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Traditional granular hydrogels showed excellent injectivity, thermal integrity, and efficient remediation of heterogeneous reservoirs. However, granular hydrogels have demonstrated their inability to adapt to fractures due to the lack of sufficient interactions. Herein, we present new nanocomposite hydrogels consisting of cationic nanogelators and anionic granular hydrogels that can chemically in situ reform bulk hydrogels in the fractures. Interestingly, our granular hydrogels showed recross-linking independence on carrying fluids, contrary to prior reported fluid-dependent recross-linking granular hydrogels. The recross-linking of nanogelators and granular hydrogels can be accomplished from room temperature to 130 °C. The nanocomposite hydrogels displayed increased shear elastic moduli compared to pristine anionic granular hydrogels, probably due to the increased covalent cross-links formed by the homogeneous regenerative approach. We found that the granular hydrogels had high salinity tolerance even in the presence of 1000 ppm divalent ions of calcium (Ca2+) since Ca2+ions often act as the cross-linker for partially hydrolyzed acrylamide-based hydrogels. Overall, we obtained new regenerative nanocomposite hydrogels based on cationic nanogelators and anionic granular hydrogels for fracture treatments.

According to research, shock, the most common complication of extremely severe burns, is also the leading cause of mortality among patients with such burns. The case fatality rate reaches 83.45% when the total burn area exceeds 90%. The American Heart Association in 2020 recommended the intraosseous (IO) access after the peripheral access and prior to the central venous access when venous cannulation is either difficult or delayed. The use and experience with intraosseous infusion in extremely severe burns are still limited. We report efficacy and safety results from 19 burn patients treated with IO infusion between June 2020 and December 2022. In these patients, the mean injury time of burns was 1.55 ± 1.10 hours, the mean burn surface area was 86.24% ± 11.33%, the mean catheterization time was 49.68 ± 10.11 seconds, and the mean emergency retention time was 2.75 ± 1.74 hours, the mean actual fluid supplement amount was 5,533.68 ± 3,077.19 mL, the mean hourly urine volume of the patient was 93.31 ± 60.94 mL, the mean emergency detention time was 4.16 ± 2.97 hours, and the mean duration of hospitalization was 34.50 ± 25.38 days. The results demonstrated a clinically meaningful improvement and higher response rate vs peripheral venous cannulation and an acceptable safety profile in those patients.

In the present work, the topological hydrogels are prepared through cross-linking Tetra-PEG chains using catenated junctions of bis(phenanthroline) complexed by metal ions. The catenated junctions are either interlocked through metal–ligand coordination, unlocked through demetalation, or relocked through remetalation. Once unlocked, the cross-links become slidable, thereby leading to a reduction of the elasticity, and the degree of reduction depends on the detailed topological structure, particularly the number of network defects. The mechanical properties of the prepared Tetra-PEG can be tuned by changing either the species of the metal ions or the pH values. In comparison, for the linear PEG precursor, the gel-to-sol transition occurs upon demetalation that leads to the formation of linear chains (i.e., precursor chains connected by the catenated junctions). The paradigm described in this work offers a synthetic approach to the hydrogels with varied cross-links.

Regular nanogels have been demonstrated their inefficiency for subterranean oil recovery due to their intrinsic drawbacks of fast swelling within minutes, thermal instability, and salinity vulnerability. Prior deployment of swelling delayed nanogels mainly depended on the reservoirs at a relatively higher temperature. To address the issues encountered during engineering deployment, hereinwe devised an integrative approach to in situform swelling delayed robust nanogels by introducing radically active monomers with thermally sensitive moieties. The nanoparticles with hydrophobic cores in brine in response to thermal input in situgenerated well-dispersed hydrophilic nanogels, which showed a pronounced delayed swelling of a week compared to traditional nanogels showing swelling kinetics within minutes. Furthermore, the formation of swelling-delayed nanogels could occur at ambient temperature. This behavior was radically different from that of temperature-controlled labile cross-linkers containing nanogels, requiring temperatures greater than 50 °C for volume increase thanks to ester hydrolysis. In addition, the in-situformed nanogels displayed long-term thermal stability and salinity tolerance under hostile media at temperatures up to 130 °C. The release of an acidic proton under aqueous conditions has been demonstrated to control the microenvironment for various scenarios. The nanotechnology of converting hydrophobic nanoparticles to hydrophilic nanogels could be applied in a wide range of practical applications such as plugging materials and foaming stabilizers for in-depth conformance control during water and CO2flooding.

It is common to obtain the topography of tidal flats by the Unmanned Aerial Vehicle (UAV) photogrammetry, but this method is not applicable in tidal creeks. The residual water will lead to inaccurate depth inversion results, and the topography of tidal creeks mainly depends on manual survey. The present study took the tidal creek of Chuandong port in Jiangsu Province, China, as the research area and used UAV oblique photogrammetry to reconstruct the topography of the exposed part above the water after the ebb tide. It also proposed a Trend Prediction Fitting (TPF) method for the topography of the unexposed part below the water to obtain a complete 3D topography. The topography above the water measured by UAV has the vertical precision of 12 cm. When the TPF method is used, the cross-section should be perpendicular the central axis of the tidal creek. A polynomial function can be adapted to most shape of sections, while a Fourier function obtains better results in asymmetrical sections. Compared with the two-order function, the three-order function lends itself to more complex sections. Generally, the TPF method is more suitable for small, straight tidal creeks with clear texture and no vegetation cover.

