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At least 1,315 records · Page 73Linked to original sources
USGS2015

Trophic ecology of northern pike and their effect on conservation of westslope cutthroat trout.

Westslope Cutthroat Trout Oncorhynchus clarkii lewisi in Coeur d’Alene Lake, Idaho, have declined in recent years; predation by Northern Pike Esox lucius , a nonnative sport fish, is thought to be a causative mechanism. The goal of this study was to describe the seasonal food habits of Northern Pike and determine their influence on Westslope Cutthroat Trout in Coeur d’Alene Lake by using a bioenergetics modeling approach. Fish were sampled monthly from March 2012 to May 2013 using pulsed-DC electrofishing and experimental gillnetting in four bays. Northern Pike catch rates from electrofishing were generally low but increased slightly each season and were highest in the southern portion of the lake; catch rates from gillnetting were approximately 50% higher during the two spring sampling periods compared with the summer and fall. Seasonal growth and food habits of 695 Northern Pike (TL = 16.2–108.0 cm; weight = 24–9,628 g) were analyzed. Diets primarily consisted of kokanee O. nerka , Westslope Cutthroat Trout, and Yellow Perch Perca flavescens . Results of a bioenergetics model estimated that Westslope Cutthroat Trout represented approximately 2–30% of the biomass consumed by age-1–4 Northern Pike. Total Westslope Cutthroat Trout biomass consumed by Northern Pike (2008–2011 year-classes) across all seasons sampled was estimated to be 1,231 kg (95% CI = 723–2,396 kg), and the total number consumed was 5,641 (95% CI = 3,311–10,979). The highest occurrence of Westslope Cutthroat Trout in Northern Pike diets was observed during spring. Thus, reducing Northern Pike predation on Westslope Cutthroat Trout would be one tool worth considering for conserving Westslope Cutthroat Trout populations in Coeur d’Alene Lake.

Idaho↗
USGS2016

Models for ecological models: Ocean primary productivity

The ocean accounts for more than 70% of planet Earth's surface, and it processes are critically important to marine and terrestrial life. Ocean ecosystems are strongly dependent on the physical state of the ocean (e.g., transports, mixing, upwelling, runoff, and ice dynamics(. As an example, consider the Coastal Gulf of Alaska (CGOA) region.

CHANCE↗
USGS2002

Patton's tracks in the Mojave Desert, USA: An ecological legacy

Recovery of soil properties from World War II-era military training exercises in the Mojave Desert was measured approximately 55 years following disturbance. Tracks from military vehicles were still visible, particularly in areas of desert pavement. Soil penetrability was much lower in visible tracks than outside the tracks. Soils in tracks had fewer rocks in the top 10cm of the soil profile than adjacent untracked soils. Larger particles (> 4.8mm) formed a moderately well-developed pavement outside of the tracks, while smaller, loose particles ( h 4.8mm) dominated the surface of the tracks. The time required to restore the desert pavement is likely to be measured in centuries. Based on biomass estimates, the cyanobacterial component of biological soil crusts had recovered 46-65% in tracks, compared to outside the tracks. Overall recovery of lichen cover has been much slower. Under plant canopies, cover of Collema tenax was not significantly different between areas inside and outside the tracks; however, recovery of Catapyrenium squamulosum was only 36%. In plant interspaces with less favorable moisture and temperature conditions, C. tenax showed a 6% recovery and C. squamulosum a 3% recovery. Assuming recovery of the biological soil crust is linear, and complete only when the most sensitive species ( C. squamulosum ) has fully recovered in the most limiting microhabitats (plant interspaces), it may require almost two millennia for full recovery of these areas.

Arid Land Research and Management↗
USGS2007

The kelp highway hypothesis: Marine ecology, the coastal migration theory, and the peopling of the Americas

