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At least 1,189 records · Page 66Linked to original sources
USGS2012

Direct geoelectrical evidence of mass transfer at the laboratory scale

Previous field-scale experimental data and numerical modeling suggest that the dual-domain mass transfer (DDMT) of electrolytic tracers has an observable geoelectrical signature. Here we present controlled laboratory experiments confirming the electrical signature of DDMT and demonstrate the use of time-lapse electrical measurements in conjunction with concentration measurements to estimate the parameters controlling DDMT, i.e., the mobile and immobile porosity and rate at which solute exchanges between mobile and immobile domains. We conducted column tracer tests on unconsolidated quartz sand and a material with a high secondary porosity: the zeolite clinoptilolite. During NaCl tracer tests we collected nearly colocated bulk direct-current electrical conductivity (σ b ) and fluid conductivity (σ f ) measurements. Our results for the zeolite show (1) extensive tailing and (2) a hysteretic relation between σ f and σ b , thus providing evidence of mass transfer not observed within the quartz sand. To identify best-fit parameters and evaluate parameter sensitivity, we performed over 2700 simulations of σ f , varying the immobile and mobile domain and mass transfer rate. We emphasized the fit to late-time tailing by minimizing the Box-Cox power transformed root-mean square error between the observed and simulated σ f . Low-field proton nuclear magnetic resonance (NMR) measurements provide an independent quantification of the volumes of the mobile and immobile domains. The best-fit parameters based on σ f match the NMR measurements of the immobile and mobile domain porosities and provide the first direct electrical evidence for DDMT. Our results underscore the potential of using electrical measurements for DDMT parameter inference.

Water Resources Research↗
USGS2010

Vulnerability of white spruce tree growth in interior Alaska in response to climate variability: Dendrochronological, demographic, and experimental perspectives

This paper integrates dendrochronological, demographic, and experimental perspectives to improve understanding of the response of white spruce ( Picea glauca (Moench) Voss) tree growth to climatic variability in interior Alaska. The dendrochronological analyses indicate that climate warming has led to widespread declines in white spruce growth throughout interior Alaska that have become more prevalent during the 20th century. Similarly, demographic studies show that white spruce tree growth is substantially limited by soil moisture availability in both mid- and late-successional stands. Interannual variability in tree growth among stands within a landscape exhibits greater synchrony than does growth of trees that occupy different landscapes, which agrees with dendrochronological findings that the responses depend on landscape position and prevailing climate. In contrast, the results from 18 years of a summer moisture limitation experiment showed that growth in midsuccessional upland stands was unaffected by moisture limitation and that moisture limitation decreased white spruce growth in floodplain stands where it was expected that growth would be less vulnerable because of tree access to river water. Taken together, the evidence from the different perspectives analyzed in this study clearly indicates that white spruce tree growth in interior Alaska is vulnerable to the effects of warming on plant water balance.

Alaska↗
USGS2015

A comparison between boat-based and diver-based methods for quantifying coral bleaching

Recent increases in both the frequency and severity of coral bleaching events have spurred numerous surveys to quantify the immediate impacts and monitor the subsequent community response. Most of these efforts utilize conventional diver-based methods, which are inherently time-consuming, expensive, and limited in spatial scope unless they deploy large teams of scientifically-trained divers. In this study, we evaluated the effectiveness of the Along-Track Reef Imaging System (ATRIS), an automated image-acquisition technology, for assessing a moderate bleaching event that occurred in the summer of 2011 in the Florida Keys. More than 100,000 images were collected over 2.7 km of transects spanning four patch reefs in a 3-h period. In contrast, divers completed 18, 10-m long transects at nine patch reefs over a 5-day period. Corals were assigned to one of four categories: not bleached, pale, partially bleached, and bleached. The prevalence of bleaching estimated by ATRIS was comparable to the results obtained by divers, but only for corals > 41 cm in size. The coral size-threshold computed for ATRIS in this study was constrained by prevailing environmental conditions (turbidity and sea state) and, consequently, needs to be determined on a study-by-study basis. Both ATRIS and diver-based methods have innate strengths and weaknesses that must be weighed with respect to project goals.

