Quantitative restoration targets for fish and wildlife habitats and populations in the Lower Green Bay and Fox River AOC

The Lower Green Bay and Fox River Area of Concern (LGB&FR AOC) is one of the most ecologically diverse but demonstrably impaired AOCs in the Laurentian Great Lakes. We outline a transparent, quantitative process for setting targets to remove two fish and wildlife-related beneficial use impairments (BUIs). The method identifies important habitats and species/species groups and weights them according to ecological and socioeconomic criteria. These weights are paired with standardized estimates of current condition ranging from 0 (worst possible) to 10 (best possible). A weighted average of the condition scores gives an overall AOC condition for each BUI, creating a baseline for setting future restoration or BUI removal targets. Weighted averages for the LGB&FR AOC yielded a current condition of 3.60 for fish and wildlife habitats and 4.65 for species/species groups. Based on achievable restoration scenarios and discussions with local experts and stakeholders, we propose removal targets of 6.0 for the “loss of fish and wildlife habitat” BUI and 6.5 for the “degradation of fish and wildlife populations” BUI. This quantitative approach illuminates multiple pathways for reaching restoration targets and facilitates informed discussions about cost effective restoration projects. According to our results, species and species groups in this AOC are generally in better current condition than habitats when compared on the same 0–10 scale. This suggests that many (though not all) desirable fish and wildlife populations in the LGB&FR AOC are able to survive in relatively degraded habitats or are able to use these habitats productively during part of their life cycle.     

Re-assessing the degradation of benthos beneficial use impairment in the Toronto and Region Area of Concern

Sediment quality of the Toronto and Region Area of Concern (AOC) waterfront was assessed using a weight of evidence approach following the Sediment Quality Triad, with the addition of contaminant bioaccumulation data, to determine current status following the 2013 re-designation of the “degradation of benthos” Beneficial Use Impairment as “no longer impaired.” Five stations within the AOC were sampled in 2015 and compared to lower Great Lakes nearshore reference areas (n = 22) selected based on similarity of sediment physicochemical properties. Sediment chemistry was comparable except for a localized instance of elevated perfluorinated compounds at one AOC site. Laboratory sediment toxicity bioassays indicated chronic toxicity associated with point sources to the AOC, corresponding to increased invertebrate body burdens measured in laboratory exposures. Diversity metrics and multivariate analysis showed that benthic invertebrate community composition present at the AOC sites was not significantly different from reference conditions of the lower Great Lakes. The weight of evidence from this study indicates benthic invertebrate communities continue to show effects of degraded sediment conditions at sites impacted by point sources. While the 2013 RAP decision was to re-designate the “degradation of benthos” BUI to “no longer impaired,” our results support the notion that life after AOC delisting must continue to prioritize monitoring efforts.     

Condition of resident fish communities in the Eighteenmile Creek Area of Concern,New York

The lower 3.5 km of Eighteenmile Creek, a tributary to Lake Ontario in New York, was designated as an Area of Concern (AOC) in 1985 under the Great Lakes Water Quality Agreement due to extensive contamination of bed sediments by polychlorinated biphenyls (PCBs) and other toxicants. Five beneficial use impairments (BUIs) have been identified in this AOC, including degraded fish and wildlife populations. We surveyed fish communities in the Eighteenmile Creek AOC and in a comparable section of a nearby reference stream (Oak Orchard Creek) during June 2019 to infer whether legacy contaminants are currently impairing fish communities in the AOC to an extent that they differ from the regional reference condition. Estimates of community abundance, biomass, diversity, and fish condition from each system were compared using a noninferiority testing framework. Biomass, diversity, and fish condition in the Eighteenmile Creek AOC were similar or superior to that in Oak Orchard Creek, while abundance was 20% lower in the AOC. These findings and those of a 2007 sampling effort suggest that fish communities in the Eighteenmile Creek AOC are not impaired despite recent studies indicating that PCBs are bioaccumulating in fish tissues at 1–2 orders of magnitude above background levels. Future assessments in the Eighteenmile Creek AOC might focus on the condition of benthic macroinvertebrate communities and potential toxicity of local contaminants to piscivorous wildlife in order to fully address the remaining aspects of the fish and wildlife populations beneficial use impairment.     

