SEARCH · USGS Science

Results for “Environments”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,567 records · Page 87Linked to original sources

USGS2023

Aging, climate, and invasions threaten reservoirs in the Mississippi basin

Reservoirs in the Mississippi River basin are facing three momentous threats. The first two, aging and climate change, are relatively slow moving and their signal can be hard to discern given their stretched temporal scales. The third, species invasions, is faster paced and discernable within shorter temporal scales and restricted spatial scales. Aging and climate directly affect reservoir environments and indirectly affect their biotic communities. Climate change is expected to interact with aging to speed up and, in some instances, slow down aging. Conversely, invasions primarily imperil biotic communities but can also impact environmental elements. This triple jeopardy is expected to transform reservoir environs and their biotic assemblages in various, often uncertain, ways. I take a broad view of these threats within the Mississippi River basin. A basin-scale perspective, in contrast to a single reservoir or regional scale, may enhance awareness of reservoirs at a larger level and produce understanding less evident at local levels, hence possibly offering a wider range of choices for confronting threats. My aim is to (1) provide a synopsis of the assemblage of reservoirs and their attributes over the Mississippi River basin, (2) describe the issues related to aging, climate change, and invasions, and (3) consider a conservation framework for confronting these pressures. Given the overlapping temporal, spatial, and ecological effects of these threats, it is essential to address their effects simultaneously.

Mississippi River basin↗

USGS2007

Geoarchaeology of stratified paleoindian deposits at the Big Eddy site, Southwest Missouri, U.S.A

The Big Eddy site (23CE426) in the Sac River valley of southwest Missouri is a rare recorded example of distinctly stratified Early through Late Paleoindian cultural deposits. Early point types recovered from the site include Gainey, Sedgwick, Dalton (fluted and unfluted), San Patrice, Wilson, and Packard. The Paleoindian record at Big Eddy represents only a fraction of the site's prehistoric cultural record; stratified cultural deposits in alluvium above the Paleoindian components span the entire known prehistoric sequence, and terminal Pleistocene alluvium may contain pre-Early Paleoindian cultural deposits. This study focused on the paleogeomorphic setting, stratigraphy, depositional environments, pedology, geochronology, and history of landscape evolution of the late Pleistocene and early Holocene alluvium at the site. The Paleoindian sequence is associated with a complex buried soil 2.85 m below the modern surface (T1a) of the first terrace of the Sac River valley in the site vicinity. This soil formed at the top of the early submember of the Rodgers Shelter Member (underlying the T1c paleogeomorphic surface) and contains at least 70 cm of stratified Paleoindian cultural deposits, all in floodplain and upper point-bar facies. A suite of 36 radiocarbon ages indicates that the alluvium hosting the Paleoindian sequence aggraded between ca. 13,250 and 11,870 cal yr B.P. (11,380 and 10,180 14C yr B.P.). Underlying deposits accumulated between ca. 15,300 and 13,250 cal yr B.P. (12,950 and 11,380 14C yr B.P.). By ca. 11,250 cal yr B.P. (9,840 14C yr B.P.) the T1c paleogeomorphic surface was buried by the earliest increment of a thick sequence of overbank sheetflood facies, ultimately resulting in deep burial and preservation of the Paleoindian record. The landform-sediment assemblage that hosts the Paleoindian and possibly earlier cultural deposits at Big Eddy is both widespread and well preserved in the lower Sac River valley. Moreover, the terminal Pleistocene and early Holocene depositional environments were favorable for the preservation of the archaeological record. ?? 2007 Wiley Periodicals, Inc.

