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.     

PCB concentrations in walleyes and their prey from the Saginaw River,Lake Huron: A comparison between 1990 and 2007

Concentrations of polychlorinated biphenyls (PCBs) were measured in composited samples of walleyes Sander vitreus and their prey during 2005–2007 from Saginaw Bay, Lake Huron. There was a linear relationship between fish length and PCB concentrations in walleyes between 356 and 608 mm, but fish 680 mm had lesser concentrations than 608-mm fish. When fish 222–550 mm from 1990 were compared with those from 2007, there was a decrease of 1315 ng PCBs/g wet wt (ww). Concentrations of PCBs in gizzard shad Dorosoma cepedianum (190 ng PCBs/g ww) were three-fold less than fish collected in 1990 (516 ng PCBs/g ww). Round gobies Neogobius melanostomus collected from the Saginaw River had the greatest concentrations of PCBs (range: 200–350 ng PCBs/g ww) compared with other prey fishes (45–190 ng PCBs/g ww). Concentrations of PCBs in Saginaw River round gobies were three-fold greater than those from Saginaw Bay. Zooplankton from 1990 and 2008 contained 8.0 and 32 ng PCBs/g ww, respectively, while zebra mussels Dreissena polymorpha from 2008 contained 351 ng PCBs/g ww. Principal components analysis showed that PCB congeners differed between the largest walleyes and other fish. There are several possible explanations for lesser concentrations of PCBs observed in 2007. These include effects of dredging, changes in the food web related to round gobies, loss of alewife Alosa pseudoharengus, which was a major walleye prey item in 1990, and replacement by yellow perch Perca flavescens, or decreases in release of PCBs from sediments due to weathering, burial, or diffusion.     

Economic Benefits of Remediating the Sheboygan River,Wisconsin Area of Concern

This study estimates the economic benefits of remediation in the Sheboygan River, WI Area of Concern (AOC) using two distinct empirical methods. The methodology parallels that described by Braden et al. (2008). The results are mixed. Using hedonic analysis of property sales, for owner-occupied homes within a 5-mile radius of the Sheboygan River AOC, the overall estimated loss of value is $158 million (8% of market value). Of this total, only $49 million in losses for homes closest to the upper river segment has strong statistical support. The impacts are greatest proportionally for properties closest to the AOC. A survey-based method yields a mean estimate of $218 million (10% of property value) in willingness to pay for full cleanup of the AOC. If remediation were to induce recovery of property values, then the local communities could benefit through increased property tax revenues.     

Economic Benefits of Remediating the Buffalo River,New York Area of Concern

This study estimates the economic benefits of remediation in the Buffalo River, NY Area of Concern (AOC) using two distinct empirical methods. One method analyzes the effects of proximity to the AOC on prices in the residential property market. The second uses a choice survey of recent home purchasers concerning the characteristics of homes and the river. After controlling for numerous structural, community, and spatial effects, the market analysis shows that single-family residential property prices south of the river are depressed due to their proximity to the AOC by $118 million (5.4% of total market value). The impacts are greater for properties closer to the AOC. Prices to the north of the AOC do not appear to be affected. Recovery of $118 million in property value losses could produce approximately $4.7 million/year in new property tax revenues. Considering only the area for which the market study shows price discounts, the survey-based estimates reveal a willingness to pay (WTP) for full cleanup of the AOC of approximately $250 million (14% of median-based market value). The reasons for discrepancies between the results of the two methods is a matter for further research.     

Changes in the benthic communities of Muskegon Lake,a Great Lakes Area of Concern

