Geology topics

Michael J. Weber

Publications and source records attributed to Michael J. Weber.

13 recordsLinked to original sources

USGS2026

Silver Carp Hypophthalmichthys molitrix broad movement patterns and dispersal dynamics in the upper Mississippi River

Rivers are important movement corridors for fishes that allow for population connectivity. Within the upper Mississippi River Basin, invasive Silver Carp ( Hypophthalmichthys molitrix ) use tributaries including the Des Moines, Iowa, and Cedar rivers; however, the extent Silver Carp move and intermix among these systems and pools of the upper Mississippi River (UMR) is largely unknown. We used acoustic telemetry and multistate models to (1) identify individual and spatial variability in movement strategies, (2) use survival and transition probability estimates to evaluate population dynamics and connectivity, and (3) evaluate the influence of temporal and environmental variables on survival and transition probabilities. Weekly transition probabilities generally increased with discharge and ranged between 0.01 from UMR Pool 20 to outside the study area at 575 m 3 /s to 0.75 from UMR Pool 18 to outside the study area at 7200 m 3 /s. Survival decreased as temperature increased from 0 to 30 °C and was higher in tributaries than mainstem pools correlated with lower discharge. Overall, Silver Carp displayed diverse movement strategies with high connectivity that can inform invasive species management strategies.

upper Mississippi River↗

USGS2021

Demographic rate variability of Bighead and Silver Carps along an invasion gradient

Invasive Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix have infested and caused largescale ecological and economic damage to the Illinois, Mississippi, and Ohio rivers. We compiled demographic data from 42,995 fish from 23 pools in the Illinois, Mississippi, and Ohio rivers, which universities and management agencies previously collected as part of management, monitoring, and research activities. We used this data set to test whether demographic rates (length–weight relations including body condition, mortality, growth curves, and female maturity curves) varied among subpopulations across a gradient of invasion status. We found that length–weight relations and growth curves varied among subpopulations, whereas maturity curves did not. Our findings demonstrated spatial variability in demographic rates for Bighead and Silver carp across a broad geographic area in relation to invasion status and river conditions. Herein, we provide general subpopulation management options and present different hypotheses to explain the observed spatial variability in demographic rates.

Illinois, Indiana, Iowa, Kentucky, West Virginia↗

USGS2021

Suitability of an upper Mississippi River tributary for invasive carp reproduction

Invasive carp are expanding throughout the upper Mississippi River basin and are of great concern due to their potential economic and ecological impacts. Identification of spawning locations provides critical information on recruitment sources to evaluate potential management strategies. Our objective was to create and validate a spawning habitat suitability model of the Des Moines River, Iowa, during low-, average-, and high-water-level conditions. Backwater availability, abundance of hardpoints (structures that create turbulence), river gradient and sinuosity, water temperature, and continuously free-flowing river lengths were used as model parameters. The model was compared to back-calculated spawning locations from invasive carp eggs collected in 2014–2015. Turbulent hardpoints, river sinuosity, and gradient were not significant predictors of invasive carp spawning locations, and backwater availability in the 25 river kilometers downstream of each reach was inversely correlated with invasive carp spawning locations. Invasive carp eggs were not caught in 2014 despite optimal spawning conditions, revealing that spawning may have high interannual variation. This study suggests that predicting invasive carp reproduction may require variables in addition to those currently proposed.

Iowa↗

USGS2020

A comparison of Grass Carp population characteristics upstream and downstream of Lock and Dam 19 of the Upper Mississippi River

Grass Carp Ctenopharyngodon idella have been intentionally stocked for aquatic vegetation control across the Midwestern United States for several decades. During the 1970s, escapement of Grass Carp into the Missouri River facilitated their naturalization into much of the Mississippi River basin, including the Upper Mississippi River. Lock and Dam 19 (LD19) in Keokuk, Iowa, is a high-head dam that represents a focal point for naturalized Grass Carp management where populations may differ between upstream and downstream pools as result of limited upstream migration, but potential differences between populations have yet to be evaluated to the best of our knowledge. The objective of this study was to compare the relative abundance, size structure, condition, growth, and recruitment variability of Grass Carp collected upstream and downstream of LD19. We sampled Grass Carp monthly (April–October) during 2014 and 2015 from four locations in the Des Moines River (downstream of LD19) and five locations throughout the Skunk, Iowa, and Cedar rivers (upstream of LD19) using boat electrofishing and trammel net sets. We captured 29 Grass Carp upstream of LD19 compared with 179 individuals captured downstream. Trammel nets only captured Grass Carp downstream of LD19; trammel net catch per unit effort upstream of LD19 was low and ranged from 0.0 to 8.0 fish/net lift (mean ± SE = 0.39 ± 0.13). Electrofishing catch per unit effort ranged from 0.0 to 22.7 fish/h (1.49 ± 0.30) and was higher downstream (2.42 ± 0.30) of LD19 than upstream (0.57 ± 0.07). Grass Carp downstream of LD19 tended to be smaller, younger, of lower body condition, had higher mortality rates, and were slower growing compared with those collected upstream and to populations documented in other systems. Understanding and monitoring adult Grass Carp population characteristics upstream and downstream of LD19 is necessary to determine how they may change in response to ongoing harvest efforts for invasive carps in these river reaches.