Large rivers throughout the world have been transformed by anthropogenic stressors that are known to influence the structure and composition of fish assemblages. Management of large rivers requires balancing socio-economic and political considerations with biodiversity conservation efforts. By exchanging best management practices between rivers, management efforts can be improved. However, data limitations have largely prevented comparative analyses among fish assemblages in large rivers, potentially limiting the effectiveness of shared management strategies. To improve understanding of the similarities and differences between the Upper Mississippi and Yangtze Rivers, we (1) compared environmental variables and functional traits of fish assemblages between the two systems, (2) identified traits responsible for distinguishing functional groups from one another, and (3) investigated relationships between similar functional groups of fishes and environmental variables to establish expectations for how fish assemblages in large rivers might respond to anthropogenic stressors. Regional species pools in the Upper Mississippi and Upper Yangtze Rivers were characterized by a similar composition of functional traits; the majority of species were omnivorous, had affinities for gravel or sand substrates, and produced sinking eggs. Few species were pelagic, planktivorous, or herbivorous. Functional groups in both rivers were primarily distinguished according to species’ trophic habits and substrate preferences, with secondary contributions from species’ water column positions and life history characteristics. Pelagic planktivores and small-bodied guarders with an affinity for structural habitat complexity tended to increase downriver in both systems, in direct association with total phosphorus concentrations, agricultural land use, and temperature. In contrast, proportions of lithophilic species with affinities for gravel or cobble substrates were highest in segments located furthest upriver. By highlighting the sensitivity of different groups of fishes to anthropogenic stressors, we provide insights into the functional ecology of fishes inhabiting the Mississippi and Yangtze Rivers.

Water-level fluctuations (WLFs) are a key influence on aquatic biodiversity in seasonally inundated freshwater ecosystems. However, how unregulated WLFs affect macroinvertebrates in lake-floodplain systems experiencing considerable annual fluctuations remains unclear. We explored spatial and temporal variability in taxonomic α and β diversity in the largest fluctuating lake in China, Poyang Lake, during two hydrological seasons. We hypothesized that taxa richness (α diversity) is greater in the floodplain than in the lake channel due to greater availability of trophic resources, and that variability in assemblage composition (β diversity) in the channel is greater during the high-water season (HWS) than the low-water season (LWS) due to increased habitat heterogeneity. Benthic macroinvertebrate assemblages were sampled, water physicochemical and hydrological variables were measured, and geographical coordinates were determined at 34 sites during the HWS (October 2017) and LWS (January and April 2018). A total of 74 taxa were recorded. Macroinvertebrate α diversity was comparable in the floodplain and the lake channel. Beta diversity in the channel was greater during HWS than LWS. Hydrological variables influenced β diversity during LWS and geographical distance between sites increased β diversity during HWS, whereas physicochemical variables did not influence β diversity in either hydrological season. Our results suggest that extensive WLFs altered macroinvertebrate biodiversity among hydrological seasons by extending water into floodplains during HWS and reducing substrate heterogeneity in the lake channel during LWS. We thus highlight the importance of WLFs that maintain such environmental seasonality in supporting the biodiversity of benthic macroinvertebrates in naturally dynamic freshwater ecosystems.

Arsenic trioxide (ATO, As2O3), an active ingredient of traditional Chinese medicine, has been approved by the U.S. Food and Drug Administration as an effective therapeutic agent for acute promyelocytic leukemia (APL). However, the application of ATO in treating advanced solid tumors like hepatocellular carcinoma (HCC) is still restricted by limited therapeutic efficacy and insufferable side effects. To solve this problem, we reported a general and facile strategy using human serum albumin (HSA) as a template for synthesizing a series of ATO-based nanoparticles with uniform single-albumin size. Then, we prepared a multifunctional drug delivery system (MDDS) based on MnAs/HSA termed MnAs/ICG/HSA-RGD, and tested its efficacy both in vitroand in vivo. Our results revealed that the photothermal effect of MnAs/ICG/HSA-RGD can not only cause irreversible damage to the tumor but also accelerate the discharge of As and Mn2+ions, enabling responsive chemotherapy and magnetic resonance imaging. Interestingly, the expression of HSP90, vimentin, and MMP-9 in tumor cells was inhibited during the treatment, resulting in less metastasis and recurrence. Moreover, no apparent side effect has been observed during the treatment. Therefore, MnAs/ICG/HSA-RGD can be considered as a promising option for HCC with excellent therapeutic efficacy and minimum side effects.