Geoarchaeology↗

USGS2017

Heat as a groundwater tracer in shallow and deep heterogeneous media: Analytical solution, spreadsheet tool, and field applications

Groundwater flow advects heat, and thus, the deviation of subsurface temperatures from an expected conduction‐dominated regime can be analysed to estimate vertical water fluxes. A number of analytical approaches have been proposed for using heat as a groundwater tracer, and these have typically assumed a homogeneous medium. However, heterogeneous thermal properties are ubiquitous in subsurface environments, both at the scale of geologic strata and at finer scales in streambeds. Herein, we apply the analytical solution of Shan and Bodvarsson (2004), developed for estimating vertical water fluxes in layered systems, in 2 new environments distinct from previous vadose zone applications. The utility of the solution for studying groundwater‐surface water exchange is demonstrated using temperature data collected from an upwelling streambed with sediment layers, and a simple sensitivity analysis using these data indicates the solution is relatively robust. Also, a deeper temperature profile recorded in a borehole in South Australia is analysed to estimate deeper water fluxes. The analytical solution is able to match observed thermal gradients, including the change in slope at sediment interfaces. Results indicate that not accounting for layering can yield errors in the magnitude and even direction of the inferred Darcy fluxes. A simple automated spreadsheet tool (Flux‐LM) is presented to allow users to input temperature and layer data and solve the inverse problem to estimate groundwater flux rates from shallow (e.g., <1 m) or deep (e.g., up to 100 m) profiles. The solution is not transient, and thus, it should be cautiously applied where diel signals propagate or in deeper zones where multi‐decadal surface signals have disturbed subsurface thermal regimes.

Hydrological Processes↗

USGS2001

Pesticides in the hydrologic system - What do we know and what's next?

Even though the occurrence and behaviour of pesticides in the environment have been studied for decades, water-quality managers and the public still demand more complete and consistent information, and there are many unanswered questions for environmental scientists. In many respects, the greatest potential for unintended adverse effects of pesticides is through contamination of the hydrologic system, which supports aquatic life and related food chains and is used for recreation, drinking water, and many other purposes. The movement of water is one of the primary mechanisms by which pesticides are transported from targeted application areas to other parts of the environment; thus, there is potential for movement into and through all components of the hydrologic system. Extensive reviews of existing information on pesticides in the hydrologic system, including the atmosphere (Majewski and Capel, 1995), ground water (Barbash and Resek, 1996), surface water (Larson et al., 1997), and fluvial sediments and aquatic biota (Nowell et al., 1999), uncovered volumes of useful information, but also noted critical information gaps. For example: (a) relatively few pesticides have been thoroughly studied, particularly transformation products; (b) most data have been collected for small-scale site and field studies in agricultural areas; (c) urban areas have received little attention for monitoring or research; (d) the geographic and temporal distributions of data collection have been highly uneven; and (e) comparing and synthesizing results from most studies is difficult because of inconsistent approaches to data collection and chemical analysis.

Hydrological Processes↗

USGS2022

Integrative monitoring strategy for marine and freshwater harmful algal blooms and toxins across the freshwater-to-marine continuum

Many coastal states throughout the USA have observed negative effects in marine and estuarine environments caused by cyanotoxins produced in inland waterbodies that were transported downstream or produced in the estuaries. Estuaries and other downstream receiving waters now face the dual risk of impacts from harmful algal blooms (HABs) that occur in the coastal ocean as well as those originating in inland watersheds. Despite this risk, most HAB monitoring efforts do not account for hydrological connections in their monitoring strategies and designs. Monitoring efforts in California have revealed the persistent detection of cyanotoxins across the freshwater-to-marine continuum. These studies underscore the importance of inland waters as conduits for the transfer of cyanotoxins to the marine environment and highlight the importance of approaches that can monitor across hydrologically connected waterbodies. A HAB monitoring strategy is presented for the freshwater-to-marine continuum to inform HAB management and mitigation efforts and address the physical and hydrologic challenges encountered when monitoring in these systems. Three main recommendations are presented based on published studies, new datasets, and existing monitoring programs. First, HAB monitoring would benefit from coordinated and cohesive efforts across hydrologically interconnected waterbodies and across organizational and political boundaries and jurisdictions. Second, a combination of sampling modalities would provide the most effective monitoring for HAB toxin dynamics and transport across hydrologically connected waterbodies, from headwater sources to downstream receiving waterbodies. Third, routine monitoring is needed for toxin mixtures at the land–sea interface including algal toxins of marine origins as well as cyanotoxins that are sourced from inland freshwater or produced in estuaries. Case studies from California are presented to illustrate the implementation of these recommendations, but these recommendations can also be applied to inland states or regions where the downstream receiving waterbody is a freshwater lake, reservoir, or river.