Toxicity of waters from the St. Lawrence River at Massena Area-of-Concern to the plankton species Selenastrum capricornutum and Ceriodaphnia dubia

In 1972, the US and Canada committed to restore the chemical, physical, and biological integrity of the Great Lakes Ecosystem under the first Great Lakes Water Quality Agreement. During subsequent amendments, part of the St. Lawrence River at Massena NY, and segments of three tributaries, were designated as one Area of Concern (AOC) due to various beneficial use impairments (BUIs). Plankton beneficial use was designated impaired within this AOC because phytoplankton and zooplankton population data were unavailable or needed “further assessment”. Contaminated sediments from industrial waste disposal have been largely remediated, thus, the plankton BUI may currently be obsolete. The St. Lawrence River at Massena AOC remedial action plan established two criteria which may be used to assess the plankton BUI; the second states that, “in the absence of community structure data, plankton bioassays confirm no toxicity impact in ambient waters”. This study was implemented during 2011 to determine whether this criterion was achieved. Acute toxicity and chronic toxicity of local waters were quantified seasonally using standardized bioassays with green alga Selenastrum capricornutum and water flea Ceriodaphnia dubia to test the hypothesis that waters from sites within the AOC were no more toxic than were waters from adjacent reference sites. The results of univariate and multivariate analyses confirm that ambient waters from most AOC sites (and seasons) were not toxic to both species. Assuming both test species represent natural plankton assemblages, the quality of surface waters throughout most of this AOC should not seriously impair the health of resident plankton communities.     

Defining community revitalization in Great Lakes Areas of Concern and investigating how revitalization can be catalyzed through remediation and restoration

An international effort to restore contaminated areas across the Great Lakes has been underway for over 50 years. Although experts have increasingly recognized the inherent connections between ecological conditions and community level benefits, Great Lakes community revitalization continues to be a broad and complex topic, lacking a comprehensive definition. The purpose of this study was to generate a testable “AOC-Revitalization Framework” for linking remediation and restoration success, represented by Beneficial Use Impairment (BUI) removal in U.S. Great Lakes Areas of Concern (AOC), to community revitalization. Using directed content analysis, we conducted a literature review and identified 433 potential revitalization metrics and indicators and grouped them into 15 broader community revitalization attributes to develop the following definition of Great Lakes community revitalization: “locally driven community resurgence resulting in resilient and equitable enhancements to social, economic, and environmental community structures.” We surveyed experts within the Great Lakes AOC program on the likelihood remediation and restoration success, would positively impact revitalization attributes. Focus groups triangulated survey results. Results identified BUI removal was expected to positively affect revitalization, but the type of revitalization outcome was based on the BUI being removed. The AOC-Revitalization Framework is the first to empirically outline these possible linkages, providing a clear testable structure for future research; it can be used to better understand how environmental improvements are or are not leading to community revitalization and more accurately identify components of revitalization impacted, thus supporting more equitable representation, communication, and measurement of the relationship.     

Condition of macroinvertebrate communities in the Buffalo River Area of Concern following sediment remediation

