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At least 1,351 records · Page 75Linked to original sources
USGS2023

Evaluate propagation efforts and determine dispersal patterns for Quadrula fragosa from tagged, artificially infested host fish (Ictalurus punctatus) in the St. Croix National Scenic Riverway (SACN)

The St. Croix National Scenic Riverway (SACN) has been the site of propagation and restoration efforts for two federally endangered unionid mussels: Higgins’ Eye, Lampsilis higginsii and Winged Mapleleaf (WML), Quadrula fragosa. Since about 2000, government agencies have collaboratively developed techniques to successfully propagate Higgins’ Eye and reintroduce the captive-reared subadult mussels into rehabilitated habitats in the upper Mississippi River Basin and several tributaries, including the SACN. However, propagation efforts for the WML have had limited success from 2003 to present. The population of WML in the SACN has high value because it is physically isolated and genetically distinct from four southern populations, and it is the only known self-sustaining population within the upper Mississippi River. Unionids have a complex reproductive cycle that includes a parasitic larval stage (glochidia) that requires species-specific fish hosts. WML are one of the few species that are fall, short-term (~6 weeks) brooders—brooding begins at end of August. In the SACN, Channel Catfish ( Ictalurus punctatus ) are the only known host for WML and glochidia are assumed to overwinter on their host fish and detach the following spring. Research has shown that holding hatchery reared channel catfish that are infested with WML glochidia in cages, either in situ or in a hatchery, over winter has been a challenge due to high fish mortality; rearing juveniles after transformation has also resulted in high mortality rates and juvenile loss (Wege et al. 2007). The importance of the overwintering parasitic period and the overall health of the host fish for successful transformation of juvenile WML is unknown, but these key criteria could play an important role in successful propagation efforts. This research has three objectives: (1) compile historic data from >14 years of Q. fragosa propagation efforts into a searchable database to identify potential knowledge gaps that could be limiting its success, (2) explore in situ and ex situ propagation techniques to optimize production of Q. fragosa juveniles, and (3) characterize the movement pattern of Channel Catfish that are artificially inoculated with the SACN strain of Q. fragosa to identify potential juvenile release survey locations in future years.

Minnesota, Wisconsin↗
USGS2022

Evaluate propagation efforts and determine dispersal patterns for Quadrula fragosa from tagged, artificially infested host fish (Ictalurus punctatus) in the St. Croix National Scenic Riverway (SACN)

The St. Croix National Scenic Riverway (SACN) has been the site of propagation and restoration efforts for two federally endangered unionid mussels: Higgins’ Eye, Lampsilis higginsii and Winged Mapleleaf (WML), Quadrula fragosa. Since about 2000, government agencies have collaboratively developed techniques to successfully propagate Higgins’ Eye and reintroduce the captive-reared subadult mussels into rehabilitated habitats in the upper Mississippi River Basin and several tributaries, including the SACN. However, propagation efforts for the WML have had limited success from 2003 to present. The population of WML in the SACN has high value because it is physically isolated and genetically distinct from four southern populations, and it is the only known self-sustaining population within the upper Mississippi River. Unionids have a complex reproductive cycle that includes a parasitic larval stage (glochidia) that requires species-specific fish hosts. WML are one of the few species that are fall, short-term (~6 weeks) brooders—brooding begins at end of August. In the SACN, Channel Catfish ( Ictalurus punctatus ) are the only known host for WML and glochidia are assumed to overwinter on their host fish and detach the following spring. Research has shown that holding hatchery reared channel catfish that are infested with WML glochidia in cages, either in situ or in a hatchery, over winter has been a challenge due to high fish mortality; rearing juveniles after transformation has also resulted in high mortality rates and juvenile loss (Wege et al. 2007). The importance of the overwintering parasitic period and the overall health of the host fish for successful transformation of juvenile WML is unknown, but these key criteria could play an important role in successful propagation efforts. This research has three objectives: (1) compile historic data from >14 years of Q. fragosa propagation efforts into a searchable database to identify potential knowledge gaps that could be limiting its success, (2) explore in situ and ex situ propagation techniques to optimize production of Q. fragosa juveniles, and (3) characterize the movement pattern of Channel Catfish that are artificially inoculated with the SACN strain of Q. fragosa to identify potential juvenile release survey locations in future years.