California, Oregon↗

USGS2022

A framework for prioritizing contaminants in retrospective ecological assessments: Application in the Milwaukee Estuary (Milwaukee, WI)

Watersheds are subjected to diverse anthropogenic inputs, exposing aquatic biota to a wide range of chemicals. Detection of multiple, different chemicals can challenge natural resource managers who often have to determine where to allocate potentially limited resources. Here, we describe a weight-of-evidence framework for retrospectively prioritizing aquatic contaminants. To demonstrate framework utility, we used data from 96-h caged fish studies to prioritize chemicals detected in the Milwaukee Estuary (WI, USA; 2017–2018). Across study years, 77/178 targeted chemicals were detected. Chemicals were assigned prioritization scores based on spatial and temporal detection frequency, environmental distribution, environmental fate, ecotoxicological potential, and effect prediction. Chemicals were sorted into priority bins based on the intersection of prioritization score and data availability. Data-limited chemicals represented those that did not have sufficient data to adequately evaluate ecotoxicological potential or environmental fate. Seven compounds (fluoranthene, benzo[ a ]pyrene, pyrene, atrazine, metolachlor, phenanthrene, and DEET) were identified as high or medium priority and data sufficient and flagged as candidates for further effects-based monitoring studies. Twenty-one compounds were identified as high or medium priority and data limited and flagged as candidates for further ecotoxicological research. Fifteen chemicals were flagged as the lowest priority in the watershed. One of these chemicals (2-methylnaphthalene) displayed no data limitations and was flagged as a definitively low-priority chemical. The remaining chemicals displayed some data limitations and were considered lower-priority compounds (contingent on further ecotoxicological and environmental fate assessments). The remaining 34 compounds were flagged as low or medium priority. Altogether, this prioritization provided a screening-level (non-definitive) assessment that could be used to focus further resource management and risk assessment activities in the Milwaukee Estuary. Furthermore, by providing detailed methodology and a practical example with real experimental data, we demonstrated that the proposed framework represents a transparent and adaptable approach for prioritizing contaminants in freshwater environments. Integr Environ Assess Manag 2023;00:1–21. © 2022 SETAC

Wisconsin↗

USGS2023

Considering pollinators' ecosystem services in the remediation and restoration of contaminated lands: Overview of research and its gaps

The concept of ecosystem services provides a useful framework for understanding how people are affected by changes to the natural environment, such as when a contaminant is introduced (e.g., oil spills, hazardous substance releases) or, conversely, when contaminated lands are remediated and restored. Pollination is one example of an important ecosystem service; pollinators play a critical role in any functioning terrestrial ecosystem. Other studies have suggested that consideration of pollinators' ecosystem services could lead to better remediation and restoration outcomes. However, the associated relationships can be complex, and evaluation requires synthesis from numerous disciplines. In this article, we discuss the possibilities for considering pollinators and their ecosystem services when planning remediation and restoration of contaminated lands. To inform the discussion, we introduce a general conceptual model of how pollinators and the ecosystem services associated with them could be affected by contamination in the environment. We review the literature on the conceptual model components, including contaminant effects on pollinators and the direct and indirect ecosystem services provided by pollinators, and identify information gaps. Though increased public interest in pollinators likely reflects increasing recognition of their role in providing many important ecosystem services, our review indicates that many gaps in understanding—about relevant natural and social systems—currently impede the rigorous quantification and evaluation of pollinators' ecosystem services required for many applications, such as in the context of natural resource damage assessment. Notable gaps include information on non-honeybee pollinators and on ecosystem services beyond those benefitting the agricultural sector. We then discuss potential research priorities and implications for practitioners. Focused research attention on the areas highlighted in this review holds promise for increasing the possibilities for considering pollinators' ecosystem services in the remediation and restoration of contaminated lands.