Sediment contamination resulting from the direct discharge of industrial and municipal wastes contributed to the designation of Muskegon Lake (Michigan) as a Great Lakes Area of Concern. To assess the changes occurring in the sedient-dwelling invertebrate communities since wastewater diversion began in 1973, benthic samples were collected three times per year (spring, summer, fall) between 2004 and 2010 from six sites and compared to historic samples. The density and diversity of invertebrate populations were analyzed to: 1) identify spatial and temporal patterns in the community structure; 2) determine if community structure patterns were related to environmental variables; and 3) assess the recovery of Muskegon Lake's benthic community following wastewater diversion. Our results revealed that invertebrate community structure changed on both annual and spatial scales, while seasonal differences were shown to be modest between 2004 and 2010. The environmental variables with the greatest explanatory power included dissolved oxygen, pH, and depth. Overall, recovery of benthic invertebrate community structure was evident based on multiple lines of evidence, including increased densities of all major taxonomic groups and species diversity since wastewater diversion, decreases in both the oligochaete–chironomid ratio (0.92 in 1972; 0.69 in 2010) and the proportion of oligochaetes, and declining sediment metal concentration over time. However, comparisons of present-day and historic sampling sites must be viewed with caution because sampling locations and protocols varied among years. Significant changes in benthic invertebrate composition and water quality metrics since 1972 suggest improved environmental conditions and the continued recovery of Muskegon Lake from historic pollution.     

Thinking outside the “water box” in the Detroit River Area of Concern

Despite sustained attention to water resource issues in the Great Lakes and around the world, many water problems remain unresolved because their sources or causes are external to the water sector. Water governance often is based on water-centric problem framings that do not take sufficient account of the role of external actors, institutions, and drivers. Recognition of this problem is growing, but identifying external connections and addressing the critical ones is challenging for water managers. Using a flexible diagnostic process, we explore external factors that are relevant in the context of the Detroit River Area of Concern (AOC) between Canada and the United States. We used a two-case multiple case study research design, triangulating data gathered from 28 key informant interviews, review of 58 documents, and personal observations. We find that the AOC program is intentionally narrowly-focused to achieve its objectives, and that a water-centric perspective may in fact be needed for delisting the Detroit River as an AOC. However, there are broader issues beyond those considered in the AOC process that affect the river, including climate change, invasive species, population and land use change, shifting public perceptions, and an unstable institutional environment. To address these external challenges, practitioners should consider engaging more proactively with the topic of “life after delisting”, and connecting more strongly with existing initiatives and networks in the area with the help of “boundary spanners.” Strengthening binational ties within the AOC, and clarifying the role of AOCs in the large governance environment are also important.     

珠江三角洲城市河涌生物--生态修复工作初探

对珠江三角洲地区开展城市河涌生物-生态修复工作的必要性和基本思路、技术路线等方面进行了探讨.认为该地区实施生物-生态修复应当认真调查研究,区分河涌自然条件、污染程度、污染类型和生态、景观问题,筛选先进、适宜的技术,循序渐进地开展工作.     

Microbial source tracking to identify fecal sources contaminating the Toronto Harbour and Don River watershed in wet and dry weather

Identification of sources of fecal pollution in urban areas is critical for protecting public health, the environment, and guiding remediation. We collected 670 water samples at 46 sites in 2018 to study fecal pollution in the Toronto Harbour and Don River watershed. Water samples were analyzed for E. coli, wastewater chemicals, and microbial source tracking DNA markers using a digital PCR technique. Microbial DNA markers were useful for interpreting the sources of elevated E. coli concentrations in the study. The HF183 marker for human sewage was the most frequently detected DNA marker, occurring in 100% of samples taken from the Don River and associated outfalls. It was also frequently detected in the Inner Harbour and outfalls along the Toronto harbour front. It was detected less frequently and at lower levels in the outer harbour. Detection of a human mitochondrial DNA marker and wastewater chemical markers such as caffeine provided additional evidence of widespread sewage contamination. The gull DNA marker was widely detected, but at lower frequencies and levels than human source DNA markers. A wet weather response of increased E. coli and human DNA marker concentrations occurred at most sites. However, human DNA markers were also widely detected on dry weather sampling days, indicating sewage cross-connections in stormwater and dry weather CSO systems. The cumulative impact of cross-connected stormwater outfalls is likely an under-recognized source of sewage contamination. E. coli and HF183 DNA marker levels observed can serve as benchmarks for evaluating future water quality improvements from wastewater infrastructure investments.     