The lower 10 km of the Buffalo River, a tributary to Lake Erie, was designated as an Area of Concern (AOC) in 1987 through the Great Lakes Water Quality Agreement because sediment contamination and habitat alteration from past industrialization caused several Beneficial Use Impairments (BUIs). Extensive remediation efforts conducted between 2011 and 2015 removed approximately 688,100 cubic meters of contaminated sediment from the Buffalo River AOC, and subsequent chemical analysis of sediments indicated that most remedial goals had been achieved. Benthic macroinvertebrate communities and sediment toxicity were evaluated in the AOC and an upstream reference area in 2017 and 2020 to determine whether remediation has improved benthic conditions sufficiently that the benthos BUI designation can be removed. Community condition was characterized using the New York State multi-metric index of biological integrity and bed sediments were used for 10-day toxicity tests with Chironomus dilutus and Hyalella azteca. Macroinvertebrate communities were classified as moderately to slightly impacted at most AOC sites compared to slightly impacted at most reference sites, but toxicity tests did not identify any evidence of toxicity in sediments from the AOC. A linear mixed effects model indicated that total organic carbon concentration in sediments, distance upstream from the river mouth, and the relative dominance of zebra mussels Dreissena polymorpha were the primary predictors of macroinvertebrate community condition. These findings are consistent with those from other AOCs in New York which indicate that contemporary benthic communities are generally shaped by legacy habitat alterations rather than AOC-specific sediment contamination and toxicity.     

Comparison of approaches for modelling submerged aquatic vegetation in the Toronto and Region Area of Concern

In freshwater aquatic ecosystems, submerged aquatic vegetation (SAV) is critical habitat for may fish species and provides a variety of ecosystem services including nutrient filtration and substrate stabilization. Characterizing habitats and assessing their suitability for fish and other aquatic and terrestrial organisms is an important component of delisting efforts in the Toronto and Region Area of Concern (AOC). The primary objective of this study was to develop a spatial model for SAV within the AOC. A variety of modelling options were explored with a two stage random forest model identified as the most accurate approach; a two stage boosted regression tree model yielded comparable accuracy but was more complicated and processing intensive to implement. The final models for presence (modelled first) and SAV percent cover (applied only where the presence model predicted SAV to occur) incorporated directionally weighted wind fetch, water depth, and clarity (Secchi depth) with relatively high predictive accuracy (87.1% for presence). When applied across the AOC, SAV was primarily found to occur within the Central Waterfront, particularly adjacent to and among the Toronto Islands. Outside of this area, SAV was generally sparse and confined to areas that were protected from wind and wave action from Lake Ontario. Future habitat creation and remediation efforts should therefore focus on creating habitat conducive to SAV establishment.     

A statistical approach for establishing tumor incidence delisting criteria in areas of concern: A case study

The Great Lakes Water Quality Agreement specifies “fish tumors or other deformities” as one of the 14 beneficial use impairments that can be used to declare a geographic area within the Great Lakes an Area of Concern (AOC). The International Joint Commission has suggested that the fish tumor impairment can be delisted when fish tumor incidence in the AOC does not exceed rates at unimpacted control sites. This paper presents a statistical technique utilizing Bayesian hierarchical logistic models to estimate tumor incidence on brown bullheads (Ameiurus nebulosus) in an AOC and in candidate least impacted control sites (LICS). Liver and skin tumor incidence are estimated using age, length, weight, and gender as possible covariates using a hierarchical framework to account for a sampling design in which sites are sampled over multiple years and/or at multiple sublocations within the site. By utilizing a Bayesian approach, estimates of uncertainty for tumor incidence in sites with no observed tumors can be obtained. The posterior distributions of tumor incidence can then be used to identify LICS for the watershed and subsequently compare the tumor incidence in the AOC to the LICS using a Bayesian form of the two one-side tests for equivalence procedure. Presque Isle Bay (Erie, PA) in the Lake Erie watershed is used as a case study to demonstrate the technique.     

Thirty-five years of restoring Great Lakes Areas of Concern: Gradual progress,hopeful future

