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Background: Urban areas are often built along large rivers and surrounded by agricultural land. This may lead to small tributary streams that have agricultural headwaters and urbanized lower reaches. Our study objectives assessed are as follows: (1) landscape, geomorphic, and water quality variables that best explained variation in aquatic communities and their integrity in a stream system following this agricultural-to-urban land use gradient; (2) ways this land use gradient caused aquatic communities to differ from what would be expected for an idealized natural stream or other longitudinal gradients; and (3) whether the impacts of this land use gradient on aquatic communities would grow larger in a downstream direction through the agricultural and urban developments. Our study area was an impaired coldwater stream in Michigan, USA. Results: Many factors structured the biological communities along the agricultural-to-urban land use gradient. Instream woody debris had the strongest relationship with EPT (Ephemeroptera, Plecoptera, and Trichoptera) abundance and richness and were most common in the lower, urbanized watershed. Fine streambed substrate had the strongest relationship with Diptera taxa and surface air breather macroinvertebrates and was dominant in agricultural headwaters. Fish community assemblage was influenced largely by stream flow and temperature regimes, while poor fish community integrity in lower urban reaches could be impacted by geomorphology and episodic urban pollution events. Scraping macroinvertebrates were most abundant in deforested, first-order agricultural headwaters, while EPT macroinvertebrate richness was the highest downstream of agricultural areas within the urban zone that had extensive forest buffers. Conclusion: Environmental variables and aquatic communities would often not conform with what we would expect from an idealized natural stream. EPT richness improved downstream of agricultural areas. This shows promise for the recovery of aquatic systems using well-planned management in watersheds with this agricultural-to-urban land use pattern. Small patches of forest can be the key to conserving aquatic biodiversity in urbanized landscapes. These findings are valuable to an international audience of researchers and water resource managers who study stream systems following this common agricultural-to-urban land use gradient, the ecological communities of which may not conform with what is generally known about land use impacts to streams. [ABSTRACT FROM AUTHOR]

The successful use of remote site incubators (RSIs) to rear eggs of Arctic Grayling Thymallus arcticus along Montana streams has sparked interest in reestablishing the species in Michigan. As a preparatory step, we assessed the efficacy of RSIs by deploying them along three Michigan streams during 2 years using surrogate eggs from Rainbow Trout Oncorhynchus mykiss. Our objectives were to (1) compare hatching success between two different RSI designs (19‐L versus 265‐L RSIs), (2) test whether the removal of dead eggs ("picking") from 19‐L RSIs affected hatching success, and (3) develop a simple model to predict fry yield and its uncertainty. Overall survival was 41.3% in 2018 and 52.4% in 2019. Differences in survival between unpicked 19‐L and 265‐L RSIs tended to be small, with mean differences from 4.82% (95% CI = –0.60 to +10.25) in 2018 to 0.08% (95% CI = –0.14 to +0.30) in 2019. On average, picked 19‐L RSIs had greater, although not always statistically significant, survival than unpicked 19‐L RSIs during both years (mean difference = 1.6% [2018] and 10.4% [2019]). We documented a significant positive correlation between survival and RSI flow rate. Survival abruptly declined in unpicked 19‐L RSIs when RSI flow rates dropped below ~0.3 L/min, suggesting that removing dead eggs from 19‐L RSIs likely increased survival when RSI flow rates were <0.3 L/min. The most notable result from our fry yield model was that increasing the number of RSIs reduced the coefficient of variation in fry yield following a pattern of diminishing returns, suggesting two or three RSIs usually will be a good choice. We showed that 19‐L and 265‐L RSIs can be used successfully in Michigan streams, with our model providing a tool for managers to explore the relative importance of several properties of RSI design and operation on fry yield and uncertainty. [ABSTRACT FROM AUTHOR]

Parks SR, McNair JN, Hausler P, Tyning P, Thum RA. 2016. Divergent responses of cryptic invasive watermilfoil to treatment with auxinic herbicides in a large Michigan lake. Lake Reserve Manage. 32:366–372. Invasive plants are a major concern for environmental managers around the world. Cryptic invasive taxa present additional challenges because of their potential to respond differently to management efforts while being difficult to distinguish morphologically. Here, we consider the potential for different responses of Eurasian watermilfoil (Myriophyllum spicatum) and hybrid watermilfoil (Myriophyllum spicatumxMyriophyllum sibiricum), which cannot be reliably distinguished based on morphological characters. Laboratory studies show that hybrid watermilfoil genotypes can grow faster, branch more, and be less responsive to herbicide control methods designed for Eurasian watermilfoil. To date, however, there have been no statistical comparisons of the responses of hybrid versus Eurasian watermilfoil under operational management in the field. In this study, we use genetic methods to distinguish morphologically cryptic Eurasian and hybrid watermilfoil in Houghton Lake, Michigan, and test whether they exhibit divergent responses for distribution and abundance following treatment with 2,4-dichlorophenoxyacetic acid-amine and triclopyr. Our results suggest that treatment reduced the frequency of occurrence and abundance of pure Eurasian watermilfoil more than it did for hybrids in Houghton Lake. These findings highlight the importance of distinguishing these cryptic taxa during management evaluations. [ABSTRACT FROM AUTHOR]

