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Invasive Silver Hypophthalmichthys molitrix and Bighead Carp H. nobilis (collectively bigheaded carp) regularly alter zooplankton communities in lentic systems but dynamics in lotic systems are less understood. Here, we investigated trends in zooplankton communities, densities, and biomass in pools 14–20 of the Upper Mississippi River (UMR) across a gradient of bigheaded carp presence and relative abundance during 2016–2018. We explored the effects of bigheaded carp presence on zooplankton communities using non-metric multidimensional scaling (NMDS) and assessed taxa-specific relationships with bigheaded carp relative abundance using ordinary least-squares regression with an indicator variable for bigheaded carp presence. Zooplankton communities in the UMR were dominated by rotifers and crustacean zooplankton densities were low, making up only 2% of the community density. Zooplankton communities differed where bigheaded carp were present. Density and biomass of cladocerans and copepods were both reduced where bigheaded carp were present but copepods increased with bigheaded carp relative abundance. Ostracod biomass increased in the presence of bigheaded carp whereas rotifers declined with bigheaded carp relative abundance. Low crustacean zooplankton densities in the UMR may limit larval/juvenile fish growth and recruitment regardless of bigheaded carp, but further declines in the crustacean community due to expanding bigheaded carp populations are concerning. [ABSTRACT FROM AUTHOR]

The mitochondrial DNA control region of six cobitids and two catostomids was sequenced and compared with sequences of other cypriniforms to study their sequence variations. The extended termination associated sequence (ETAS) domain, central domain, and conserved sequence block (CSB) domain were partitioned It is suggested that the hairpin TACAT-ATGTA is the key sequence of ETAS and GACATA is the symbol of CSB1. Phylogenetic analysis based on the CSB domain showed that all cyprinids evolved as one monophyletic group, while the non-cyprinid Cypriniformes could be another monophyly. Of the nearly 6000 species of ostariophysans, over 40% are cypriniforms, which are widely distributed through Africa, Asia, Europe, North American, and the islands of Sumatra, Java, Borneo, and the Philippines. Like that of other vertebrates, the control region of the Cypriniformes can also be partitioned into three domains and some similar conserved-sequence blocks can be found. Two main lineages are recognized in the Cyprinidae, the Barbinii and the Leuciscini, based on morphological characters. The analysis also showed closer relationships between the Cobitinae, Nemacheilinae and Homalopteridae, which is again different from the morphological results.

An exotic species, channel catfish Ictalurus punctatus, has been recorded in the ichthyofauna of the Republic of Kazakhstan for the first time. The specimens were caught in the Ili River upstream of the Kapchagai Reservoir in October 2020. Based on repeated findings of Nile tilapia Oreochromis niloticus and its hatchlings in the Borokhudzir River (a tributary of the Ili River), it has been concluded that a self-reproducing population of this species has appeared here. The possibility of naturalization of channel catfish in the Balkhash basin, which poses a threat to the remains of the native Ili ichthyofauna, is discussed. [ABSTRACT FROM AUTHOR]

Bichirs (Polypterus spp.) have frequently been studied with regard to comparative and developmental anatomy; however, very little information has been published regarding diseases, aging changes, and medical and surgical management in these species. Neoplasia represents one such example of conditions for which a dearth of information in these species exists. There has been increasing recognition of various types of neoplasms, including cutaneous tumors, particularly in ornamental fish; some of which may be related to environmental or to infectious causes. When excision of such tumors is indicated, surgical anaesthesia is required. However, special considerations may be warranted when employing immersion anaesthesia protocols in facultative air-breathing fish that can utilise the lungs for respiration. This anatomophysiological feature of Polypterus spp. may not only influence induction and maintenance of surgical anaesthesia but may theoretically have implications for drowning. Herein, we describe the management of a case of a rapidly growing gular neoplasm in a juvenile saddled bichir and considerations for surgical anaesthesia in this "lunged" species. Induction and maintenance of surgical anaesthesia using tricaine methanesulfonate (MS-222) in this species were found to be effective at significantly lower concentrations than standard recommended doses. Histopathological analysis identified the mass as a fibrosarcoma. To the best of our knowledge, this is the first report of a cutaneous fibrosarcoma in a bichir, representing the first report of neoplasia in Polypterus spp. and the first description of surgical anaesthesia in this amphibious fish. [ABSTRACT FROM AUTHOR]

