New records of Spotted Bass, Micropterus punctulatus, within the Mississippi River Basin, Illinois

Spotted Bass Micropterus punctulatus, like many sport fishes, have experienced range expansion through intentional introductions (i.e., legal stocking and illegal transfers) and migration across the United States. In Illinois, USA, native populations of Spotted Bass occur along the eastern and southern border of the state. We report new records of Spotted Bass in their non-native range of the Illinois Waterway and the Illinois portion of the Upper Mississippi River in addition to collections in their native range in the Illinois sections of the Ohio and Wabash rivers to better understand their current distribution. Continuous, collaborative efforts to track the distribution and expansion of non-native fishes are important for maintaining and establishing native and non-native fisheries management objectives and education, as non-native fishes can influence native species population distribution and dynamics.

Ecosystem responses to aquatic invasive species management: A synthesis of two decades of bigheaded carp suppression in a large river

The invasion of silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) or "bigheaded carps" has caused extensive ecological and economic harm throughout the Mississippi River and its tributaries. To prevent their continued spread upstream toward the Great Lakes, intense commercial harvest was implemented on the Illinois River, a large tributary that connects the Mississippi River to Lake Michigan. Since implementation, harvest has reduced densities at the invasion front while also presenting an opportunity to generate a synthesis on ecosystem resilience in the face of accelerating invasion. Resilience, the ability of an ecosystem to recover after perturbation, was observed at local scales and within some taxa but has yet to manifest at a river-wide scale and often co-varied with abiotic environmental or seasonal factors. Thus, while intensive harvest has limited further spread of bigheaded carps, and evidence of additional secondary ecosystem benefits exists, opportunities remain to identify potential pathways that could spread such ecosystem benefits even farther.

Threats to Neglected Biodiversity: Conservation Success Requires More Than Charisma

Our planet is home to an incredible array of species; however, relatively few studies have compared how anthropogenic threats impact taxonomic groups over time. Our objective was to identify temporal trends in threats facing the four most speciose phyla protected by the United States Endangered Species Act: angiosperms, arthropods, chordates, and mollusks. We determined presence or absence of threats for each species in these phyla by reviewing Final Rule listing decisions. For each phylum, we evaluated whether there was a linear, quadratic, or pseudo-threshold association between year of listing and the presence of 24 anthropogenic threats. We identified temporal trends for 80% of the 96 threat-phylum combinations. We classified threats as topmost (probability of being included in a species' listing decision peaking at ≥ 0.81) and escalating (probability of being included in a listing decision increasing by ≥ 0.81 between a species' first and most recent years of listing). Angiosperms, arthropods, and mollusks each had more topmost and escalating threats than chordates. Percentages of topmost threats were 42.9% (N = 21) for mollusks, 36.4% (N = 22) for angiosperms, and 33.3% (N = 21) for arthropods. Percentages of escalating threats were 22.7% (N = 22) for angiosperms and 14.3% (N = 21) for arthropods and mollusks. In contrast, percentages of topmost and escalating threats were only 4.2% (N = 24) for chordates, this one threat being climate change. Our research suggests potential conservation successes; some overutilization and pollution threats showed only gradually increasing or declining trends for certain phyla. We identified authorized take impacting angiosperms as the sole threat-phylum combination for which the threat had been consistently decreasing since the phylum's first year of listing. Conversely, species interactions, environmental stochasticity, and demographic stochasticity threats have seen drastic increases across all phyla; we suggest conservation efforts focus on these areas of increasing concern. We also recommend that resources be allocated to phyla with numerous topmost and escalating threats, not just to chordates.