Conventional poly(acrylamide) (PAM)-based hydrogels suffered from mechanical instability during water flooding, which markedly reduced their performance for water management and oil recovery. In this report, divinylbenzene (DVB) nanostructured cross-linker-bridged nanocomposite hydrogels with high elasticity were described to increase hydrogel mechanical integrity. Precipitation polymerization of DVB monomers generated well-defined DVB nano-cross-linkers having styrenyl moieties on the surfaces, as demonstrated by proton nuclear magnetic resonance analysis. Frequency sweeps of the hydrogels confirmed the formation of covalent junctions between PAM chains and DVB nano-cross-linkers within the network. The nanocomposite hydrogels with covalent cross-links showed a high degree of extensibility, greater than 40 times compared to self-cross-linked N,N′-dimethylacrylamide hydrogels with elongation of 14 and N,N′-methylenebis(acrylamide) cross-linked PAM hydrogel having stretchability less than 2 times. The concentration of ammonium persulfate initiator showed a greater effect on mechanical robustness than DVB nano-cross-linkers. The increase in the initiator significantly increased hydrogel extensibility upon stress. In addition, nano-cross-linker-based hydrogel displayed slow swelling kinetics in brine in comparison to commercially available LiquiBlock 40K gel. Low-cost DVB monomer-based nano-cross-linker-bridged highly deformable hydrogels with excellent elasticity rendered hydrogel production in industrial-scale feasible. High deformation characteristics facilitated hydrogel propagation through pore throats for in-depth fluid diversion.

Improving quality and better availability of continuous stream temperature data allow natural resource managers, particularly in fisheries, to understand associations between different characteristics of stream thermal regimes and stream fishes. However, there is no convenient tool to efficiently characterize multiple metrics reflecting stream thermal regimes with the increasing amount of data from continuously recording data loggers. This article describes a software program packaged as a library in R to facilitate this process. With this freely available package, users will be able to quickly summarize metrics that describe five categories of stream thermal regimes: magnitude, variability, frequency, timing, and rate of change. The installation and usage instruction of this package, the definition of calculated thermal metrics, as well as the output format from the package are described, along with an application showing the utility for multiple metrics. We believe that this package can be widely utilized by interested stakeholders and can greatly assist future fisheries studies. Mejorar la calidad y disponibilidad de datos continuos de temperatura en los ríos permite a manejadores de recursos naturales, particularmente en pesquerías, entender la relación entre diferentes características de regímenes térmicos en los ríos y los peces que los habitan. No obstante, no existe una herramienta conveniente para caracterizar de forma eficiente diferente métricas que reflejen regímenes térmicos fluviales mediante la creciente cantidad de datos provenientes de dispositivos de registro continuo. En este artículo se describe un software programado en lenguaje R con el fin de facilitar dicho proceso. Con este software de acceso gratuito, los usuarios serán capaces de resumir rápidamente las métricas que describen cinco categorías de regímenes térmicos en ríos: magnitud, variabilidad, frecuencia, sincronización y tasa de cambio. Se describe la instalación e instrucciones de uso, la definición de las métricas utilizadas y el formato de salida de los archivos del programa; así mismo se ofrece una aplicación que muestra la utilidad de diferentes métricas. Creemos que este paquete puede ser ampliamente utilizado por usuarios interesados y puede ser de ayuda en un futuro para estudios de pesquerías. L'amélioration de la qualité et une meilleure disponibilité des données en continu de la température des cours d'eau permet aux gestionnaires de ressources naturelles, en particulier dans les pêcheries, de comprendre les associations entre les différentes caractéristiques des régimes thermiques des cours d'eau et les poissons de ruisseaux. Cependant, il n'existe pas d'outil pratique pour caractériser efficacement plusieurs paramètres reflétant les régimes thermiques des cours d'eau avec une quantité croissante de données provenant d'enregistreurs de données en continu. Cet article décrit un logiciel conditionné en package sous R pour faciliter ce processus. Avec ce package, disponible gratuitement, les utilisateurs seront en mesure de résumer rapidement les paramètres décrivant cinq catégories de régimes thermiques des cours d'eau: l'amplitude, la variabilité, la fréquence, le temps, et le taux de changement. Les instructions d'installation et d'utilisation de ce package, la définition des paramètres thermiques calculés, ainsi que le format de sortie du package sont décrits, et une application montre l'utilité de plusieurs paramètres. Nous croyons que ce package peut être largement utilisé par les parties intéressées et peut grandement aider les futures études sur les pêches.

Freshwater biota are more comprehensive and direct indicators of biological impacts, and more meaningful to the public than water quality or physical habitat surrogates. Freshwater biotic data and the multiple biological indicators developed from them offer a much richer array of data for assessing the impacts of pollution controls than a limited set of physical or chemical measures. In recent decades, assemblage-based assessments by ecologists, environmental scientists, and water quality agencies have been employed globally for determining the condition of, and threats to, freshwater ecosystems. A key step in this advance has been the development of multimetric indices (MMIs) or indices of biotic integrity (IBIs) based on quantitative assessments of algae, macrophyte, macroinvertebrate, fish or riparian bird assemblages. In Europe, where biological assemblages are mandated for assessing freshwater ecosystem health, many indices are multimetric. However, the proliferation of MMIs globally has not always occurred through the application of rigorous study designs and monitoring protocols, nor have they always effectively incorporated functional metrics, stressor assessments, and statistical analyses. Therefore, in this review, we discuss eleven major concerns with the development and application (including logistical limitations) of multimetric indicators based on freshwater biota to encourage more rigorous and widely applicable (transferable) MMI use and implementation. Specifically, our concerns focus on reference conditions; sampling effort, methods, and season; trophic guild definition; metric comprehensiveness, options, screening and scoring; and MMI validation. MMIs could also benefit from increased attention to ecological mechanisms and metric development, to further improve our understanding of anthropogenic impacts as well as rehabilitation effects on freshwater ecosystems globally. Paying closer attention to study designs, ecological mechanisms and metric development should further improve our understanding of anthropogenic impacts and better facilitate rehabilitation of degraded freshwater ecosystems, as well as aiding in the conservation of healthy freshwater ecosystems globally.

