Geology topics

Cari-Ann Hayer

Publications and source records attributed to Cari-Ann Hayer.

8 recordsLinked to original sources

USGS2025

Placing environmental DNA monitoring for new detections into perspective: Fishes in the Milwaukee River, Wisconsin

Invasive species management frameworks, such as the early detection of and rapid response to invasive species, use monitoring programs to detect new species occurrences. Resource managers use environmental DNA (eDNA) as one tool for these monitoring programs. An eDNA detection in a new location may lack perspective for resource managers and researchers because of the rarity of potential invaders and the randomness in their dispersal and detection. An example monitoring program is the eDNA-based sampling approach used by the U.S. Fish and Wildlife Service for bigheaded carps Hypophthalmichthys spp. in the upper Mississippi River and Great Lakes Basins that collects hundreds of water samples per event. The U.S. Fish and Wildlife Service detected a single positive sample for Bighead Carp Hypophthalmichthys nobilis during the spring 2021 sampling event in the Kinnickinnic River within the Milwaukee River Basin, and detected a second single positive sample for bigheaded carps during the fall 2021 sampling event in the Milwaukee River. The U.S. Fish and Wildlife Service did not detect any bigheaded carps in previous years (2015 to 2020) or in either the spring or fall 2022 sampling events. These detections lacked perspective, such as detection numbers for other species. We reanalyzed the 2021 and 2022 samples for four existing species of fish: two fairly common species (Common Carp Cyprinus carpio and Gizzard Shad Dorosoma cepedianum ) and two fairly rare species (Burbot Lota lota and Grass Carp Ctenopharyngodon idella ). We detected Common Carp during all four sampling events, Gizzard Shad during three of four sampling events, and Burbot and Grass Carp during two of four sampling events. These results demonstrated that current sampling efforts could detect other species, and bigheaded carp eDNA was not common in the Milwaukee River compared to these species. More specifically, this finding indicates bigheaded carp eDNA detections are as rare as, or rarer than, Grass Carp eDNA detections, a recent invader to the basin. Our findings also demonstrated how reanalyzing eDNA samples after positive detections for targeted species can help managers understand the context of the detections and provide perspective for the relative abundance of the targeted species. Additionally, our results highlight the importance of completing long-term eDNA-based monitoring rather than a single sampling or inventory event. These detections may have been missed in a single year or sampling event, whereas a multiyear monitoring program provides an opportunity to observe trends through time.

Wisconsin↗

USGS2025

Predator effects on the survival of juvenile invasive carp in simulated backwater habitats

Numerous control methods are in use and under development to manage invasive carps in the United States. Commercial harvest, electric deterrents, and chemical toxicants, among other methods, are most efficient at targeting larger individuals. Research on methods to control recruitment of juvenile invasive carps has been limited. Our primary objective was to assess the vulnerability of juvenile invasive carp and common native forage species, gizzard shad ( Dorosoma cepedianum ) to native fish predators. Eighteen two-week long experiments, from April–October in 2015 and 2016, were conducted in experimental ponds with differing habitats (structure, vegetation, or open), simulating backwater habitats that are commonly used by juvenile invasive carps. Bowfin ( Amia calva ), channel catfish ( Icatalurus punctatus ), shortnose gar ( Lepisosteus platostomus ), hybrid striped bass ( Morone saxatilis × Morone chrysops ), largemouth bass ( Micropterus salmoides ), blue catfish ( Ictalurus furcatus ), flathead catfish ( Pylodictis olivaris ), walleye ( Sander vitreus ), northern pike ( Esox lucius ), and smallmouth bass ( Micropterus dolomieu ) were tested as predators of bighead carp ( Hypophthalmichthys nobilis ), silver carp ( Hypophthalmichthys molitrix ), grass carp ( Ctenopharyngodon idella ), and gizzard shad. We observed prey survival rates across seasons, habitats, and predator species. Invasive carp odds of survival varied from those of native gizzard shad between years. Hybrid striped bass, largemouth bass, smallmouth bass, and northern pike were effective predators of all tested prey species. Largemouth bass and smallmouth bass consumed bighead carp and silver carp over gizzard shad and grass carp (log OR < 0.5). Our results demonstrate the importance of habitat and cover availability, and that predator management may be a potential control method for juvenile invasive carps. Future research may consider effective predator densities, as well as studies in natural habitats.

Management of Biological Invasions↗

USGS2021

Grass carp reproduction in small tributaries of Truman Reservoir, Missouri: Implications for establishment in novel habitats

Substantial work has been conducted to estimate the river length required for recruitment of invasive Grass Carp Ctenopharyngodon idella and bigheaded carps (Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix ); however, the distance upstream and size of stream required for spawning remain unclear. Adult Grass Carp are regularly captured in Harry S. Truman Reservoir, Missouri, although there have been only unconfirmed sightings of Silver Carp. Fertile diploid Grass Carp are used legally for vegetation control in Missouri; however, it is uncertain whether Grass Carp in Harry S. Truman Reservoir are the result of natural reproduction or escapees. We used ichthyoplankton tows and environmental DNA (eDNA) to investigate which carp species were present in the reservoir basin and to determine whether these carps were spawning in reservoir tributaries. Grass Carp eggs were collected in four of five tributaries during June 2014. We did not detect eggs, larvae, or eDNA of Bighead Carp or Silver Carp. The occurrence of Grass Carp eggs generally coincided with rapid increases in discharge and turbidity. These tributaries may be the smallest rivers worldwide in which spawning of Grass Carp has been documented. We infer from the developmental stages captured and the distance from the reservoir that sufficient river length exists for egg survival. These results have broad implications concerning the establishment of Grass Carp in other novel habitats, including other reservoirs and lake basins, smaller rivers, and the Laurentian Great Lakes ecosystem.