Minnesota, Wisconsin↗
USGS2017

Responses of invasive silver and bighead carp to a carbon dioxide barrier in outdoor ponds

Resource managers need for effective methods to prevent the movement of silver ( Hypophthalmichthys molitrix ) and bighead carp ( H. nobilis ) from the Mississippi River basin into the Laurentian Great Lakes. In this study, we evaluated dissolved carbon dioxide (CO 2 ) as a barrier and deterrent to silver (278 ± 30.5 mm) and bighead (212 ± 7.7 mm) carp movement in continuous-flow outdoor ponds. As a barrier, CO 2 significantly reduced upstream movement but was not 100% effective at blocking fish passage. As a deterrent, we observed a significant shift away from areas of high CO 2 relative to normal movement before and after injection. Carbon dioxide concentrations varied across the pond during injection and reached maximum concentrations of 74.5±1.9 mg/L CO 2 ; 29 532 – 41 393 µatm at the site of injection during three independent trials. We conclude that CO 2 altered silver and bighead carp movement in outdoor ponds and recommend further research to determine barrier effectiveness during field applications.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2024

The Khonkho tephra: A large-magnitude volcanic eruption coincided with the rise of Tiwanaku in the Andes

We report a tephra deposit in the southern Lake Titicaca Basin, Bolivia, which was deposited by a major, previously unrecognized eruption sometime between AD 400 and 720. Archaeological data suggest these centuries were characterized by a substantial community migration to Tiwanaku, where social interaction networks gave birth to one of the Andes’ first large complex societies. Here we provide an initial characterization of this tephra, based on samples from the archaeological site Khonkho Wankane. The same tephra is present at two other archaeological sites in the region. Given the great distance to the nearest active volcano, this tephra layer likely derives from a large-magnitude, Late-Holocene explosive eruption of a Central Andean volcano. We suggest that this major event be included in the human history of the region, given its inferred magnitude and wide dispersal area. Future research could confirm the Khonkho tephra at other sites, identify the source volcano, estimate its volume, and more precisely date the eruption.

southern Lake Titicaca Basin↗
USGS2009

Anisotropic Velocities of Gas Hydrate-Bearing Sediments in Fractured Reservoirs

During the Indian National Gas Hydrate Program Expedition 01 (NGHP-01), one of the richest marine gas hydrate accumulations was discovered at drill site NGHP-01-10 in the Krishna-Godavari Basin, offshore of southeast India. The occurrence of concentrated gas hydrate at this site is primarily controlled by the presence of fractures. Gas hydrate saturations estimated from P- and S-wave velocities, assuming that gas hydrate-bearing sediments (GHBS) are isotropic, are much higher than those estimated from the pressure cores. To reconcile this difference, an anisotropic GHBS model is developed and applied to estimate gas hydrate saturations. Gas hydrate saturations estimated from the P-wave velocities, assuming high-angle fractures, agree well with saturations estimated from the cores. An anisotropic GHBS model assuming two-component laminated media - one component is fracture filled with 100-percent gas hydrate, and the other component is the isotropic water-saturated sediment - adequately predicts anisotropic velocities at the research site.

Scientific Investigations Report↗
USGS2006

Palynology and age of some Cretaceous nonmarine deposits in Mongolia and China

To provide biostratigraphic and paleoecologic data for a major international project studying dinosaur trackways in eastern Asia, samples were collected for palynological analysis from the Choyr Basin of southeastern Mongolia and the Yanji Basin, Jilin Province, northeastern China. Palynologically productive samples from the Choyr Basin are from strata previously identified as either the Shinekhudag Formation or the Zuunbayan Formation but recently renamed the Khuren Dukh Formation; productive samples from the Yanji Basin are from the Tongfosi Formation. The biostratigraphically most important palynomorphs from both units are angiosperm pollen. The Khuren Dukh Formation is determined to be middle to late Albian in age. The Tongfosi Formation is determined to be early Cenomanian in age. These results conflict with some previously published interpretations of the ages of these units. Lacustrine depositional environments are indicated for both units by the presence of freshwater algae in both deposits. ?? 2006 Elsevier Ltd. All rights reserved.