In 1985, remedial action plan development was initiated to restore impaired beneficial uses in 42 Great Lakes Areas of Concern (AOCs). A 43rd AOC was designated in 1991. AOC restoration has not been easy as it requires networks focused on gathering stakeholders, coordinating efforts, and ensuring use restoration. As of 2019, seven AOCs were delisted, two were designated as Areas of Concern in Recovery, and 79 of 137 known use impairments in Canadian AOCs and 90 of 255 known use impairments in U.S. AOCs were eliminated. Between 1985 and 2019, a total of $22.78 billion U.S. was spent on restoring all AOCs. Pollution prevention investments should be viewed as spending to avoid future cleanups, and AOC restoration investments should be viewed as spending to help revitalize communities that has over a 3 to 1 return on investment. The pace of U.S. AOC restoration has accelerated under the Great Lakes Legacy Act (GLLA) and Great Lakes Restoration Initiative (GLRI). Sustained funding through U.S. programs like GLRI and GLLA and Canadian programs such as Canada-Ontario Agreement Respecting Great Lakes Water Quality and Ecosystem Health and the Great Lakes Protection Initiative is needed to restore all AOCs. Other major AOC program achievements include use of locally-designed ecosystem approaches, contaminated sediment remediation, habitat rehabilitation, controlling eutrophication, and advancing science. Key lessons learned include: ensure meaningful public participation; engage local leaders; establish a compelling vision; establish measurable targets; practice adaptive management; build partnerships; pursue collaborative financing; build a record of success; quantify benefits; and focus on life after delisting.     

Towards improving an Area of Concern: Main-channel habitat rehabilitation priorities for the Maumee River

The Maumee River watershed in the Laurentian Great Lakes Basin has been impacted by decades of pollution and habitat modification due to human settlement and development. As such, the lower 35 km of the Maumee River and several smaller adjacent watersheds comprising over 2000 km² were designated the Maumee Area of Concern (AOC) under the revised Great Lakes Water Quality Agreement in 1987. As part of pre-rehabilitation assessments in the Maumee AOC, we assessed fish and invertebrate communities in river km 24–11 of the Maumee River to identify: 1) areas that exhibit the highest biodiversity, 2) habitat characteristics associated with high biodiversity areas, 3) areas in need of protection from further degradation, and 4) areas that could feasibly be rehabilitated to increase biodiversity. Based on benthic trawl data, shallow water habitats surrounding large island complexes had the highest fish diversity and catch per unit effort (CPUE). Electrofishing displayed similar fish diversity and CPUE patterns across habitat types early in the study but yielded no discernable fish diversity or CPUE patterns towards the end of our study. Although highly variable among study sites, macroinvertebrate density was greatest in shallow water habitats <2.5 m and around large island complexes. Our results provide valuable baseline data that could act as a foundation for developing rehabilitation strategies in the lower Maumee River and for assessing the effectiveness of future aquatic habitat rehabilitation projects. In addition to increasing in-channel habitat, watershed-scale improvements of water quality might be necessary to ensure rehabilitation strategies are successful.     

An exploratory investigation of the landscape-lake interface: Land cover controls over consumer N and C isotopic composition in Lake Michigan rivermouths

Rivermouth ecosystems are areas where tributary waters mix with lentic near-shore waters and provide habitat for many Laurentian Great Lakes fish and wildlife species. Rivermouths are the interface between terrestrial activities that influence rivers and the ecologically important nearshore. Stable isotopes of nitrogen (N) and carbon (C) in consumers were measured from a range of rivermouths systems to address two questions: 1) What is the effect of rivermouth ecosystems and land cover on the isotopic composition of N available to rivermouth consumers? 2) Are rivermouth consumers composed of lake-like or river-like C? For question 1, data suggest that strong relationships between watershed agriculture and consumer N are weakened or eliminated at the rivermouth, in favor of stronger relationships between consumer N and depositional areas that may favor denitrification. For question 2, despite apparently large riverine inputs, consumers only occasionally appear river-like. More often consumers seem to incorporate large amounts of C from either the nearshore or primary production within the rivermouth itself. Rivermouths appear to be active C and N processing environments, thus necessitating their explicit incorporation into models estimating nearshore loading and possibly contributing to their importance to Great Lakes biota.     

