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Nesting animals require information about their environment to place nests in optimal locations. This information can either be derived from an animal's previous experiences (private information), or it may be gained through the observation of the success of conspecifics (public information). This use of public information to locate suitable nesting sites has been explored in birds but not fishes. Many fish construct nests to protect their offspring, and the utilisation of public information could be a suitable strategy for determining which nesting locations would maximise fitness. We studied public and private information use in the bluehead chub, a species of nesting leuciscid in the Southeastern United States, by observing nesting activity and measuring habitat variables along a 0.65 km reach of Toms Creek in Blacksburg, Virginia. We clustered activity data and created generalised linear models to determine if bluehead chubs construct nests within discrete nesting periods during the spawning season and if they use public or private information to select nest sites between these periods. Our results suggest that bluehead chubs construct nests periodically within a single spawning season and use a combination of public and private information when determining suitable nesting sites from one nesting period to another. This study provides some of the first evidence suggesting public information use for nest site selection in a species of fish and opens up a new frontier of research into public information use among fishes. [ABSTRACT FROM AUTHOR]

Summary Sleep loss is associated with reduced health and quality of life, and increased risk of Alzheimer's disease and related dementias. Up to 66% of persons with Alzheimer's disease and related dementias experience poor sleep, which can predict or accelerate the progression of cognitive decline. Exercise is a widely accessible intervention for poor sleep that can protect against functional and cognitive decline. No previous systematic reviews have investigated the effectiveness of exercise for sleep in older adults with mild cognitive impairment or Alzheimer's disease and related dementias. We systematically reviewed controlled interventional studies of exercise targeting subjectively or objectively (polysomnography/actigraphy) assessed sleep in persons with mild cognitive impairment or Alzheimer's disease and related dementias. We conducted searches in PubMed, Embase, Scopus and Cochrane‐Library (n = 6745). Nineteen randomised and one non‐randomised controlled interventional trials were included, representing the experiences of 3278 persons with mild cognitive impairment or Alzheimer's disease and related dementias. Ten had low‐risk, nine moderate‐risk, and one high‐risk of bias. Six studies with subjective and eight with objective sleep outcomes were meta‐analysed (random‐effects model). We found moderate‐ to high‐quality evidence for the beneficial effects of exercise on self‐reported and objectively‐measured sleep outcomes in persons with mild cognitive impairment or Alzheimer's disease and related dementias. However, no studies examined key potential moderators of these effects, such as sex, napping or medication use. Our results have important implications for clinical practice. Sleep may be one of the most important modifiable risk factors for a range of health conditions, including cognitive decline and the progression of Alzheimer's disease and related dementias. Given our findings, clinicians may consider adding exercise as an effective intervention or adjuvant strategy for improving sleep in older persons with mild cognitive impairment or Alzheimer's disease and related dementias. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that the autonomic nervous system can contribute to memory consolidation during sleep. Whether fluctuations in cardiac autonomic activity during sleep following physical exercise contribute to the process of memory consolidation has not been studied. We assessed the effects of a non‐rapid eye movement (NREM) nap following acute exercise on cardiac autonomic regulation assessed with heart rate variability (HRV) to examine if HRV influences memory processes. Fifty‐six (59% female) healthy young adults (23.14 ± 3.74 years) were randomly allocated to either the exercise plus nap (ExNap, n = 27) or nap alone (NoExNap, n = 29) groups. The ExNap group performed a 40‐minute moderate‐intensity cycling, while the NoExNap group was sedentary prior to learning 45 neutral pictures for a later test. Subsequently, participants underwent a 60‐minute NREM nap while measuring EKG, followed by a visual recognition test. Our results indicated that heart rate did not significantly differ between the groups (p =.243), whereas vagally mediated HRV indices were lower in the ExNap group compared to the NoExNap group (p <.05). There were no significant differences in sleep variables between the groups (p >.05). Recognition accuracy was significantly higher in the ExNap group than in the NoExNap group (p =.027). In addition, the recognition accuracy of the ExNap group was negatively associated with vagally mediated HRV (p <.05). Pre‐nap acute exercise appears to attenuate parasympathetic activity and to alter the relationship between memory and cardiac autonomic activity. Our findings reinforce those of previous studies and together show the contribution of parasympathetic tone to memory consolidation during sleep. The negative relationship between recognition memory performance and parasympathetic activity indicates that the alteration of parasympathetic tone following acute exercise may be unfavorable to memory consolidation. [ABSTRACT FROM AUTHOR]

Tragocephala nobilis (Fabricius) (Coleoptera:Cerambycidae), an insect pest (herbivorous insect), was recently found on a multipurpose tropical tree species, Tetrapleura tetraptera (Schum and Thonn.) Taub, in Ghana. Although the pest has been previously reported on other tree crops such as cocoa and Coffea arabica, this is the first report on T. tetraptera. T. tetraptera is a deciduous tree crop with numerous nutritional and medicinal benefits. The pest, a long‐horned beetle is found to attack T. tetraptera tree and damage is first observed as die‐back of twigs and branches leading to the formation of a witches broom in the crown. This is followed by a series of tunnels created by the larvae on the main stem resulting in branch death and/or tree mortality. In view of the threat posed by the pest to T. tetraptera, a broader study is needed urgently to develop an integrated pest management strategy for T. nobilis pest in T. tetraptera plantations as the interest in its domestication as a tree crop is burgeoning in response to increasing herbal medicine and food supplements demand. [ABSTRACT FROM AUTHOR]

The goal of 6G is to make far-reaching changes in communication systems with stricter demands, such as high throughput, extremely low latency, stronger security, and ubiquitous connectivity. Several promising techniques, such as reconfigurable intelligent surfaces (RISs), have been introduced to achieve these goals. An RIS is a 2D low-cost array of reflecting elements that can adjust the electromagnetic properties of an incident signal. In this paper, we guarantee secrecy by using an irregular RIS (IRIS). The main idea of an IRIS is to irregularly activate reflecting elements for a given number of RIS elements. In this work, we consider a communication scenario in which, with the aid of an IRIS, a multi-antenna base station establishes a secure link with a legitimate single-antenna user in the presence of a single-antenna eavesdropper. To this end, we formulate a topology-and-precoding optimization problem to maximize the secrecy rate. We then propose a Tabu search-based algorithm to jointly optimize the RIS topology and the precoding design. Finally, we present simulation results to validate the proposed algorithm, which highlights the performance gain of the IRIS in improving secure transmissions compared to an RIS. Our results show that exploiting an IRIS can allow additional spatial diversity to be achieved, resulting in secrecy performance improvement and overcoming the limitations of conventional RIS-assisted systems (e.g., a large number of active elements). [ABSTRACT FROM AUTHOR]

We compared the influence of biological traits (morphology, physiology, reproduction, and life history), ecological traits (geographic distribution, habitat associations, food habits), and introduction attributes (propagule pressure, human use of a species, residence time) on invasion success of native and introduced stream fishes during the colonisation and spread stages in an Appalachian (U.S.A.) river basin.Colonisation success was positively related to residence time, benthic feeding, an equilibrium life‐history strategy, and nest spawning. Successful spread was associated with tolerance to increased temperature and an equilibrium life‐history strategy. The spread of introduced fishes was negatively related to gamefish status. No effect of propagule pressure was detected.Traits linked to invasion success were consistent with the hypothesis that human land‐use practices increase the invasibility of highland catchments by creating novel conditions better suited to lowland and equilibrium invaders.We found biological traits to be more useful than ecological traits in predicting invasion success and suggesting invasion mechanisms. Parental care and nest association can facilitate invasions over large spatial extents for both native and introduced fishes. Analyses of suites of traits can reveal mechanisms of invasions and tactics for controlling them; such mechanisms and tactics may be system‐specific and scale‐dependent. [ABSTRACT FROM AUTHOR]

