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MWC 2005 SPONSORS
U.S. Geological Survey . Senator George J. Mitchell Center . Maine DHS / Drinking Water Program . Portland Water District . Aqua Maine . Maine Coastal Program / State Planning Office . Maine Dept. of Environmental Protection . Maine Geological Survey . Maine Rural Water Association . Maine Wastewater Control Association . Maine Water Utilities Association . Maine Congress of Lake Associations . Maine Volunteer Lake Monitoring Program . Maine Rivers . University of Maine Cooperative Extension . Maine Sea Grant
Estuaries: Where Rivers Meet the Sea
Co-Chairs: Hilary Neckles (USGS), Paul Anderson (Maine Sea Grant)
Lea, Peter D.1, Kingsbury, Holly E.1, McKenna, Owen E.1, Proctor, Christopher W.1, Supcharoen, Ratsirin1, Caron, Heather2, Lichter, John2, Reblin, Jaret2, and Souther, Christina2.
1Geology Department, Bowdoin College, Brunswick, Maine
2Biology Department, Bowdoin College, Brunswick, Maine
FLOW DYNAMICS IN A COMPLEX FRESHWATER ESTUARY, MERRYMEETING BAY, MID-COAST MAINE
Water flow in Merrymeeting Bay reflects the complex interaction of bedrock/glacial topography, tidal forcing, and freshwater inputs. Traverses with an Acoustic Doppler Current Profiler in summer 2004 revealed that tidal flow dominated through the Chops, the bedrock constriction that connects the bay to the lower Kennebec estuary. Total discharge peaked at ~3500 and ~5000 m3/s during neap and spring tides, respectively, while combined river inputs contributed only ~150 m3/s. Flood tide has carved a deep central channel leading to a sandy tidal delta, while marginal flood currents are weaker due to gentler barotropic gradients in the major river channels. Ebbing tides are strongest in marginal channels, and create a distinct convergence front in the Chops, with peak downwelling velocities in excess of 0.3 m/s.
Physical and chemical parameters allow differentiation of water masses that vary in time and space throughout the summer. Flood-tide water is cooler, more conductive, and less turbid than water that has mixed within the bay. Water within the broad and shallow Androscoggin portion is warmer, fresher, and more turbid than that within the narrow and deep Kennebec portion of the bay. The Androscoggin and Kennebec portions contribute about 60% and 40%, respectively, of the total flow passing out through the Chops, the reverse of the non-tidal river inputs. Salinity/conductance changes in the bay are controlled by river discharge and by semidiurnal and fortnightly tidal variation. Overall circulation is complex, presenting challenges to quantifying sediment and nutrient fluxes.
Joceline Boucher1 and Lauren Sahl2
Corning School of Ocean Studies, Maine Maritime Academy, Castine, ME 04420
1207/326-2489, jbouch@mma.edu
2207/326-2393, lsahl@mma.edu
Does An Estuarine Turbidity Maximum Exist in Penobscot Bay?
Penobscot Bay is the second largest estuary by volume on the U.S. east coast. Despite its size and regional importance, little is known of particle concentration and transport in its waters. In other estuaries, particle-rich zones known as estuarine turbidity maxima (ETM) can form from the combined effects of circulation, salinity gradients, tides, fluvial discharge and sediment resuspension. ETM sustain parts of food webs in some estuaries, and are linked to enhanced dissolved metals in others. In this study, we examine the possibility of an ETM in Penobscot Bay. Our work includes light attenuation and suspended solids data from student cruises in 2003 and 2004. The data, which span a variety of tidal, salinity and discharge conditions, suggest an upper Bay ETM that may migrate along stream in response to variable discharge and tide. Sediment traps deployed for 2 weeks in late March 2003 also indicate the presence of an ETM in this region. Our traps filled too quickly, with exceedingly large volumes of sediment, to accurately record sedimentation rates.
Kocik, John F.1, Hawkes, James P.1, and Derek Williamson2
1NOAA-Fisheries, Northeast Fisheries Science Center, Orono, Maine, 207/866-7341, John.Kocik@noaa.gov, James.Hawkes@noaa.gov
2W.F. Baird & Associates, Coastal Engineers Ltd., Ottawa, Ontario, 613/731-8900, dwilliamson@baird.com
Integrating estuarine environmental modeling, telemetry data, and visualization to understand migration ecology of Atlantic salmon in eastern Maine
To better understand the emigration ecology of Atlantic salmon smolts in eastern Maine rivers, we tracked salmon smolts in the Narraguagus River using ultrasonic tags and a large array of fixed receivers that monitored fish movements from river kilometer 7.65 seaward into the Gulf of Maine. Telemetry information was related to environmental data using advanced modeling and visualization techniques. In spring 2003, a series of instruments was placed in the Narraguagus River and surrounding regions to collect data on current patterns, water levels, temperature, and salinity to calibrate and verify the numerical model. The modeling efforts have proved useful in developing critical insights on the processes affecting Atlantic salmon emigration dynamics in eastern Maine and in identifying mortality factors constraining the recovery of the populations.