Cretaceous Research↗
USGS2005

Sub-seafloor acoustic characterization of seamounts near the Ogasawara Fracture Zone in the western Pacific using chirp (3-7 kHz) subbottom profiles

A detailed analysis of chirp (3-7 kHz) subbottom profiles and bathymetry was performed on data collected from seamounts near the Ogasawara Fracture Zone (OFZ) in the western Pacific. The OFZ, which is a 150 km wide rift zone showing 600 km of right-lateral movement in a NW-SE direction, is unique among the fracture zones of the Pacific in that it includes many old seamounts (e.g., Magellan Seamounts and seamounts on Dutton Ridge). Sub-seafloor acoustic echoes on the seamounts are classified into nine specific types based on the nature and continuity of the echoes, subbottom structure, and morphology of the seafloor: (1) distinct echoes (types I-1, I-2, I-3), (2) indistinct echoes (types II-1, II-2, II-3), and (3) hyperbolic echoes (types III-1, III-2, III-3). Type I-2 pelagic sediments, characterized by thin and intermittent coverage, were probably deposited in topographically sheltered areas when bottom currents were strong, whereas type I-1 pelagic sediments accumulated during continuous and widespread sedimentation. Development of seamount flank rift zones in the OFZ may have been influenced by preexisting structures in the transform fracture zone at the time of volcanism, whereas those on Ita Mai Tai seamount in the Pigafetta Basin originated solely by edifice-building processes. Flank rift zones that formed by dike intrusions and eruptions played an important role in mass wasting. Mass-wasting processes included block faulting or block slides around the summit margin, sliding/slumping, debris flows, and turbidites, which may have been triggered by faulting, volcanism, dike injection, and weathering during various stages in the evolution of the seamounts. ?? 2005 Elsevier Ltd. All rights reserved.

Deep-Sea Research Part I: Oceanographic Research P↗
USGS2023

Microfaunal recording of recent environmental changes in the Herschel Basin, western Arctic Ocean

Microfaunal assemblages of benthic foraminifera, ostracods, and tintinnids from two marine sediment cores retrieved from the Herschel Basin of the Canadian Beaufort Sea shelf document relationships with environmental parameters such as salinity, sea-ice cover, and turbulence. Cores YC18-HB-GC01 and PG2303-1 were collected at 18 and 32 m water depth, respectively. At these sites, sediment accumulation rates range between 0.6 and 1.7 cm yr –1 allowing a near-annual temporal resolution over the last 50 years. Multivariate analyses indicate that benthic foraminiferal assemblages respond primarily to food supply. Dissimilarities between the microfaunal assemblages of the two cores are mainly the result of bottom water salinity levels linked to water depth. High abundance of the benthic foraminiferal species Elphidium clavatum and occurrences of Elphidium bartletti point to varying, but relatively low, salinities at the shallow core site YC18-HB-GC01, which may be affected by variations in the summer halocline depth. Higher species diversity and more abundant Cassidulina reniforme and Stainforthia feylingi characterize the deeper core PG2303-1, which might reflect more stable conditions and higher bottom-water salinities throughout the studied time interval. The most important microfaunal shift of the last 50 years, observed in the shallower longer core YC18-HB-GC01, occurred at the turn of the 21 st century. Prior to ∼2000 CE, the presence of Islandiella norcrossi indicates more stable and saline conditions. Since ∼2000 CE, increased abundances of Haynesina nivea and of the ciliate Tintinnopsis fimbriata suggest decreased salinity and increased turbidity. An increased abundance of Eoeponidella pulchella after ∼2000 CE suggests a concurrent increase in productivity in the last two decades. This shift is nearly synchronous with a decrease in mean summer sea-ice concentration, which can play an important role in bottom water stability on the shelf. Easterly winds can induce a reduction in the sea-ice cover, but also foster a westward spreading of the Mackenzie River plume and the upwelling of nutrient-rich Pacific waters onto the shelf. Both factors would explain the increased freshening and productivity of the Herschel Basin. The last two decades were also marked by a decrease in ostracod abundance that may relate to higher water turbidity. This study shows that combining information from benthic foraminifera, ostracods, and tintinnids provides a comprehensive insight into recent hydrographic/climatic changes in nearshore Arctic habitats, where productivity is critical for the food security of local communities.