Florida↗
USGS1984

Chromatographic investigations of the configurational and geometrical isomerism of allylic N-terpenyl-N-hydroxyethyl-nitrosamines

A preparative adsorption column chromatographic method is reported for the separation of cis and trans geometrical isomers of two types of N-nitrosamines derived from allylic terpenyl ethanolamines (experimental fish toxicants). Column eluates were monitored by gas chromatography in which a Carbowax 20M stationary phase was used. Further separation of E and Z configurational isomers was achieved by reversed-phase and normal-phase high-performance liquid chromatography. In the reversed-phase high-performance liquid chromatography system (acetonitrilewater), the 6′,7′-acetylenic nitrosamines (NMOA) were efficiently resolved by using an argentous (AgNO 3 ) mobile phase, whereas the presence of sodium alkanesulfonate in the aqueous acetonitrile mobile phase favored the base-line resolution of the 6′,7′-olefinic nitrosamines (NDOA). For normal-phase separation on a silica column, addition of tetrahydrofuran to the mobile phase (methylene chloride-2-propanol) resulted in a varying degree of improvement in peak resolution ( R ) and column selectivity (α). Effects of temperature on the chromatographic behavior of the nitrosamine components are described. The high-performance liquid chromatographic separation method has proved to be applicable for the trace analysis of the title nitrosamines in organic tissues by way of thermal energy analysis.

Journal of Chromatography↗
USGS2020

Does the Darcy-Buckingham Law apply to flow through unsaturated porous rock?

The Darcy–Buckingham (DB) law, critical to the prediction of unsaturated flow, is widely used but has rarely been experimentally tested, and therefore may not be adequate in certain conditions. Failure of this law would imply that the unsaturated hydraulic conductivity is not constant for a given water content, as assumed in nearly all subsurface flow models. This study aims to test the DB law on unsaturated porous rock, complementing the few previous tests, all done on soils. Two lithotypes of calcareous porous rocks were tested. The quasi-steady centrifuge method was used to measure the flux density for different centrifugal driving forces while maintaining essentially constant water content, as required. Any deviations from the direct proportionality of the measured flux and the applied force would indicate a violation of the DB law. Our results show that, for the tested rocks and conditions, no physical phenomena occurred to cause a failure of the DB law.

Water↗
USGS1985

EVALUATION OF THE EFFECTS OF WEATHERING ON A 50-YEAR OLD RETORTED OIL-SHALE WASTE PILE, RULISON EXPERIMENTAL RETORT, COLORADO.

An oil-shale mine and experimental retort were operated near Rulison, Colorado by the U. S. Bureau of Mines from 1926 to 1929. Samples from seven drill cores from a retorted oil-shale waste pile were analyzed to determine 1) the chemical and mineral composition of the retorted oil shale and 2) variations in the composition that could be attributed to weathering. Unweathered, freshly-mined samples of oil shale from the Mahogany zone of the Green River Formation and slope wash collected away from the waste pile were also analyzed for comparison. The waste pile is composed of oil shale retorted under either low-temperature (400-500 degree C) or high-temperature (750 degree C) conditions. The results of the analyses show that the spent shale within the waste pile contains higher concentrations of most elements relative to unretorted oil shale.

Conference Paper↗
USGS2020

Bottom trawl assessment of Lake Ontario prey fishes, 2019

Multi-agency, collaborative Lake Ontario bottom trawl surveys provide information for decision making related to Fish Community Objectives including predator-prey balance and understanding prey fish community diversity. In 2019, bottom trawl surveys in April (n = 252 tows) and October (n = 160 tows) sampled main lake and embayments at depths from 5–226 m. Combined, the surveys captured 283,383 fish from 39 species. Alewife were 67% of the total catch by number while round goby, deepwater sculpin, and rainbow smelt comprised 13, 10, and 4% of the catch, respectively. In 2019, the lake-wide adult alewife biomass index declined from 2018 and age-1 biomass, a measure of reproductive success the previous year, was low. Year-class catch curve models identified years where estimates from surveys conducted only in U.S. waters were biased, potentially due to a greater portion of the alewife population inhabiting unsampled Canadian waters. Accounting for spatial survey bias, these model estimates indicated the 2019 adult alewife biomass was the lowest value in the 42-year time series. Models also identified the extent to which age-1 alewife biomass was historically underestimated, however lake-wide results from 2016-2019 appear less biased. If below-average year-class estimates from 2017 and 2018 are accurate, adult alewife biomass will continue to decline in 2020. Abundance indices for other pelagic prey fishes such as rainbow smelt, threespine stickleback, emerald shiner, and cisco were low and similar to 2018 values. Pelagic prey fish diversity is low because a single species, alewife, dominates the community. Deepwater sculpin and round goby were the most abundant demersal (bottom-oriented) prey fishes in 2019. Despite declines in slimy sculpin and other nearshore prey fishes, demersal prey fish community diversity has increased as deepwater sculpin and round goby comprise more even portions of the community. New experimental trawl sites in embayment habitats generally captured more species, a higher proportion of native species, and higher densities relative to main lake habitats. In 2019, a western tubenose goby (Proterorhinus semilunaris) was captured for the first time in the trawl surveys.