Contaminant-associated health effects in fishes from the Ottawa and Ashtabula Rivers,Ohio

The health of resident fishes serves as a biologically relevant barometer of aquatic ecosystem integrity. Here, the health of the Ottawa River and Ashtabula River (both within the Lake Erie Basin) were assessed using morphological and immunological biomarkers in brown bullheads (Ameiurus nebulosus) and largemouth bass (Micropterus salmoides). Biomarker metrics were compared to fish collected from a reference site (Conneaut Creek). Data utilized for analyses were collected between 2003 and 2011. Fish collected from all three river systems had markedly different contaminant profiles. Total PCBs were the dominant contaminant class by mass. In bullhead, PCBs were highest in fish from the Ashtabula River and there were no differences in fish collected pre- or post-remediation of Ashtabula Harbor (median = 4.6 and 5.5 mg/kg respectively). Excluding PCBs, the Ottawa River was dominated by organochlorine pesticides. Liver tumor prevalence exceeded the 5% trigger level at both the Ashtabula (7.7%) and Ottawa Rivers (10.2%), but was not statistically different than that at the reference site. There was no statistically significant association between microscopic lesions, gross pathology and contaminant body burdens. Collectively, contaminant body burdens were generally negatively correlated with functional immune responses including bactericidal, cytotoxic-cell and respiratory burst activity in both species. Exceptions were positive correlations of HCB and heptachlor epoxide with respiratory burst activity in largemouth bass, and HCB with respiratory burst activity in bullhead and ΣBHC for all three functional assays in bullhead. Data here provide additional support that organochlorine contamination is associated with immunomodulation, and that species differences exist within sites.     

A socioeconomic analysis of habitat restoration in the Muskegon Lake area of concern

As part of the 2009 American Recovery and Reinvestment Act (ARRA), a $10 million grant was awarded to restore wetlands and stabilize shoreline along the south shore of Muskegon Lake (MI), a Great Lakes Area of Concern. A socioeconomic analysis was conducted as part of this award, which included a travel cost survey for lake recreation and a hedonic housing valuation to estimate return on investment. The value of a trip to Muskegon Lake was estimated to be $39.76; when applied to the anticipated increase in post-restoration recreational trips to Muskegon Lake, and using a conservative 7% discount rate, the Net Present Value over 20 years is $38.1 million. The hedonic analysis examined values for houses between 100 and 800 m from the shoreline, using both the current shoreline distances and the new shoreline distances after restoration; this resulted in a predicted $11.9 million in additional housing value as a result of the improved shoreline features. Summing the hedonic value and travel cost estimates, along with the original $10 million spent, the result is that over 20 years, the total value generated for the local region is nearly six times the initial ARRA spending. In other words, of the $60 million of value created on the Muskegon Lake restoration, $50 million is increased environmental value over the 20 year period.     

Determining preferences for ecosystem benefits in Great Lakes Areas of Concern from photographs posted to social media

Relative valuation of potentially affected ecosystem benefits can increase the legitimacy and social acceptance of ecosystem restoration projects. As an alternative or supplement to traditional methods of deriving beneficiary preference, we downloaded from social media and classified ≈ 21,000 photographs taken in two Great Lakes Areas of Concern (AOC), the St. Louis River and the Milwaukee Estuary.Our motivating presumption was that the act of taking a photograph constitutes some measure of the photographer's individual preference for, or choice of, the depicted subject matter among myriad possible subject matter. Overall, 17% of photos downloaded from the photo-sharing sites Flickr, Instagram, and Panoramio depicted an ecosystem benefit of the AOC. Percent of photographs depicting a benefit and the photographs' subject matter varied between AOCs and among photo-sharing sites. Photos shared on Instagram were less user-gender biased than other photo-sharing sites and depicted active recreation (e.g., trail use) more frequently than passive recreation (e.g., landscape viewing). Local users shared more photos depicting a benefit than non-local users. The spatial distribution of photograph locations varied between photos depicting and not depicting a benefit, and identified areas within AOCs from which few photographs were shared. As a source of beneficiary preference information, we think Instagram has some advantages over the other photo-sharing sites. When combined with other information, spatially-explicit relative valuation derived from aggregate social preference can be translated into information and knowledge useful for Great Lakes restoration decision making.