The survival rate of esophageal squamous carcinoma (ESCC) after surgical resection is estimated to be only 30.3% due to the difficulty in identifying microinfiltration and subtle metastases. In this study, we explored the value of near-infrared fluorescence in the second window (NIR-II) using an epidermal growth factor receptor (EGFR)-targeted probe (cetuximab-IR800) for the intraoperative navigation of ESCC in xenograft mouse models. Immunohistochemical results showed that EGFR was aberrantly expressed in 94.49% (120/127) of ESCC tissues and 90.63% (58/64) of metastatic lymph nodes. Western blot results demonstrated that EGFR protein was highly expressed in ESCC cell lines. Flow cytometry data revealed that cetuximab-IR800 showed a stronger binding specificity in EGFR-positive KYSE-30 cells than in A2780 control cells (P< 0.01). In vivoimaging data showed that the ratio of mean fluorescent intensity (MFI) and tumor to background (TBR) was significantly higher in KYSE-30 subcutaneous tumors with the infusion of cetuximab-IR800 than in those with the infusion of IgG1-IR800 (P< 0.05). Surgical navigation with NIR-II imaging showed that the TBR in orthotopic ESCC was significantly higher than that of NIR in the first window (NIR-I) (2.11 ± 0.46 vs 1.58 ± 0.31, P< 0.05), and NIR-II was more sensitive than NIR-I in detecting subcentimeter metastases (94.87% (37/39) vs 58.97% (23/39), P< 0.001). In conclusion, cetuximab-IR800 with high specificity for ESCC was first used in NIR-II surgical navigation. This probe showed better imaging resolution and higher sensitivity in detecting subtle metastases derived from an orthotopic ESCC model than NIR-I, which indicates that NIR-II has promise in guiding precise surgery for ESCC patients.

Unselective fishing involves activities that target the entire assemblage rather than specific fish species, size classes, or trophic levels. This common fishing approach has been in practice for decades in inland waters in China but its implications for biodiversity remain unclear. We addressed this issue by studying fish assemblages in freshwater lakes (five fishing lakes, one reference lake, and a total of 51 sampling sites) between pre- and post-fishing time-periods in Eastern China during 2017–2019. The effects of lake, fishing period, and their interactions on fish abundance, biomass, and diversity indices were assessed. Multivariate analysis was conducted to test for differences in fish assemblages among lakes and between fishing periods. After the implementation of fishing activities, significant reductions in fish species richness, abundance, biomass, and all three life-history strategies (opportunistic, equilibrium, and periodic) were observed in fishing lakes, whereas opposite trends were observed in the reference lake. Compositional similarity of fish assemblages among fishing lakes increased over the three-year monitoring period. Our results suggest that unselective fishing reduces fish diversity and homogenizes fish assemblage structure in lakes. These findings have important implications for protecting both biodiversity and fisheries in inland waters in China and are applicable to other countries or regions that rely on fish as a major food source.

AbstractWe evaluated relationships between residential development intensity and littoral zone habitat and disturbance characteristics in 332 Michigan lakes 4 ha and larger. We also developed a landscape-based model to estimate lakeshore status in more than 6500 unsampled lakes. Residential development had strong negative effects on large woody debris and strong positive effects on shoreline armoring and docks at both local and whole-lake scales. Lakes having greater cumulative residential development showed greater littoral zone impacts at local scales. Littoral habitats were more heavily impacted in larger lakes and in lakes in southern Michigan. Results of our predictive modeling identified the following as important predictors of residential shoreline development: the amount of urban land use, public ownership, and wetlands in a 100 m buffer around a lake as well as distance to major population centers. Statewide estimates of shoreline development showed that in southern Michigan only 8% of lakes were undeveloped and that 23% had low and 69% had high development intensity. In contrast, 30% of northern Michigan lakes were undeveloped and 48% had low and only 22% had high development intensity. Land planning policy and lake management should consider cumulative effects of lakeshore development as well as the effects of region and lake type. Our study provides the basis for developing regional strategies to protect, restore, and manage lake ecosystems.

We related fish species patterns and landscape-scale environmental data from 216 Michigan lakes to identify repeatable types of fish assemblages, identify environmental factors related to assemblage types, and classify fish assemblages in unsampled lakes. Multivariate regression tree modeling of fish species abundances identified six assemblage types that were explained by degree-days during the ice-free period, lake surface area, and mean lake surface temperature. Warmwater species dominated southern lakes, while coolwater and coldwater species had higher abundances in northern lakes. Coolwater species were present in large southern lakes, whereas warmwater species were excluded from northern lakes that had low mean surface temperatures or low degree-days. These results suggest that patterns of lake fish assemblages are shaped by differences in climate as well as lake-specific differences in surface temperature regimes and in vertical availability of coldwater and coolwater habitats. Because we related fish patterns to readily available landscape-level data, our approach can be used to characterize fish assemblages in all lakes across broad geographic extents.