Purpose: To describe objectively measured changes in the volume and pattern of physical activity and sedentary behavior in patients undergoing total knee arthroplasty for osteoarthritis.Methods: Physical activity and sedentary behavior were measured in patients (13 males, 76 females) with a mean age of 64 years (range 55-80) and end-stage osteoarthritis of the knee, using an accelerometer (ActiGraph GT3X+) for seven consecutive days (24 h/day) prior to, 6 weeks and 6 months after total knee arthroplasty. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), University of California Los Angeles (UCLA) Activity index and range of motion (ROM) were also assessed.Results: Proportion of time spent in sedentary behavior decreased from baseline to 6 months (mean 70.1 vs. 64.0%; p = 0.009) and the interruptions to sedentary behavior improved between baseline and 6 months after total knee arthroplasty (mean 85.0-93.0 breaks/day, p = 0.014). Proportion of time spent in light physical activity increased from baseline to 6 months after total knee arthroplasty (29.0 vs. 34.8%; p = 0.008). There was no change in time spent in moderate to vigorous physical activity after total knee arthroplasty. WOMAC (median 71.0 vs. 4.0, p < 0.001), UCLA (median 2.0 vs. 5.0, p < 0.001) as well as ROM [median (0.0°-90.0°) vs. (0.0°-110°), p < 0.05] scores improved between baseline and 6 months after total knee arthroplasty.Conclusion: Clinically, functional improvements in patients following total knee arthroplasty may be assessed by objectively measuring changes in low intensity activity behaviors. The use of accelerometers in this study gives new insights into activity accumulation patterns in a clinical population and highlights their use in determining a behavioral response to an intervention.Level Of Evidence: II. [ABSTRACT FROM AUTHOR]

Despite the establishment of a national protected area system at the beginning of the 20th century to protect some of the world's most biodiverse forests, Indonesia has one of the highest deforestation rates in the world, due in part to the expansion of the global palm oil industry. The unique ecosystems of Sumatra, Indonesia provide habitat for critically endangered Sumatran tigers (Panthera tigris sumatrae), Sumatran elephants (Elephas maximus sumatrensis), and two species of orangutans (Pongo abelii and Pongo tapanuliensis). In this study, we use a matching method with generalized boosted models to determine the effectiveness of three nationally protected areas in preventing deforestation from 2002 to 2016. We also examine leakage – an increase in deforestation directly outside of protected areas relative to the wider landscape – to provide a clearer picture of the effects of agricultural expansion in this landscape. We found that Tesso Nilo National Park, with its lowland rain forest and conditions suitable for oil palm, offered the least protection from deforestation (avoided deforestation rate = 4.18%, p < 0.05 95% CI [1.97% - 6.45%]). Bukit Tigapuluh National Park, which may experience some de facto protection (i.e. protection due to factors independent of policy) with its mountainous terrain and difficult access, had the highest avoided deforestation rate (26.36%, p < 0.05 95% CI [24.17–28.55]), but had relatively high leakage (10.21%, p < 0.05 95% CI [7.51–12.98]). The low avoided deforestation rate in Tesso Nilo could be due to high localized human population and/or other socio-economic factors we were unable to control for in this study. The quantitative evidence of deforestation and effectiveness of protected areas in this heavily modified landscape supports the need for increased enforcement around protected areas locally, and globally in other oil palm production regions. These actions are critical in the preservation of global, tropical endemic flora and fauna. Meskipun telah membangun sistem kawasan konservasi sejak awal abad ke 20 untuk melindungi hutan dengan keanekaragaman hayati yang sangat tinggi, Indonesia masih merupakan negara yang memiliki laju deforestasi yang tertinggi di dunia, akibat penkembangan industri sawit di dunia. Ekosistem-ekosistem endemic di Sumatera-Indonesia merupakan habitat bagi spesies-spesies yang memiliki status konservasi kritis yaitu harimau Sumatera (Panthera tigris sumatrae), gajah Sumatera (Elephas maximus sumatrensis), dan dua species orangutan (Pongo abelii dan Pongo tapanuliensis). Dalam penelitian ini, kami menggunakan metode matching dengan model generalized boosted untuk menentukan efektivitas dari tiga kawasan konservasi dalam mencegah terjadinya deforestasi dari tahun 2002–2016. Kami juga menilai leakage (kebocoran) – yang merupakan kenaikan laju deforestasi pada area yang berdekatan dengan kawasan konservasi– untuk memberikan gambaran yang utuh atas dampak industri sawit dunia. Kami menemukan bahwa Taman Nasional Tesso Nilo, dengan habitat dan kondisi hutan tropis dataran rendah, yang juga sesuai untuk tanaman sawit, merupakan kawasan konservasi yang memiliki kemampuan paling rendah dalam melindungi dari deforestasi (laju pencegahan deforestasi = 4.18%, p < 0.05 95% CI [1.97% - 6.45%]). Sedangkan Taman Nasional Bukit Tigapuluh yang merupakan kawasan pegunungan memiliki laju pencegahan deforestasi tertinggi (26.36%, p < 0.05 95% CI [24.17–28.55]), namun memilki nilai kebocoran yang relatif tinggi (10.21%, p < 0.05 95% CI [7.51–12.98]). Fakta kuantitatif dari deforestasi dan efektivitas kawasan konservasi pada landskap yang termodifikasi sangat berat ini mengkonfirmasi adanya kebutuhan yang mendesak untuk melakukan penguatan di sekitar kawasan konservasi baik di tingkat lokal maupun global pada wilayah yang ditujukan untuk produksi sawit. Aksi-aksi tersebut sangat dibutuhkan untuk mendukung perlindungan flora dan fauna endemik di dunia. [ABSTRACT FROM AUTHOR]

The article offers the author's insights on the study which examined fishes in the middle and upper New River in North Carolina and Virginia. Topics discussed include nest and nesting activity of Nocomis, interactions of common species, and fish conservation and ecology. He also mentions the need for understanding the natural history and ecology of Afrotropical fishes in Africa.

Aim Knowledge of expanding and contracting ranges is critical for monitoring invasions and assessing conservation status, yet reliable data on distributional trends are lacking for most freshwater species. We developed a quantitative technique to detect the sign (expansion or contraction) and functional form of range-size changes for freshwater species based on collections data, while accounting for possible biases due to variable collection effort. We applied this technique to quantify stream-fish range expansions and contractions in a highly invaded river system. Location Upper and middle New River ( UMNR) basin, Appalachian Mountains, USA. Methods We compiled a 77-year stream-fish collections dataset partitioned into ten time periods. To account for variable collection effort among time periods, we aggregated the collections into 100 watersheds and expressed a species' range size as detections per watershed ( HUC) sampled ( DPHS). We regressed DPHS against time by species and used an information-theoretic approach to compare linear and nonlinear functional forms fitted to the data points and to classify each species as spreader, stable or decliner. Results We analysed changes in range size for 74 UMNR fishes, including 35 native and 39 established introduced species. We classified the majority (51%) of introduced species as spreaders, compared to 31% of natives. An exponential functional form fits best for 84% of spreaders. Three natives were among the most rapid spreaders. All four decliners were New River natives. Main conclusions Our DPHS-based approach facilitated quantitative analyses of distributional trends for stream fishes based on collections data. Partitioning the dataset into multiple time periods allowed us to distinguish long-term trends from population fluctuations and to examine nonlinear forms of spread. Our framework sets the stage for further study of drivers of stream-fish invasions and declines in the UMNR and is widely transferable to other freshwater taxa and geographic regions. [ABSTRACT FROM AUTHOR]

A scheme to predict transient stability status following a disturbance is presented. The scheme is activated upon the tripping of a line or bus and operates as follows: Two samples of frequency deviation values at all generator buses are obtained. At each generator bus, the maximum frequency deviation within the two samples is extracted. A vector is then constructed from the extracted maximum frequency deviations. The Euclidean norm of the constructed vector is calculated and then fed as input to a trained multilayer perceptron neural network which predicts the stability status of the system. The scheme was tested using data generated from the New England test system. The scheme successfully predicted the stability status of all two hundred and five disturbance test cases. [ABSTRACT FROM AUTHOR]

Fish occurrence data to support high-resolution distribution models and test various community and macroecological hypotheses have not been available at the national scale. We presentIchthyMaps, a high-resolution database of historical freshwater fish occurrences throughout the conterminous United States. Designed on the principles of metacommunity ecology,IchthyMapsis a large compilation of fish presence records collected through approximately 1990, digitized from regional atlases, appended to 1:100,000 National Hydrography Dataset plus version 2 (NHDPlusV2) interconfluence stream segments, and readily aggregated within hierarchically coarser units (e.g., 8-digit and 12-digit U. S. Geological Survey [USGS] hydrologic units).IchthyMapscontains 606,550 presence records for 1,038 species and subspecies, spatially joined to 224,305 NHDPlusV2 interconfluence stream segments, representing more than 10% average sampling intensity considering all the NHDPlusV2 segments as the sampling frame.IchthyMapsis freely and publicly accessible through the USGS ScienceBase web portal. It offers new opportunities for both basic and applied research and conservation programs in areas such as modeling species distributions, community ecology, gap analysis, and assessments of impacts of land use, species invasions, climate change, conservation biogeography, and fisheries management. [ABSTRACT FROM PUBLISHER]