A reflection on restoration progress in the Saginaw Bay watershed

The Saginaw Bay watershed is unique and remains one of the most diverse watersheds in Michigan, containing the largest contiguous freshwater coastal wetland system in the United States. The watershed and Saginaw Bay support a wide variety of flora and fauna, agriculture and recreation opportunities. However, the rapid industrialization and population growth of the watershed in the 20th century strained the region's natural resources. Excessive nutrient loading, elevated bacteria levels, aquatic habitat loss, and chemical contamination all altered the watershed's ecosystem. These stressors contributed to declining fish and wildlife populations, loss of coastal wetlands, water quality concerns, beach closings, and the buildup of contaminants in the food web. Over the past four decades, extensive federal, state, and regional priority-based assessments and planning have positioned the Saginaw Bay watershed for significant restoration. There is a continued commitment by federal, state, and regional partners to advance restoration efforts. This paper reflects upon those activities and provides additional actions that would aid restoration work in the Saginaw Bay watershed and in the Saginaw Bay, a region of the Great Lakes that still must address significant environmental challenges to reach its full potential.     

Great Lakes coastal fish habitat classification and assessment

Basin-scale assessment of fish habitat in Great Lakes coastal ecosystems would increase our ability to prioritize fish habitat management and restoration actions. As a first step in this direction, we identified key habitat factors associated with highest probability of occurrence for several societally and ecologically important coastal fish species as well as community metrics, using data from the Great Lakes Aquatic Habitat Framework (GLAHF), Great Lakes Environmental Indicators (GLEI) and Coastal Wetland Monitoring Program (CWMP). Secondly, we assessed whether species-specific habitat was threatened by watershed-level anthropogenic stressors. In the southern Great Lakes, key habitat factors for determining presence/absence of several species of coastal fish were chlorophyll concentrations, turbidity, and wave height, whereas in the northern ecoprovince temperature was the major habitat driver for most of the species modeled. Habitat factors best explaining fish richness and diversity were bottom slope and chlorophyll a. These models could likely be further improved with addition of high-resolution submerged macrophyte complexity data which are currently unavailable at the basin-wide scale. Proportion of invasive species was correlated primarily with increasing maximum observed inorganic turbidity and chlorophyll a. We also demonstrate that preferred habitat for several coastal species and high-diversity areas overlap with areas of high watershed stress. Great Lakes coastal wetland fish are a large contributor to ecosystem services as well as commercial and recreational fishery harvest, and scalable basin-wide habitat models developed in this study may be useful for informing management actions targeting specific species or overall coastal fish biodiversity.     

Genetic Structure Among Breeding Herring Gulls (Larus argentatus) from the Great Lakes and Eastern Canada

Herring gulls (Larus argentatus) have been used as sentinel species for exposure to toxic chemicals since the 1960s. Reference populations in these studies have never been characterized to determine whether genetic differences might explain some of the effects seen in gulls at contaminated locations. Previously it was shown that there were higher rates of germline minisatellite DNA mutation rates in herring gulls colonizing sites located near steel industries in urban areas in the Great Lakes. It was suggested that population substructuring among gull colonies could account for differences in the mutation rates observed as a result of surveying different minisatellite loci. Here this explanation is dismissed by showing that genetic exchange among herring gull populations within the Great Lakes appears to be sufficient to ensure genetic homogeneity of these populations; in contrast, differences exist at the minisatellite loci scored between the gulls in the Great Lakes and the Maritimes. It is suggested that reference samples for future Great Lakes herring gull studies be selected from within the Great Lakes, and that potential genetic divergence from Maritime gulls should be investigated in more detail.     

Landscape-scale modeling of water quality in Lake Superior and Lake Michigan watersheds: How useful are forest-based indicators?