Laurie Osher1, Christopher Flannagan1, Jennifer Jespersen1, and Teresa Thornton2
1Dept. of Plant, Soil & Environmental Sciences, UMaine, Orono, ME, 207/581-2957, Laurie@maine.edu
2Senator George J. Mitchell Center, University of Maine, Orono, Maine 207/581-3233
Unraveling the mystery of rapid recent eelgrass decline in Taunton Bay
Taunton Bay, a shallow inland estuary located in Downeast Maine, lost 85% of its eelgrass (Zoster marina) between 1996 and 2002 (Moore and Barker, 2002). Citizens from the area report that the most significant die-off occurred between 2000 and 2002. The decline continued (~95% in 2003) and by 2004, very little was observed in the Bay. The most common cause of the eelgrass die-off in other shallow New England estuaries is nutrient enrichment. In the Great Barrier Reef of Australia, another relatively pristine system, the agricultural herbicide Atrizine, from the triazine group of chemicals, was identified as the cause of significant eelgrass losses. In the watershed of the Taunton Bay estuary, hexazinone, another triazine, is commonly used to eliminate weed competition in low bush blueberries. Ubiquitous in groundwater, hexazinone has been used in the watershed for two decades, but may have only reached the estuary in the last 5 years. A less common cause of die-off of eelgrass is the wasting disease caused by the pathogen Labrinthula. We investigated these three potential causes of eelgrass decline: 1) increased nutrient inputs, 2) hexazinone entering the Bay via groundwater and 3) Labrinthula. After observing the extremely low incidence of pathogen-caused lesions on the eelgrass, disease was eliminated as a potential cause of the decline. In the past year, we identified the concentration and movement of herbicide-contaminated groundwater in the watershed and determined concentration in the estuary. In the last few months, we collected data on nitrogen loading to the estuary from on-site and community wastewater treatment systems and estimated the loading of N from agriculture and lawn care. This presentation will summarize the results to date and discuss implications of these results for management of other protected shallow estuarine systems along the Maine coast.
Karen Young1, Matt Craig2, Diane Gould3, Stacie Grove4
1Director, Casco Bay Estuary Project, University of Southern Maine, Portland, ME, 207/780-4820, kyoung@usm.maine.edu
2Casco Bay Estuary Project, University of Southern Maine, Portland, ME, 207/228-8359, mcraig@usm.maine.edu
3United States Environmental Protection Agency, Boston, MA, 617/918-1569, gould.diane@epa.gov
4Northern Ecological Associates, Inc., Portland, Maine, 207/879-9496, SGrove@neamaine.com
Casco Bay Estuary Project Inventory of Habitat Restoration Sites along the Lower Presumpscot River, its Tributaries and Estuary
The removal of Smelt Hill Dam and the cessation of a paper pulping operation along the Presumpscot River has opened up opportunities for habitat restoration, including improving fish habitat, establishing vegetated buffers, and restoring wetlands and estuarine habitat. Supported by funding from the Gulf of Maine Council and the National Oceanic and Atmospheric Administration (NOAA), the Casco Bay Estuary Project worked with Northern Ecological Associates to develop an inventory of potential habitat restoration sites along the Presumpscot River below Cumberland Mills Dam, its tributaries and estuary. Throughout the project, guidance was provided by the state and federal agency and citizen partners of the Casco Bay Habitat Restoration Committee.
A field survey conducted in summer/fall 2004 covered 28.2 miles of river and tributary streams and resulted in the identification of over 135 potential restoration sites. The problems encountered include lack of adequate vegetated riparian buffer, erosion, siltation and ATV damage. Along the estuarine portion of the river, many patches of the invasive species Phragmites were observed. A digital database of the restoration sites has been developed which includes GIS maps, photos, problem details and proposed restoration approaches. The database also includes priority rankings for each site identified, based on restoration need and potential. The inventory will be included in the online database of regional restoration projects under development by the Gulf of Maine Council. Casco Bay Estuary Project is currently moving forward on the restoration of priority sites, working with funding partners and citizen volunteers.
Lee Doggett1 and Diane Gould2
1Maine Department of Environmental Protection, Bureau of Land and Water Quality, Augusta, Maine, 207/287-7666, lee.doggett@maine.gov
2United States Environmental Protection Agency, Boston, MA, 617/918-1569, gould.diane@epa.gov
Concentration of Toxic Pollutants in Casco Bay Sediments and Blue Mussels as Indicators of Ecosystem Contamination
Casco Bay Estuary Project sampled the Bay's bottom sediments in the early 1990s and again in 2000/2001 for heavy metals, pesticides, PAHs, polychlorinated biphenyls (PCBs), butyltins, dioxins (organochlorines) and furans. The results of the earlier sampling indicated that toxics were found throughout the Bay and that "high" concentrations (based on the NOAA Status and Trends Program standards) occurred primarily in the Inner Bay, the area nearest to Portland, with some hot spots in other parts of the Bay. Analysis of the 2000/2001 data indicates that total pesticides, tributyl tin, total PCBs and most trace metals decreased in the Bay over the past decade. PAHs showed some localized increases. In general, the concentrations of toxics in the Bay appear to be decreasing or staying the same. To assess the impact of toxic pollution on biota, CBEP summarized blue mussel monitoring data from Maine DEP and CBEP. Mussels from most areas in the Bay do not have concentrations elevated above those of "pollution-free" reference sites, with the exception of selected heavy metals in some developed sites (e.g., Mill Creek, Great Diamond Island and the inner Fore River). Also, PAHs are highly elevated in the Inner Fore River. This data is discussed in a regional context by looking at a recent review of 9 years of Gulfwatch mussel data, which showed the highest mercury concentrations in the Gulf of Maine were in Casco Bay, Great Bay, NH, and coastal Nova Scotia, while the highest levels of PAHs were seen in Portland Harbor.
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