Background: Physical activity levels are decreased and sedentary behaviour levels are increased in patients with knee osteoarthritis (OA). However, previous studies have shown that following total knee arthroplasty (TKA), objectively measured physical activity levels do not change compared to before the surgery. Very few studies have objectively assessed sedentary behaviour following TKA. This study aims to assess patterns of objective habitual physical activity and sedentary behaviour in patients with knee OA and to determine whether these change following TKA.Methods: Patients diagnosed with knee osteoarthritis and scheduled for unilateral primary total knee arthroplasty will be recruited from the Orthopaedic Division at the Charlotte Maxeke Johannesburg Academic Hospital. Eligible participants will have assessments completed one week before the scheduled arthroplasty, six weeks, and six months post-operatively. The primary outcomes are habitual physical activity and sedentary behaviour which will be measured using accelerometry (Actigraph GTX3+ and activPal monitors) at the specific time points. The secondary outcomes will be improvements in osteoarthritis-specific quality of life measures using the following questionnaires: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), Knee Society Clinical Rating System (KSS), UCLA activity index; subjective pain scores, and self reported sleep quality.Discussion: The present study will contribute to the field of musculoskeletal health by providing a rich detailed description of the patterns of accumulation of physical activity and sedentary behaviour in patients with knee OA. These data will contribute to existing knowledge using an objective measurement for the assessment of functional ability after total knee arthroplasty. Although studies have used accelerometry to measure physical activity in knee OA patients, the data provided thus far have not delved into the detailed patterns of how and when physical activity is accumulated before and after TKA. Accurate assessment of physical activity is important for physical activity interventions that target special populations.Trial Registration: NCT02675062 (4 February 2016). [ABSTRACT FROM AUTHOR]

The southeastern United States has undergone anthropogenic changes in landscape structure, with the potential to increase (e.g., urbanization) and decrease (e.g., reservoir construction) stream flashiness and flooding. Assessment of the outcome of such change can provide insight into the efficacy of current strategies and policies to manage water resources. We (1) examined trends in precipitation, floods, and stream flashiness and (2) assessed the relative influence of land cover and flow-regulating features (e.g., best management practices and artificial water bodies) on stream flashiness from 1991 to 2013. We found mean annual precipitation decreased, which coincided with decreasing trends in floods. In contrast, stream flashiness, overall, showed an increasing trend during the period of study. However, upon closer examination, 20 watersheds showed stable stream flashiness, whereas 5 increased and 6 decreased in flashiness. Urban watersheds were among those that increased or decreased in flashiness. Watersheds that increased in stream flashiness gained more urban cover, lost more forested cover and had fewer best management practices installed than urban watersheds that decreased in stream flashiness. We found best management practices are more effective than artificial water bodies in regulating flashy floods. Flashiness index is a valuable and straightforward metric to characterize changes in streamflow and help to assess the efficacy of management interventions. [ABSTRACT FROM AUTHOR]

Aim We aim to assess the temporary transferability of species distribution models ( SDMs) for stream fish species in terms of discrimination power and calibration. Location New River basin, eastern United States. Methods In this study, we used Lasso-regularized logistic regression ( LLR), boosted regression trees ( BRT), MaxEnt, and ensemble model ( ENS) to evaluate the habitat suitability of 16 fish species with different rarity and temperature preference based on historical species occurrences obtained during 1950-1990. These SDMs were used to make probabilistic predictions of species presence in the independent datasets sampled during 2012-2014. We evaluated the temporal transferability of these SDMs in terms of discrimination power and calibration with the temporarily independent datasets. Results The area under the receiver-operating-characteristic curve ( AUC) was over 0.6 for 13 (81%) of the species in the evaluations of ENS models with the independent datasets. Cool-water species and species with small local population size traits tended to have good temporal transferability. With observed species prevalence as the discrimination cut-off, LLR had the highest overall accuracy for 13 of the 16 species and highest specificity for 10 species, whereas MaxEnt had the highest sensitivity for 14 species. Biases, under- or over-fitting problems were common in the temporal model transfers, among the modelling approaches used here. Main conclusions SDMs developed with historical data generally had moderate to good discrimination power but they tended to systematically underestimate current probability of species presence. To predict species distribution shifts over time, SDMs should be well-calibrated with high discrimination power. We suggest reclassifying predicted probability of species occurrence to ordinal ranks to deal with (under- and over-estimation) bias, and fine-tuning variable selection with regularization or cross validation to remedy under- and over-fitting. [ABSTRACT FROM AUTHOR]

Spatial transfers of species distribution models (SDMs) are often applied in the study of land use and climate-change effects, spread of invasive species and conservation planning. However, model transferability and risk of error are rarely evaluated prior to predicting species distribution to different regions. We aim to assess spatial transferability of SDMs for stream fish and to evaluate the effect of model types and habitat heterogeneity on transferability., We developed SDMs for 21 fish species and made predictions of occurrence of these species among five pairs of river catchments (i.e. model transfers). Forty eight transfers were made for each of three modelling approaches (Lasso-regularised logistic regression (LLR), boosted regression trees (BRT) and MaxEnt) after incorporating spatial autocorrelation. In addition to internal and external evaluation of discrimination power, we assessed the cross-catchment consistency of variable selections, fish-habitat relationships and predicted probabilities of species presences., Approximately half of 144 spatial transfers of SDMs had moderate to high discrimination power. Discrimination power was low for the rest of the models. Incorporating spatial autocorrelation could not improve discrimination power in the model transfers. Friedman test showed that BRT did not differ significantly from LLR but it outperformed MaxEnt in terms of AUC in the model transfers. BRT and LLR models tended to have high overall accuracy and specificity, whereas MaxEnt tended to have high sensitivity in the model transfers., The degree of model transferability varied among species, and was asymmetric when reciprocal transfers were made between paired catchments. Ranks of variable importance in BRT models differed among catchments for most species. Temperature, base flow index, altitude and habitat condition index were more often ranked as the most important predictors in the five study river catchments, although the functional forms of their effects on fish presence were sometimes inconsistent between paired catchments., Compared to published transferability of some terrestrial taxa SDMs, spatial transferability of stream-fish distribution models was limited, reflecting the natural barriers to dispersal among catchments, and the necessity of evaluating model transferability in conservation applications (e.g. evaluation of climate- or landscape-change effects, invasive species risk assessments and species reintroduction planning). We suggest the following strategies to enhance spatial transferability: (i) match the range and location of the habitat predictors between the model region and prediction region, or alternatively choose a model training region with a large extent and a wide range of environmental gradients; (ii) use presence-absence models such as BRT and LLR and (iii) include habitat features with a sound ecological basis such as temperature and hydrology. [ABSTRACT FROM AUTHOR]

Aim The role of biotic interactions in determining species distributions is difficult to decouple from abiotic factors. Most research to date has focused on negative biotic interactions, but the importance of positive interactions such as mutualism and facilitation at large scales is less understood. We used a two-species occupancy modelling approach to decouple the relative effects of abiotic factors and biotic interactions between a habitat-modifying North American stream fish ( Nocomis leptocephalus) and two of its nearly-obligate beneficiary species ( Chrosomus oreas and Clinostomus funduloides). Location Sixty-one sites on tributaries to the New River basin in the Appalachian mountains of the eastern United States. Methods We sampled fishes using backpack electrofishing in the summers of 2012-2014. We gathered 10 habitat covariates from the National Hydrography Dataset and from instream measurements. We reduced dimensionality in habitat variables, corrected them for spatial autocorrelation and selected two eigenvectors as habitat covariates. We then used an information-theoretic approach to compare two-species occupancy models representing hypotheses specifying the importance of only habitat, only biotic interactions, or combinations of both. Results The best model for each species combination specified the importance of biotic interactions. For both associate species, probabilities that associates would occur in the absence of their host were considerably lower than probabilities of co-occurrence. Species interaction factors indicated positive patterns of co-occurrence between hosts and associates. Models suggested that habitat variables mediated host-associate interactions for C. oreas but not for C. funduloides. Main conclusions This study provides some of the first large-scale quantitative evidence of positive co-occurrence among vertebrates, and demonstrates the importance of abiotic context for mediating interspecific interactions. Two-species occupancy modelling may be superior to traditional co-occurrence analyses for parsing out the relative importance of biotic interactions and habitat variables for determining species distributions. However, experiments and small-scale behavioural observations will also be necessary to confirm mechanisms. [ABSTRACT FROM AUTHOR]

