Geology topics

Clay Pierce

Publications and source records attributed to Clay Pierce.

At least 19 recordsLinked to original sources

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

Fish growth changes over time in a Midwestern U.S. lake

Growth of Walleyes Sander vitreus, Yellow Bass Morone mississippiensis, Common Carp Cyprinus carpio, and Black Bullheads Ameiurus melas was assessed in Clear Lake, Iowa, over several decades and in relation to environmental variables. Growth of Common Carp was positively correlated with phytoplankton concentration. Recent Black Bullhead growth was faster than in the 1950s and 1990s, which may be a consequence of their recent decline in abundance. Growth of Common Carp and Yellow Bass was faster in the 1940s than in more recent time periods. Relative to their entire range, Common Carp first‐year growth was below average, whereas length at later ages was above average. Walleye relative growth showed a similar pattern. The large changes in growth over several decades suggest that as the Clear Lake ecosystem continues to change, growth rates of its important fish species are also likely to continue changing.

Transactions of the American Fisheries Society↗

USGS2019

Factors influencing anuran wetland occupancy in an agricultural landscape

Habitat disturbance is an important cause of global amphibian declines, with especially strong effects in areas of high agricultural use. Determining the influence of site characteristics on amphibian presence and success is vital to developing effective conservation strategies. We used occupancy analysis to estimate presence of four anuran species at wetlands in northern Iowa as a function of eight environmental covariates hypothesized to affect occupancy: fish and salamander abundance, invertebrate density, aquatic vegetative cover, wetland area, atrazine concentration in water, surrounding agricultural land use, and an overall wetland health score (wetland condition index [WCI]). We surveyed 27 wetlands multiple times in 2015 and 2016. Leopard Frogs ( Lithobates pipiens ) and American Toads ( Anaxyrus americanus ) were observed at 100% of the sites, Boreal Chorus Frogs ( Pseudacris maculata ) at 96%, and Gray Treefrogs ( Hyla spp.) at 81%. Wetland site occupancy for all species in our study ranged from 0.23 ( Hyla spp. tadpoles) to 0.95 ( L. pipiens adults), indicating that agricultural wetlands can provide refuge or habitat for amphibians. Fish abundance, percentage of cropland cover within 500 m of the wetland, and salamander abundance were among the variables best supported by our models although their estimated effects were weak. Wetland area, atrazine concentration, vegetative cover, and WCI also influenced occupancy probability, but for only a small number of species and life stages. The direction of predicted effects varied by species and life stage. Despite only weak evidence that the environmental factors we measured influenced anuran occupancy, our results provide insights for managers seeking to understand how amphibians use landscapes modified by agriculture.

Iowa↗

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

A food web modeling assessment of Asian Carp impacts in the Middle and Upper Mississippi River, USA

The invasion of non-native fishes has caused a great detriment to many of our native fishes. Since the introduction of invasive carps, such as Silver, Bighead, Common and Grass Carp , managers and researcher have been struggling to remove these species while also hypothesizing the detriment of further invasion. This study developed a food web model of four locations on the Mississippi River and used those models to assess the impacts of two scenarios: carp removal and carp invasion. In the Middle Mississippi River where these invasive carps are already present, the models found that it would take a sustained exploitation of up to 30% of initial biomass over an extended period to remove Grass Carp and up to 90% removal of initial biomass to remove Silver and Bighead Carp. In the locations where Silver, Bighead, and Grass Carp are not yet established (i.e., Pools 4,8, and 13) the invasion of these species could cause declines from 10 to 30% in initial biomass of native fishes as well as already established nonnative invasive species.