Integrated Environmental Assessment and Management↗

USGS2026

Detecting snow avalanche activity using infrasound: Hooker Valley, New Zealand

Snow avalanches pose considerable hazards to people and infrastructure in alpine environments. Traditional avalanche monitoring relies on meteorological data and visual observations, which can be limited in scope and timeliness. Infrasound offers a promising complementary monitoring tool by detecting the low-frequency sound waves generated by avalanches. Here, we present infrasound and camera observations during a 50-day field campaign in the Hooker Valley of Aoraki/Mount Cook National Park, New Zealand. Our study detected seven avalanches with the cameras, whereas the infrasound system identified only one of these events, which was the largest and occurred under conditions that likely favoured infrasound propagation. The infrasound system recorded numerous other events not captured by the cameras, indicating the benefit of further investigation to determine their sources. These findings highlight the potential of infrasound technology for detecting avalanches and providing broad spatial coverage, capturing events in areas not monitored by cameras, while also showcasing limitations in infrasound capabilities. The limited detection of smaller avalanches underscores the opportunity for further research to enhance detection capabilities and understand environmental influences such as snow cover and wind noise. Overall, this study emphasises the utility of multidisciplinary monitoring techniques to improve avalanche detection in alpine environments.

Hooker Valley↗

USGS2017

Quantifying changes and influences on mottled duck density in Texas

Understanding the relative influence of environmental and intrinsic effects on populations is important for managing and conserving harvested species, especially those species inhabiting changing environments. Additionally, climate change can increase the uncertainty associated with management of species in these changing environments, making understanding factors affecting their populations even more important. Coastal ecosystems are particularly threatened by climate change; the combined effects of increasing severe weather events, sea level rise, and drought will likely have non-linear effects on coastal marsh wildlife species and their associated habitats. A species of conservation concern that persists in these coastal areas is the mottled duck ( Anas fulvigula ). Mottled ducks in the western Gulf Coast are approximately 50% below target abundance numbers established by the Gulf Coast Joint Venture for Texas and Louisiana, USA. Although evidence for declines in mottled duck abundance is apparent, specific causes of the decrease remain unknown. Our goals were to determine where the largest declines in mottled duck population were occurring along the system of Texas Gulf Coast National Wildlife Refuges and quantify the relative contribution of environmental and intrinsic effects on changes to relative population density. We modeled aerial survey data of mottled duck density along the Texas Gulf Coast from 1986–2015 to quantify effects of extreme weather events on an index to mottled duck density using the United States Climate Extremes Index and Palmer Drought Severity Index. Our results indicate that decreases in abundance are best described by an increase in days with extreme 1-day precipitation from June to November (hurricane season) and an increase in drought severity. Better understanding those portions of the life cycle affected by environmental conditions, and how to manage mottled duck habitat in conjunction with these events will likely be key to persistence of the species under future environmental conditions.

Texas↗

USGS2013

Population ecology of polar bears in Davis Strait, Canada and Greenland

Until recently, the sea ice habitat of polar bears was understood to be variable, but environmental variability was considered to be cyclic or random, rather than progressive. Harvested populations were believed to be at levels where density effects were considered not significant. However, because we now understand that polar bear demography can also be influenced by progressive change in the environment, and some populations have increased to greater densities than historically lower numbers, a broader suite of factors should be considered in demographic studies and management. We analyzed 35 years of capture and harvest data from the polar bear ( Ursus maritimus ) subpopulation in Davis Strait, including data from a new study (2005–2007), to quantify its current demography. We estimated the population size in 2007 to be 2,158 ± 180 (SE), a likely increase from the 1970s. We detected variation in survival, reproductive rates, and age-structure of polar bears from geographic sub-regions. Survival and reproduction of bears in southern Davis Strait was greater than in the north and tied to a concurrent dramatic increase in breeding harp seals ( Pagophilus groenlandicus ) in Labrador. The most supported survival models contained geographic and temporal variables. Harp seal abundance was significantly related to polar bear survival. Our estimates of declining harvest recovery rate, and increasing total survival, suggest that the rate of harvest declined over time. Low recruitment rates, average adult survival rates, and high population density, in an environment of high prey density, but deteriorating and variable ice conditions, currently characterize the Davis Strait polar bears. Low reproductive rates may reflect negative effects of greater densities or worsening ice conditions.