AbstractFisheries management programs, such as the National Fish Habitat Action Plan (NFHAP), urgently need a nationwide spatial framework and database for health assessment and policy development to protect and improve riverine systems. To meet this need, we developed a spatial framework and database using National Hydrography Dataset Plus (I-.100,000-scale); http://www.horizon-systems.com/nhdplus). This framework uses interconfluence river reaches and their local and network catchments as fundamental spatial river units and a series of ecological and political spatial descriptors as hierarchy structures to allow users to extract or analyze information at spatial scales that they define. This database consists of variables describing channel characteristics, network position/connectivity, climate, elevation, gradient, and size. It contains a series of catchment-natural and human-induced factors that are known to influence river characteristics. Our framework and database assembles aü river reaches and their descriptors in one place for the first time for the conterminous United States. This framework and database provides users with the capability of adding data, conducting analyses, developing management scenarios and regulation, and tracking management progresses at a variety of spatial scales. This database provides the essential data needs for achieving the objectives of NFHAP and other management programs. The downloadable beta version database is available at http://ec2-184-73-40-15.compute-1.amazonaws.com/nfhap/main/.

Abstract:Reversal of widespread fish habitat degradation in the conterminous United States will require effective spatial planning, which begins with spatial assessment of current habitat conditions. We present an assessment of cumulative anthropogenic disturbance to fish habitats in approximately 2.23 million U.S. river reaches under the assumption that downstream local habitat conditions will reflect conditions in the catchment upstream. We used geographic information systems data to attribute 15 disturbance variables to the catchments of mapped river reaches to calibrate an index of cumulative disturbance that considered effects originating from both local and upstream catchments. The influence of each variable was adjusted in the index based on the results of multiple linear regression analyses of all variables against percent intolerant fishes at a site—a commonly used biological indicator of habitat condition. Urban landscape indicators were weighted most heavily, followed by point-source pollution, pasture lands, and dam densities. Local factors were found to be less influential on fishes than those originating from the upstream river network. Skewed cumulative disturbance scores indicated that disturbance levels of some reaches far exceeded the national median. Future assessments should include stratification of analyses within regions, expanded use of response metrics and datasets, and alternative analytical approaches to help tease apart the influences of interacting landscape disturbance types. We demonstrate how our results can be visualized and used to make regional comparisons among large-scale planning units and also show how reach-level information about upstream versus local disturbance levels can be used to identify potential habitat management strategies that are suitable to different landscape contexts.

Regional assessment of cumulative impacts of dams on riverine fish assemblages provides resource managers essential information for dam operation, potential dam removal, river health assessment and overall ecosystem management. Such an assessment is challenging because characteristics of fish assemblages are not only affected by dams, but also influenced by natural variation and human‐induced modification (in addition to dams) in thermal and flow regimes, physicochemical habitats and biological assemblages. This study evaluated the impacts of dams on river fish assemblages in the non‐impoundment sections of rivers in the states of Michigan and Wisconsin using multiple fish assemblage indicators and multiple approaches to distinguish the influences of dams from those of other natural and human‐induced factors. We found that environmental factors that influence fish assemblages in addition to dams should be incorporated when evaluating regional effects of dams on fish assemblages. Without considering such co‐influential factors, the evaluation is inadequate and potentially misleading. The role of dams alone in determining fish assemblages at a regional spatial scale is relatively small (explained less than 20% of variance) compared with the other environmental factors, such as river size, flow and thermal regimes and land uses jointly. However, our results do demonstrate that downstream and upstream dams can substantially modify fish assemblages in the non‐impoundment sections of rivers. After excluding river size and land‐use influences, our results clearly demonstrate that dams have significant impacts on fish biotic‐integrity and habitat‐and‐social‐preference indicators. The influences of the upstream dams, downstream dams, distance to dams, and dam density differ among the fish indicators, which have different implications for maintaining river biotic integrity, protecting biodiversity and managing fisheries. Copyright © 2010 John Wiley & Sons, Ltd.

AbstractCoolwater streams, which are intermediate in character between coldwater “trout” streams and more diverse warmwater streams, occur widely in temperate regions but are poorly understood. We used modeled water temperature data and fish assemblage samples from 371 stream sites in Michigan and Wisconsin to define, describe, and map coolwater streams and their fish assemblages. We defined coolwater streams as ones having summer water temperatures suitable for both coldwater and warmwater species and used the observed distributions of the 99 fish species at our sites to identify coolwater thermal boundaries. Coolwater streams had June-through-August mean water temperatures of 17.0–20.5°C, July mean temperatures of 17.5–21.0°C, and maximum daily mean temperatures of 20.7–24.6°C. We delineated two subclasses of coolwater streams: “cold transition” (having July mean water temperatures of 17.5–19.5°C) and “warm transition” (having July mean temperatures of 19.5–21.0°C). Fish assemblages in coolwater streams were variable and lacked diagnostic species but were generally intermediate in species richness and overlapped in composition with coldwater and warmwater streams. In cold-transition streams, coldwater (e.g., salmonids and cottids) and transitional species (e.g., creek chub Semotilus atromaculatus, eastern blacknose dace Rhynichthys atratulus, white sucker Catostomus commersonii, and johnny darter Etheostoma nigrum) were common and warmwater species (e.g., ictalurids and centrarchids) were uncommon; in warm-transition streams warmwater and transitional species were common and coldwater species were uncommon. Coolwater was the most widespread and abundant thermal class in Michigan and Wisconsin, comprising 65% of the combined total stream length in the two states (cold-transition streams being more common than warm-transition ones). Our approach can be used to identify and characterize coolwater streams elsewhere in the temperate region, benefiting many aspects of fisheries management and environmental protection.