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗

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↗

USGS2019

Multipurpose oxbows as a nitrate export reduction practice in the agricultural Midwest

Core Ideas Oxbows reduce nitrate export from agricultural fields to adjacent rivers and streams. Oxbows are important habitat for wildlife, including the endangered Topeka shiner. Oxbows have largely disappeared from midwestern landscapes modified for agriculture. Restoring multipurpose oxbows provides multiple benefits in the agricultural Midwest. Nutrient export from the agricultural US Midwest influences streams and rivers and contributes to the development of hypoxia in the Gulf of Mexico. Oxbows are natural waterbodies formed when a river cuts off a meander loop as it migrates within its floodplain. Creation of multipurpose oxbows by restoration of former oxbows can potentially reduce export of nitrate-nitrogen (nitrate) from agricultural land as well as provide important habitat for many species, including the endangered Topeka shiner. Recent studies of nitrate export reduction by oxbows in Iowa are encouraging, demonstrating a 45% reduction in nitrate export of water entering oxbows from subsurface tiles compared with water discharged to the adjacent stream. Oxbow restorations are as effective as several other nutrient reduction practices, are relatively inexpensive, last for decades if not centuries, remove little or no land from agricultural production, and provide significant ecosystem services. Multipurpose oxbows are a promising new best management practice for reducing nitrate export from agricultural lands.

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

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↗

USGS2018

Exploring the amphibian exposome in an agricultural landscape using telemetry and passive sampling

This is the first field study of its kind to combine radio telemetry, passive samplers, and pesticide accumulation in tissues to characterize the amphibian exposome as it relates to pesticides. Understanding how habitat drives exposure in individuals ( i . e ., their exposome), and how that relates to individual health is critical to managing species in an agricultural landscape where pesticide exposure is likely. We followed 72 northern leopard frogs ( Lithobates pipiens ) in two agricultural wetlands for insight into where and when individuals are at high risk of pesticide exposure. Novel passive sampling devices (PSDs) were deployed at sites where telemetered frogs were located, then moved to subsequent locations as frogs were radio-tracked. Pesticide concentration in PSDs varied by habitat and was greatest in agricultural fields where frogs were rarely found. Pesticide concentrations in frogs were greatest in spring when frogs were occupying wetlands compared to late summer when frogs occupied terrestrial habitats. Our results indicate that habitat and time of year influence exposure and accumulation of pesticides in amphibians. Our study illustrates the feasibility of quantifying the amphibian exposome to interpret the role of habitat use in pesticide accumulation in frogs to better manage amphibians in agricultural landscapes.

Scientific Reports↗

USGS2018

A case study and a meta-analysis of seasonal variation in fish mercury concentrations

Mercury contamination in aquatic ecosystems is a concern due to health risks of consuming fish. Fish mercury concentrations are highly variable and influenced by a range of environmental factors. However, seasonal variation in mercury levels are typically overlooked when monitoring fish mercury concentrations, establishing consumption advisories, or creating accumulation models. Temporal variation in sampling could bias mercury concentration estimates of accumulation potential. Thus, the objectives of this study were to first evaluate seasonal variation of largemouth bass ( Micropterus salmoides ) axial muscle mercury concentration from two Iowa, USA impoundments. Second, we conducted a meta-analysis to evaluate if seasonal variation in mercury concentration is dependent upon mean mercury concentration, waterbody type, or fish trophic level or mean length. Largemouth bass were collected four times between May and October (24–36 fish per month) from Twelve Mile (2013) and Red Haw (2014) lakes. Largemouth bass axial muscle mercury concentrations were variable within and between lakes, ranging from undetectable ( < 0.05 mg/kg) to 0.54 mg/kg. Largemouth bass mercury concentrations were similar across months in Twelve Mile but varied temporally in Red Haw and were highest in July, intermediate in May and September, and lowest during October. Results of the meta-analysis suggest that seasonal variation in mercury concentrations is more likely to occur as mean mercury concentration of the population increases but is unrelated to waterbody type, trophic status, and fish size. Understanding seasonal variation in fish mercury concentrations will aid in the development of standardized sampling programs for long-term monitoring programs and fish consumption advisories.