Iowa↗

USGS2019

Morphological identification of Bighead Carp, Silver Carp, and Grass Carp eggs using random forests machine learning classification

Visual identification of fish eggs is difficult and unreliable due to a lack of information on the morphological egg characteristics of many species. We used random forests machine learning to predict the identity of genetically identified Bighead Carp Hypophthalmichthys nobilis , Grass Carp Ctenopharyngodon idella , and Silver Carp H. molitrix eggs based on egg morphometric and environmental characteristics. Family, genus, and species taxonomic-level random forests models were explored to assess the performance and accuracy of the predictor variables. The egg characteristics of Bighead Carp, Grass Carp, and Silver Carp were similar, and they were difficult to distinguish from one another. When combined into a single invasive carp class, the random forests models were ≥ 97% accurate at identifying invasive carp eggs, with a ≤5% false positive rate. Egg membrane diameter was the most important predictive variable, but the addition of ten other variables resulted in a 98% success rate for identifying invasive carp eggs from 26 other upper Mississippi River basin species. Our results revealed that a combination of morphometric and environmental measurements can be used to identify invasive carp eggs. Similar machine learning approaches could be used to identify the eggs of other fishes. These results will help managers more easily and quickly assess invasive carp reproduction.

Iowa↗

USGS2019

Occurrence, Abundance, and Associations of Topeka Shiners (Notropis topeka) in Restored and Unrestored Oxbows in Iowa and Minnesota, USA

In the USA, the Topeka shiner ( Notropis topeka ) is a federally listed endangered species that has been in decline for decades. A key reason for the decline is the alteration of naturally flowing streams and associated oxbow habitats resulting from land-use changes. The focus of recent conservation efforts for Topeka shiners has been the restoration of oxbow habitats by removing sediment from natural oxbows until a groundwater connection is re-established. This restoration practice has become common in portions of Iowa and south-west Minnesota. The goals of this study were to compare the occurrence and abundance of Topeka shiners in restored and unrestored oxbows and to determine the characteristics that influenced their presence in these systems. In 2016–2017, 34 unrestored and 64 restored oxbows in the Boone, Beaver Creek, North Raccoon and Rock River basins in Iowa and Minnesota were sampled for their fish assemblages and abiotic features. Topeka shiners were present more often and with higher average relative abundances in restored oxbows. Nonmetric multidimensional scaling ordinations indicated that fish assemblages found in oxbows where Topeka shiners were present were less variable than assemblages found at oxbows where they were absent, but that abiotic characteristics were similar between oxbow types. Logistic regression models suggested that the presence of Topeka shiners in oxbows was positively associated with species richness, brassy minnow ( Hybognathus hankinsoni ) catch per unit effort (no. fish/100 m 2 ; CPUE), orangespotted sunfish ( Lepomis humilis ) CPUE, dissolved oxygen and turbidity, and negatively associated with oxbow wetted length. These results highlight the use of restored oxbows by Topeka shiners while also providing new information to help guide restoration and conservation efforts.