Background: Due to the rapidly changing climatic conditions, South Korea faces the grand challenge of exotic species. With the increasing human movement, the influx of alien species to novel regions is prevalent across the globe. The latest research suggests that it is easy to prevent the introduction and establishment of alien species rather than controlling their spread and eradication. Like other countries, the Korean Ministry of Environment released a list (in 2018) of 45 potential risky exotic fish species considered likely to be invasive candidate fish species if they ever succeed in entering the Korean aquatic ecosystems. Results: The investigation into the invasion suitability traits showed that potential risky fish species could utilize those features in becoming invasive once they arrive in the Korean aquatic ecosystems. If the novel species establish viable populations, they are likely to incur higher economic costs, damage the native aquatic fauna and flora, and jeopardize the already perilled species. Furthermore, they can damage the installed infrastructure, decline overall abundance and biodiversity, and disturb the ecosystem services. Here we reviewed the list of fish species concerning their family, native origin, preferred aquatic biomes, main food items, current status in Korea, and potential threats to humans and the ecosystems. Data shows that most species are either already designated as invasive in the neighboring counties, including Japan, Vietnam, Thailand, and China, or originate from these countries. Such species have a higher climate match with the Korean territories. Conclusions: Therefore, it is exceptionally essential to study their most critical features and take regulatory measures to restrict their entry. The incoming fish species must be screened before letting them in the country in the future. The regulatory authorities must highlight the threatening traits of such species and strictly monitor their entrance. Detailed research is required to explore the other species, especially targeting the neighboring countries fish biodiversity, having demonstrated invasive features and matching the Korean climate. [ABSTRACT FROM AUTHOR]

Copyright of Parasite (1252607X) is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Most of the world's large river ecosystems are subject to multiple anthropogenic stressors including climate change, disconnection between the main river channel and floodplain, flow regulation, and land‐use modification. Viewed through a resilience lens, these ecosystems are potentially in a new regime, exhibiting a different structure, function, and set of feedbacks. We investigated the trophic status and food web character response to anthropogenic stressors over 150 years in the Illinois River. Differences in stable isotope ratios, community niche space, basal resource contribution to higher levels in the food web, mean trophic position of fish functional feeding guilds, and food chain length among four stressor phases suggest changes in ecosystem function in the Illinois River. Moreover, the river did not return to pre‐stressor conditions following watershed‐wide restoration efforts. Differences in trophic status and food web character also varied between the upper‐ and lower‐river zones of the Illinois River over time. This spatial divergence further highlights the complexity of responses to multiple stressors in this ecosystem. Overall, differences in trophic status and food web character suggest a shift to a new regime–an Anthropocene regime–and one that has a reduced capacity to absorb additional disturbances. Given human pressures are a global issue, our results based on a 150 years data set, could assist in the management of riverine landscapes that face regime shifts due to human stressors. Plain Language Summary: Resilience is the ability to absorb shocks and retain a normal functioning. This study indicates a loss of resilience in the aquatic ecosystem of the Illinois River, USA as a result of multiple stressors. A novel approach of using museum and recent specimens of mollusks and fish enabled the trophic status and food web character over a 150‐year period to be investigated, for the Illinois River, USA, a system heavily impacted by watershed development and urban pollution. Marked differences in stable isotope ratios, community niche space, basal resource contribution to higher levels in the food web, mean trophic position of fish functional feeding guilds, and food chain length were detected over time. Changes in trophic status and food web character occurred despite watershed scale restoration activities and general improvement in water quality. The sustained changes represent a flip to a new regime–an Anthropocene regime–and the loss of resilience of this river system. Key Points: Persistent change to the trophic status and food web character indicate the Illinois River, USA, to be in new a regimeChanges in the trophic status and food web character were irreversible despite significant water shed restoration effortsThis Anthropocene River has a reduced capacity to absorb additional disturbances and observed functional responses were spatially complex [ABSTRACT FROM AUTHOR]

Ecosystems worldwide have been impacted by multiple anthropogenic stressors, yet efforts to understand and manage these impacts have been hindered by difficulties in disentangling relative stressor effects. Theoretically, the actions of individual stressors can be delineated based on associated changes in functional traits and these relationships should be generalizable across communities comprised of different species. Thus, combining trait perspectives with community composition data could help to identify the relative influence of different stressors. We evaluated the utility of this combined approach by quantifying shifts in fish species and trait composition in Lake Erie during the past 50 years (1969–2018) in relation to human‐driven changes in nutrient inputs, climate warming, and biological invasions. Species and trait shifts were also compared between two Lake Erie basins, which differ in their environmental and biological characteristics, to identify trait responses that were generalizable across different ecosystems versus those that were context dependent. Our analyses revealed consistent species changes across basins, and shifts in feeding and thermal traits, that were primarily associated with altered nutrient inputs (oligotrophication followed by eutrophication). We found no or inconsistent trait‐based evidence for the effects of warming and two invasive fishes. Context‐dependent trait responses were also evident; nutrient inputs were related to shifts in species tolerant of turbidity in the shallow, eutrophic western basin, which contrasted to shifts between benthopelagic and benthic species in the deeper central basin. Our results reveal the dominant effects of specific stressors on a large freshwater lake and offer a framework for combining species‐based and trait‐based approaches to delineate the impacts of simultaneous stressors on communities of perturbed natural ecosystems. [ABSTRACT FROM AUTHOR]