Herschel Basin↗
USGS2023

Quality of thermal refuges influences use by the cold-intolerant Florida manatee

ABSTRACT: Thermal refuges are habitats used by species for behavioral thermoregulation. These habitats can be highly dynamic and are often influenced by fluctuations in local climate. When protected species require thermal refuges, it is necessary to identify stable and high-quality areas by evaluating species use in response to variation in thermal refuge quality. Here, we assessed behavioral thermoregulation in the Florida manatee Trichechus manatus latirostris , a cold-intolerant marine mammal. Using metrics from ectotherm physiology, we evaluated thermal quality of 2 refuge types (passive thermal basins, natural springs) in 2 areas of their distribution. Thermal refuge quality was assessed with respect to the lower critical threshold of the manatee (20°C) and the surrounding ambient temperatures and compared between refuge types. We used GPS locations of manatees to quantify visits to refuges and calculated total visit duration in each refuge by individual manatees. At natural springs, we found a negative correlation between visit duration and ambient temperature during cold weather; visit duration also increased with the temperature differential between the spring and the lower critical thermal threshold. Visit duration at passive thermal basins was negatively correlated with the thermal differential between the refuge and the lower critical thermal threshold. The relationship between thermal refuge quality and time-use metrics sheds light on the potential implications of habitat degradation on animal energetics and behavior. Given these results, focusing on potential key refuges in each system may inform targeted management and habitat restoration efforts to maintain adequate thermal refuge environments for this listed species.

Florida↗
USGS1990

Anomalous chloride flux discharges from Yellowstone National Park

The chloride concentration of some thermal springs in and adjacent to Yellowstone National Park is constant through time although their discharge varies seasonally. As a result the chloride flux from these springs increases during periods of increased discharge. We believe that this is caused by changes in the height of the local groundwater table, which affects the discharge of the springs but not their chloride concentration. The discharge from Mammoth Hot Springs varies seasonally, but its chloride concentration remains constant. We take this as evidence that this major thermal feature is derived from orifices that are tapping the local water table close to its surface. Three of the four major rivers (Yellowstone, Snake and Falls) exiting the Park also show an increased chloride flux during the spring runoff that cannot be explained solely by the contribution of snowmelt, nor by release of hot-spring-derived chloride stored in the soil during the winter and released in the spring. The increased chloride flux in these rivers is attributed to their draining shallow hot springs similar to those mentioned above. In contrast to the Yellowstone, Snake and Falls Rivers, the Firehole and Gibbon Rivers, which unite to form the Madison River and which collectively drain several major geyser basins, display a poor correlation between chloride flux and discharge. The cause, we believe, is that a large part of the thermal water input to these two rivers originated at great depths where the seasonal variation in the height of the water table had a negligible effect on hot spring discharge. Monitoring of seasonal discharge and chloride concentration of thermal features yields information on the depths at which these thermal features tap the local water table. ?? 1990.

Journal of Volcanology and Geothermal Research↗
USGS2000

A review of the geologic framework of the Long Island Sound Basin, with some observations relating to postglacial sedimentation

Most of the papers in this thematic section present regional perspectives that build on more than 100 years of geologic investigation in Long Island Sound. When viewed collectively, a common theme emerges in these works. The major geologic components of the Long Island Sound basin (bedrock, buried coastal-plain strata, recessional moraines, glacial-lake deposits, and the remains of a large marine delta) interact with the water body to affect the way the modern sedimentary system functions. Previous work, along with our present knowledge of the geologic framework of the Long Island Sound basin, is comprehensively reviewed with this theme in mind. Aspects of the crystalline bedrock, and the deltaic deposits associated with glacial Lake Connecticut, are examined with respect to their influence on sedimentation along the Connecticut coast and in the northern and western Sound. We also discuss the influence of the glacial drift that mantles the coastal-plain remnant along the north shore of Long Island and in the southern Sound. A total of approximately 22.7 billion m 3 of marine sediment has accumulated in the Long Island Sound basin. A significant portion (44%) of the fine-grained marine section in the central and western basins was redistributed there from the eastern Sound, as tidal scour removed slightly over 5 billion m 3 (5.3 X 10 12 kg) of fine material from glacial lake and early-marine deposits east of the Connecticut River. The remainder of the estimated 1.2 X 10 13 kg of fine-grained marine sediment that now resides in the central and western Sound can be accounted for by riverine input over the past 13.5 ka.

