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USGS2012

Wave energy saturation on a natural beach of variable slope

Time series of flow were measured across the inner surf zone during a storm. These data were used to quantify the dependence of wave height (transformed from measured flow) and velocity on local slope and depth. Similar to previous studies, as incident waves broke and propagated into the surf zone, wave energy became saturated, and wave height was strongly dependent on depth. However, the ratio of rms wave height to local depth (γ rms ) was found not to be constant but to vary between 0.29 and 0.55; γ rms increased with local slope and was independent of deepwater wave steepness. Thus the surf zone similarity parameter (the ratio of slope to the square root of steepness) did not adequately parameterize γ rms .

Journal of Geophysical Research - Oceans↗

USGS2022

Industrial energy development decouples ungulate migration from the green wave

The ability to freely move across the landscape to track the emergence of nutritious spring green-up (termed ‘green-wave surfing’) is key to the foraging strategy of migratory ungulates. Across the vast landscapes traversed by many migratory herds, habitats are being altered by development with unknown consequences for surfing. Using a unique long-term tracking dataset, we found that when energy development occurs within mule deer ( Odocoileus hemionus ) migration corridors, migrating animals become decoupled from the green wave. During the early phases of a coalbed natural gas development, deer synchronized their movements with peak green-up. But faced with increasing disturbance as development expanded, deer altered their movements by holding up at the edge of the gas field and letting the green wave pass them by. Development often modified only a small portion of the migration corridor but had far-reaching effects on behaviour before and after migrating deer encountered it, thus reducing surfing along the entire route by 38.65% over the 14-year study period. Our study suggests that industrial development within migratory corridors can change the behaviour of migrating ungulates and diminish the benefits of migration. Such disruptions to migratory behaviour present a common mechanism whereby corridors become unprofitable and could ultimately be lost on highly developed landscapes.

Wyoming↗

USGS1992

Momentum and energy coefficients based on power-law velocity profile

The theoretical momentum coefficient (β) and energy coefficient (α) for turbulent shear flow in circular pipes and wide channels are derived from the power law, then compared with their counterparts on the basis of the logarithmic law. For such unidirectional flows, the exponent (m) of the power‐law velocity distribution is the sole parameter that determines the values of β and α. A comparison of the corresponding expressions for β and α derived using both laws shows that their values differ only slightly within a valid range of small m's. Use of a power‐law‐based β expression along with a power‐law resistance formula in the cross‐section‐averaged equation of momentum cannot only eliminate the theoretical incompatibility that results from mixing logarithmic and power laws in the equation but also remove the inconsistent assumption of β = 1 "> β = 1 made in the equation. Improvement on the accuracy of the flow computation by incorporating a power‐law‐based p expression in the equation of momentum is demonstrated through an example in which a new stability limit for the Froude number for turbulent shear flow in wide channels can be accurately derived without assuming β = 1 . "> β = 1 .

Journal of Hydraulic Engineering↗

USGS2015

Energy flow and the “grassification” of desert shrublands

In our directionally and continuously changing world, history still matters, and it does so in increasingly novel and important ways. Human adaptation to global change will rely heavily on robust baselines of historic environmental variability and detailed understanding of how both past and modern ecosystems have responded to both individual and multiple stressors. The question of global change has motivated an upsurge in paleoecological studies that span the late Quaternary and the modern era, and has inspired a growing consideration of time as a fundamental axis in ecology ( 1 ). A major challenge in developing pertinent ecological baselines remains how to fuse, into continuous time series, observations and experiments from living systems with paleoecological reconstructions from the same sites ( 2 , 3 ). Tracing and disentangling complex responses to environmental stress from paleological to present-day communities is especially daunting; for example, how climate change; accelerated land use; and biological invasions are influencing the flows of water, nutrients, and energy. The paper by Terry and Rowe in PNAS ( 4 ) is a shining example of how modern ecology and paleoecology can be spliced together to decipher how ecological processes unfold over time scales inaccessible to direct observation or experimentation, and how they can be disrupted by human impacts.

Proceedings of the National Academy of Sciences↗

USGS2016

Effects of energy development on wetland plants and macroinvertebrate communities in Prairie Pothole Region wetlands

Energy production in the Williston Basin, USA, results in the coproduction of highly saline, sodium chloride-dominated water (brine). The Prairie Pothole Region (PPR) overlies the northeastern portion of the Williston Basin. Although PPR wetlands span a range of salinity, the dominant salt is sodium sulfate, and salinities are much lower than brine. Introduction of brine to wetlands can result in pronounced water-quality changes; however, the ecological effects of such contamination are poorly understood. We examined the effects of brine contamination on primary productivity, emergent macrophyte tissue chemistry, and invertebrate communities from 10 wetlands in the PPR. Based on a recognized Contamination Index (CI) used to identify brine contamination in the PPR, water-quality samples indicated that six wetlands were uncontaminated while four were contaminated. Across this gradient, we observed a significant decrease in above-ground biomass and a significant increase in tissue chloride concentrations of hardstem bulrush ( Schoenoplectus acutus ) with increased CI values. Additionally, a significant decrease in macroinvertebrate taxonomic richness with increased CI values was observed. These findings provide needed insight on the biological effects of brine contamination on PPR wetlands.