The 125 km2 East Kolkata Wetlands (EKW) is not only the world’s largest wastewater fed aquaculture site but also a Ramsar recognized eco-diversity zone. The EKW, comprising of multiple water-bodies, interspersed with cultivable land and human settlements, came into existence in the early twentieth century from an interaction between the then newly established wastewater disposal system of the city of Kolkata and the large salt lakes that once existed in the region. The wastewater solids being let into the natural salt-water marshes transformed them into captive water-bodies by cutting them off from the tidal creeks joining the ocean. Local traders converted some of these shallow wetlands by around 1930-s into fish farming ponds fed by wastewater after appropriate treatment. Since then these water-bodies have not only provided livelihood opportunities to several marginalized groups, it has helped to meet a bulk of the city’s fish requirement. The area has also developed into a unique ecosystem sheltering a wide variety of flora which acts as a green lung to the city. For the past couple of decades, however, land encroachment for real estate has threatened the biodiversity of this region. Further, the younger generation of the farming community has largely shifted to other professions, leading to a decline in the wastewater-fed fish farming activities. The paper thus attempts to evaluate the benefits of the wetlands vis-à-vis concerns like the possible uptake of harmful elements by the fish population. The benefits, nevertheless, are seen to outweigh the disadvantages and the EKW appears to emerge as a model for a low-cost, ecologically sustainable bio-treatment plant of wastewater in an era when low-energy, low-impact developments are being vigorously promoted to counter global warming and climate change adversities. [ABSTRACT FROM AUTHOR]

Morphological and molecular evaluation of tapeworms of the order Caryophyllidea from suckers (Cypriniformes: Catostomidae) in North America made it possible to redescribe the insufficiently known and rare species Biacetabulum giganteum Hunter, 1929, based on specimens from the type host, small mouth buffalo, Ictiobus bubalus. This cestode is mainly typified by an elongate bottle-shaped body with a narrow, long neck region distinctly separating a relatively large scolex with deep loculi and a sharply widening body. Molecular phylogenetic analysis based on sequences of the large subunits of the nuclear ribosomal RNA genes (lsrDNA or 28S rDNA) placed B. giganteum in a clade called herein the B. giganteum-species complex, which also includes two morphologically similar new species. Biacetabulum magdae sp. nov. is described from the blacktail redhorse, Moxostoma poecilurum (type host), and the spotted sucker, Minytrema melanops, in Mississippi, USA. It differs from B. giganteum by the scolex with a weakly developed apical disc and shallow median and lateral loculi. Biacetabulum johni sp. nov. is described from Minytrema melanops (type host) in Florida and Moxostoma poecilurum in Mississippi, USA. Biacetabulum johni sp. nov. can be distinguished from B. magdae sp. nov. by a smaller size of the body (5–7 mm versus 10–12 mm) and a relatively longer neck, with the first vitelline follicles beginning at about the mid-length of the body in B. johni (versus at the first third or fourth of the body in B. magdae). With two new species described herein, Biacetabulum becomes the most species-rich genus of caryophyllidean tapeworms, with a total of 14 nominal species known to date (recently described B. hypentelii is synonymized with B. longicollum based on newly generated molecular data). Host specificity of species of Biacetabulum Hunter, 1927 was critically reviewed and it is shown that the actual host specificity is considerably higher than that reported in the literature. [ABSTRACT FROM AUTHOR]

Background: Some of the introduced alien species introduced settle, multiply, and spread to become invasive alien species (IAS) that threaten biodiversity. To prevent this, Korea and other countries legally designate and manage alien species that pose a risk to the environment. Moreover, 2160 alien species have been introduced in South Korea, of which 1826 animals and 334 plants are designated. The inflow of IAS can have negative effects such as ecosystem disturbance, habitat destruction, economic damage, and health damage to humans. To prevent damage caused by the inflow of IAS in advance, species that could potentially pose a risk to the environment if introduced in South Korea were designated as alert alien species (AAS). Results: The designation criteria were in accordance with the "Act on the Conservation and Use of Biological Diversity" and the "Regulations on the Ecological Risk Assessment of AAS and IAS" by the National Institute of Ecology. The analysis result of risk and damage cases indicated that mammals affect predation, competition, human economic activity, virus infection, and parasite infection. Birds have been demonstrated to affect predation, competition, human economic activity, and health. It was indicated that plants intrude on the ecosystem by competing with native species with their high-population density and capacity to multiply and cause allergic inducement. Interestingly, 300 species, including 25 mammals, 7 birds, 84 fishes, 28 amphibians, 22 reptiles, 1 insect, 32 spiders, 1 mollusk, 1 arthropod, and 99 plants, are included in the list of AAS. Conclusions: AAS designation plays a role in preventing the reduction of biodiversity by IAS in South Korea and preserving native species. Moreover, it is determined to provide considerable economic benefits by preventing socio-economic losses and ecological damage. [ABSTRACT FROM AUTHOR]