Connecticut, New York↗
USGS1974

Regional flow system and ground-water quality in western Ohio

Most relatively deep wells drilled in the carbonate aquifers in western Ohio tap a recognizable regional flow system encompassing all or parts of several major basins. The principal recharge area includes the higher, central part of the region, where much of the terrane is hummocky to hilly glacial moraine. The principal discharge areas are the valleys of the major streams and lowlands along Lake Erie. Ground water moving through this system undergoes a progressive change in chemical quality, from a calcium bicarbonate type in recharge areas to a calcium sulfate type in discharge areas. Changes in selected chemical constituents are orderly and, within the observed parameters, predictable.

Ohio↗
USGS2012

Remarkable isotopic and trace element trends in potassic through sodic Cretaceous plutons of the Yukon-Koyukuk Basin, Alaska, and the nature of the lithosphere beneath the Koyukuk terrane

During the period from 110 to 80 m.y. ago, a 450-km-long magmatic belt was active along the northern margin of Yukon-Koyukuk basin and on eastern Seward Peninsula. The plutons intruded Upper Jurassic(?) and Lower Cretaceous volcanic arc rocks and Cretaceous sedimentary rocks in Yukon-Koyukuk basin and Proterozoic and lower Paleozoic continental rocks in Seward Peninsula. Within Yukon-Koyukuk basin, the plutons vary in composition from calc-alkalic plutons on the east to potassic and ultrapotassic alkalic plutons on the west. Plutons within Yukon-Koyukuk basin were analyzed for trace element and isotopic compositions in order to discern their origin and the nature of the underling lithosphere. Farthest to the east, the calc-alkalic rocks of Indian Mountain pluton are largely tonalite and sodic granodiorite, and have low Rb (average 82 ppm), high Sr (>600 ppm), high chondrite-normalized (cn) Ce/Yb (16–37), low δ 18 O (+6.5 to +7.1), low initial 87 Sr/ 86 Sr (SIR) (0.704), and high initial 143 Nd/ 144 Nd (NIR) (0.5126). These rocks resemble those modelled elsewhere as partial melts and subsequent fractionates of basaltic or gabbroic metaigneous rocks, and may be products of melting in the deeper parts of the Late Jurassic(?) and Early Cretaceous volcanic arc. Farthest to the west, the two ultrapotassic bodies of Selawik and Inland Lake are high in Cs (up to 93 ppm), Rb (up to 997 ppm), Sr, Ba, Th, and light rare earth elements, have high (Ce/Yb)cn (30, 27), moderate to low δ 18 O (+8.4, +6.9), high SIR (0.712, 0.710), and moderate NIR (0.5121–0.5122). These rocks resemble rocks of Australia and elsewhere that were modelled as melts of continental mantle that had been previously enriched in large cations. This mantle may be Paleozoic or older. The farthest west alkalic pluton of Selawik Hills is largely monzonite, quartz monzonite, and granite; has moderate Rb (average 284 ppm), high Sr (>600 ppm), high (Ce/Yb)cn (15–25), moderate δ 18 O (+8.3 to +8.6), high SIR (0.708–0.712), and moderate NIR (0.5121–0.5122). These rocks may be the product of interaction of magma derived from old continental mantle and magma derived from old continental crust. Plutons between eastern and western extremes show completely gradational variations in the concentration of K and Rb and in the isotopic compositions of Sr, Nd, and O. These plutons probably originated either by melting in a mixed source composed of a Paleozoic or older continental section (mantle + crust) overlain by Mesozoic mafic arc rocks, or by mixing of ultrapotassic to potassic magmas from continental sources (mantle + crust), and tonalitic magmas from arc sources. We infer from these results that the northwest portion of Yukon-Koyukuk basin is underlain by a substantial continental basement of Paleozoic or greater age. This basement probably thins out to the east. There is no geochemical evidence for continental basement east of about longitude 157°, or along a belt of at least 50 km width flanking Ruby Geanticline as far to the southwest as about longitude 161°. These areas are probably underlain by oceanic and Mesozoic arc rocks.