• E. coli levels were measured with Colilert® and qPCR at >100 beaches in 2016–2020. • Michigan's proposed qPCR threshold value (qTV) for beach notifications was assessed. • The proposed qTV predicted Colilert decisions 95% correctly during 2019–2020. • The false-negative rate (FNR) for qPCR on the sampling day was 25–29%. • For comparison, the effective FNR for Colilert on the sampling day was 100%. Michigan's water-quality standards specify that E. coli concentrations at bathing beaches must not exceed 300 E. coli per 100 mL, as determined by the geometric mean of culture-based concentrations in three or more representative samples from a given beach on a given day. Culture-based analysis requires 18⁠–⁠24 h to complete, so results are not available on the day of sampling. This one-day delay is problematic because results cannot be used to prevent recreation at beaches that are unsafe on the sampling day, nor do they reliably indicate whether recreation should be prevented the next day, due to high between-day variability in E. coli concentrations demonstrated by previous studies. By contrast, qPCR-based E. coli concentrations can be obtained in 3–4 h, making same-day beach notification decisions possible. Michigan has proposed a qPCR threshold value (qTV) for E. coli of 1.863 log 10 gene copies per reaction as a potential equivalent value to the state standard, based on statistical analysis of a set of state-wide training data from 2016 to 2018. The main purpose of the present study is to assess the validity of the proposed qTV by determining whether the implied qPCR-based beach notification decisions agree well with culture-based decisions on two sets of test data from 2016⁠–⁠2018 (6,564 samples) and 2019–2020 (3,205 samples), and whether performance of the proposed qTV is similar on the test and training data. The results show that performance of Michigan's proposed qTV on both sets of test data was consistently good (e.g., 95% agreement with culture-based beach notification decisions during 2019⁠–⁠2020) and was as good as or better than its performance on the training data set. The false-negative rate for the proposed qTV was 25–29%, meaning that beach notification decisions based on the qTV would be expected to permit recreation on the day of sampling in 25–29% of cases where the beach exceeds the state standard for FIB contamination. This false-negative rate is higher than one would hope to see but is well below the corresponding error rate for culture-based decisions, which permit recreation at beaches that exceed the state standard on the day of sampling in 100% of cases because of the one-day delay in obtaining results. The key advantage of qPCR-based analysis is that it permits a large percentage (71−75%) of unsafe beaches to be identified in time to prevent recreation on the day of sampling. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] We derive three new methods for estimating components of lake metabolism. [•] Each method is based on a continuous-time model of dissolved-oxygen dynamics. [•] We obtain closed-form unbiased least-squares estimators for model parameters. [•] We illustrate the new methods by applying them to data from Muskegon Lake, Michigan. [Copyright &y& Elsevier]

Streambank erosion is difficult to quantify; models and field methods are needed to assess this important sediment source to streams. Our objectives were to (1) evaluate and compare three techniques for quantifying streambank erosion: erosion pins, total station, and laser scanning, (2) spatially assess streambank erosion rates in the Indian Mill Creek watershed of Michigan, USA, and (3) relate results with modeling of nonpoint source pollution. We found large absolute and relative errors between the different measurement techniques. However, we were unable to determine any statistically significant differences between techniques and only observed a correlation between total station and laser scanner. This suggests that the three methods have limited comparability and differences between measurements were largely not systemic. Further, the application of each technique should be dependent on site conditions, project goals, desired resolution, and resources. The laser scanner collected high-resolution data on clear, barren streambanks, but the erosion pin and total station were more representative of complex vegetated banks. Streambank erosion rates varied throughout the watershed and were influenced by fluvial processes. We estimate that streambank erosion contributed 28.5% of the creek's total sediment load. These findings are important to address sources of watershed impairments related to sedimentation, as choosing an applicable technique for individual purposes can help reduce the challenges and costs of a streambank erosion study. [ABSTRACT FROM AUTHOR]

We evaluated data from 10 laboratories that analyzed water samples from 82 recreational water sites across the state of Michigan between 2016 and 2018. Water sample replicates were analyzed by experienced U.S. Environmental Protection Agency (EPA) analysts and Michigan laboratories personnel, many of whom were newly trained, using EPA Draft Method C—a rapid quantitative polymerase chain reaction (qPCR) technique that provides same day Escherichia coli (E. coli) concentration results. Beach management decisions (i.e. remain open or issue an advisory or closure) based on E. coli concentration estimates obtained by Michigan labs and by the EPA were compared; the beach management decision agreed in 94% of the samples analyzed. We used the Wilcoxon one-sample signed rank test and nonparametric quantile regression to assess (1) the degree of agreement between E. coli concentrations quantified by Michigan labs versus the EPA and (2) Michigan lab E. coli measurement precision, relative to EPA results, in different years and water body types. The median quantile regression curve for Michigan labs versus EPA approximated the 1:1 line of perfect agreement more closely as years progressed. Similarly, Michigan lab E. coli estimates precision also demonstrated yearly improvements. No meaningful difference was observed in the degree of association between Michigan lab and EPA E. coli concentration estimates for inland lake and Great Lakes samples (median regression curve average slopes 0.93 and 0.95, respectively). Overall, our study shows that properly trained laboratory personnel can perform Draft Method C to a degree comparable with experienced EPA analysts. This allows health departments that oversee recreational water quality monitoring to be confident in qPCR results generated by the local laboratories responsible for analyzing the water samples. • The beach management decision agreed for 94% of samples analyzed. • Michigan lab degree of agreement and precision improved in consecutive years. • Michigan labs tended to underestimate U.S. EPA E. coli results in most years. [ABSTRACT FROM AUTHOR]