, Texas A&M University; Daniel Campbell, US Environmental Protection Agency; Chris Garside, Bigelow Laboratory for Ocean Sciences; Joseph Kelley, University of Maine; Peter Larsen, Bigelow Laboratory for Ocean Sciences; David Phinney, Bigelow Laboratory for Ocean Sciences; John Sowles, Maine Department of Marine Resources; Thomas Trott, 2004 P.F. Larsen and D.E. Campbell 437 Suffolk University; Robert Vadas, University of Maine; and Charles Yentsch, Bigelow Laboratory for Ocean Sciences. It is a rare experience to work with such a positive, mutually supportive, and good-natured group. Literature Cited Beal, B.F., R.L. Vadas, Sr., W.A. Wright, and S. Nickl. 2004. Annual aboveground biomass and productivity estimates for intertidal eelgrass (Zostera marina L.) in Cobscook Bay, Maine. 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