Alaska↗
USGS2010

Space, time, and the third dimension (model error)

The space-time tradeoff of hydrologic data collection (the ability to substitute spatial coverage for temporal extension of records or vice versa) is controlled jointly by the statistical properties of the phenomena that are being measured and by the model that is used to meld the information sources. The control exerted on the space-time tradeoff by the model and its accompanying errors has seldom been studied explicitly. The technique, known as Network Analyses for Regional Information (NARI), permits such a study of the regional regression model that is used to relate streamflow parameters to the physical and climatic characteristics of the drainage basin. The NARI technique shows that model improvement is a viable and sometimes necessary means of improving regional data collection systems. Model improvement provides an immediate increase in the accuracy of regional parameter estimation and also increases the information potential of future data collection. Model improvement, which can only be measured in a statistical sense, cannot be quantitatively estimated prior to its achievement; thus an attempt to upgrade a particular model entails a certain degree of risk on the part of the hydrologist.

Water Resources Research↗
USGS2010

Chemical weathering in the Loch Vale Watershed, Rocky Mountain National Park, Colorado

Mineralogic, hydrologic, and geochemical data were used to determine the source of solutes to surface waters draining the Loch Vale Watershed (LVWS), an alpine-subalpine drainage located in the Front Range of Colorado. The flux of dissolved solids from LVWS is primarily controlled by interactions between snowmelt and materials derived from the local bedrock; the biomass has only a minor effect on solute budgets except for ammonium. LVWS is underlain by Precambrian granite and gneiss, the major minerals include quartz, microcline, plagioclase, biotite, and sillimanite. Small amounts of calcite were found along hydrothermally altered zones in the bedrock. Mass balance calculations indicate that the weathering of calcite contributes nearly 40% of the cations derived within the basin. The importance of calcite weathering in LVWS is a result of its chemical reactivity and the high rate of physical erosion in this alpine environment. The average cationic denudation rate in the drainage (390 eq/ha/yr) is similar to long-term rates in forested Adirondack watersheds (500–600 eq/ha/yr), but much lower than the average for the North American Continent (3800 eq/ha/yr). Surface waters in LVWS are susceptible to acidification should acid deposition from the atmosphere increase.

Colorado↗
USGS1999

Cruise report for O1-99-SC Southern California Earthquake Hazards project

The focus of the Southern California Earthquake Hazards project is to identify the landslide and earthquake hazards and related ground-deformation processes occurring in the offshore areas that have significant potential to impact the inhabitants of the Southern California coastal region. The project activity is supported through the Coastal and Marine Geology Program of the Geologic Division of the U. S. Geological Survey (USGS) and is a component of the Geologic Division's Science Strategy under Goal 1—Conduct Geologic Hazard Assessments for Mitigation Planning (Bohlen et al., 1998). The project research is specifically stated under Activity 1.1.2 of the Science Strategy: Earthquake Hazard Assessments and Loss Reduction Products in Urban Regions. This activity involves "research, seismic and geodetic monitoring, field studies, geologic mapping, and analyses needed to provide seismic hazard assessments of major urban centers in earthquake-prone regions including adjoining coastal and offshore areas." The southern California urban areas, which form the most populated urban corridor along the U.S. Pacific margin, are among a few specifically designated for special emphasis under the Division's science strategy (Bohlen et al., 1998). The primary objective of the project is to help mitigate the earthquake hazards for the Southern California region by improving our understanding of how deformation is distributed (spatially and temporally) in the offshore with respect to the onshore region. To meet this objective, we are conducting field investigations to observe the distribution, character, and relative intensity of active (i.e., primarily Holocene) deformation within the basins and along the shelf adjacent to the most highly populated areas (Fig. 1). In addition, acoustic imaging should help determine the subsurface dimensions of the faults and identify the size and frequency of submarine landslides, both of which are necessary for evaluating the potential for generating destructive tsunamis in the southern California offshore. In order to evaluate the strain associated with the offshore structures, the initial results from the field mapping under this project will be used to identify possible sites for deployment of acoustic geodetic instruments to monitor strain in the offshore region. A major goal of mapping under this project is to provide detailed geologic and geophysical information in GIS data bases that build on the earlier studies and use the new data to precisely locate active faults and to map recent submarine landslide deposits.