Background: Reproducing populations of invasive carps (Hypophthalmichthys spp.) could alter aquatic food webs and negatively affect native fishes in the Mississippi National River and Recreation Area (MISS) and the St. Croix National Scenic Riverway (SACN). However, proposed invasive carp barriers may also threaten populations of native migratory fishes by preventing movements of fish between rivers that are necessary for life history requirements. In this study, nonlethal chemical techniques were used to provide baseline data related to the condition, trophic position, and migratory histories of lake sturgeon (Acipenser fulvescens) captured in the Mississippi and St. Croix Rivers. Results: Fish length and weight measurements and age estimates determined from pectoral fin rays demonstrated that lake sturgeon from the Mississippi River had greater lengths-at-age compared to sturgeon from the St. Croix River. However, length–weight relations were similar for sturgeon from the Mississippi and St. Croix Rivers. Lake sturgeon captured from different locations had distinguishable fatty acid signatures, and stable isotope analyses demonstrated that lake sturgeon from the Mississippi River generally feed at a higher trophic level than those in the St. Croix River. Strontium-to-calcium ratios (Sr:Ca) from fin ray cross sections indicated that sturgeon captured from the Mississippi River had higher Sr:Ca values than sturgeon captured from the St. Croix River, and natal origins and capture locations were not significantly different among sturgeon captured within individual rivers. Most sturgeon were captured in water with a similar Sr:Ca signature as their natal waters, indicating that there is some separation between populations of lake sturgeon in the St. Croix and Mississippi Rivers. However, Sr:Ca data indicated substantial variation in movement patterns among individual lake sturgeon, indicating that populations interact through migrations of individual fish between rivers. Conclusions: Study results provide baseline condition and food web structure index data for assessing changes in lake sturgeon populations should invasive carps become established in these areas of the Mississippi and St. Croix Rivers. Controlled-exposure and telemetry studies would help verify and enhance the relations between Sr:Ca signatures in water and lake sturgeon pectoral fin rays to further assess mixing of sturgeons between rivers. [ABSTRACT FROM AUTHOR]

Uncontrolled biological invasions are reducing freshwater ecosystem diversity and resilience. Research is needed to evaluate whether non-structural deterrents are feasible within lock or canal environments. This study examined common carp (Cyprinus carpio) and buffalo hybrid (Ictiobus) movement patterns in response to acoustic and stroboscopic deterrents. Twelve strobe lights and one underwater speaker were deployed across the centre of a ship slip, with an environment analogous to a navigation canal. Common carp (n = 6) and Ictiobus (n = 4) were implanted with acoustic telemetry tags, and their behaviours were examined under control, stroboscopic, and acoustic stimuli for 60-min trial periods. Trials were run during the day and night for six straight days. Linear models determined that the stroboscopic and acoustic stimuli altered fish positioning within the ship slip, but produced weaker avoidance responses than those observed elsewhere. Weak responses were likely due to a strong preference for the open end of the ship slip and a lack of acoustic refuge during the acoustic treatment. Avoidance responses also differed widely among individuals of the same species, with fish expressing repeatability of avoidance radius size across trials. Ambient and stimulus sound-pressure levels should be carefully considered when deploying acoustic deterrents. Research is urgently needed to evaluate whether non-structural deterrents are feasible within lock or canal environments. Common carp and Ictiobus were tracked for 6 days and nights in a canal-like environment while exposed to an underwater speaker or strobe-lights. Avoidance responses were weak and varied widely among individual fish. Effective acoustic deterrents require acoustic refuge. [ABSTRACT FROM AUTHOR]