Davis Strait↗

USGS2026

Aquatic reflectance derived from Sentinel-2 Multispectral Imager data for inland waters in the conterminous United States

Satellite-based earth observation is a robust tool for tracking change in ecosystems. While terrestrially focused applications of remote sensing have empowered wide adoption for research and management, remote sensing of inland aquatic ecosystems remains comparably nascent. This divergence, in part, stems from the lack of standardized, accessible, and near real-time remotely sensed surface reflectance, atmospherically corrected for aquatic environments. To date, surface reflectance products at national scales and with minimal latency are typically designed exclusively for terrestrial environments. Rectifying this situation can be accomplished by applying aquatic-focused atmospheric correction algorithms independent of those used for terrestrial ecosystems. As a first step to filling this data gap, we present the first national scale, dynamically updated, analysis-ready, aquatic reflectance dataset for inland water derived from Sentinel-2 for the conterminous United States.

conterminous United States↗

USGS2025

Spatial mapping of dissolved methane using an in situ sensor in Puget Sound

Release of methane, as gas bubbles or in the dissolved phase, from the seafloor has been observed in coastal waters (< 200 m) and deep ocean basins (> 1000 m). Methane dissolution within the water column affects the geochemistry of the surrounding water, leading to localized oxygen loss and potential escape to the atmosphere, particularly from shallower sites. Traditional methods for detecting and quantifying dissolved methane rely on collecting discrete water samples for ship- or land-based ex situ analysis and post processing. Here, we report on the use of a reduced response time, in situ methane sensor, the Sensor for Aqueous Gases in the Environment (SAGE), for detecting and quantifying dissolved methane concentrations in a wide range of seafloor environments. During a Fall 2022 research cruise on the R/V Thomas G. Thompson in Puget Sound, SAGE was integrated onto a towed conductivity/temperature/depth rosette and deep-sea camera system with live-stream 1 Hz telemetry and used to spatially map the concentration of methane approximately 1 m above the seafloor. The site had been previously identified as an active methane plume field characterized by gas bubbles, fluid venting, and a faulted seabed. The widespread background dissolved concentration of methane measured by SAGE was 83 nM, and a range of 78–670 nM was observed throughout the survey. The results highlight the capacity of SAGE to map the spatial and temporal variability of dissolved methane concentrations in situ and to identify and localize sites of variable methane emissions from the seafloor.

Washington↗

USGS2020

Effects of temperature on hatching rate and early development of alligator gar and spotted gar in a laboratory setting

Water temperature influences both morphological and physiological development in fishes. However, the effects of water temperature on the early development of Alligator Gar Atractosteus spatula and Spotted Gar Lepisosteus oculatus are not well understood. Both gar species were collected from natural environments and spawned in a hatchery setting. After spawning, fertilized embryos were collected and transferred to the Oklahoma Fishery Research Laboratory, where the embryos (50–72 embryos/treatment) were placed into one of five water temperature treatments (15.5, 20.0, 23.8, 27.5, and 32.2°C) and observed over time to estimate the time to hatch and the time to reach the free-swimming stage. Both species showed an inverse relationship between temperature and the timing of hatch and advancement to free-swimming fingerlings for all treatments. In addition, Alligator Gar embryos did not develop at the coldest water temperature tested, and Alligator Gar juveniles held at the warmest temperature tested were observed with developmental abnormalities, potentially affecting their survival. The same temperature extremes had no comparable negative effect on Spotted Gar. The results of this study are useful for understanding early life history dynamics of these two species in their natural environments and can also be used by hatchery managers who are seeking to optimize their production protocols.