Iowa, Minnesota↗

USGS2019

Factors influencing fish mercury concentrations in Iowa rivers

Fish mercury concentrations have received considerable attention due to human health implications. Fish mercury concentrations are variable within and among systems due to a suite of biotic and abiotic influences that vary among regions and are difficult to predict. Understanding factors associated with variability in fish mercury concentrations would help guide consumption advisories. Mercury concentrations in channel catfish ( Ictalurus punctatus , n = 205), flathead catfish ( Pylodictis olivaris , n = 123), northern pike ( Esox lucius , n = 60), smallmouth bass ( Micropterus dolomieu , n = 176), and walleye ( Sander vitreus , n = 176) were assessed in ten Iowa rivers and relationships with land use, water chemistry, and fish characteristics were explored. Mercury concentrations were generally low (mean among all species = 0.17 mg/kg, n = 740) but higher in flathead catfish, northern pike, smallmouth bass, and walleye than channel catfish and were positively related to fish length, age, trophic position, and δ 13 C signatures. Phosphorus, sulfate, and percent open water and grassland were negatively related to fish mercury concentrations, whereas water hardness, nitrogen-ammonia, Human Threat Index, and percent wetland and forest were positively related to fish mercury concentrations. Fish collected from the Paleozoic Plateau ecoregion in northeast Iowa had higher mercury concentrations than other ecoregions in Iowa. Combined, these factors explained 70% of the variation in fish mercury concentrations. This study provides a comprehensive analysis of abiotic and biotic factors influencing fish mercury concentrations in lotic ecosystems at the individual and system scale that will help guide fish consumption advisories.

Iowa↗

USGS2019

Status of the Topeka shiner in Iowa

The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota and has been federally listed as endangered since 1998. Our goals were to determine the present distribution and qualitative status of Topeka shiners throughout its current range in Iowa and characterize the extent of decline in relation to its historic distribution. We compared the current (2016–2017) distribution to distributions portrayed in three earlier time periods. In 2016–2017 Topeka shiners were found in 12 of 20 HUC10 watersheds where they occurred historically. Their status was classified as stable in 21% of the HUC10 watersheds, possibly stable in 25%, possibly recovering in 8%, at risk in 33%, and possibly extirpated in 13% of the watersheds. The increasing trend in percent decline evident in earlier time periods reversed, going from 68% in 2010–11 to 40% in the most recent surveys. Following decades of decline, the status of Topeka shiners in Iowa appears to be improving. One potential reason for the reversal in the distributional decline of Topeka shiners in Iowa is the increasing number of oxbow restorations. Until a standardized monitoring program is established for Iowa, periodic status assessments such as this will be necessary to chronicle progress toward conserving this endangered fish species.

Iowa↗

USGS2018

The development of a GIS methodology to identify oxbows and former stream meanders from LiDAR-derived digital elevation models

Anthropogenic development of floodplains and alteration to natural hydrological regimes have resulted in extensive loss of off-channel habitat. Interest has grown in restoring these habitats as an effective conservation strategy for numerous aquatic species. This study developed a process to reproducibly identify areas of former stream meanders to assist future off-channel restoration site selections. Three watersheds in Iowa and Minnesota where off-channel restorations are currently being conducted to aid the conservation of the Topeka Shiner ( Notropis topeka ) were selected as the study area. Floodplain depressions were identified with LiDAR-derived digital elevation models, and their morphologic and topographic characteristics were described. Classification tree models were developed to distinguish relic streams and oxbows from other landscape features. All models demonstrated a strong ability to distinguish between target and non-target features with area under the receiver operator curve (AUC) values ≥ 0.82 and correct classification rates ≥ 0.88. Solidity, concavity, and mean height above channel metrics were among the first splits in all trees. To compensate for the noise associated with the final model designation, features were ranked by their conditional probability. The results of this study will provide conservation managers with an improved process to identify candidate restoration sites.

Iowa, Minnesota↗

USGS2018

Development of a quantitative PCR method for screening ichthyoplankton samples for bigheaded carps

Monitoring ichthyoplankton is useful for identifying reproductive fronts and spawning locations of bigheaded carps (Hypophthalmichthys spp.). Unfortunately, sorting and identifying ichthyoplankton to monitor for bigheaded carp reproduction is time consuming and expensive. Traditional methods require frequent egg-larvae sampling, sorting of all samples to obtain presumptively identified bigheaded carp, and genetic validation of presumptively identified eggs. Quantitative PCR (qPCR) has the potential to streamline this process by identifying samples that likely do or do not contain a target species. Our objective was to develop a genetic screening tool using qPCR with the duplex assays SCTM4/5 and BHTM1/2 to prioritize samples that have a higher likelihood of containing bigheaded carp eggs or larvae. We used tandem ichthyoplankton samples collected for monitoring bigheaded carps in the Upper Mississippi, Illinois, and St. Croix rivers to evaluate the effectiveness of qPCR as a screening tool. Samples with > 10,000 copies of DNA had 100% occurrence of bigheaded carp eggs or larvae in the traditionally sorted samples, whereas samples with < 10 copies of DNA had 0% occurrence of ichthyoplankton from these invasive species. We used a logistic regression model to calculate the probability of finding bigheaded carp eggs or larvae based upon the number of DNA copies; 406 copies corresponded with a 50% probability of having bigheaded carp ichthyoplankton present in a sample. These data can be used to inform management actions (i.e., control, containment) for these invasive fishes, and this tool could be adapted for monitoring for reproduction of other aquatic invasive species.