Silver carp (Hypophthalmichthys molitrix) dispersed to the Wabash River, Indiana in the mid-1990s. These fish compete with native, filter-feeding fish species in other central US rivers but relatively little information is available for impacts in the Wabash River. We collected fishes by boat electrofisher on the Wabash River as part of a long-term study. Abundances of six Wabash River species varied temporally, and three had stronger relationships with year than the other species: common carp (Cyprinus carpio) decreased before and after silver carp introduction, freshwater drum (Aplodinotus grunniens) increased prior to silver carp introduction, and gizzard shad (Dorosoma cepedianum) decreased before silver carp introduction. Silver carp abundance was significantly correlated only with abundance of gizzard shad. Nonmetric multidimensional scaling analysis of long-term Wabash River fish assemblages resulted in distinctive temporal and spatial patterns. Silver carp abundance increased from zero in the early 1990s to 28 individuals/km in recent years. Gizzard shad declined to low abundance simultaneous to silver carp increases, yet we did not detect significant patterns for silver carp with other Wabash River fishes. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Monozoic tapeworms (Caryophyllidea) are dominant components of parasite communities of suckers (Catostomidae) in North America, with Biacetabulum Hunter, 1927 representing one of the more species-rich genera. Molecular (28S rDNA) and morphological (including scanning electron microscopy and histology) evaluation of newly collected tapeworms from different fish hosts revealed the existence of four similar (and three closely related) species of Biacetabulum. These four species differ from their congeners by having a long body (up to 48 mm long) with a very long, slender neck (its length represents ≥30% of total body length), a large, globular scolex with a prominent central acetabulum-like loculus on the dorsal and ventral sides, two pairs of shallow lateral loculi and a distinct, slightly convex apical disc, and a cirrus-sac that is situated between the anterior arms of the ovarian wings. Taken together, the morphological and molecular data and the host associations of these species provide evidence of their host specificity. Biacetabulum isaureae n. sp. occurs in notch clip redhorse, Moxostoma collapsum, in South Carolina (USA), B. longicollum n. sp. in silver redhorse, Moxostoma anisurum (type host), and golden redhorse, M. erythrurum, in Manitoba (Canada) and West Virginia (USA), B. overstreeti n. sp. in a spotted sucker, Minytrema melanops, in Mississippi, and B. hypentelii n. sp. in northern hogsucker, Hypentelium nigricans, in Tennessee (USA). The new species differ from each other in the number of postovarian vitelline follicles, the posterior extent of preovarian vitelline follicles and relative size of the cirrus sac. [ABSTRACT FROM AUTHOR]

During 9–10 February 2018 and 21–22 February 2020, 7 adult Blue Suckers, Cycleptus elongatus, were collected by hoop nets from the Red River, Little River County (n = 3), and the Black River, Lawrence County (n = 4), Arkansas, and their gills, gallbladders, fins, integument, other major organs, and musculature were examined for myxozoans. All 7 (100%) were infected with an unknown species of gill-infecting Myxobolus sp. Twenty formalin-fixed plasmodia (cysts) of Myxobolus cloutmani n. sp. were elliptoidal, 407 µm long × 270 µm wide. Formalin-fixed myxospores were orbicular to broadly elliptoidal, 8.7 µm long × 7.8 µm wide. Two polar capsules were pyriform and subequal in size, extending over halfway in the myxospore. The larger polar capsule was 5.5 µm long × 3.1 µm wide, while the shorter was 5.1 × 2.9 µm. A coiled polar filament possessed 5 or 6 coils. The myxospore was 3.7 µm thick in sutural view, with a distinct sutural ridge. Qualitative and quantitative morphological data were from formalin-fixed as well as ethanol-preserved spores, while molecular data consisted of a 2,010 base pair sequence of the partial 18S ribosomal RNA gene and a 2,502 base pair sequence of the partial 28S ribosomal RNA gene. Phylogenetic analysis grouped M. cloutmani n. sp. with the other catostomid-infecting myxobolids. This is the first myxozoan reported from C. elongatus. [ABSTRACT FROM AUTHOR]

Many fish species of greatest conservation need (SGCN) in Iowa and Minnesota, USA, have been in decline for decades. A key reason for the decline is the alteration and degradation of naturally flowing streams owing to land use changes resulting from agricultural practices. Populations of several fishes have been adversely affected by widespread stream channelization that has resulted in more homogeneous stream habitats throughout Iowa and Minnesota.The goal of this study was to determine the abiotic and fish assemblage characteristics associated with the presence of these rare fishes. Electrofishing and seining were used to sample fish assemblages and 43 abiotic characteristics were measured at 111 sites in the North Raccoon and Boone River basins in central Iowa and the Rock River and Beaver Creek basins in north‐west Iowa and south‐west Minnesota during 2016 and 2017.Six SGCN, including the federally endangered Topeka shiner (Notropis topeka), were included in statistical modelling to determine habitat and fish assemblage characteristics associated with their presence.Species‐specific nonmetric multidimensional scaling ordinations indicated that abiotic characteristics and fish assemblages often differed between sites where SGCN were present and absent. Random forest and logistic regression models suggested that the presence of four of six SGCN were positively associated with species richness, whereas all other 10 important abiotic and fish assemblage variables were unique to only one or two of the six SGCN.Topeka shiners were present at 36% of sites and were positively associated with orangespotted sunfish (Lepomis humilis) catch per unit effort while being negatively associated with canopy cover and fantail darter (Etheostoma flabellare) catch per unit effort. [ABSTRACT FROM AUTHOR]