In this article, a collaborative effort between archaeologists and marine ecologists, we discuss the role kelp forest ecosystems may have played in facilitating the movement of maritime peoples from Asia to the Americas near the end of the Pleistocene. Growing in cool nearshore waters along rocky coastlines, kelp forests offer some of the most productive habitats on earth, with high primary productivity, magnified secondary productivity, and three-dimensional habitat supporting a diverse array of marine organisms. Today, extensive kelp forests are found around the North Pacific from Japan to Baja California. After a break in the tropics—where nearshore mangrove forests and coral reefs are highly productive—kelp forests are also found along the Andean Coast of South America. These Pacific Rim kelp forests support or shelter a wealth of shellfish, fish, marine mammals, seabirds, and seaweeds, resources heavily used historically by coastal peoples. By about 16,000 years ago, the North Pacific Coast offered a linear migration route, essentially unobstructed and entirely at sea level, from northeast Asia into the Americas. Recent reconstructions suggest that rising sea levels early in the postglacial created a highly convoluted and island-rich coast along Beringia's southern shore, conditions highly favorable to maritime hunter-gatherers. Along with the terrestrial resources available in adjacent landscapes, kelp forests and other nearshore habitats sheltered similar suites of food resources that required minimal adaptive adjustments for migrating coastal peoples. With reduced wave energy, holdfasts for boats, and productive fishing, these linear kelp forest ecosystems may have provided a kind of “kelp highway” for early maritime peoples colonizing the New World.

Journal of Island and Coastal Archaeology↗
USGS2021

Atlantic sturgeon status and movement ecology in an extremely small spawning habitat: The Nanticoke River-Marshyhope Creek, Chesapeake Bay

Biotelemetry of Atlantic sturgeon Acipenser oxyrinchus oxyrinchus has exposed spawning behaviors in ever-smaller estuaries, surprising for the NW Atlantic’s largest anadromous species. Small estuary — the Nanticoke River and Marshyhope Creek (Chesapeake Bay) — spawning-run adults and their habitat affinities are described based upon direct sampling and biotelemetry for the period 2014–2018. High rates of recapture over this period indicate a very small adult population size. Genetics revealed a very small effective population size ( N e = 12.2, 95% CI = 6.7–21.9). Most returns occurred during September at 20–27 °C. All fish departed as fall temperatures declined below 20 °C. Multi-beam sonar identified small-dispersed areas of sand-cobble and cobble, which could support adhesive embryo attachment. Movements of adults were higher during nighttime than daytime, with habitat preference for hard bottom habitats. Genetic evidence indicates that the sudden discovery of this population was unrelated to a hatchery release of several thousand juvenile sturgeon (Hudson River progeny) in 1997. The newly discovered population in the Nanticoke River exhibits a degree of resilience including multiple spawning regions and suitable spawning habitat. Still, critical vulnerabilities persist including curtailed habitat, continued agricultural and maritime development, invasive blue catfish, and a very small apparent population size.

Delaware, Maryland↗
USGS2016

Evaluating the adequacy of a reference site pool for ecological assessments in environmentally complex regions

Many advances in the field of bioassessment have focused on approaches for objectively selecting the pool of reference sites used to establish expectations for healthy waterbodies, but little emphasis has been placed on ways to evaluate the suitability of the reference-site pool for its intended applications (e.g., compliance assessment vs ambient monitoring). These evaluations are critical because an inadequately evaluated reference pool may bias assessments in some settings. We present an approach for evaluating the adequacy of a reference-site pool for supporting biotic-index development in environmentally heterogeneous and pervasively altered regions. We followed common approaches for selecting sites with low levels of anthropogenic stress to screen 1985 candidate stream reaches to create a pool of 590 reference sites for assessing the biological integrity of streams in California, USA. We assessed the resulting pool of reference sites against 2 performance criteria. First, we evaluated how well the reference-site pool represented the range of natural gradients present in the entire population of streams as estimated by sites sampled through probabilistic surveys. Second, we evaluated the degree to which we were successful in rejecting sites influenced by anthropogenic stress by comparing biological metric scores at reference sites with the most vs fewest potential sources of stress. Using this approach, we established a reference-site pool with low levels of human-associated stress and broad coverage of environmental heterogeneity. This approach should be widely applicable and customizable to particular regional or programmatic needs.