The development of encompassing general models of ecology is precluded by underrepresentation of certain taxa and systems. Models predicting context-dependent outcomes of biotic interactions have been tested using plants and bacteria, but their applicability to higher taxa is largely unknown., We examined context dependency in a reproductive mutualism between two stream fish species: mound nest-building bluehead chub Nocomis leptocephalus and mountain redbelly dace Chrosomus oreas, which often uses N. leptocephalus nests for spawning. We hypothesized that increased predator density and decreased substrate availability would increase the propensity of C. oreas to associate with N. leptocephalus and decrease reproductive success of both species., In a large-scale in situ experiment, we manipulated egg predator density and presence of both symbionts (biotic context), and replicated the experiment in habitats containing high- and low-quality spawning substrate (abiotic context)., Contradictory to our first hypothesis, we observed that C. oreas did not spawn without its host. The interaction outcome switched from commensalistic to mutualistic with changing abiotic and biotic contexts, although the net outcome was mutualistic., The results of this study yielded novel insight into how context dependency operates in vertebrate mutualisms. Although the dilution effect provided by C. oreas positively influenced reproductive success of N. leptocephalus, it was not enough to overcome both egg predation and poor spawning habitat quality. Outcomes of the interaction may be ultimately determined by associate density. Studies of context dependency in vertebrate systems require detailed knowledge of species life-history traits. [ABSTRACT FROM AUTHOR]

Riverine flooding is a significant global issue. Although it is well documented that the influence of landscape structure on floods decreases as flood size increases, studies that define a threshold flood-return period, above which landscape features such as topography, land cover and impoundments can curtail floods, are lacking. Further, the relative influences of natural versus built features on floods is poorly understood. Assumptions about the types of floods that can be managed have considerable implications for the cost-effectiveness of decisions to invest in transforming land cover (e.g., reforestation) and in constructing structures (e.g., storm-water ponds) to control floods. This study defines parameters of floods for which changes in landscape structure can have an impact. We compare nine flood-return periods across 31 watersheds with widely varying topography and land cover in the southeastern United States, using long-term hydrologic records (≥20 years). We also assess the effects of built flow-regulating features (best management practices and artificial water bodies) on selected flood metrics across urban watersheds. We show that landscape features affect magnitude and duration of only those floods with return periods ≤10 years, which suggests that larger floods cannot be managed effectively by manipulating landscape structure. Overall, urban watersheds exhibited larger (270 m 3 /s) but quicker (0.41 days) floods than non-urban watersheds (50 m 3 /s and 1.5 days). However, urban watersheds with more flow-regulating features had lower flood magnitudes (154 m 3 /s), but similar flood durations (0.55 days), compared to urban watersheds with fewer flow-regulating features (360 m 3 /s and 0.23 days). Our analysis provides insight into the magnitude, duration and count of floods that can be curtailed by landscape structure and its management. Our findings are relevant to other areas with similar climate, topography, and land use, and can help ensure that investments in flood management are made wisely after considering the limitations of landscape features to regulate floods. [ABSTRACT FROM AUTHOR]

Understanding the spatial pattern of species distributions is fundamental in biogeography, and conservation and resource management applications. Most species distribution models (SDMs) require or prefer species presence and absence data for adequate estimation of model parameters. However, observations with unreliable or unreported species absences dominate and limit the implementation of SDMs. Presence-only models generally yield less accurate predictions of species distribution, and make it difficult to incorporate spatial autocorrelation. The availability of large amounts of historical presence records for freshwater fishes of the United States provides an opportunity for deriving reliable absences from data reported as presence-only, when sampling was predominantly community-based. In this study, we used boosted regression trees (BRT), logistic regression, and MaxEnt models to assess the performance of a historical metacommunity database with inferred absences, for modeling fish distributions, investigating the effect of model choice and data properties thereby. With models of the distribution of 76 native, non-game fish species of varied traits and rarity attributes in four river basins across the United States, we show that model accuracy depends on data quality (e.g., sample size, location precision), species’ rarity, statistical modeling technique, and consideration of spatial autocorrelation. The cross-validation area under the receiver-operating-characteristic curve (AUC) tended to be high in the spatial presence-absence models at the highest level of resolution for species with large geographic ranges and small local populations. Prevalence affected training but not validation AUC. The key habitat predictors identified and the fish-habitat relationships evaluated through partial dependence plots corroborated most previous studies. The community-based SDM framework broadens our capability to model species distributions by innovatively removing the constraint of lack of species absence data, thus providing a robust prediction of distribution for stream fishes in other regions where historical data exist, and for other taxa (e.g., benthic macroinvertebrates, birds) usually observed by community-based sampling designs. [ABSTRACT FROM AUTHOR]

Despite the global importance of the Nile tilapia Oreochromis niloticus, especially to aquaculture, knowledge of genetic variability within native populations is still limited. While several studies have assessed genetic differentiation across the major drainage basins of Africa, relatively little effort has focused on characterizing genetic differentiation at finer scales. We assessed genetic variation in O. niloticus within and among nine drainage basins in Ghana using nuclear microsatellite DNA markers as the basis for identifying potential units of conservation among wild populations. We screened 312 wild individuals using eight nuclear microsatellite DNA markers. We found moderate genetic diversity within and differentiation among all wild populations studied, with strong signals of recent demographic bottlenecks in several populations. Genetic structure among 11 populations suggested the presence of up to ten management units (MUs). In particular, the Black Volta and the Tano–Asuhyea populations, which were the most genetically distinct and geographically isolated and may be most at risk of loss of genetic diversity over time, may well represent evolutionary significant units. Therefore, at the minimum, the Black Volta and Tano–Asuhyea populations should be prioritized for conservation actions to sustain them over the long-term. [ABSTRACT FROM AUTHOR]

Abstract: Rare stream fish species are important indicators in bioassessment and conservation. We examined the effect of sampling intensity on observed rarity and fish community assessment in backpack electrofishing samples by comparing one-backpack and two-backpack protocols, single-pass and multiple-pass protocols, and increasing sample reach length. Based on generalized linear mixed models, we found that increasing the number of backpack units, number of passes, and sample reach length led to an increased number of species labeled as rare, with stronger evidence favoring this conclusion when rarity was defined by proportional abundance criteria compared with numerical criteria. We found the least difference in the assessment of stream fish communities between the one-backpack and two-backpack protocols, but there was a significant difference in assessments among one-, two-, and three-pass electrofishing. At the watershed level, increasing the number of electrofishing passes led to increased similarity among sites and sometimes greater species richness estimates derived from three commonly-used species richness estimators. Additional electrofishing passes also increased the likelihood of detecting rare endemic species. A trade-off between information collected and necessary sampling resources should be carefully considered when sampling for rare species or to characterize community composition. [Copyright &y& Elsevier]

Conserving rare species and protecting biodiversity and ecosystem functioning depends on sound information on the nature of rarity. Rarity is multidimensional and has a variety of definitions, which presents the need for a quantitative classification scheme with which to categorize species as rare or common. We constructed such a classification for North American freshwater fishes to better describe rarity in fishes and provide researchers and managers with a tool to streamline conservation efforts. We used data on range extents, habitat specificities, and local population sizes of North American freshwater fishes and a variety of quantitative methods and statistical decision criteria, including quantile regression and a cost-function algorithm to determine thresholds for categorizing a species as rare or common. Species fell into eight groups that conform to an established framework for rarity. Fishes listed by the American Fisheries Society (AFS) as endangered, threatened, or vulnerable were most often rare because their local population sizes were low, ranges were small, and they had specific habitat needs, in that order, whereas unlisted species were most often considered common on the basis of these three factors. Species with large ranges generally had few specific habitat needs, whereas those with small ranges tended to have narrow habitat specificities. We identified 30 species not designated as imperiled by AFS that were rare along all dimensions of rarity and may warrant further study or protection, and we found three designated species that were common along all dimensions and may require a review of their imperilment status. Our approach could be applied to other taxa to aid conservation decisions and serve as a useful tool for future revisions of listings of fish species. [ABSTRACT FROM AUTHOR]