North American Journal of Fisheries Management↗

USGS2025

Cultivating reciprocity and supporting Indigenous lifeways through the cultural transformation of natural resource management in North America

Recent decades have seen increasing calls for implementing Indigenous Knowledges (IK) in natural resource management (NRM). However, efforts have been limited by the cultural incommensurabilities between (1) NRM institutions, which are rooted in worldviews that prioritize extraction for dominant cultures and assume dominance over nature and (2) Indigenous worldviews that prioritize kincentric reciprocity with the environment. This manuscript addresses how transforming NRM institutions enables management to better support Indigenous Knowledges and lifeways. This manuscript examines incommensurabilities between NRM institutional cultures and Indigenous cultures, with the value and lifeway of reciprocity as the focal point. Through synthesizing interdisciplinary scholarship and examples from author experiences, we explore how NRM institutions in North America can transform to honour and facilitate reciprocity, especially within efforts to implement IK and support Indigenous lifeways. NRM institutions are cultural products, and in North America were born of colonial histories and cultural roots connected to modern governance and power dynamics. These cultural foundations led to NRM approaches that prioritize maximizing economic growth while guarding against overexploitation. Kincentric reciprocal relations with the environment often emphasize interdependency with more-than-human kin, place-based holistic Knowledges grounded in cultural practices and communal responsibility to cultivate social-ecological abundance for present and future generations. Incommensurabilities between NRM institutional cultures and Indigenous cultures impede efforts to implement IK and support Indigenous lifeways as: (1) rigid institutional structures do not account for Indigenous worldviews and values but instead attempt to fit IK within dominant paradigms; (2) the siloing of NRM leads to the piecemealing and invalidation of IK at the expense of Knowledge Holders and (3) ineffective public engagement strategies limit the possibility of reciprocal relations between NRM institutions and communities throughout management processes. Incommensurabilities between NRM institutional cultures and Indigenous cultures impede efforts to implement IK and support Indigenous lifeways as: (1) rigid institutional structures do not account for Indigenous worldviews and values but instead attempt to fit IK within dominant paradigms; (2) the siloing of NRM leads to the piecemealing and invalidation of IK at the expense of Knowledge Holders and (3) ineffective public engagement strategies limit the possibility of reciprocal relations between NRM institutions and communities throughout management processes. Transforming NRM institutional cultures to better implement IK and support Indigenous lifeways is key for redressing long-standing issues and ensuring social-ecological resilience and abundance. Heavy investments of time, personnel and resources are necessary for transforming NRM institutions to appropriately cultivate reciprocal relations with Indigenous communities and lands. Strategies towards transformation include decentralization through decolonial frameworks, knowledge co-production and using place-based cultural evaluation processes to improve cultural alignment.

People and Nature↗

USGS2007

Chloroethene dechlorination in acidic groundwater: Implications for combining fenton's treatment with natural attenuation

A sulfuric acid leak in 1988 at a chloroethene-contaminated groundwater site at the Naval Air Station Pensacola has resulted in a long-term record of the behavior of chloroethene contaminants at low pH and a unique opportunity to assess the potential impact of source area treatment technologies, which involve acidification of the groundwater environment (e.g., Fenton's-based in situ chemical oxidation), on downgradient natural attenuation processes. The greater than 75 percent decrease in trichloroethene (TCE) concentrations and the shift in contaminant composition toward predominantly reduced daughter products (dichloroethene [DCE] and vinyl chloride [VC]) that were observed along a 30-m groundwater flow path characterized by highly acidic conditions (pH = 3.5 ± 0.4) demonstrated that chloroethene reductive dechlorination can continue to be efficient under persistent acidic conditions. The detection of Dehalococcoides -type bacteria within the sulfuric acid/chloroethene co-contaminant plume was consistent with biotic chloroethene reductive dechlorination. Microcosm studies conducted with 14 C-TCE and 14 C-VC confirmed biotic reductive dechlorination in sediment collected from within the sulfuric acid/chloroethene co-contaminant plume. Microcosms prepared with sediment from two other locations within the acid plume, however, demonstrated only a limited mineralization to 14 CO 2 and 14 CO, which was attributed to abiotic degradation because no significant differences were observed between experimental and autoclaved control treatments. These results indicated that biotic and abiotic mechanisms contributed to chloroethene attenuation in the acid plume at NAS Pensacola and that remediation techniques involving acidification of the groundwater environment (e.g., Fenton's-based source area treatment) do not necessarily preclude efficient chloroethene degradation.