Lake Ontario↗
USGS2020

Effect of an environmental flow on vegetation growth and health using ground and remote sensing metrics

Understanding the effectiveness of environmental flow deliveries along rivers requires monitoring vegetation. Monitoring data are often collected at multiple spatial scales. For riparian vegetation, optical remote sensing methods can estimate growth responses at the riparian corridor scale, and field‐based measures can quantify species composition; however, the extent to which these different measures are duplicative or complementary is important to understand when planning monitoring programmes with limited resources. In this study, we analysed riparian vegetation growth in the delta of the Colorado River in response to an experimental pulse flow. Our goal was to compare ground‐based measurements of vegetation structure and composition with satellite‐based Landsat radiometric variables, such as the normalized difference vegetation index (NDVI). We made this comparison in 21 transects following the delivery of 131.8 million cubic meters (mcm) of water in the stream channel during the spring of 2014 as a pulse flow and 38.4 mcm as base flows. Vegetation cover increased 14% and NDVI increased 0.02 (15%) by October 2015, and both variables returned to pre‐pulse flow values in October 2016. Observed changes in vegetation structure and composition did not persist after the second year. The highest increase in vegetation cover in October 2014 and October 2015 resulted from species that could respond rapidly to additional water such as reeds ( Arundo donax and Phragmites australis ), cattail ( Typha domingensis ), and herbaceous plants. Dominant shrubs, saltcedar ( Tamarix spp.) and arrowweed ( Pluchea sericea ), both indicative of nonrestored habitats showed variable increases in cover, and native trees ( Salicaceae family) presented low increases (1%). The strong NDVI–vegetation cover relationship indicates that NDVI is appropriate to detect changes at the riparian corridor scale but needs to be complemented with ground data to determine the contributions by different species to the observed trends.

Colorado River↗
USGS2011

Response of an algal assemblage to nutrient enrichment and shading in a Hawaiian stream

To investigate the effects of nitrate enrichment, phosphate enrichment, and light availability on benthic algae, nutrient-diffusing clay flowerpots were colonized with algae at two sites in a Hawaiian stream during spring and autumn 2002 using a randomized factorial design. The algal assemblage that developed under the experimental conditions was investigated by determining biomass (ash-free dry mass and chlorophyll a concentrations) and composition of the diatom assemblage. In situ pulse amplitude-modulated fluorometry was also used to model photosynthetic rate of the algal assemblage. Algal biomass and maximum photosynthetic rate were significantly higher at the unshaded site than at the shaded site. These parameters were higher at the unshaded site with either nitrate, or to a lesser degree, nitrate plus phosphate enrichment. Analysis of similarity of diatom assemblages showed significant differences between shaded and unshaded sites, as well as between spring and autumn experiments, but not between nutrient treatments. However, several individual species of diatoms responded significantly to nitrate enrichment. These results demonstrate that light availability (shaded vs. unshaded) is the primary limiting factor to algal growth in this stream, with nitrogen as a secondary limiting factor.

Hawaii↗
USGS1986

Evaluation of coded wire tags for marking lake trout

Among hatchery-reared lake trout ( Salvelinus namaycush ) of the 1979-1982 year classes stocked in New York waters of Lake Ontario, more than 3 million fish were marked with a coded wire tag (CWT) plus an adipose fin clip, and 1.5 million with only conventional fin clips. Altogether, 7,640 tags were recovered from fish collected with bottom trawls and gill nets or caught by anglers during 1980-1983. One person was able to extract and decipher 200 or more CWTs per day with about a 1% error rate in reading and recording codes. Presence of the CWT did not affect growth. The adipose fin clip did not regenerate. The occurrence of fish with an adipose fin clip but no CWT resulted primarily from the regeneration of paired fins among fish marked with a combination of the adipose fin and a paired fin. Loss of CWTs between marking and stocking (generally 4-5 months for fish stocked in spring and 1-8 d for fish stocked in fall) declined from nearly 11% for the 1979 year class stocked as fall fingerlings to less than 3% for the 1981 and 1982 year classes - a difference that primarily reflected improvements in instrumentation and tagging technique. The rate of CWT loss after the marked fish were stocked was probably less than 1% per year. The CWT is a reliable method for marking hatchery-reared lake trout. A large number of experimental groups can be uniquely marked, and fish from each group can be accurately identified throughout their life. Use of this technique should greatly facilitate evaluations of genetic strain, hatchery experience, condition at time of stocking, season of stocking, size at stocking, method of stocking and other factors that affect poststocking survival and performance of lake trout stocked in the Great Lakes.