This paper presents the results of cost effectiveness (CE) analysis of vegetative filter strips (VFS) and instream half-logs as tools for recovering scores on a fish Index of Biotic Integrity (IBI) in the upper Wabash River watershed (UW) in Indiana. Three assumptions were made about recovery time for IBI scores (5, 15, and 30 years) and social discount rates (1, 3, and 5 percent), which were tested for sensitivity of the estimated CE ratios. Effectiveness of VFS was estimated using fish IBIs and riparian forest cover from 49 first-order to fifth-order stream reaches. Half-log structures had been installed for approximately two years in the UW prior to the study and provided a basis for estimates of cost and maintenance. Cost effectiveness ratios for VFS decreased from $387 to $277 per 100 m for a 1 percent increase in IBI scores from first- to fifth-order streams with 3 percent discount and 30-year recovery. This cost weighted by proportion of stream orders was $360. The ratio decreased with decreasing time of recovery and discount rate. Based on installation costs and an assumption of equal recovery rates, half-logs were two-thirds to one-half as cost-effective as VFS. Half-logs would be a cost-effective supplement to VFS in low order streams if they can be proven to recover IBI scores faster than VFS do. This study provides baseline data and a framework for planning and determining the cost of stream restoration. [ABSTRACT FROM AUTHOR]

The dimensions of riparian buffers selected for stream biota–landscape association models determine correlation strength and subsequent model interpretation. Efforts have been made to optimize buffer dimensions incorporated into models, but none has explicitly determined a single optimum based on both longitudinal and lateral buffer dimensions. We applied partial correlation and multivariate linear regression on functional fish community response attributes and the index of biotic integrity using stream samples (N = 107) from the Eastern Corn Belt Plain Ecoregion of Indiana, USA. Land-cover data in digital format were processed in geographic information systems for an area covering 300 m on either side of selected streams and within 2000 m longitudinally. The optimal buffer dimension for the study area was 30 m laterally and 600 m longitudinally, with a partial correlation of 0.29 (P = 0.002), and there was agreement in the partial correlation and multiple regression models. The longitudinal dimension was more conclusively determined, but the lateral dimension was optimum only with respect to the resolution of the land-use data used. Based on these results, we propose the use of this approach to optimize the riparian buffer parameter in landscape models. [ABSTRACT FROM AUTHOR]

Summary: The discrepancies in the effects of napping on sleep quality may be due to differences in methodologies, napping behaviours, and daytime activity levels across studies. We determined whether napping behaviours and daytime activity levels are associated with night‐time sleep fragmentation and sleep quality in young adults. A total of 62 healthy adults (mean [SD] age 23.5 [4.2] years) completed screening questionnaires for sleep habits, physical activity, medical and psychological history. Actigraphy was used to record sleep including naps. The fragmentation algorithm (KRA) was applied to the actigraphic data to measure night‐time sleep fragmentation. We classified participants' nap frequency as "non‐nappers" (0 naps/8 days), "moderate nappers" (1–2 naps/8 days) or "frequent nappers" (≥3 naps/8 days) naps. Nap duration was defined as "short" (≤60 min) or "long" (>60 min). Naps' proximity to the night sleep episode was defined as "early" (≥7 h) and "late" (<7 h) naps. Outcome variables were night‐time KRA and actigraphic sleep variables. Frequent nappers had a significantly higher KRA than moderate nappers (p < 0.01) and non‐nappers (p < 0.02). Late naps were associated with poorer measures of night sleep quality versus early naps (all p ≤ 0.02). Nap duration and daytime activity were not associated with significant differences in the outcome variables (all p > 0.05). KRA correlated with sleep duration, sleep efficiency, and awakenings (r = −0.32, −0.32, and 0.53, respectively; all p < 0.05). Frequent napping and late naps may be associated with increased sleep fragmentation and poorer sleep quality, reflected in longer sleep onsets and increased awakenings. These findings have implications for public health sleep hygiene recommendations. [ABSTRACT FROM AUTHOR]

The paper presents a framework to guide industrial trips in engineering training. The framework was developed through an assessment of various practices relating to industrial trips, gathered from institutional websites and published works on industrial trips, as well as the authors’ experience in leading students for industrial trips. A draft framework was first shared with some lecturers and students as well as electrical engineers working in Ghana’s power sector. Comments from them were incorporated in the draft framework to produce the final document. The finalized framework when adopted by institutions will greatly enhance the effectiveness of industrial trips which will lead to improved training of students. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Mapping the Changing Landscape of Fish-Related Journals: Setting a Course for Successful Communication of Scientific Information," by M. E. Mather et al. which appeared in a 2008 issue.

The need for improved aquaculture productivity has led to widespread pressure to introduce the Genetically Improved Farmed Tilapia (GIFT) strains of Nile tilapia (Oreochromis niloticus) into Africa. However, the physical and regulatory infrastructures for preventing the escape of farmed stocks into wild populations and ecosystems are generally lacking. This study characterized the genetic background of O. niloticus being farmed in Ghana and assessed the genetic effects of aquaculture on wild populations. We characterized O. niloticus collected in 2017 using mitochondrial and microsatellite DNA markers from 140 farmed individuals sampled from five major aquaculture facilities on the Volta Lake, and from 72 individuals sampled from the wild in the Lower Volta River downstream of the lake and the Black Volta tributary upstream of the lake. Our results revealed that two farms were culturing non-native O. niloticus stocks, which were distinct from the native Akosombo strain. The non-native tilapia stocks were identical to several GIFT strains, some of which showed introgression of mitochondrial DNA from non-native Oreochromis mossambicus. We also found that the non-native cultured tilapias have escaped into the wild and interbred with local populations, and also observed potentially admixed individuals on some farms. Our results highlight aquaculture as a vector in the spread of invasive non-native species and strains, and underscore the importance of genetic baseline studies to guide conservation planning for wild populations. [ABSTRACT FROM AUTHOR]

Aim: We developed a new technique, utilizing species‐specific counts of individuals from historical fish community samples, to examine landscape‐level, spatio‐temporal trends in relative abundance distributions. Abundance‐based historical distribution analyses are often plagued by data comparability issues, but provide critical information about community composition trends inaccessible to those using analyses based only on species presence–absence. We established trends in native and non‐native fish abundance and community homogenization, uniqueness and diversity to help local conservation managers prioritize targets and motivate similar studies globally to support fish conservation. Location: Upper and middle New River (UMNR) basin, Appalachian Mountains, USA. Methods: We compiled catch data from 61 years of fish community surveys (1958–2019) and tested for community homogenization by comparing data from repeatedly sampled sites (1900s versus 2000s samples) using dispersion analyses. We measured community uniqueness (site contributions to beta diversity) and species diversity (Shannon index) at sampled streams to identify potential conservation hotspots. We then used regression analyses and Wilcoxon signed‐rank tests to examine species‐specific basin‐wide and local abundance trends and identify species of potential conservation concern. Results: Dispersion of sites in species abundance space was significantly greater in the 1900s compared with the 2000s, indicating homogenization had occurred. Of 36 native species analysed, 44.4% (16) showed basin‐wide declines. Non‐native species exhibited mixed patterns; site‐level abundance increased in 2 of 15 species analysed (13%). Main conclusions: Our results indicate basin‐wide community homogenization has occurred within the UMNR, but many unique and diverse communities persist. If conserved, these could help maintain regional fish diversity. We found basin‐wide declines in four endemic species, as well as spread patterns of non‐native and native species that were not detected by a presence–absence analysis applied within the same study area. This finding illustrates the importance of considering both species' abundance and occurrence patterns as separate dimensions of biodiversity to inform conservation planning. [ABSTRACT FROM AUTHOR]

Prey species often congregate in groups to detect and evade predators, yet not all group members benefit equally. We observed the nesting aggregations of bluehead chub (Nocomis leptocephalus), where one nest "hosts" as many as several hundred "nest associates." We predicted that the male chub exploits the aggregation in a manner consistent with selfish‐herd theory – specifically, by locating itself in the safest location within the aggregation (the centre) and using the aggregation to reduce its own vigilance requirements.Vigilance was measured as the time it took the host (male) chub, first chub female and first individual of each associate species to return to the nest under differing associate abundances (hypothesised to be inversely related to risk) following a simulated predator scare. Spatial position was investigated by digitising host movement and overlaying it with the aggregation and nest's spawning pit area.We used information theoretic statistics to analyse the effect of aggregation characteristics on the return time of chub and their nest associates. The best‐supported model included both species composition and abundance (inverse of risk) as predictors of return time. Hosts returned last under nearly all scenarios and the aggregation as a whole took longest to return in high‐risk environments. The 95% and 99% confidence ellipses of host spatial position contained the centroids of the aggregation and spawning pits, respectively, for all nests analysed (n = 11).We conclude that the host locates itself at the centre of both the aggregation and the spawning pit area of the nest, and that the host uses the aggregation to reduce its own vigilance requirements. These results support our hypothesis that hosts use their nest associates to disproportionately decrease their risk of predation during spawning.This is the first study to show any mixed‐species fish spawning aggregation as a selfish shoal, and to identify bluehead chub as a selfish participant in the mutualistic reproductive interactions that they host. [ABSTRACT FROM AUTHOR]