AbstractWater resource managers are frequently interested in river and stream classification systems to generalize stream conditions and establish management policies over large spatial scales. We used fish assemblage data from 745 river valley segments to develop a two-level, river valley segment-scale classification system of rivers and streams throughout Michigan. Regression tree analyses distinguished 10 segment types based on mean July temperature and network catchment area and 26 segment types when channel gradient was also considered. Nonmetric multidimensional scaling analyses suggested that fish assemblages differed among segment types but were only slightly influenced by channel gradient. Species that were indicative of specific segment types generally had habitat requirements that matched segment attributes. A test of classification strength using fish assemblage data from an additional 77 river valley segments indicated that the classification system performed significantly better than random groupings of river valley segments. Our classification system for river valley segments overcomes several weaknesses of the classifications previously used in Michigan, and our approach may prove beneficial for developing classifications elsewhere.

AbstractThe use of model-predicted, local-scale habitat data as inputs in analyses intended to evaluate multiscale fish assemblage-habitat relationships in streams has become increasingly common as the scale at which such studies are conducted has increased. We used fish assemblage and habitat data from 208 wadeable streams in Wisconsin and Michigan to determine whether model-predicted habitat data would yield results similar to those of field-measured data in multiscale analyses of fish assemblage-habitat relationships. Predictions of local habitat features from landscape variables were generated by means of generalized additive modeling with likelihood-based boosting. Relationships between fish assemblage measures and landscape and local habitat features were studied via partial constrained multivariate ordination analyses. The total variation explained in the fish assemblage data sets was similar for model-predicted local habitat features and field-measured data, as was the proportion of variation explained that was due independently to local and regional (i.e., landscape) habitat features. We observed dissimilar results in the magnitude of ordination scores for local habitat features and the directional relationships between local habitat ordination scores and individual species and assemblage metric scores. Our findings indicate that model-predicted, local-scale habitat data can be useful for evaluating the relative strengths of local and regional habitat features in structuring fish assemblages, but caution may be necessary when evaluating species-habitat or assemblage metric-habitat relationships.

We used temperature and fish data from streams across Michigan and Wisconsin to estimate upper thermal tolerance limits for brook trout Salvelinus fontinalisand brown trout Salmo trutta. Tolerance limits were estimated for the maximum daily mean temperature (MEANT), maximum daily maximum temperature (MAXT), and maximum daily temperature range (RNGT) at exposure lengths of 1, 3, 7, 14, 21, 28, 35, 42, 49, 56, and 63 d. We found no difference in the upper thermal tolerance limit for brook and brown trout. For time periods of 1–14 d, the upper temperatures tolerated by trout decreased rapidly from 25.3°C to 22.5°C for MEANT and from 27.6°C to 24.6°C for MAXT. For time periods from 21 to 63 d, the upper temperatures tolerated by trout declined more gradually from 22.1°C to 21.0°C for MEANT and from 24.2°C to 22.9°C for MAXT. The 7-d upper tolerance limit was 23.3°C for MEANT and 25.4°C for MAXT. The maximum RNGT tolerated by trout varied as a function of mean temperature and length of exposure. Our findings suggest that chronic temperature effects as well as temperature fluctuation play an important role in limiting salmonid distributions and therefore should be considered when developing management objectives and water quality standards.

We examined relations between the amounts and spatial patterns of urban land cover and fish assemblages, physical habitat, base flow, and water temperature at 39 sites in small, coldwater trout streams in Wisconsin and Minnesota. The amount of connected impervious surface area in the watershed was negatively correlated with a fish-based coldwater index of biotic integrity (IBI), catches of all coldwater and coolwater fishes and trout, and the percentage of intolerant fish; it was positively correlated with fish species richness and the percentage of tolerant fish. Nonlinear models were developed by means of 90% quantile regression to predict the maximum possible IBI score, abundance of trout, and percentage of intolerant fish at a given level of imperviousness. At a connected imperviousness of less than about 6% for a watershed, all three variables could have high values, whereas at a connected imperviousness above 11% the values were inevitably low. Between 6% and 11%, minor changes in urbanization could result in major changes in stream fishes. Canonical correspondence analysis identified water temperature and base flow as the key instream habitat factors explaining stream fish assemblages patterns. The percentage of connected impervious area in the watershed had a positive, linear relation with water temperature and a negative, nonlinear relation with base flow, suggesting pathways by which urbanization affected fish assemblages. Partial redundancy analysis indicated that land cover within 30 m of the stream channel explained considerably more variance in fish assemblages and instream habitat and physical conditions than land cover beyond 30 m. Our study suggests that low levels of urban development can damage coldwater stream systems. Development strategies that protect the riparian area and minimize imperviousness may reduce this damage.