North American Journal of Fisheries Management↗
USGS1999

Duck plague

Duck plague is caused by a herpesvirus. Infection often results in an acute, contagious, and fatal disease. As with many other herpesviruses, duck plague virus can establish inapparent infections in birds that survive exposure to it, a state referred to as latency. During latency, the virus cannot be detected by standard methods for virus isolation. Studies of domestic species of waterfowl have detected multiple strains of the virus that vary in their ability to cause disease and death. Little is known about the response of wild waterfowl to strain differences. Duck plague outbreaks are thought to be caused when birds that carry the virus shed it through fecal or oral discharge, thus releasing the virus into food and water with which susceptible birds may have contact. Experimental studies have demonstrated spontaneous virus shedding by duck plague carriers during spring. Changes in the duration of daylight and onset of breeding are thought to be physiological stresses that stimulate virus shedding at this time of year. The carriers are immune to the disease, but the virus shed by them causes infection and disease among susceptible waterfowl. Bird-to-bird contact and contact with virus that has contaminated the environment perpetuate an outbreak. Scavenging and decomposition of carcasses of infected birds also contaminate the environment by releasing viruses from tissues and body fluids. Virus transmission through the egg has been reported, but the role of the egg in the disease cycle remains to be resolved.

Information and Technology Report↗
USGS2019

Experimental study on the impact of thermal maturity on shale microstructures using hydrous pyrolysis

Hydrous pyrolysis was applied to four low-maturity aliquots from the Utica, Excello, Monterey, and Niobrara Shale Formations in North America to create artificial maturation sequences, which could be used to study the impact of maturation on geochemical and microstructural properties. Modified Rock-Eval pyrolysis, reflectance, organic petrology, and Fourier transform infrared spectroscopy (FTIR) were employed to analyze their geochemical properties, while gas adsorption (CO 2 and N 2 ) was used to characterize their pore structures (pores < 200 nm). Organic petrography using white and blue light (fluorescence) before and after hydrous pyrolysis showed that amorphous organic matter cracked into solid bitumen, oil, and gas during hydrous pyrolysis. A reduction of the CH 2 /CH 3 ratio in hydrous pyrolysis residues was observed from FTIR analysis. Rock-Eval pyrolysis showed that kerogens in the four samples were dissimilar, and hydrous pyrolysis residues showed smaller hydrogen index and Sh2 values than starting materials. Results from CO 2 and N 2 gas adsorption analysis showed that pore structures (micropore volume, micropore surface area, meso-macropore volume, and meso-macropore surface area) changed significantly during hydrous pyrolysis. However, changes in pore structure were dissimilar among the four samples, which was attributed to different activation energies of organic matter. A thermodynamic fractal model showed a decrease in fractal dimensions of Utica, Monterey, and Excello after hydrous pyrolysis, indicating a decrease in surface roughness. The pore size heterogeneity in the Utica sample increased as hydrous pyrolysis temperature increased, whereas the pore size heterogeneity distributions in the Monterey and Excello decreased based on the N 2 adsorption data.

Energy & Fuels↗
USGS2012

Probing the Earth's strength: Can we measure small stress at high pressure?

Simulating the conditions and processes that occur in the Earth's deep interior has been a major goal of experimental geophysics since the 1920s. In particular, pioneers such as P. W. Bridgman, David Griggs, Hugh Heard, Mervyn Paterson, William Brace, and their colleagues sought to establish the basic relations between differential stresses and rock and mineral deformation under pressure-temperature conditions that favor such inelastic processes as brittle fracture, frictional sliding, plastic deformation, and dynamic metamorphism. This work has been applied to diverse problems in the Earth sciences, including the physical nature of earth quake sources, the forces that drive and resist plate movement, deformation under partial-melting conditions at the tops of mantle plumes, the flexure of the lithosphere, post-glacial rebound, and the origin of the preferred orientation of minerals and the resultant seismic anisotropy and metamorphic textures.