Photoreceptor cells in the vertebrate retina have a highly compartmentalized morphology for efficient phototransduction and vision. Rhodopsin, the visual pigment in rod photoreceptors, is densely packaged into the rod outer segment sensory cilium and continuously renewed through essential synthesis and trafficking pathways housed in the rod inner segment. Despite the importance of this region for rod health and maintenance, the subcellular organization of rhodopsin and its trafficking regulators in the mammalian rod inner segment remain undefined. We used super-resolution fluorescence microscopy with optimized retinal immunolabeling techniques to perform a single molecule localization analysis of rhodopsin in the inner segments of mouse rods. We found that a significant fraction of rhodopsin molecules was localized at the plasma membrane, at the surface, in an even distribution along the entire length of the inner segment, where markers of transport vesicles also colocalized. Thus, our results collectively establish a model of rhodopsin trafficking through the inner segment plasma membrane as an essential subcellular pathway in mouse rod photoreceptors. Photoreceptor cells of the retina are maintained through a complex protein trafficking network. This study uses quantitative super-resolution microscopy to reveal the trafficking of the essential visual pigment rhodopsin in the inner segment region of rod photoreceptors. [ABSTRACT FROM AUTHOR]

Small-scale fisheries (SSF) account for much of the global fish catch, but data to assess them often do not exist, impeding assessments of their historical dynamics and status. Here, we propose an approach to assess 'data-less' SSF using local knowledge to produce data, life history theory to describe their historical multispecies dynamics, and length-based reference points to evaluate stock status. We demonstrate use of this approach in three data-less SSFs of the Congo Basin. Fishers' recalls of past fishing events indicated fish catch declined by 65–80% over the last half-century. Declines in and depletion of many historically important species reduced the diversity of exploited species, making the species composition of the catch more homogenous in recent years. Length-at-catch of 11 of the 12 most important species were below their respective lengths-at-maturity and optimal lengths (obtained from Fishbase) in recent years, indicating overfishing. The most overfished species were large-bodied and found in the Congo mainstem. These results show the approach can suitably assess data-less SSF. Fishers' knowledge produced data at a fraction of the cost and effort of collecting fisheries landings data. Historical and current data on fish catch, length-at-catch, and species diversity can inform management and restoration efforts to curb shifting baselines of these fisheries. Classification of stock status allows prioritizing management efforts. The approach is easy to apply and generates intuitive results, having potential to complement the toolkits of researchers and managers working in SSF and engage stakeholders in decision-making processes. [ABSTRACT FROM AUTHOR]

Post‐harvest management constraints are economically significant in Africa for a broad range of commodities, resulting in a substantial negative impact on food security and livelihoods. Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) coexists with Sitophilus oryzae (L.) (Coleoptera: Dryophthoridae) – they infest stored cereal grains, especially in sub‐Saharan Africa, and cause significant losses in storage. Laboratory studies were carried out to determine the efficacy of Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) and Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae), alone or in combination, in suppressing populations of R. dominica and S. oryzae in stored rice and wheat grains. The weight loss and moisture of the infested grains were assessed, for the various combinations of the two pest insects and the two natural enemies. In rice there was a synergistic effect of the combined release of T. elegans and X. flavipes against both R. dominica and S. oryzae compared to the effect of one natural enemy alone. With the combined release, only 2% F1 progeny of the pest beetles emerged compared to the untreated control (100%), whereas 3.5 and 6% emerged when X. flavipes and T. elegans, respectively, were released alone. When the two natural enemies were released in combination, 0.4% R. dominica F1 progeny emerged, compared to 1.6% with X. flavipes or T. elegans alone. In the combined release only 0.3% S. oryzae F1 progeny emerged, whereas 65% emerged with X. flavipes alone and 41% with T. elegans alone. No synergistic effect of the combined release of the two natural enemies was detected in wheat. In stored rice, the lowest percentage of weight loss (44%) was found when both natural enemies and both beetle species were present. We conclude that the combination of the predator and the parasitoid should be recommended when R. domininca and S. oryzae coexist and feed on stored cereals, especially rice. Rhyzopertha dominica and Sitophilus oryzae (Coleoptera: Bostrichidae, Dryophthoridae) infest stored cereal grains. Their natural enemies Xylocoris flavipes (Hemiptera: Anthocoridae) and Theocolax elegans (Hymenoptera: Pteromalidae), alone or in combination, suppressed beetle populations in stored rice and wheat grains in the laboratory. In rice a synergistic effect of the combined release of T. elegans and X. flavipes against both pest beetles was found, but no synergistic effect was detected in wheat. [ABSTRACT FROM AUTHOR]

Understanding the reproductive ecology of stream fishes is critical for their conservation. Nest association is a common reproductive interaction among minnows (Cyprinidae) in which individuals of 'associate' species spawn in nests of host species. Nest association behavior is nearly obligate for 'strong' associates, while it is facultative for other species. Facultative associates may begin spawning before host nesting begins and then visit host nests either to continue spawning or to feed. This is particularly evident for Central Stoneroller Campostoma anomalum, which frequently visits nests of host Bluehead Chub Nocomis leptocephalus but also spawns separately. We monitored the reproductive condition (gonadosomatic index, GSI) of minnows at longitudinally-positioned sites in a central Appalachian stream throughout the spring and summer of 2013. We also conducted daily visual nesting surveys to document chub spawning behavior and reproductive interactions that occurred on their nests. We used nonmetric multidimensional scaling (NMDS) to compare weekly GSI patterns of reproductive groups and hypothesized stoneroller GSI would be more similar to facultative associates than chubs. We also used piecewise regression to identify temporal thresholds in GSI (indicating the onset of spawning) in relation to the visually-confirmed onset of chub spawning. NMDS results suggest clear differences in reproductive condition between chubs/strong associates and stoneroller/weak associates. The onset of chub spawning was contained within the GSI thresholds estimate of strong associates but not of other groups. Stonerollers began spawning several weeks before chubs but were documented to be excavating pits on each nest. Paired together, the GSI and behavioral observations suggest stoneroller does not require chub nests for spawning and may exploit nests as a trophic resource if no eggs are contributed. Moreover, these results demonstrate the close reproductive link between some symbiotic species and their hosts that is required for successful reproduction. [ABSTRACT FROM AUTHOR]

Several nest-building North American minnows (Cyprinidae) function as reproductive hosts to nest associates–species that require nests of other species for spawning. Understanding the microhabitat preferences of hosts can yield insight into the reproductive ecology of many species, especially of nest associates that can utilize nests of two or more hosts. We observed nests of Central stonerollerCampostoma anomalumin which several associate species were actively spawning. Bluehead chubsNocomis leptocephalusbegan constructing nests two days later in the same stream, at which time associates abandoned stoneroller nests and continued on to spawn on chub nests. This presented a unique opportunity for accomplishing two objectives: (1) quantifying stoneroller nesting microhabitat preference and (2) comparing stoneroller and chub habitat preference to gain insight into the mechanisms that may drive host switching by nest associates. We measured substrate size, current velocity, water depth, and egg depth on seven paired stoneroller and chub nests, and compared these measurements to paired microhabitat measurements at a randomly selected point near each nest. Repeated measures analysis of variance withpost hocTukey tests revealed that stonerollers exhibited distinct nesting microhabitat preferences from chubs. Gravel on stoneroller nests was considerably smaller than on chub nests and stonerollers nested in shallower depths than chubs. However, both species nested at similar current velocities. If nest associates switch partners based on the physical characteristics of nests, then substrate size is likely the most important factor. The larger gravel sizes on chub nests likely provide better egg aeration than stoneroller nests. Chub nests may also be safer for associate broods because male Bluehead chubs cover eggs with gravel after spawning; stonerollers do not. Future work should take an experimental approach to elucidate these mechanisms. [ABSTRACT FROM AUTHOR]