Missouri↗

USGS2020

Use of environmental DNA to detect grass carp spawning events

The timing and location of spawning events are important data for managers seeking to control invasive grass carp populations. Ichthyoplankton tows for grass carp eggs and larvae can be used to detect spawning events; however, these samples can be highly debris-laden, and are expensive and laborious to process. An alternative method, environmental DNA (eDNA) technology, has proven effective in determining the presence of aquatic species. The objectives of this project were to assess the use of eDNA collections and quantitative eDNA analysis to assess the potential spawning of grass carp in five reservoir tributaries, and to compare those results to the more traditional method of ichthyoplankton tows. Grass carp eDNA was detected in 56% of sampling occasions and was detected in all five rivers. Concentrations of grass carp eDNA were orders of magnitude higher in June, corresponding to elevated discharge and egg presence. Grass carp environmental DNA flux (copies/h) was lower when no eggs were present and was higher when velocities and discharge increased and eggs were present. There was a positive relationship between grass carp eDNA flux and egg flux. Our results support the further development of eDNA analysis as a method to detect the spawning events of grass carp or other rheophilic spawners.

Fishes↗

USGS2016

Assessment of dreissenid biodeposits as a potential food resource for invasive Asian carp

Silver carp ( Hypophthalmichthys molitrix ) and bighead carp ( H. nobilis ) are poised to invade the Laurentian Great Lakes. Zebra mussels ( Dreissena polymorpha ) and quagga mussels ( D. rostriformis bugensis ) have shifted nutrient pathways towards the benthos, partly through deposition of feces and rejected food particles called biodeposits. When biodeposit material was fed to bighead and silver carp, they fed on the material, but on average lost weight. Energy density between fed and unfed fish did not differ, but a few individual fish did gain weight on the biodeposits diet. Our results demonstrate that biodeposits might be considered a supplemental food for bigheaded carps.

Michigan↗

USGS2015

Effects of sediment burial on grass carp, Ctenopharyngodon idella (Valenciennes,1844), eggs

It is thought that grass carp ( Ctenopharyngodon idella ) eggs must remain suspended in the water column in order to hatch successfully. Using sand, the effects of varying sediment levels on grass carp eggs were tested at different developmental states and temperatures. Survival was high (15–35%, depending on temperature and trial) in the unburied treatment where eggs rested on a sand bed but were not covered by sediment. Survival was lower in the partial burial (5–10%) and very low (0–4%) in the full burial treatment. In all treatments, delayed hatching (organisms remaining in membranes past the stage of hatching competence) was noted. Deformities such as missing heads and pericardial edema occurred at high rates in the partial and full burials. Eggs that come in contact with the benthos and are resuspended in the water column should be considered in embryonic drift models.

Journal of Applied Ichthyology↗

USGS2012

A generalized model for estimating the energy density of invertebrates

Invertebrate energy density (ED) values are traditionally measured using bomb calorimetry. However, many researchers rely on a few published literature sources to obtain ED values because of time and sampling constraints on measuring ED with bomb calorimetry. Literature values often do not account for spatial or temporal variability associated with invertebrate ED. Thus, these values can be unreliable for use in models and other ecological applications. We evaluated the generality of the relationship between invertebrate ED and proportion of dry-to-wet mass (pDM). We then developed and tested a regression model to predict ED from pDM based on a taxonomically, spatially, and temporally diverse sample of invertebrates representing 28 orders in aquatic (freshwater, estuarine, and marine) and terrestrial (temperate and arid) habitats from 4 continents and 2 oceans. Samples included invertebrates collected in all seasons over the last 19 y. Evaluation of these data revealed a significant relationship between ED and pDM ( r 2 = 0.96, p < 0.0001), where ED (as J/g wet mass) was estimated from pDM as ED = 22,960pDM − 174.2. Model evaluation showed that nearly all (98.8%) of the variability between observed and predicted values for invertebrate ED could be attributed to residual error in the model. Regression of observed on predicted values revealed that the 97.5% joint confidence region included the intercept of 0 (−103.0 ± 707.9) and slope of 1 (1.01 ± 0.12). Use of this model requires that only dry and wet mass measurements be obtained, resulting in significant time, sample size, and cost savings compared to traditional bomb calorimetry approaches. This model should prove useful for a wide range of ecological studies because it is unaffected by taxonomic, seasonal, or spatial variability.

Freshwater Science↗

USGS2010

Influence of Physiochemical and watershed characteristics on mercury concentration in walleye, Sander vitreus , M.

Elevated mercury concentration has been documented in a variety of fish and is a growing concern for human consumption. Here, we explore the influence of physiochemical and watershed attributes on mercury concentration in walleye ( Sander vitreus, M . ) from natural, glacial lakes in South Dakota. Regression analysis showed that water quality attributes were poor predictors of walleye mercury concentration (R 2 = 0.57, p = 0.13). In contrast, models based on watershed features (e.g., lake level changes, watershed slope, agricultural land, wetlands) and local habitat features (i.e., substrate composition, maximum lake depth) explained 81% ( p = 0.001) and 80% ( p = 0.002) of the variation in walleye mercury concentration. Using an information theoretic approach we evaluated hypotheses related to water quality, physical habitat and watershed features. The best model explaining variation in walleye mercury concentration included local habitat features (W i = 0.991). These results show that physical habitat and watershed features were better predictors of walleye mercury concentration than water chemistry in glacial lakes of the Northern Great Plains.

Bulletin of Environmental Contamination and Toxico↗