The Great Lakes watersheds have an important influence on the water quality of the nearshore environment, therefore, watershed characteristics can be used to predict what will be observed in the streams. We used novel landscape information describing the forest cover change, along with forest census data and established land cover data to predict total phosphorus and turbidity in Great Lakes streams. In Lake Superior, we modeled increased phosphorus as a function of the increase in the proportion of persisting forest, forest disturbed during 2000–2009, and agricultural land, and we modeled increased turbidity as a function of the increase in the proportion of persisting forest, forest disturbed during 2000–2009, agricultural land, and urban land. In Lake Michigan, we modeled increased phosphorus as a function of ecoregion, decrease in the proportion of forest disturbed during 1984–1999 and watershed storage, and increase in the proportion of urban land, and we modeled increased turbidity as a function of ecoregion, increase in the proportion of forest disturbed during 2000–2009, and decrease in the proportion softwood forest. We used these relationships to identify priority areas for restoration in the Lake Superior basin in the southwestern watersheds, and in west central and southwest watersheds of the Lake Michigan basin. We then used the models to estimate water quality in watersheds without observed instream data to prioritize those areas for management. Prioritizing watersheds will aid effective management of the Great Lakes watershed and result in efficient use of restoration funds, which will lead to improved nearshore water quality.     

Tributary use and large-scale movements of grass carp in Lake Erie

Infrequent captures of invasive, non-native grass carp (Ctenopharyngodon idella) have occurred in Lake Erie over the last 30+ years, with recent evidence suggesting wild reproduction in the lake’s western basin (WB) is occurring. Information on grass carp movements in the Laurentian Great Lakes is lacking, but an improved understanding of large-scale movements and potential areas of aggregation will help inform control strategies and risk assessment if grass carp spread to other parts of Lake Erie and other Great Lakes. Twenty-three grass carp captured in Lake Erie’s WB were implanted with acoustic transmitters and released. Movements were monitored with acoustic receivers deployed throughout Lake Erie and elsewhere in the Great Lakes. Grass carp dispersed up to 236 km, with approximately 25% of fish dispersing greater than 100 km from their release location. Mean daily movements ranged from <0.01 to 2.49 km/day, with the highest daily averages occurring in the spring and summer. The Sandusky, Detroit, and Maumee Rivers, and Plum Creek were the most heavily used WB tributaries. Seventeen percent of grass carp moved into Lake Erie’s central or eastern basins, although all fish eventually returned to the WB. One fish emigrated from Lake Erie through the Huron-Erie Corridor and into Lake Huron. Based on our results, past assessments may have underestimated the potential for grass carp to spread in the Great Lakes. We recommend focusing grass carp control efforts on Sandusky River and Plum Creek given their high use by tagged fish, and secondarily on Maumee and Detroit Rivers.     

Drivers of revitalization in Great Lakes coastal communities

Sediment remediation and habitat restoration projects have been increasingly employed along the coast of the Great Lakes to improve environmental quality since the designation of 43 highly degraded Areas of Concern (AOCs) by the 1987 Great Lakes Water Quality Agreement between the U.S. and Canada. Improvements in water quality, habitat, and other environmental conditions can also support community wellbeing and revitalization; however, the mechanisms that support these connections are relatively unclear. We address this gap through a case study of three AOCs near Lake Michigan: 1) Grand Calumet River; 2) White Lake, and 3) Muskegon Lake. By analyzing secondary data and planning documents, we found that alongside environmental cleanup, anchor institutions, housing and economic development, and local events drive revitalization. Our research also illustrates that, rather than acting as discrete processes, environmental cleanup and revitalization drivers overlap in time and space. Finally, our research reveals a high level of variation within and across AOCs in terms of diverse socioeconomic contexts, planning capacities, and existing partnerships. Together, our findings point to the need for collaborative and inclusive planning processes that account for the heterogeneity present within and across AOCs to simultaneously support remediation, restoration, and revitalization and to sustain continued revitalization in AOC communities after delisting.     