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↗

USGS2017

Placement of intracoelomic radio transmitters and silicone passive sampling devices in northern leopard frogs (Lithobates pipiens)

Historically, wetland toxin exposure studies have relied on single time point samples from stationary sampling devices. Development of passive sampling devices (PSDs) that can be attached to individual animals within wetland habitats has greatly improved in recent years, presenting an innovative sampling technology that can potentially yield individual-specific, quantifiable data about chemical exposure. In this study, silicone based PSDs were attached to the ventral skin of 20 northern leopard frogs (Lithobates pipiens) with polypropylene sutures after radio transmitters had been surgically implanted into the coleomic cavity. After a recovery period frogs were released back into the wetland habitat where they were acquired. The animals were located daily using radio telemetry to assess how long PSDs would remain attached in the frogs' natural habitat. After one week, PSDs remained on 18 of the original 20 frogs. At 2 weeks 17 frogs were recovered and no PSDs remained attached. Although valuable data can be obtained over a short time period, more research will be necessary to demonstrate effectiveness of externally attaching silicone PSDs to northern leopard frogs for time periods longer than 1-2 weeks.

Journal of Herpetological Medicine and Surgery↗

USGS2017

Amphibians, pesticides, and the amphibian chytrid fungus in restored wetlands in agricultural landscapes

Information on interactions between pesticide exposure and disease prevalence in amphibian populations is limited, especially from field data. Exposure to certain herbicides and insecticides has the potential to decrease the immune response in frogs, which can potentially lead to increased abundance of Batrachochytrium dendrobatidis (Bd) zoospores on individuals and in the wetlands. In contrast, exposure to certain fungicides can decrease Bd abundance on frog skin. We examined the relationships between the abundance of Bd on the skin of individual Boreal Chorus Frogs (Pseudacris maculata) and the concentrations of pesticides in the water and in frog tissue at six agriculturally dominated wetlands in Iowa, USA. We collected frogs from each wetland, swabbed them for Bd, and analyzed their tissues for a suite of fungicides, herbicides, and insecticides. We collected surface water from the wetlands and we analyzed it for the same suite of pesticides. We observed no relationship between Bd zoospores on the skin of individual frogs and the concentrations of total pesticides, total herbicides/insecticides and total fungicides in frog tissue. Similarly, we observed no relationship between Bd zoospore abundance in water and the concentration of total pesticides or total herbicides in water. However, we observed a negative relationship between Bd zoospore abundance in water and neonicotinoid concentrations in surface water. Negative results are seldom reported but can be important contributors to a more complete understanding of the complex and potentially synergistic relationships between disease and pesticides. Data from field studies on these relationships are particularly scarce. As our laboratory understanding of these relationships expands, the need for field based, or applied, studies grow.

Iowa↗

USGS2015

Restored agricultural wetlands in Central Iowa: habitat quality and amphibian response

Amphibians are declining throughout the United States and worldwide due, partly, to habitat loss. Conservation practices on the landscape restore wetlands to denitrify tile drainage effluent and restore ecosystem services. Understanding how water quality, hydroperiod, predation, and disease affect amphibians in restored wetlands is central to maintaining healthy amphibian populations in the region. We examined the quality of amphibian habitat in restored wetlands relative to reference wetlands by comparing species richness, developmental stress, and adult leopard frog (Lithobates pipiens) survival probabilities to a suite of environmental metrics. Although measured habitat variables differed between restored and reference wetlands, differences appeared to have sub-lethal rather than lethal effects on resident amphibian populations. There were few differences in amphibian species richness and no difference in estimated survival probabilities between wetland types. Restored wetlands had more nitrate and alkaline pH, longer hydroperiods, and were deeper, whereas reference wetlands had more amphibian chytrid fungus zoospores in water samples and resident amphibians exhibited increased developmental stress. Restored and reference wetlands are both important components of the landscape in central Iowa and maintaining a complex of fish-free wetlands with a variety of hydroperiods will likely contribute to the persistence of amphibians in this landscape.

Iowa↗