AbstractPhysical habitat was quantified in 105 randomly selected streams across the Northern Lakes and Forests Ecoregion during 1998 and 1999 to develop a stream habitat index for the region. Physical habitat measures (106) were classified into four groups: substrate, instream cover, riparian zone–land use, and geomorphology–hydrology. Variable reduction procedures yielded seven variables: sinuosity, percent of substrate gravel or larger, percent substrate as detritus or muck, percent of bank with forested cover, amount of bank erosion, number of large logs per 100 m, and mean length of pools. Streams were separated by a gradient value of 3 m/km (low N= 70; high N= 35) and assigned to model and test data sets. For low-gradient streams in the model data set, the seven habitat variables explained 47% of the variation in index of biotic integrity (IBI) scores. To produce the habitat index, the coefficients in the regression were used to weight each of the seven variables. For low-gradient streams in the test data set, the habitat index explained 20% of the variation in IBI scores. A habitat index could not be developed for high-gradient sites, probably due to the low number of sites. Comparison of habitat to IBI scores provides resource managers with a method to evaluate the contribution of habitat quality to the IBI score.

AbstractMost existing habitat indices and models have been developed for medium- to high-gradient streams and, therefore, tend to undervalue low-gradient streams. We analyzed physical habitat and fish community biotic integrity data from 50 low-gradient stream stations to develop a habitat rating index for the assessment of low-gradient streams in Wisconsin. Low-gradient stations were defined as having gradients of 3 m/km or lower and less than 5% of their length as riffles. Of 43 habitat variables considered, we selected 7 for use in the index: percent channelization, channelization age, percent instream cover, percent bank erosion, sinuosity, standard deviation of thalweg depth, and percent buffer vegetation. Based on a multiple-regression analysis, channelization age and percent instream cover were given greater weight in the index than the other five variables. Habitat index values explained 58% of the variation in index of biotic integrity (IBI) scores among the 50 stations used to develop the index and explained 64% of the variation in IBI scores for an independent test data set of 42 other low-gradient stations. In contrast, a habitat index designed for medium- to high-gradient streams explained only 47% of the variation in IBI scores for these 42 other low-gradient stations. We conclude that our new index more accurately represents the quality of physical habitat for fish communities in Wisconsin low-gradient streams and suggest that it also may be useful for assessing low-gradient streams elsewhere in North America.

Abstract: A simple and reliable technique to study bacterial chemotaxis in natural aquatic environments is reported. This technique uses the test chemicals in known volumes of semi-solid agar media placed in double layered, highly porous, polyester tubes. Following in situ incubation, bacteria attracted by the test chemicals are enumerated with fluorescence microscopy following acridine orange staining. Studies in an eutrophic reservoir showed that significant numbers of bacteria were attracted to D-glucose and glycine; no significant effects were observed with L-serine, sodium succinate, or sodium chloride.

We analyzed relationships between watershed land use and habitat quality, and between watershed land use and biotic integrity for 134 sites on 103 streams located throughout Wisconsin. Habitat quality and index of biotic integrity (IBI) scores were significantly positively correlated with the amount of forested land and negatively correlated with the amount of agricultural land in the entire watershed and in a 100-m-wide buffer along the stream. Correlations were generally stronger for the entire watershed than for the buffer. Relationships between forested land and habitat and biotic integrity were linear, although there were several outlying sites with lower-than-expected IBI scores. Relationships with agricultural land use were more complex, with an obvious decline in habitat quality and IBI scores apparent only when agricultural land use exceeded 50%. Even when agricultural land use exceeded 80%, some sites maintained relatively good habitat quality and biotic integrity. These “good” sites tended to have relatively high gradients and rocky substrates, and had not been channelized. High urban land use was strongly associated with poor biotic integrity and was weakly but significantly associated with poor habitat quality. There appeared to be a threshold value of urbanization between 10% and 20% beyond which IBI scores were consistently very low. Overall, watershed land uses had strong effects on habitat quality and biotic integrity in Wisconsin streams.

The index of biotic integrity (IBI). developed from information on the structure, composition, and functional organization of fish assemblages, is used to assess the health of aquatic ecosystems. We analyzed two large statewide data sets on stream fish assemblages to develop and test a version of the IBI for application to Wisconsin coldwater streams (maximum daily mean water temperature usually <22°C). This new IBI is needed because fish assemblages in Wisconsin coldwater streams differ significantly from those in warmwater streams (maximum daily mean temperature >24°C), for which an IBI already exists. High-quality coldwater streams have few species, with salmonids and cottids dominating. and lack many of the taxonomic groups that are important in high-quality warmwater streams. In contrast, high-quality warmwater streams have numerous species, and cyprinids, catostomids, centrarchids, and percids typically dominate. Environmental degradation often causes an increase in species richness in coldwater fish assemblages, the opposite of what occurs in warmwater assemblages, as a small number of coldwater species are replaced by a larger number of more tolerant eurythermal and warmwater species. The new coldwater IBI has five metrics: (1) number of intolerant species, (2) percent of all individuals that are tolerant species, (3) percent of all individuals that are top carnivore species, (4) percent of all individuals that are native or exotic stenothermal coldwater or coolwater species, and (5) percent of salmonid individuals that are brook trout Salvelinus fontinalis. No regional or stream-size adjustments in metric scoring criteria are needed. Relative coldwater IBI scores and ratings of stream sites throughout Wisconsin closely match independent rankings of environmental quality on the basis of physical habitat and water quality of the sites. Variation in IBI scores within and among years is gencrally low. The new coldwater IBI is not appropriate for coolwater streams (typical maximum summer daily mean temperature 22–24°C).