Eos, Transactions, American Geophysical Union↗
USGS2005

Distribution, foraging behavior, and capture results of the spotted bat (Euderma maculatum) in central Oregon

The spotted bat (Euderma maculatum) has been virtually unknown in Oregon despite the existence of potential habitat in many areas of the state. In 2002 and 2003 we searched for spotted bats along the John Day, Deschutes, and Crooked Rivers and at a remote dry canyon southeast of the city of Bend in central Oregon. The species was documented through the use of mist-nets, a bat detector, and recognition of audible spotted bat calls. Spotted bats were found at 11 locations in 6 Oregon counties. Nightly activity patterns of spotted bats were unpredictable. Spotted bats were found in 78% of search areas but on only 48% of survey nights. We observed spotted bats foraging above fields and low upland slopes adjacent to rivers and creeks and along the rims of cliffs. Estimated flying heights of spotted bats ranged from 3 m to 50 m aboveground. The species was difficult to capture and was captured only after considerable experimentation with methods and materials. Three spotted bats were captured toward the end of the project in 2003 and accounted for only 0.5% of all bats captured during the study. Although we attached radio transmitters to 2 spotted bats, we found no roost locations. We believe additional spotted bat surveys in Oregon are warranted, especially in higher-elevation habitats, but recommend that to increase their effectiveness, surveys accommodate the unique foraging behavior of the species.

Western North American Naturalist↗
USGS2019

Geese mediate vegetation state changes with parallel effects on N cycling that leave nutritional legacies for offspring

Along the coastal fringe of the Yukon–Kuskokwim River Delta in southwestern Alaska, geese maintain grazing lawns dominated by a rhizomatous sedge that, when ungrazed, transitions to a taller, less palatable growth form that is taxonomically described as a different species. Nutrients recycled in goose feces, in conjunction with grazing, are critical to the rapid, nutritious growth of grazing lawns, and selective foraging on lawns has positive life‐history consequences for goslings. To examine whether bidirectional vegetation shifts were accompanied by parallel changes in N cycling, we studied how 15 N‐urea and 13 C 15 N‐glycine were processed through soils and plants of native and recently reverted vegetation states. Biomass and plant 15 N uptake from plots reverted to the tall growth form using exclosures and from those shifted to grazing lawns by experimental clipping and then goose grazing were identical to their native counterparts. Total recovery of 15 N within the tall vegetation types was significantly greater than within grazing lawns, although when expressed on a per‐gram biomass basis, percentage of 15 N recovery was significantly higher in grazing lawns compared with the tall vegetation state. Patterns of 13 C enrichment in CO 2 soil efflux showed rapid use of 13 C‐glycine as a respiratory substrate within the first hour following injection, with both the timing and magnitude of efflux occurring at similar time points for all four vegetation types. However, higher soil respiration rates and a shorter half‐life for 13 C‐glycine in soils from tall meadows resulted in a greater proportional loss of 13 CO 2 compared with grazing lawns. Despite daily‐to‐weekly tidal inundation, all of 15 N from labeled substrates could be accounted for within 1 m of the injection grid from soils of both states after 30 d, with significant levels of 15 N in soils and vegetation after one year. Geese have remarkably high fidelity to brood‐rearing areas, returning as adults to the same grazing lawns where they were raised as goslings. Our data suggest that the role fecal‐derived nutrients play in the positive feedback loop between geese and their food resources can provide a long‐term legacy that spans generations.

Alaska↗
USGS2023

Assessing contaminants of emerging concern in the Great Lakes Ecosystem: A decade of method development and practical application

Assessing the ecological risk of contaminants in the field typically involves consideration of a complex mixture of compounds which may or may not be detected via instrumental analyses. Further, there are insufficient data to predict the potential biological effects of many detected compounds, leading to their being characterized as contaminants of emerging concern (CECs). Over the past several years, advances in chemistry, toxicology, and bioinformatics have resulted in a variety of concepts and tools that can enhance the pragmatic assessment of the ecological risk of CECs. The present Focus article describes a 10+- year multiagency effort supported through the U.S. Great Lakes Restoration Initiative to assess the occurrence and implications of CECs in the North American Great Lakes. State-of-the-science methods and models were used to evaluate more than 700 sites in about approximately 200 tributaries across lakes Ontario, Erie, Huron, Michigan, and Superior, sometimes on multiple occasions. Studies featured measurement of up to 500 different target analytes in different environmental matrices, coupled with evaluation of biological effects in resident species, animals from in situ and laboratory exposures, and in vitro systems. Experimental taxa included birds, fish, and a variety of invertebrates, and measured endpoints ranged from molecular to apical responses. Data were integrated and evaluated using a diversity of curated knowledgebases and models with the goal of producing actionable insights for risk assessors and managers charged with evaluating and mitigating the effects of CECs in the Great Lakes. This overview is based on research and data captured in approximately about 90 peer-reviewed journal articles and reports, including approximately about 30 appearing in a virtual issue comprised of highlighted papers published in Environmental Toxicology and Chemistry or Integrated Environmental Assessment and Management . Environ Toxicol Chem 2023;42:2506–2518. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Environmental Toxicology and Chemistry↗
USGS2025