Understanding spatial variation in non‐native fish species population ecology is imperative, where environmental, biotic and invasion‐related mechanisms contribute to spatial heterogeneity. Established populations of invasive silver carp Hypophthalmichthys molitrix are currently found throughout a large portion of the upper Mississippi River (UMR) basin. Despite their recent invasion and broad environmental tolerances, silver carp population ecology and linkages to environmental conditions in the UMR remain understudied. There were two objectives for this investigation: (a) to estimate correlations among population characteristics and the influence of latitude and the time since first detection, and (b) to model the influence of river discharge and temperature on growth early in life to age 3. We estimated spatial variability in silver carp population characteristics and dynamics from nine sites across the UMR and assessed if biotic, abiotic or invasion‐related (time since first detection) variables influence spatial patterns. Silver carp body weight, size structure, annual mortality, and growth parameters varied among locations. Silver carp recruitment was less stable for populations with higher relative abundance estimates and where carp were first detected ≥20 years ago whereas maximum carp age decreased with increasing latitude. Although model selection indicated silver carp length at age 3 was associated with mean daily discharge (m3/s) coefficient of variation, mean May‐June temperatures, and ordinal date of maximum discharge, parameter coefficients and effect sizes were small and not biologically meaningful. Our results suggest that silver carp populations are governed by intraspecific mechanisms, but time‐dependent changes in populations may partially underpin heterogeneity across populations. Our study helped further disentangle silver carp population ecology in the UMR by understanding carp ecology as a function of their invasion. [ABSTRACT FROM AUTHOR]

Plankton communities have important roles in aquatic ecosystems, but studies of plankton in lotic systems are infrequent. We collected over 100 water, phytoplankton, and zooplankton samples during 2016–2018 to explore spatiotemporal trends in Minnesota River plankton communities and evaluate relationships with physico‐chemical factors. Phytoplankton and zooplankton community structure exhibited temporal patterns but only the zooplankton community differed spatially. Cyanobacteria (M ± SE; 11.27 ± 1.43 mm3/L) and diatoms (8.12 ± 1.08 mm3/L) dominated phytoplankton biovolume with seasonal peaks in Cyanobacteria occurring during July–September and peaks in diatoms occurring during May, August, and September. All phytoplankton taxa except Cryptophyta exhibited a negative relationship with relative discharge. Crustacean zooplankton biomass was greatest at two upstream sites (146.7 ± 32.6 μg/L) where cladocerans and copepods were likely exported from upstream of dams where water residence time is greater. Within the lower free‐flowing reach rotifers dominated the zooplankton community (207.9 ± 40.9 individuals/L and 6.5 ± 1.0 μg/L). Thus, spatial differences in zooplankton community structure were primarily attributed to the influence of dams. Seasonal patterns in zooplankton community structure included peaks in Chydoridae, cyclopoid, immature copepod, and rotifer biomass during May and Bosminidae biomass during October. Excluding the influence of dams on zooplankton, the cumulative effects of month and relative discharge were the most important for explaining variability in plankton community structure. Baseline understanding of plankton community dynamics provides the ability to quantify responses to future perturbations such as climate change and establishment of invasive planktivores. [ABSTRACT FROM AUTHOR]

As the number of non-native species introductions continues to increase, the need for tools to predict potential invaders is a central focus in invasion ecology. Trait-based models are a popular method used to predict non-native species success; however, they have many challenges to overcome and often fail to address the role of propagule pressure in failed invasions. Due to a lack of data, many studies cannot incorporate failed invasions into their models examining the success of invaders. Here, we analyzed the relationship between the functional traits of non-native species, both successful and failed, and native species in the Laurentian Great Lakes over three time periods between 1870 and 2010. We only examined failed invasions where there was an environmental match and sufficient propagule pressure for establishment as determined through records of authorized stocking, allowing us to directly test the contribution of traits to invasion success. We evaluated whether nearest neighbor functional distance (NNFD), mean functional distance (MFD), lake, time, and functional traits predicted invasion success and impact using logistic regression models. Our results indicate that species with functional traits associated with r-selected life-history strategies were more likely to establish and predators were more likely to have high impact. While smaller NNFD and MFD values predicted establishment success, higher MFD values predicted high impact. This study examined the role of functional traits in invasion success and demonstrated the importance that a change in community context contributes to regulating invasion success. [ABSTRACT FROM AUTHOR]

Asian carps continue to expand their range in North America, necessitating efforts to limit the spread and establishment of reproducing populations. Mississippi River Lock and Dam 19 is a high-head dam that represents a population 'pinch-point' as passage through the lock chamber is the only means by which fishes can complete upstream movement. As such, this location could be a pivotal control point for minimizing the spread of invasive fishes in the Upper Mississippi River and a possible candidate site for installation of deterrent measures. Our objectives were (1) to study the timing (i.e., weekly and diel) and behavior of fishes in the downstream lock approach, (2) evaluate the relation of presence in the downstream lock approach with environmental factors and lock operation, and (3) identify any upstream or downstream passage events through the lock chamber and the relation between these events and the operation of the lock. Acoustic transmitters were surgically implanted into 262 Asian carps and 216 native fishes to monitor fish activity on a telemetry receiver array deployed around and within the lock for 622 days during 2017–2018. One hundred eighty-six telemetered fish were detected in the downstream lock approach. We documented 14 upstream Asian carp passages and 10 upstream native fish passages; these passages coincided with a specific sequence of large vessel lockages. The results of this study advance our understanding of fish presence and behavior at a Mississippi River mainstem lock and dam and inform the development and testing of deterrent systems at this location or at similar pinch-point lock and dams. [ABSTRACT FROM AUTHOR]