California↗
USGS2019

Applying the ecology of aquatic–terrestrial linkages to freshwater and riparian management

Global stressors such as climate change, invasive species, urbanization, agricultural practices, and pollution can alter aquatic resource subsidies to terrestrial consumers. The effects of these stressors on timing, quality, and quantity of aquatic subsidies, such as adult aquatic insects, to birds, herpetofauna, and mammals, have large implications for wildlife management (Baxter et al. 2004 , Saunders and Fausch 2007 , Walters et al. 2008 , Sullivan and Rodewald 2012 , Morrissey et al. 2015 , Kraus et al. 2016 , Larsen et al. 2016 , Sullivan et al. 2019 ). For example, insect-mediated contaminant transport from polluted rivers expose song bird nestlings and other protected birds to potentially toxic levels of persistent organic contaminants and pharmaceuticals (Walters et al. 2010 , Richmond et al. 2018 ). Recent declines in aquatic insect production caused by pollution and changes in land use have been tied to global declines in terrestrial insectivores such as birds and bats (Hallmann et al. 2014 , Morrissey et al. 2015 , Raby et al. 2018 ). These natural-resource impacts from aquatic–terrestrial exposure and loss of resource subsidies are leading to changes in monitoring protocols and how management agencies evaluate the effectiveness of corrective remedies (Muehlbauer et al. 2019 ). For researchers interested in the application of resource subsidy research, a logical next step is to help practitioners anticipate effects of global stressors on aquatic-terrestrial linkages and incorporate these principles into decision making.

Freshwater Science↗
USGS2026

Local water use and climate variability drive water stress and alter ecological flows over the conterminous United States

Consistent, large-scale estimates of water availability are needed to identify and avoid potential conflicts among human and ecosystem uses of water. We present an assessment of water limitation, defined as the monthly balance (difference) between water supply ( ws ) and human consumptive water use ( wc ), for the conterminous United States (CONUS) during water years 2010–2020. We estimate that 26.7 million Americans, 8% of CONUS population, live in areas with chronic high or severe water limitation. Although ws greatly exceeds wc at the CONUS scale, water is limited locally or regionally due to spatial and temporal patterns in climate and wc . Our water limitation metric, the monthly supply and use index (SUI), peaked in 2012 during a widespread drought when 38% of the CONUS land area experienced elevated water stress. The central and Southwestern U.S. experienced the highest SUI due to the combination of low ws and high wc , especially for irrigation. Spatial overlays of SUI and fish habitat ranges, including those of conservation concern, revealed that several species had notable proportions of their habitat exposed to high or severe water limitation during spawning season over the modeled time period, especially the Arkansas River shiner. ws was calculated from two CONUS, physically-based, hydrologic models while wc was calculated from three CONUS models of water use for crop irrigation, thermoelectric power generation, and public supply. The ws and wc values were routed through a stream network and compared to calculate water limitation and SUI for human populations and fish species at the scale of 12-digit hydrologic unit codes. Evaluation of water availability at higher spatial and temporal resolution promotes more comprehensive analyses of the drivers of water availability and can be combined with complementary studies of water quality and water limiting thresholds to better understand the limitations on water availability.

conterminous United States↗
USGS2020

Ecology and management of plague in diverse communities of rodents and fleas

Plague originated in Asia as a flea-borne zoonosis of mammalian hosts. Today, the disease is distributed nearly worldwide. In western United States of America, plague is maintained, transmitted, and amplified in diverse communities of rodents and fleas. We examined flea diversity on three species of prairie dogs ( Cynomys spp., PDs) and six species of sympatric small rodents in Montana and Utah, United States of America. Among 2896 fleas, 19 species were identified; 13 were found on PDs and 9 were found on small rodents. In Montana, three flea species were found on PDs; the three species parasitize PDs and mice. In Utah, 12 flea species were found on PDs; the 12 species parasitize PDs, mice, voles, chipmunks, ground squirrels, rock squirrels, and marmots. Diverse flea communities and their willingness to parasitize many types of hosts, across multiple seasons and habitats, may favor plague maintenance and transmission. Flea parasitism on Peromyscus deer mice varied directly with elevation. Fleas are prone to desiccation, and might prosper at higher, mesic elevations; in addition, Peromyscus nest characteristics may vary with elevation. Effective management of plague is critical. Plague management is probably most effective when encompassing communities of rodents and fleas. Treatment of PD burrows with 0.05% deltamethrin dust, which suppressed fleas on PDs for >365 days, suppressed fleas on small rodents for at least 58 days. At one site, deltamethrin suppressed fleas on small rodents for at least 383 days. By simultaneously suppressing fleas on PDs and small rodents, deltamethrin should promote ecosystem resilience and One Health objectives.