Reaction kinetics and accelerant effects of sulfides in early mature hydrocarbon generation using hydrous pyrolysis

Hydrocarbon generation in organic-rich sediments is influenced by the molecular organic composition and relative abundance of associated minerals. Certain mineral-derived elements act as catalysts and reaction intermediaries, facilitating early-stage hydrocarbon formation in potential source rocks. This study investigated the role of sulfur contributed from pyrite as an accelerant in thermal reaction, focusing on its effects on early maturation and consequent hydrocarbon generation from gilsonite (low-sulfur solid petroleum). Hydrous pyrolysis (HP) experiments were conducted on mixtures of gilsonite and pyrite in varying ratios (1:0.1, 1:0.5, 1:1, 1:2, and 1:10 w/w gilsonite:pyrite) at 320, 350, and 370 °C for 72 h. Untreated and thermally altered residues were analyzed using solid bitumen reflectance (BR o , %), total organic carbon (TOC) content, programmed temperature pyrolysis, scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) to evaluate the potential accelerant role of pyritic sulfur in hydrocarbon formation. The results show HP residues at 320 and 350 °C with greater pyrite concentrations had higher BR o , while reflectance values were similar in the 370 °C residues, regardless of pyrite concentration, suggesting enhanced reaction at lower thermal conditions. Increasing pyrite content systematically decreased hydrogen index (HI) values while increasing the transformation ratio (TR) and production index (PI), indicating enhanced conversion of organic matter to hydrocarbons with increasing pyrite concentrations. Gas yields increased with pyrite addition, particularly at 350 °C, confirming secondary cracking effects. However, gas production stabilized or declined at higher pyrite loadings (1:10), suggesting alternative reaction pathways such as coke formation. Our data indicate the presence of pyrite lowers the activation energy for thermal cracking, shifting peak experimental hydrocarbon generation temperatures downward by 20–30 °C, with the most pronounced accelerant effects observed at moderate pyrite concentrations (1:0.5 and 1:1). The thermodynamic framework reveals that pyrite stability is influenced by experimental conditions, with pyrrhotite formation favored in the presence of gilsonite due to reduced oxygen fugacity. Pyrite transformation to pyrrhotite, as observed through XRD, SEM-EDS, and predicted by thermodynamic data, further supports the accelerant role of S, as pyrrhotite exhibits a higher hydrogen transfer potential, promoting early oil generation. These findings highlight the importance of pyrite in modulating hydrocarbon generation pathways in organic-rich systems.

Journal of Analytical and Applied Pyrolysis↗
USGS2024

On the survival and habitat use of hatchery-reared cisco (Coregonus artedi) in Lake Erie

Cisco ( Coregonus artedi ) have been extirpated from Lake Erie in North America since the 1960s, but they once supported one of the largest Laurentian Great Lakes fisheries. Numerous potential impediments to rehabilitation have been identified, including summer habitat refugia and predation. We used acoustic telemetry to investigate the thermal habitat use and survival of hatchery-reared adult cisco in Lake Erie. Fish were experimentally released (n = 50 per site) offshore at Dunkirk, New York, in the eastern basin and Huron, Ohio, in the central basin. Cisco in both basins found suitable summer oxythermal habitat in the metalimnion, suggesting that coldwater habitat availability is likely not an impediment for reestablishment. However, track end dates or predation dates were distributed across only four months with the last detection at 155 days. Predation sensors combined with temperature values during digestion indicated different potential predators: lake trout ( Salvelinus namaycush ) for the Dunkirk group and walleye ( Sander vitreus ) for the Huron group. Additionally, digestion temperatures of two tags indicated bird predation was also important, likely underestimated and suggested substantial use of the epilimnion by tagged fish. The results highlight the need for additional studies to address stocking optimization questions in support of future reintroduction experiments and related cisco conservation efforts.

Lake Erie↗