Recent evidence shows that in lotic, physically‐dominated ecosystems like large rivers, zooplankton can develop spatially structured assemblages and fulfill functionally important roles. While refuting the long‐standing notion that riverine zooplankton communities are numerically depauperate and spatially homogeneous, this also shows that the importance of abiotic and biotic drivers and the consistency of ecological patterns are still poorly understood for these communities.We collected zooplankton along 300 km of the Illinois River for 5 years to test the influence of a suite of biotic and abiotic variables on zooplankton density, biomass, and diversity. We hypothesized abiotic variables such as temperature, turbidity, and velocity would be predominant predictors, with biotic variables like planktivory becoming important when physical factors do not constrain them.Results showed basin‐wide declines in zooplankton taxonomic richness as planktivory from the invading silver carp (Hypophthalmichthysmolitrix) increased. In contrast, density and biomass were explained by abiotic factors at the basin scale, with velocity, turbidity, and pH driving biomass and velocity driving density. We also found that both the driving factors and the plankton responses varied among the upper, middle, and lower sections of the Illinois River.We conclude that while zooplankton communities of the Illinois River are highly structured in space, the driving forces behind their distribution patterns are not simple. Instead, there is a complex spatio‐temporal template of biological, chemical, and hydraulic factors shaping these communities in the Illinois River. Along with emphasizing the importance of spatial heterogeneity in large river ecosystems, these results also support a growing view that invasive species interactions can supersede the well‐established role of abiotic factors in explaining global freshwater diversity losses. This also highlights the importance of including long‐term zooplankton sampling in ecological monitoring programs in diverse and productive large river systems like the Illinois. [ABSTRACT FROM AUTHOR]

In many applications, conservation organizations depend on one species to indicate the presence of another. While extensive research has gone into methods for selecting these indicator species, few studies have directly measured the performance of indicator species in guiding conservation actions. Here, we evaluated whether a small number of indicator species could be used to efficiently select barrier removal projects to restore breeding habitat access for many other Great Lakes migratory fishes in the highly fragmented tributaries of the North American Great Lakes. First, we used a dataset of the historical distributions of 35 species of native migratory fishes to identify four clusters of co-occurring species, and then selected an indicator species for each cluster based on within-group co-occurrence or range width. We evaluated the utility of these indicator species by using upstream habitat and removal costs for 103,894 dams and road culverts across 1800 tributaries of the Great Lakes. We compared the potential increase in accessible tributary habitat for each species when barrier removals were prioritized to maximize benefits for (1) each species itself, versus (2) possible indicator species. We found that for 80% of the species, habitat gains from indicator-based project selection were at least 75% of the maximum gains possible under species-specific planning. However, a small subset of species would receive few habitat gains under indicator-directed project selection. Overall, our findings suggest that a suite of indicator species could be an efficient basis for planning restoration efforts for a majority of native migratory fishes in the Great Lakes. [ABSTRACT FROM AUTHOR]

The data on the composition of fish fauna of the Tsimlyansk Reservoir, artificial propagation and operation of fish elevator of the Tsimlyansk hydro-engineering complex for period since 1950th until nowadays are presented. The information on the distribution of innumerous, non-commercial and alien fish species in the reservoir is given. Currently, 58 species including eight invaders, inhabit the reservoir. [ABSTRACT FROM AUTHOR]

We provide an updated review regarding the presence of alien vertebrates in Romania (i.e., fish, reptiles, birds, and mammals), taking into consideration both published data and a selection of international, regional and national public online databases. The literature review resulted in a preliminary checklist of 51 alien vertebrates in Romania, of which 41 were validated. The review of international and regional databases resulted in a preliminary checklist of 116 alien vertebrates, of which only 44 were validated after a quality check. The review of the national online databases resulted in a list of seven alien bird species in Romania, all of them valid. The final list contains 46 alien vertebrate species for Romania, of which 17 are established, and 29 are considered casual. Fish are the most abundant group (29 species) representing 63% of all vertebrate species, followed by mammals (eight species), birds (seven species), and reptiles (two species). [ABSTRACT FROM AUTHOR]