Why the Stall? Using metabolomics to define the lack of upstream movement of invasive bigheaded carp in the Illinois River

Bigheaded Carp have spread throughout the Mississippi River basin since the 1970s. Little has stopped the spread as carp have the ability to pass through locks and dams, and they are currently approaching the Great Lakes. However, the location of the leading edge in the Illinois River has stalled for over a decade, even though there is no barrier preventing further advancement towards the Great Lakes. Defining why carp are not moving towards the Great Lakes is important for predicting why they might advance in the future. The aim of this study was to test the hypothesis that anthropogenic contaminants in the Illinois River may be playing a role in preventing further upstream movement of Bigheaded Carp. Ninety three livers were collected from carp at several locations between May and October of 2018. Liver samples were analyzed using gas chromatography-mass spectrometry in a targeted metabolite profiling approach. Livers from carp at the leading edge had differences in energy use and metabolism, and suppression of protective mechanisms relative to downstream fish; differences were consistent across time. This body of work provides evidence that water quality is linked to carp movement in the Illinois River. As water quality in this region continues to improve, consideration of this impact on carp spread is essential to protect the Great Lakes.

How Surface Water Management Can Benefit Fish Conservation in Urban Streams

We analyzed 33 y of fish community data collected from a low-order, urban stream in central Illinois, USA, to determine the effects of municipal wastewater management projects and urbanization on fish communities. From 1985 to 2017, species richness, number of pollution-intolerant species, and alternative index of biotic integrity significantly increased at sites across this system. Species diversity likewise increased, but was mostly significant only at sites downstream of the effluent outflow. Ceasing the chlorination of wastewater in 1990 resulted in significant increases in fish community metrics both upstream and downstream of effluent outflow, although effects varied from site to site. Completing a combined sewer overflow abatement project in 2008 resulted in some significant increases in species richness, diversity, and number of pollution-intolerant species at sites downstream of effluent outflow. From 2001 to 2016, the change in the number of pollution-intolerant species correlated inversely with the increased percentage of impervious cover in the study system. There was no significant correlation of other metrics with the change in percent impervious surfaces. These results suggest that urbanization at upstream sites limited to some extent the benefits of water management interventions that improved fish community metrics at downstream sites.

Evaluating the potential role of bioactive chemicals on the distribution of invasive Asian carp upstream and downstream from river mile 278 in the Illinois waterway

Two non-native carp species have invaded the Illinois Waterway and are a threat to Great Lakes ecosystems. Poor water quality in the upper Illinois Waterway may be a factor contributing to the stalling of the carp population front near river mile 278. In 2015, the U.S. Geological Survey collected 4 sets of water samples from two sites upstream and 4 sites downstream from river mile 278, and one tributary. Each sample was analyzed for up to 649 unique constituents of which 287 were detected including 96 pesticides, 62 pharmaceuticals, 39 wastewater indicator chemicals, 29 metals, 19 volatile organic compounds (VOCs), 6 disinfection by-products (DBPs), 5 hormones, and 5 carboxylic acids. Potential for bioactivity was estimated by comparing chemical concentrations to aquatic life or human health criteria and to in-vitro bioactivity screening results in the U.S Environmental Protection Agency ToxCast™ database. The resulting hazard quotients and exposure-activity ratios (EARs) are toxicity indexes that can be used to rank potential bioactivity of individual chemicals and chemical mixtures. This analysis indicates that several bioactive chemicals (BCs) including: carbendazim, 2,4-D, metolachlor, terbuthylazine, and acetochlor (pesticides); 1,4-dioxane (VOC); metformin, diphenhydramine, sulfamethoxazole, tramadol, fexofenadine, and the anti-depressants (pharmaceuticals); bisphenol A, 4-nonylphenol, galaxolide, 4-tert-octylphenol (wastewater indicator chemical); lead and boron (metals); and estrone (hormone) all occur in the upper Illinois Waterway at concentrations that produce elevated EARs values and may be adversely affecting carp reproduction and health. The clear differences in water quality upstream and downstream from river mile 278 with higher contaminant concentrations and potential bioactivity upstream could represent a barrier to carp range expansion.