Chubs of the genusNocomisbuild large pebble nests that may serve as an important microhabitat for macroinvertebrates and small vertebrates in streams of eastern North America. Macroinvertebrates that use chub nests have not been systematically documented. In this study, we examined the macroinvertebrate communities present inside bluehead chubNocomis leptocephalusnests in a small tributary creek of the New River in Virginia, USA. Individuals from 38 families of macroinvertebrates were recovered from nests. Snails from the family Pleuroceridae were the most numerous invertebrates in four nests examined, making up an average of 13.6 ± 7.53% of the macroinvertebrate community. This study revealed that communities in chub nests are diverse but not necessarily unique from the surrounding stream substrate. More long-term studies on macroinvertebrate communities of chub nests are needed to elucidate the function of nests as a stream microhabitat. [ABSTRACT FROM AUTHOR]

Flood regulation is a widely valued and studied service provided by watersheds. Flood regulation benefits people directly by decreasing the socio-economic costs of flooding and indirectly by its positive impacts on cultural (e.g., fishing) and provisioning (e.g., water supply) ecosystem services. Like other regulating ecosystem services (e.g., pollination, water purification), flood regulation is often enhanced or replaced by technology, but the relative efficacy of natural versus technological features in controlling floods has scarcely been examined. In an effort to assess flood regulation capacity for selected urban watersheds in the southeastern United States, we: (1) used long-term flood records to assess relative influence of technological and biophysical indicators on flood magnitude and duration, (2) compared the widely used runoff curve number (RCN) approach for assessing the biophysical capacity to regulate floods to an alternative approach that acknowledges land cover and soil properties separately, and (3) mapped technological and biophysical flood regulation capacities based on indicator importance-values derived for flood magnitude and duration. We found that watersheds with high biophysical (via the alternative approach) and technological capacities lengthened the duration and lowered the peak of floods. We found the RCN approach yielded results opposite that expected, possibly because it confounds soil and land cover processes, particularly in urban landscapes, while our alternative approach coherently separates these processes. Mapping biophysical (via the alternative approach) and technological capacities revealed great differences among watersheds. Our study improves on previous mapping of flood regulation by (1) incorporating technological capacity, (2) providing high spatial resolution (i.e., 10-m pixel) maps of watershed capacities, and (3) deriving importance-values for selected landscape indicators. By accounting for technology that enhances or replaces natural flood regulation, our approach enables watershed managers to make more informed choices in their flood-control investments. [ABSTRACT FROM AUTHOR]

Understanding the reproductive microhabitat requirements of keystone species such as the gravel mound nesting bluehead chubNocomis leptocephaluscan be useful for whole-community management.Nocomishave been shown to be microhabitat specialists, but no study has accounted for interannual variability in microhabitat use or for the possibility that substrate choices are constrained by mouth size. Our goals were to quantify the spawning microhabitat requirements of bluehead chub in the North Fork Roanoke River, Virginia, USA. Specifically, we sought to (1) account for gape limitation of nesting chubs when quantifying substrate size preference and (2) to examine interannual variability in their nesting microhabitat preferences. In June 2012 and 2013, we measured pebbles on chub nests and determined the gape limit as the largest measured pebble. With the gape limit as a ceiling for measurable particles, we compared substrate used by chubs to randomly selected particles adjacent to each nest. Depth and velocity were also measured at nests during both years and compared to random points near nests. Patterns in microhabitat selection differed between years. Chubs exhibited substrate size preference in 2012, but not 2013. The mean size difference in 2012 was approximately 3 mm but we do not consider this biologically meaningful. This stands in contrast with other studies showing large mean differences in preferred and available substrate. We suggest that the gape limitation of adult maleNocomisimposes a restriction on usable nesting substrate, causing observed significant differences between preferred and available substrate sizes. Current velocities used by chubs were significantly slower than paired measurements in 2013, but did not differ in 2012; depth preference did not differ between years. Differences in velocity preference likely represent adjustment to the above-average instream flow conditions of 2013. This study demonstrates the importance of examining interannual variability in fish spawning habitat requirements. [ABSTRACT FROM AUTHOR]

Little is known about how positive biotic interactions structure animal communities. Nest association is a common reproductive facilitation in which associate species spawn in nests constructed by host species. Nest-associative behaviour is nearly obligate for some species, but facultative for others; this can complicate interaction network topology., Nest web diagrams can be used to depict interactions in nesting-structured communities and generate predictions about those interactions, but have thus far only been applied to cavity-nesting vertebrate communities. Likewise, the stress-gradient hypothesis ( SGH) predicts that prevalent biotic interactions shift from competition to facilitation as abiotic and biotic stress increase; this model has been hardly applied to animal communities. Here, both of these models were applied to nest-associative fish communities and extended in novel ways to broaden their applicability., A nest web was constructed using spawning observations over 3 years in several streams in south-western Virginia, USA. Structural equation modelling ( SEM) was then implemented through an information-theoretic framework to identify the most plausible nest web topology in stream fish communities at 45 sites in the New River basin of the central Appalachian Mountains, USA. To test the SGH, the per-nest reproductive success of 'strong' (nearly obligate) nest associates was used to represent interaction importance. Eigenvectors were extracted from a principal coordinate analysis ( PCoA) of proportional species abundances to represent community structure. Both of these metrics were regressed on physical stress, a combination of catchment-scale agricultural land use and stream size (representing spatiotemporal habitat variability)., Seventy-one per cent of SEM model evidence supported a parsimonious interaction topology in which strong associates rely on a single host ( Nocomis), but not other species. PCoA identified a gradient of community structure dominated by Nocomis and associates, to communities dominated by other reproductive groups. Both metrics of interaction importance responded positively to physical stress., This study demonstrates that nest webs can be useful in a variety of systems and that SEM can be a quantitative extension of this framework. Likewise, the SGH can be used to understand positive interactions in animal communities and can be extended to predict proportional representation of facilitating and beneficiary species in communities. [ABSTRACT FROM AUTHOR]

Understanding the effects of hydrology on fish populations is essential to managing for native fish conservation. However, despite decades of research illustrating streamflow influences on fish habitat, reproduction, and survival, biologists remain challenged when tasked with predicting how fish populations will respond to changes in flow regimes. This uncertainty stems from insufficient understanding of the context‐dependent mechanisms underlying fish responses to, for example, periods of reduced flow or altered frequency of high‐flow events. We aim to address this gap by drawing on previous research to hypothesize mechanisms by which low and high flows influence fish populations and communities, identifying challenges that stem from data limitations and ecological complexity, and outlining research directions that can advance an empirical basis for prediction. Focusing flow ecology research on testing and refining mechanistic hypotheses can help narrow management uncertainties and better support species conservation in changing flow regimes. [ABSTRACT FROM AUTHOR]

The freshwater pearl mussel Margaritifera margaritifera has been suffering major population declines in Europe. This endangered species is a host specialist and exclusively requires salmonid species (Salmo trutta and Salmo salar) to complete its life cycle. In theory, obligatory biotic interactions should deserve special conservation attention, because the loss or massive decline of fish hosts may elicit the extirpation of their affiliated species. While many threats disturbing M. margaritifera are similarly affecting salmonids, climate change is particularly alarming, with the potential to significantly change the fish‐mussel dynamics.To evaluate the importance of including the occurrence of fish hosts for predicting the distribution of M. margaritifera in Europe, three datasets were used to build species distribution models (SDMs) with a maximum entropy (MaxEnt) approach: (1) environmental variables (ENV); (2) probability of fish hosts occurrence (FH); and (3) environmental variables and probability of fish hosts occurrence (ENV + FH). We identified the environmental variables that better explain M. margaritifera distribution and modelled its current and future distribution under a suite of climate change scenarios. Furthermore, projections were used to evaluate the adequacy of current networks of European protected areas in covering the suitable habitats for M. margaritifera.Results showed that incorporating data about fish hosts into M. margaritifera SDMs avoided the overprediction of geographical projections and, to a minor extent, improved model performance (area under the curve: ENV = 0.851; FH = 0.848; ENV + FH = 0.867). The distribution range of M. margaritifera in Europe is expected to contract in all future timeframes and emission scenarios considered. Forecasts point to large contractions particularly in central and southern Europe and lowland regions. The European network of protected areas fails to protect 69% of the current and 66%–67% of the future predicted M. margaritifera distribution.This study clearly illustrates the importance of including mussel–fish hosts interactions for accurately predicting M. margaritifera's distribution. The response of M. margaritifera to environmental variables highlights its vulnerability to the higher temperatures, particularly in southern Europe. While predictions indicate large contractions in M. margaritifera's distribution as a result of future climate change, the current European network of protected areas fails to safeguard M. margaritifera.This work provides strong evidence for proposing the generalised use of biotic information about hosts in addition to purely environmental variables to model the distribution of freshwater mussels, as well as for other species with obligatory biotic interactions. Building SDMs such as those discussed here can inform political decision‐making about the likely scenarios for species occurrence in future decades, the requirements needed for an effective conservation strategy, and the regions where conservation should be a priority. [ABSTRACT FROM AUTHOR]