Florida↗

USGS2010

Simulated effects of host fish distribution on juvenile unionid mussel dispersal in a large river

Larval mussels (Family Unionidae) are obligate parasites on fish, and after excystment from their host, as juveniles, they are transported with flow. We know relatively little about the mechanisms that affect dispersal and subsequent settlement of juvenile mussels in large rivers. We used a three-dimensional hydrodynamic model of a reach of the Upper Mississippi River with stochastic Lagrangian particle tracking to simulate juvenile dispersal. Sensitivity analyses were used to determine the importance of excystment location in two-dimensional space (lateral and longitudinal) and to assess the effects of vertical location (depth in the water column) on dispersal distances and juvenile settling distributions. In our simulations, greater than 50% of juveniles mussels settled on the river bottom within 500 m of their point of excystment, regardless of the vertical location of the fish in the water column. Dispersal distances were most variable in environments with higher velocity and high gradients in velocity, such as along channel margins, near the channel bed, or where effects of river bed morphology caused large changes in hydraulics. Dispersal distance was greater and variance was greater when juvenile excystment occurred in areas where vertical velocity ( w ) was positive (indicating an upward velocity) than when w was negative. Juvenile dispersal distance is likely to be more variable for mussels species whose hosts inhabit areas with steeper velocity gradients (e.g. channel margins) than a host that generally inhabits low-flow environments (e.g. impounded areas).

Illinois;Iowa↗

USGS2013

Reservoir floodplains support distinct fish assemblages

Reservoirs constructed on floodplain rivers are unique because the upper reaches of the impoundment may include extensive floodplain environments. Moreover, reservoirs that experience large periodic water level fluctuations as part of their operational objectives seasonally inundate and dewater floodplains in their upper reaches, partly mimicking natural inundations of river floodplains. In four flood control reservoirs in Mississippi, USA, we explored the dynamics of connectivity between reservoirs and adjacent floodplains and the characteristics of fish assemblages that develop in reservoir floodplains relative to those that develop in reservoir bays. Although fish species richness in floodplains and bays were similar, species composition differed. Floodplains emphasized fish species largely associated with backwater shallow environments, often resistant to harsh environmental conditions. Conversely, dominant species in bays represented mainly generalists that benefit from the continuous connectivity between the bay and the main reservoir. Floodplains in the study reservoirs provided desirable vegetated habitats at lower water level elevations, earlier in the year, and more frequently than in bays. Inundating dense vegetation in bays requires raising reservoir water levels above the levels required to reach floodplains. Therefore, aside from promoting distinct fish assemblages within reservoirs and helping promote diversity in regulated rivers, reservoir floodplains are valued because they can provide suitable vegetated habitats for fish species at elevations below the normal pool, precluding the need to annually flood upland vegetation that would inevitably be impaired by regular flooding. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Mississippi↗

USGS2021

Habitat associations of black basses in a reservoir system

The habitat associations of three species of black bass Micropterus spp. were examined in six habitat types (i.e., sediment, gravel, rock, riprap, brush, and aquatic plants) along a cascade of 10 reservoirs in the Tennessee River. We tested whether habitat selection differed among the three species and whether species’ co-occurrence depended on habitat type. We found that some species occurred in some habitats in proportion to habitat availability (some at higher frequencies and some at frequencies lower than availability) and that juveniles and adults exhibited similar occurrence patterns. Our habitat selection results largely corroborate previous descriptions of black bass habitat associations and generally track preference for lithic habitats, as reported in native streams. We expected the different black bass species to show negative co-occurrence to avoid competitive interactions. Nevertheless, we found that with few exceptions, adults co-occurred in habitats mostly as expected by chance and juveniles co-occurred more often than was expected by chance. Our findings imply that environmental filtering, rather than competitive interactions that dominate in natural environments, may be the dominant mechanism shaping black bass assemblages in reservoirs of the Tennessee River. The observed patterns of habitat selection and co-occurrence further suggest that the conservation and management of black bass assemblages in reservoirs can be supported through habitat management activities. Protecting and enhancing the remaining lithic habitat in the reservoirs as well as recovering habitat that is blanketed by sediment could provide desirable environments for all black bass species.

Tennessee River basin↗