California↗
USGS2020

Fisheries research and monitoring activities of the Lake Erie Biological Station, 2019

A comprehensive understanding of fish populations and their interactions is the cornerstone of modern fishery management and the basis for Fish Community Goals and Objectives for Lake Erie (Ryan et al. 2003). This report is responsive to U.S. Geological Survey (USGS) obligations via Memorandum of Understanding (MOU) with the Great Lakes Council of Lake Committees (CLC) to provide scientific information in support of fishery management. Goals for the USGS Great Lakes Deepwater Fish Assessment and Ecological Studies in 2019 were to monitor long-term changes in the fish community and population dynamics of key fishes of interest to management agencies. Specific to Lake Erie, expectations of this agreement were sustained investigations of native percids, forage (prey) fish populations, and Lake Trout. Our 2019 deepwater program operations began in April and concluded in December, and utilized trawl, gillnet, hydroacoustic, lower trophic sampling, and telemetry methods. This work resulted in 88 bottom trawls covering 65 ha of lake-bottom and catching 24,140 fish totaling 3,622 kg during three separate trawl surveys in the West and Central basins of Lake Erie. Overnight gillnet sets (n=44) for cold water species were performed at 42 unique locations in the West and East basins of Lake Erie. A total of 8.0 km of gillnet was deployed during these surveys, which caught 286 fish, 114 of which were native coldwater species: Lake Trout, Burbot, and Lake Whitefish. USGS hydroacoustic surveys in 2019 produced 240 km of transects, and lower trophic sampling provided data from zooplankton samples (n=21) and water quality profiles (n=21) to populate a database maintained by the Ontario Ministry of Natural Resources and Forestry (OMNRF), Ohio Division of Natural Resources (ODNR), Michigan Division of Natural Resources (MDNR), Pennsylvania Fish and Boat Commission (PFBC), and New York State Department of Environmental Conservation (NYSDEC). USGS also assisted CLC member agencies with deployment and maintenance of the Great Lakes Acoustic Telemetry Observation System (GLATOS) throughout all three Lake Erie sub-basins, supporting multiple coordinated telemetry investigations. In 2019, Lake Trout investigations included annual gill net surveys and acoustic telemetry of spawning migration and habitat use in coordination with OMNRF, NYSDEC, and PFBC. Results from Lake Trout investigations were reported in the Coldwater Task Group annual report to the Great Lakes Fishery Commission (GLFC) and the CLC (Coldwater Task Group 2020). Likewise, interagency forage fish assessments conducted with hydroacoustics were summarized and reported in the Forage Task Group annual report (Forage Task Group 2020). This report presents biomass-based summaries of fish communities in western Lake Erie derived from USGS bottom trawl surveys conducted from 2013 to 2019 during June and September. The survey design provided temporal and spatial coverage that did not exist in the historic interagency trawl database, and thus complemented the August ODNR-OMNRF effort to reinforce stock assessments with more robust data. Analyses herein evaluated trends in: total biomass, abundance of dominant predator and forage species, non-native species composition, biodiversity and community structure. Data from this effort can be explored interactively online (https://lebs.shinyapps.io/western-basin/), and are accessible for download (https://doi.org/10.5066/P9LL6YOR, Keretz et al. 2020). Annual survey data are added to these sources as the data become available.

Lake Erie↗
USGS2014

Polar bears from space: Assessing satellite imagery as a tool to track Arctic wildlife

Development of efficient techniques for monitoring wildlife is a priority in the Arctic, where the impacts of climate change are acute and remoteness and logistical constraints hinder access. We evaluated high resolution satellite imagery as a tool to track the distribution and abundance of polar bears. We examined satellite images of a small island in Foxe Basin, Canada, occupied by a high density of bears during the summer ice-free season. Bears were distinguished from other light-colored spots by comparing images collected on different dates. A sample of ground-truthed points demonstrated that we accurately classified bears. Independent observers reviewed images and a population estimate was obtained using mark- recapture models. This estimate (N: 94; 95% Confidence Interval: 92-105) was remarkably similar to an abundance estimate derived from a line transect aerial survey conducted a few days earlier (N: 102; 95% CI: 69-152). Our findings suggest that satellite imagery is a promising tool for monitoring polar bears on land, with implications for use with other Arctic wildlife. Large scale applications may require development of automated detection processes to expedite review and analysis. Future research should assess the utility of multi-spectral imagery and examine sites with different environmental characteristics.

PLoS ONE↗