Many warmwater streams in the midwestern United States have been negatively influenced by human land-use practices. From Jun. through Aug. 2002 and 2003, tributaries (n = 50) of the upper Wabash River basin, Indiana, were sampled to investigate ecosystem health and integrity. Stream fish and macroinvertebrates were sampled along with in-stream habitat according to National Water-Quality Assessment Program protocols to examine relationships among fish community structure, benthic macroinvertebrate assemblages, physical-habitat complexity and water chemistry under varying land-use practices. Stream fish abundance was best explained by in-stream habitat quality (QHEI), watershed area and the amount of forested hand use upstream of each sampling site. Overall index of biotic integrity (IBI) scores were low (mean = 35.58; range, 20 to 52), and varied predictably by riparian land-use type. The abundance of benthic macroinvertebrate taxa was best explained by the substrate QHEI metric (λ = 0.24; P = 0.005). Macroinvertebrate community index (ICI) scores showed more variability than IBI scores (mean = 20.40; range, 0 to 36). In-stream habitat quality (QHEI) was directly related to riparian land-use practices. Forested sites had higher QHEI scores than fallow field and agricultural sites due to increased habitat heterogeneity, large-woody debris loading and larger substrate sizes. The best model for predicting IBI scores incorporated both watershed and reach-scale variables combining slope and erosion power with maximum depth, percent canopy closure, percent line substrates. degree of channelization and LWDI (r² = 0.24; adir² = 0.19). Reach-scale variables (i.e., QHEI score, stream width, the proportion of unstable banks and percent fine substrates) best predicted ICI scores (r² = 0.69; adjr² = 0.66). Based on these results, we recommend that resource managers incorporate both biotic and abiotic factors at various temporal and spatial scales to predict the effects of land-use practices on community health in agriculturally dominated, warmwater streams. [ABSTRACT FROM AUTHOR]

Understanding the reproductive biology of the endangered Epioblasma capsaeformis of the eastern United States is critical to conservation efforts at mussel hatcheries. We studied how males influenced gravidity among females held in captivity. Percent males (0%, 33%, 50%, and 67%) within a holding system was used as the predictor variable. Our response variables were percent females observed gravid, number of eggs and glochidia per gravid female, total eggs (sum of eggs and glochidia) per gravid female, and proportion of total eggs successfully fertilized and developed into glochidia. Mean percent of females gravid in the male treatments were 73%, 85%, 69%, and 60%, respectively, with no evidence that treatments differed significantly from one another. However, the treatment without males had significantly lower mean number of total eggs observed (4,533 vs. 5,868 to 7,330), with fewer viable glochidia (1,354 vs. 5,645 to 6,920). Most of the eggs in the treatment without males were unfertilized at experiment completion (3,179 vs. 206 to 410), with a much lower percentage of transformed glochidia (27% vs. 94 to 97%). Our study documents the important role that males play in fertilizing females for production of glochidia and that key reproductive processes occurred in captivity. [ABSTRACT FROM AUTHOR]

Aquaculture development in Ghana is currently limited by inadequate supply of fingerlings and prohibitive cost of commercial feeds among other challenges. This study tested the feasibility of using low‐cost feeds containing soybean meal instead of fishmeal for nursing Nile tilapia (Oreochromis niloticus) fry. Three isonitrogenous (~48% crude protein) and isoenergetic (~17 kJ/g) diets with increasing inclusions of soybean meal as partial replacements for fishmeal were formulated. A commercial fishmeal‐based fry feed served as the control diet. Triplicate groups of 225 fish per tank (average initial weight: 2.09 ± 0.14 g) were stocked in a recirculating aquaculture system and fed the experimental diets for 21 days. Afterwards, we investigated the postprandial metabolism, nutrient digestibility, growth and gut histology in Nile tilapia fry. Simple economic analyses were also conducted to assess the cost‐effectiveness of the diets used in the feed trial. The dietary inclusions of the soybean meal significantly reduced feed cost by ~43% relative to the control diet. The growth performance and feed utilization parameters did not vary significantly among the different treatments. The soybean diets elicited significant reductions in villi heights and goblet cell numbers, which corresponded with increasing dietary levels of soybean meal. This study confirms the potential of soybean meal as a partial replacement for fishmeal in Nile tilapia fry diets in terms of lower feed costs, fish growth performance, nutrient digestibility and postprandial nitrogenous excretions. The inclusion of soybean, however, affected negatively the gut integrity of the fry. [ABSTRACT FROM AUTHOR]

Introduction: commercial motor vehicle drivers are at risk of metabolic syndrome (MetS) due to the nature of their work as they tend to go to work early, work for more hours, have irregular dietary habits and patterns, have little sleep and live sedentary lifestyle. The study sought to determine the prevalence and lifestyle-related risk factors of MetS among commercial taxi drivers around Kwame Nkrumah University of Science and Technology (KNUST) campus, in the Kumasi metropolis, Ghana. Methods: a cross-sectional survey was conducted among 100 commercial taxi drivers in 3 selected taxi ranks around KNUST campus. Fasting blood lipid and fasting blood glucose levels, blood pressure and anthropometric characteristics were determined using WHO and NCEP-ATP III criteria. Lifestyle-related risk factors of MetS were assessed using a semi-structured questionnaire and dietary pattern was assessed using food frequency questionnaire. Bivariate analysis and linear correlation were used to determine the relationship between lifestyle practices and MetS. Results: the prevalence of diabetes, high blood pressure, dyslipidemia, overweight and obesity were 12%, 63%, 40%, 32% and 13% respectively. The prevalence of MetS was 5% according to NCEP-ATP III (2005) criteria. The lifestyle behaviours of the drivers were, alcohol intake, irregular dietary pattern, long working hours, lack of exercise and tiredness due to driving. Tobacco use (R = 0.405, p = 0.041) and time of supper (R = 0.931, p = 0.047) were related with MetS among the participants. Conclusion: though prevalence of MetS (5%) was low among the drivers, the need for intervention to promote positive lifestyle change and curb the high prevalence of overweight/obesity, diabetes, high blood pressure and dyslipidemia is necessary to improve the health of the drivers and the safety of passengers. [ABSTRACT FROM AUTHOR]

Positive interspecific interactions such as mutualism, commensalism, and facilitation are globally ubiquitous. Although research on positive interactions in terrestrial and marine systems has progressed over the past few decades, comparatively little is known about them in freshwater ecosystems. However, recent advances have brought the study of positive interactions in freshwater systems to a point where synthesis is warranted.In this review, we catalogue the variety of direct positive interactions described to date in freshwater ecosystems, discuss factors that could influence prevalence and impact of these interactions, and provide a framework for future research.In positive interactions, organisms exchange key resources such as nutrients, protection, transportation, or habitat to a net benefit for at least one participant. A few mutualistic relationships have received research attention to date, namely seed‐dispersing fishes, crayfishes and their ectosymbiotic cleaners, and communal‐spawning stream fishes. Similarly, only a handful of commensalisms have been studied, primarily phoretic relationships. Facilitation via ecosystem engineering has received more attention, for example habitat modification by beavers and bioturbation by salmon.It is well known that interaction outcomes vary with abiotic and biotic context. However, only a few of studies have examined context dependency in positive interactions in freshwater systems. Likewise, positive interactions incur costs as well as benefits; conceptualising interactions in terms of net cost/benefit to participants will help to clarify complex interactions.It is likely that there are many positive interactions that have yet to be discovered in freshwater systems. To identify these interactions, we encourage inductive natural history studies combined with hypotheses deduced from general ecological models. Research on positive interactions must move beyond small‐scale experiments and observational studies and adopt a cross‐scale approach. Likewise, we must progress from reducing systems to oversimplified pairwise interactions, toward studying positive interactions in broader community contexts. Positive interactions have been greatly overlooked in applied freshwater ecology, but have great potential for conservation, restoration, and aquaculture. [ABSTRACT FROM AUTHOR]