Prior to European settlement, swamps, marshes, lakes, and streams were the major landscape features of the Chicago region. Much of this has been altered or lost in the past one-hundred-and-fifty years. We examined the changes in aquatic environments and fauna in Cook County, Illinois, using 1890–1910 and 1997–2017 as our focus intervals. The extents of aquatic features from historical topographic maps were imported into a GIS database and compared with the modern USGS National Hydrography Dataset. Historical and modern spatial data on aquatic animals were collected from museum collection and survey reports. Overall, the total area of wetlands and water bodies has decreased by about a third, while swamps and marshes have been drained or converted into lakes and ponds. Fifty-four of 80 historic molluscan species are not recently recorded, and 26 current species are not recorded in the historical data, including 6 considered to be invasive. Of 54 fish species in the historic data, 23 are no longer present and about 50% of the remaining species have undergone range reductions. Three out of 10 species of reptiles have disappeared. All 25 aquatic birds reported from the 1890–1910 period are still extant and an additional 13 have been reported in recent times, possibly due to increased collection effort. The Chicago region provides a case study of the impact of anthropogenic landscape change on biota. Large scale extirpations of native species have corresponded to a shift to a highly fragmented landscape of small ponds and reduced swamps and marshes. [ABSTRACT FROM AUTHOR]

Population demographics are used by biologists and managers to determine the quality of a fishery and set regulations to achieve desired management goals. Regulating a large river system fishery that spans a substantial geographical region is often complicated by spatially variable environmental factors that affect fish population dynamics (e.g. habitat, water quality); these dynamics are rarely examined within an entire system. In this study we compared spatial differences in population age and length at capture, growth, fecundity and body condition of bluegill Lepomis macrochirus among two different river reaches (e.g. basin width, gradient, velocity) of the Illinois River (Illinois, USA) and a disconnected floodplain lake, the Emiquon Preserve. Variations in selected population demographics were evaluated in relation to well-documented habitat characteristics (e.g. water quality, aquatic vegetation, backwater availability). Differences in bluegill demographic traits between the disconnected floodplain lake and river reaches were distinct, and variations between river reaches were sex specific. The floodplain lake generally had older bluegill that expressed a higher maximum length at age and a lower growth rate and fecundity than bluegill in river reaches. River bluegill differed between river reaches in male growth, and fecundity in both sexes. Body condition was not significantly different among bluegill populations. Early research on floodplain lakes indicates that this habitat supports greater fish growth and higher reproductive fitness than mainstem habitat. We conclude that increasing the availability of quality backwater habitat, even within a highly modified large river system like the Illinois River, could substantially increase the quality and stability of bluegill populations. [ABSTRACT FROM AUTHOR]

The Missouri River in South Dakota was dammed in the 1950s and 1960s, altering the biotic and abiotic factors that potentially affect native species in the mainstem reservoirs. Little research has been conducted regarding what factors regulate age-0 catch per unit effort (CPUE) of native fish species since the damming occurred. Thus, we examined age-0 CPUE for 13 native fish species in the four Missouri River mainstem reservoirs. We analyzed data from 1995 to 2015 in Lake Oahe, 2002 to 2016 in Lake Sharpe, 1998 to 2008 in Lake Francis Case, and 2000 to 2013 in Lewis and Clark Lake. Not all species were sampled in all reservoirs. We evaluated potential environmental (inflow, gauge height, peak flow, precipitation, air temperature) and biological (CPUE of other native species, nonnative species, and predators) factors that have documented impacts on age-0 native fish. Significant relationships existed between age-0 native fish CPUE and both biotic and abiotic factors in all four reservoirs, but were species- and reservoir-dependent. Age-0 CPUE was either stable or increasing in all species examined in all reservoirs except age-0 Emerald Shiner Notropis atherinoides in Lewis and Clark Lake. Age-0 Emerald Shiner CPUE in Lewis and Clark Lake was most supported by biological models (e.g., total age-0 nonnative and adult White Bass Morone chrysops CPUE), and a positive relationship existed between age-0 Emerald Shiner and both factors. We believe our findings provide valuable insight into successful management of native fish populations. [ABSTRACT FROM AUTHOR]

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Understanding insect and fish interactions from a spatial and temporal perspective can have implications on large‐scale phenology in freshwater systems, yet current information is limited. We employed a novel approach of combining information from acoustic telemetry for six freshwater fish species and weather radar to assess the phenology of mayfly emergence and foraging patterns of freshwater fish. We hypothesized that freshwater fish conduct synchronous movements with annual mayfly hatches as a pulse resource opportunity. Generalized additive models were developed to assess movement distance as a function of species and time; before, during, and after annual mayfly hatch events. A cross‐section abundance index was also employed to quantify dynamics of aerial mayflies. Hatch dynamics revealed nocturnal emergence behaviour with annual variations in intensity, spatial extent, and origin. We found that the hatch was likely a pulse resource feeding opportunity for channel catfish, common carp, freshwater drum, and walleye instead of a synchronized feeding event. Bigmouth buffalo and lake sturgeon utilized riverine habitat away from the hatch and did not likely forage on the emerging mayflies. Remote sensing of fishes and emergent insects using our approach is the first attempt at bridging the capabilities of fisheries ecology and aeroecology to advance movement ecology. [ABSTRACT FROM AUTHOR]