Assessment of fish consumption beneficial use impairment at the Great Lakes Thunder Bay and St. Marys River Areas of Concern,Canada

The North American Great Lakes were designated with 43 locally degraded Areas of Concern (AOCs) in the 1980s. Remediation activities geared towards restoring beneficial use impairments (BUIs) at the AOCs have been conducted by both the American and Canadian governments. Here we examine if the fish consumption BUI has been restored at the Thunder Bay Harbour and St. Marys River AOCs within the Canadian waters by applying a three-tier assessment framework using the fish contaminant data collected by the Government of Ontario, Canada. Fish consumption advisories published by the government as well as simulated advisories based on the post-2005 data were examined in Tiers 1 and 2. The results highlighted that the restrictions advised on eating fish from the AOCs are mild and are typically similar to other non-AOC areas of lakes Superior and Huron. Temporal trend analyses of three contaminants of concern, mercury, PCB and dioxins/furans, generally showed substantial improvements over the last 30+ years and mostly continued declining trends in the recent years. These findings support a re-designation of the fish consumption BUI to “not impaired” at the two AOCs. As a follow up, it is recommended to confirm improvements in the dioxin/furan/dioxin-like PCB levels in fish at the Thunder Bay AOC. It is also advisable to conduct a survey to properly define “beneficial use” of fish consumption for the AOCs (i.e., which fish and in what quantity do people eat), and thereby validate the critical assumption of 8+ meals/month as a non-restrictive advice used in this assessment.     

Nonpoint source reduction to the nearshore zone via watershed management practices: Nutrient fluxes,fate, transport and biotic responses — Background and objectives

Studies that evaluate the linkages between watershed improvement through Best Management Practices (BMPs) and downstream outcomes are few. Water quality of coastal waters is often impacted by soil and nutrient loss from watersheds in agriculture. Mitigation of these impacts is of concern in the Great Lakes, the Finger Lakes Region of New York State, and generally in water bodies of North America. In this issue, we report on hypothesis-based research at the watershed level evaluating the impact of BMPs on mitigation of nonpoint sources of nutrient and soil loss to streams and the nearshore zone of a lake. Specifically, we hypothesize not only reductions in nutrient and soil losses from watersheds but also a resultant decrease in metaphyton (filamentous algae), coliform bacteria, and macrophyte populations in the nearshore at stream mouths draining sub-watersheds where BMPs were introduced. Small experimental sub-watersheds, predominantly in agriculture (> 70%), were selected to ensure that effects on downstream systems would not be confounded by other land use practices often observed in large watershed approaches. In this introductory paper, we provide background information on Conesus Lake, its watershed, and the Conesus Lake watershed project, a large multi-disciplinary study evaluating agricultural management practices. The series of papers in this volume consider the effect of BMPs designed to control nonpoint sources on water chemistry, metaphyton, macrophytes, and microbial populations in the coastal zone of a lake. Ultimately, this volume expands the basic understanding of the ability of BMPs to control nonpoint source pollution while contributing toward the goal of improving water quality of downstream systems including streams, embayments, and the nearshore of large lakes.     

Climate Change and Shifts in Potential Tree Species Range Limits in the Great Lakes Region

The model STASH (STAtic SHell) was used to generate current and future potential geographic ranges of ten important forest tree species within the Great Lakes region. This model uses bioclimatic variables to predict the suitable climate-space for tree species. Current climate values were derived from weather records, and two general circulation models (CGCM1 and HadCM2) predicted future climate scenarios. Shifts in potential ranges that were predicted by the two climate models were similar in direction, but different in magnitude. Important timber trees with southern limits within the Great Lakes region, including white, jack, and red pine, aspen, and yellow birch are predicted to retreat northward under both scenarios due to increasing summer temperatures. Under CGCM1, these trees are predicted to disappear from most of the region by the end of the century, whereas under HadCM2 they are predicted to contract 100 to 200 km from their southern range limits. A number of broadleaf trees (red oak, sugar maple, and beech) are expected to remain in the region and may gain potential habitat to the west. Broadleaf trees with current northern range limits within the Great Lakes region (black walnut and black cherry) are predicted to gain potential habitat to the north due to increases in growing degree-days and coldest month temperatures. Both trees are predicted to be able to grow throughout the region by the end of the century under CGCM1, and a less dramatic gain is predicted under HadCM2.