The precision and accuracy of estimates of stream habitat variables were evaluated in three southern Wisconsin streams. Among-observer precision was estimated from six observers with three different levels of experience. The precision of estimates for 27 stream habitat variables was generally good; 46% of the confidence intervals of the overall means for six observers were less than or equal to the field measurement precision. Stream width and water depth were estimated most precisely; these were followed by substrate composition, cover for fish, and bank susceptibility to erosion. Estimates of bank vegetation or land use and gravel embeddedness were the least precise. We determined accuracy of quantifying substrate composition by comparing direct visual observations from the same six observers with values obtained from digitized photographs of the same area of substrate. The results showed that 73% of the differences between visually estimated substrate values and digitized values were less than 5 percentage points, and none were greater than 12 percentage points. Accuracy and precision were lowest in the streams with the most heterogeneous habitat. Overall, our results indicate that visual estimates of substrate composition are sufficiently accurate for many fisheries applications. No significant differences in accuracy were found for estimates of substrate compositions obtained by the least and the most experienced observers. Variation among trained observers was relatively low for most habitat variables but fairly high for bank vegetation or land use and for gravel embeddedness. If initial training is adequate, experience of observers has little effect on the accuracy and precision of estimates.

The time-course response of bacterioplankton and phytoplankton to enrichment with NH4+, PO4-3, and mannitol (singly and in various combinations) were measured over two years during June, August, and October in a north-temperate, eutrophic lake. Bacterial cell concentration and activity (3H-thymidine incorporation) increased significantly (p < 0.05) with addition of po4-3 in June, additions of PO4-3 NH4+, and mannitol in August, and addition of mannitol in October, 1988. In these same experiments, phytoplankton biomass (chlorophyll-a) and activity (14CO2 uptake) increased significantly (p < 0.05) with addition of po4-3 in June; 14CO2 uptake increased significantly (p < 0.05) with additions of nh4 + in August and October. During 1989, bacterial cell concentration and activity increased significantly (p < 0.05) with most nutrient additions, except po4-3 in June, which showed no stimulation. Concomitantly, the addition of NH4+ in June, and NH4+ and PO4-3 in August significantly (p < 0.05) increased 14CO2 uptake and chlorophyll-a during the 1989 experiments. Inorganic nutrient enrichments appeared to stimulate bacterial activity both directly and indirectly via phytoplankton products. Our results lead us to contend that inorganic nutrients may be as important as organic nutrients in the regulation of bacterioplankton growth in certain aquatic environments.

In a stream aquarium, we examined microhabitat use and agonistic behavior for evidence of competition between age-1 wild brown trout Salmo truttaand age-1 hatchery-reared greenback cutthroat trout Oncorhynchus clarki stomiasof partly wild parentage, The brown trout were more aggressive than the greenback cutthroat trout, even though hatchery influences may have heightened aggressiveness of the latter. In sympatric tests with equal-sized fish within the range of 127–154 mm fork length, brown trout were involved in more inter- and intraspecific agonistic events, initiated 92% of observed attacks, and displaced the greenback cutthroat trout from energetically profitable sites in pools and near food sources. When we placed single, intermediate-sized brown trout within groups of cutthroat trout containing a range of sizes, the brown trout dominated all the cutthroat trout, including some that were as much as 1.3 times longer and 1.7 times heavier. The results suggest that greenback cutthroat trout are at a competitive disadvantage in the presence of brown trout. This finding supports the policy of eradicating brown trout (and other nonindigenous fishes) from streams managed to preserve or restore greenback and other subspecies of cutthroat trout. Also, it emphasizes the importance of restricting further stocking of brown trout and other exotics into cutthroat trout streams.

Sea dikes, as a commonly used type of coastal protection structures, are often attacked or damaged by violent waves overtopping under tsunamis and storm surges. In this study, the behavior of solitary waves traveling on a sloping sea dike is simulated, and solitary wave overtopping characteristics are analyzed using a complete Lagrangian numerical method, the moving particle semi-implicit (MPS) method. To better describe the complicated fluid motions during the wave overtopping process, the original MPS method is modified by introducing a new free surface detection method, i.e., the area filling rate identification method, and a modified gradient operator to provide higher precision. Meanwhile, the approximation method for sloping boundaries in particle methods is enhanced, and a smooth slope approximation method is proposed and recommended. To verify the improved MPS method, a solitary wave traveling over a steep sloping bed is studied. The entire solitary wave run-up and run-down processes and exquisite water movements are reproduced well by the present method, and are consistent with the corresponding experimental results. Subsequently, the improved MPS method is applied to investigate the overtopping process of a single solitary wave over a sloping sea dike. The results show that the hydraulic jump phenomenon is also possible to occur during the run-down motion of the solitary wave overtopping. Finally, the characteristics of the propagation and overtopping of two successive solitary waves on a sloping sea dike are discussed. The result manifests that the interaction between adjacent solitary waves affects wave overtopping patterns and overtopping velocities. • A new free surface detection method is proposed. • A new method for approximating sloping boundaries is developed. • A modified pressure gradient model is incorporated in the improved MPS method. • The propagation processes of solitary waves on slopes is meticulously reproduced. • The hydraulic jump phenomenon is investigated during the solitary wave overtopping. [ABSTRACT FROM AUTHOR]