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗

USGS2018

Influence of river discharge on grass carp occupancy dynamics in south-eastern Iowa rivers

Despite the longstanding presence of grass carp Ctenopharyngodon idella in the Upper Mississippi River (UMR) watershed, information regarding their populations remains largely unknown, in part because capture is difficult. Occupancy models are a popular wildlife assessment tool to account for imperfect detections but have been slow to be adopted in fisheries. Herein, we used occupancy modelling to evaluate the influence of two environmental covariates (river discharge and water temperature) on grass carp occupancy, extinction, colonization, and detection at nine sites within south-eastern Iowa rivers from April to October 2014 and 2015. Grass carp were detected at least once at all but one site. The most parsimonious model indicated that grass carp colonization probability increased from 0.15 to 0.67 with increases in river discharge. In contrast, occupancy (0.20), extinction (0.29), and detection (0.50) probabilities were temporally constant. Models indicated that water temperatures did not influence grass carp extinction or colonization probabilities relative to river discharge. Cumulative grass carp detection probability approached 1.0, whereas conditional occupancy estimates were less than 0.1 when using five or more sampling transects. The use of a robust design occupancy model allowed us to estimate site occupancy rates of grass carp corrected for imperfect detections, while demonstrating the importance of river discharge for site colonization. These results can be used to assess the distribution of a cryptic fish while helping to guide grass carp sampling and removal efforts.

Iowa↗

USGS2017

Intra‐annual variability of Silver Carp populations in the Des Moines River, USA

Since their introduction in the 1970s, Silver Carp Hypophthalmichthys molitrix have spread throughout the Mississippi River basin. Management of any species relies on an accurate understanding of population characteristics and dynamics. However, Silver Carp seasonal sampling variation is unknown. Sampling during periods of peak catch rates would facilitate Silver Carp assessment and management, improving monitoring and removal techniques. The objective of this study was to evaluate adult Silver Carp seasonal sampling variation with boat electroshocking and trammel nets. Silver Carp were collected monthly (April–October) during 2014 and 2015 from four locations in the Des Moines River, Iowa. Trammel nets rarely captured Silver Carp (mean ± SE = 4.9 ± 1.6 fish/net; 60% of fish were captured in 6.3% of net sets) and therefore were not included in analyses. Electroshocking catch rates (CPUEs) exhibited a bimodal distribution, with peak CPUEs generally occurring in May, June, and September and lower catch rates observed during July and August. Catch rates were positively related to river discharge at upstream sites but not at downstream sites. Silver Carp size structure was similar among months and sites except at Cliffland, where fish were smaller during August and October compared to earlier in the year. Finally, Silver Carp condition peaked during April and May and decreased throughout the year except at Keokuk, where peaks were observed during both May and August. Although spatiotemporal variability was substantial, these results suggest that sampling of Silver Carp via electroshocking in May–June and September–October generally produces higher catch rates compared to July–August sampling and generates a more representative size structure. Using site‐specific knowledge, monitoring and surveillance programs could more effectively sample during these periods of high vulnerability and densities in order to manage the spread and impacts of Silver Carp at statewide and regionwide scales.

Iowa↗

USGS1998

Asymmetric radiation of seismic waves from an atoll: nuclear tests in French Polynesia

Seismic records of nuclear tests detonated in the Mururoa Atoll in French Polynesia show large unpredicted arrivals 2.2 and 4.5 seconds (X1 and X2) after the P-wave at the Australian Warramunga Array. These arrivals are not observed at the Canadian Yellowknife Array. X1 and X2 are also absent on Warramunga Array recordings of tests carried out at the Fangataufa Atoll situated 40 km SSE of Mururoa. Array analysis shows that X1 and X2 are produced within the source area. The layered crustal structure of the atoll, significant local inhomogeneities, and focusing effects due to the elongated shape and the steep flanks of the Mururoa Atoll are most likely responsible for X1 and X2. The form of Mururoa (28 × 10 km) and its East-West orientation is due to its location on the Austral Fracture Zone (AFZ). The Fangataufa Atoll on the other hand is almost circular (10 km diameter) and is unaffected by the dynamics along the AFZ. Our observations demonstrate that complicated structures in the source area can significantly alter the wave field at teleseismic distances and produce a large magnitude (m b ) bias. A better understanding of the exact cause of these unusual seismic observations will only become possible, if the coordinates of the tests and information on the detailed 3-D structure of the atolls are released.

Geophysical Research Letters↗