Assessment of Long-Term Trends in Fish Distributions at Multiple Scales Decreases Uncertainty Associated with Historical Datasets

Monitoring long-term changes in aquatic biodiversity requires the effective use of historical data that were collected with different methods and varying levels of effort. Aggregating data into different spatial scales can control for such differences and provide a robust framework for monitoring distribution trends. We used a quantitative, multi-scale assessment to evaluate the potential drivers of distribution change for 60 fish species at three spatial scales, using 503 unique sampling events conducted between 1931 and 2019 in a stream biodiversity hotspot (French Creek, Pennsylvania, U.S.A). Trends delineated at multiple scales demonstrated that only one cyprinid species consistently declined through time. In contrast, several species, particularly centrarchids (bass and sunfish), appeared to increase with time. However, evidence for species' increases varied among the different spatial scales, and our observations suggest that differences in effort and detection across time periods may contribute to patterns of species increases. There was agreement among scales that agricultural land use, non-native brown trout (Salmo trutta), and anthropogenic barriers did not explain patterns in biodiversity change from the distribution trends in this study. The lack of species declines is likely due to the limited levels of historical impacts in the watershed compared with other locations in the region that experienced more acute pollution bottlenecks. Species increases were most prevalent for sportfish and baitfish species, suggesting that distribution increases were human mediated. Similar multi-scale assessments should provide more robust insight into patterns of biodiversity loss and distribution changes by maximizing the use of historical data.

Long-term fish assemblages of the Ohio River: Altered trophic and life history strategies with hydrologic alterations and land use modifications

Long-term monitoring of species assemblages provides a unique opportunity to test hypotheses regarding environmentally induced directional trajectories of freshwater species assemblages. We used 57 years of lockchamber fish rotenone and boat electrofishing survey data (1957-2014) collected by the Ohio River Valley Water Sanitation Commission (ORSANCO) to test for directional trajectories in taxonomy, trophic classifications, and life history strategies of freshwater fish assemblages in the Ohio River Basin. We found significant changes in taxonomic and trophic composition of freshwater fishes in the Ohio River Basin. Annual species richness varied from 31 to 90 species and generally increased with year. Temporal trajectories were present for taxonomic and trophic assemblages. Assemblage structure based on taxonomy was correlated with land use change (decrease in agriculture and increase in forest). Taxonomic assemblage structure was also correlated with altered hydrology variables of increased minimum discharge, decreased fall rate, and increased rise rate. Trophic composition of fish catch correlated with land use change (decrease in agriculture and increase in forest) and altered hydrology. Altered hydrology of increased minimum discharge, increased fall discharge, decreased base flows, and increased number of high pulse events was correlated with increased counts of herbivore-detritivores and decreased counts of piscivores and planktivores. We did not find directional changes in life history composition. We hypothesized a shift occurred from benthic to phytoplankton production throughout the basin that may have decreased secondary production of benthic invertebrates. This may also be responsible for lower trophic position of invertivore and piscivore fishes observed in other studies.

Survey of Intersex (Testicular Oocytes) in Black Crappie Collected from the Illinois River Waterway

Researchers have documented intersex (testicular oocytes) in male fishes in many species worldwide and prevalence of the condition is strongly related to exposure to endocrine-disrupting compounds in aquatic ecosystems. There is no available knowledge about the incidence of intersex in Black Crappie Pomoxis nigromaculatus, an important North American sport fish. The objective of this survey was to investigate the prevalence and distribution of the intersex condition in Black Crappie collected from portions of the Illinois River waterway. We collected and examined 83 Black Crappie. We observed testicular oocytes in 22 individuals (27% intersex), representing the first documentation of intersex condition in wild Black Crappie. The number of oocytes that we observed in intersex Black Crappie ranged from 1 to 67. We documented intersex in individuals collected from all habitats, but there were no significant differences in the prevalence of the condition (Kruskal–Wallis P = 0.56) or the number of oocytes present (P = 0.25) in intersex males from the different habitats. Permutational multivariate analysis of variance indicated that morphometric parameters varied significantly among locations (P = 0.0001), but did not vary significantly between intersex and normal males. We have little information about the current distribution of endocrine-disrupting compounds in the specific regions where we collected Black Crappie for our study. However, we believe our study represents a valuable effort to detect the condition in an important sport fish and lays a foundation for future research.