Montana, Utah↗
USGS1983

Mechanism and ecological significance of sperm storage in the Northern Fulmar with reference to its occurrence in other birds

Sperm-storage glands were found in the uterovaginal (UV) region of the oviduct in Northern Fulmars ( Fulmarus glacialis ), Horned Puffins ( Fratercula corniculata ), and Leach's Storm-Petrels ( Oceanodroma leucorhoa ) collected before or shortly after egg laying. Previously described only in domestic Galliformes, UV sperm-storage glands may prove to be a common feature of the avian reproductive system. There is as yet no compelling explanation of their function in the Horned Puffin. In the Northern Fulmar, and probably in other petrels, however, sperm-storage glands allow the separation of the male and female over pelagic waters for several weeks immediately before egg laying. The likelihood of prolonged viability of sperm in the female reproductive tract should be considered in interpreting the sexual behavior of other wild birds.

Alaska↗
USGS2017

An unparalleled opportunity for an important ecological study

Wolves ( Canis lupus ) and moose ( Alces americanus ) have been studied since 1958 on 540-square-kilometer Isle Royale National Park, in Lake Superior. Wolves arrived there across the ice around 1949, and the population once increased to about 50, averaging about 25 annually (Mech 1966 , Jordan et al. 1967 , Vucetich and Peterson 2009 ). However, for various reasons, wolf numbers there have now dwindled to 2 nonbreeders, and the US National Park Service has proposed reintroducing 20–30 wolves over 3 years (National Park Service 2016 ). This situation offers an unparalleled opportunity to promote science-based management of this unique national park. The park has long been in the public eye for its world-renowned wolf and moose populations. Visitors to this island wilderness are especially interested in the scientific studies it has yielded and in maintaining its ecosystem.

Michigan↗
USGS2019

Traversing the wasteland: A framework for assessing ecological threats to drylands

Drylands cover 41% of the Earth's terrestrial surface, play a critical role in global ecosystem function, and are home to over two billion people. Like other biomes, drylands face increasing pressure from global change, but many of these ecosystems are close to tipping points, which, if crossed, can lead to abrupt transitions and persistent degraded states. Their limited but variable precipitation, low soil fertility, and low productivity have given rise to a perception that drylands are wastelands, needing societal intervention to bring value to them. Negative perceptions of drylands synergistically combine with conflicting sociocultural values regarding what constitutes a threat to these ecosystems. In the present article, we propose a framework for assessing threats to dryland ecosystems and suggest we must also combat the negative perceptions of drylands in order to preserve the ecosystem services that they offer.

Arizona, Colorado, New Mexico, Utah↗
USGS2001

Some considerations on the use of ecological models to predict species' geographic distributions

Peterson (2001) used Genetic Algorithm for Rule-set Prediction (GARP) models to predict distribution patterns from Breeding Bird Survey (BBS) data. Evaluations of these models should consider inherent limitations of BBS data: (1) BBS methods may not sample species and habitats equally; (2) using BBS data for both model development and testing may overlook poor fit of some models; and (3) BBS data may not provide the desired spatial resolution or capture temporal changes in species distributions. The predictive value of GARP models requires additional study, especially comparisons with distribution patterns from independent data sets. When employed at appropriate temporal and geographic scales, GARP models show considerable promise for conservation biology applications but provide limited inferences concerning processes responsible for the observed patterns.

Condor↗
USGS2004

Winter ecology of Spectacled Eiders: Environmental characteristics and population change

We described characteristics of the wintering area used by Spectacled Eiders ( Somateria fischeri ) in the Bering Sea, Alaska, and evaluated these characteristics in relation to long-term population trends. Remoteness, limited daylight, and extreme weather conditions precluded direct observations, so we derived the location of the wintering area from satellite telemetry, ice conditions from remotely sensed data, weather conditions from archived data sets, and benthic communities from the literature. Based on analyses of two indices spanning 1957-2002 and 1988-2002, we identified no single environmental parameter that explained the precipitous decline in nesting populations in western Alaska. In general, we found that the number of days with extreme sea ice in winter, extreme winds, and winds in spring explained the greatest variability in annual indices. These analyses support the conclusion that annual population estimates on the breeding grounds can be negatively impacted by extended periods of dense sea-ice concentration and weather during the previous winter. Examination of population indices did not support the hypothesis that changes in benthic community on the wintering grounds have contributed to the decline or inhibited the recovery of the Spectacled Eider breeding population in western Alaska.

Alaska↗