Journal of Freshwater Ecology↗

USGS2007

High rates of energy expenditure and water flux in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea

We measured water flux and energy expenditure in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea by using the doubly labeled water method. Previous laboratory investigations have suggested weak urinary concentrating ability, high rates of water flux, and low basal metabolic rates in this species. However, free-ranging measurements from hygric mammals are rare, and it is not known how these features interact in the environment. Rates of water flux (210 ?? 32 mL d-1) and field metabolic rates (1,488 ?? 486 kJ d-1) were 159% and 265%, respectively, of values predicted by allometric equations for similar-sized herbivores. Mountain beavers can likely meet their water needs through metabolic water production and preformed water in food and thus remain in water balance without access to free water. Arginine-vasopressin levels were strongly correlated with rates of water flux and plasma urea : creatinine ratios, suggesting an important role for this hormone in regulating urinary water loss in mountain beavers. High field metabolic rates may result from cool burrow temperatures that are well below lower critical temperatures measured in previous laboratory studies and suggest that thermoregulation costs may strongly influence field energetics and water flux in semifossorial mammals. ?? 2007 by The University of Chicago. All rights reserved.

Physiological and Biochemical Zoology↗

USGS2026

The effect of solar energy development on plant diversity across spatial scales

Utility-scale solar energy development is a novel and rapidly expanding land-use with largely unknown consequences for plant diversity. Construction disturbance and associated increases in environmental heterogeneity in solar facilities relative to undisturbed ecosystems can affect plant diversity at multiple spatial scales. We assessed the effects of modified construction methods, designed to reduce impacts of a utility-scale solar facility, on plant diversity across spatial scales (1–4000 m 2 ) in the Mojave Desert, USA one year after construction. Vegetation surveys across three soil–vegetation types revealed that species richness and evenness were largely unaffected by solar infrastructure at local scales in two of the three soil–vegetation types, but in creosote bush ( Larrea tridentata )-white bursage ( Ambrosia dumosa ) communities with deep soils, both metrics increased. Beta diversity remained unchanged by solar infrastructure while gamma diversity (4000 m 2 ) increased or had a small reduction depending on the soil–vegetation type. These results suggest that low-impact construction can have neutral to positive effects on plant diversity.

Nevada↗

USGS2021

Heatwave-induced synchrony within forage fish portfolio disrupts energy flow to top pelagic predators

During the Pacific marine heatwave of 2014–2016, abundance and quality of several key forage fish species in the Gulf of Alaska were simultaneously reduced throughout the system. Capelin ( Mallotus catervarius ), sand lance ( Ammodytes personatus ), and herring ( Clupea pallasii ) populations were at historically low levels, and within this community abrupt declines in portfolio effects identify trophic instability at the onset of the heatwave. Although compensatory changes in age‐structure, size, growth or energy content of forage fish were observed to varying degrees among all these forage fish, none were able to fully mitigate adverse impacts of the heatwave, which likely included both top‐down and bottom‐up forcing. Notably, changes to the demographic structure of forage fish suggested size‐selective removals typical of top‐down regulation. At the same time, zooplankton community structure may have driven bottom‐up regulation as copepod community structure shifted towards smaller, warm‐water species, and euphausiid biomass was reduced owing to the loss of cold‐water species. Mediated by these impacts on the forage fish community, an unprecedented disruption of the normal pelagic food web was signaled by higher trophic level disruptions during 2015–2016, when seabirds, marine mammals, and groundfish experienced shifts in distribution, mass mortalities, and reproductive failures. Unlike decadal‐scale variability underlying ecosystem regime shifts, the heatwave appeared to temporarily overwhelm the ability of the forage fish community to buffer against changes imposed by warm water anomalies, thereby eliminating any ecological advantages that may have accrued from having a suite of coexisting forage species with differing life history compensations.

Alaska↗

USGS2005

Species-energy relationship in the deep sea: A test using the Quaternary fossil record

Little is known about the processes regulating species richness in deep-sea communities. Here we take advantage of natural experiments involving climate change to test whether predictions of the species-energy hypothesis hold in the deep sea. In addition, we test for the relationship between temperature and species richness predicted by a recent model based on biochemical kinetics of metabolism. Using the deep-sea fossil record of benthic foraminifera and statistical meta-analyses of temperature-richness and productivity-richness relationships in 10 deep-sea cores, we show that temperature but not productivity is a significant predictor of species richness over the past c. 130 000 years. Our results not only show that the temperature-richness relationship in the deep-sea is remarkably similar to that found in terrestrial and shallow marine habitats, but also that species richness tracks temperature change over geological time, at least on scales of c. 100 000 years. Thus, predicting biotic response to global climate change in the deep sea would require better understanding of how temperature regulates the occurrences and geographical ranges of species. ??2005 Blackwell Publishing Ltd/CNRS.

Ecology Letters↗

USGS1970

Missile impacts as sources of seismic energy on the moon

Seismic signals recorded from impacts of missiles at the White Sands Missile Range are radically different from the signal recorded from the Apollo 12 lunar module impact. This implies that lunar structure to depths of at least 10 to 20 kilometers is quite different from the typical structure of the earth's crust. Results obtained from this study can be used to predict seismic wave amplitudes from future man-made lunar impacts. Seismic energy and crater dimensions from impacts are compared with measurements from chemical explosions.

New Mexico↗

USGS1993

Lime-mud layers in high-energy tidal channels: A record of hurricane deposition

During or immediately following the transit of Hurricane Andrew (August 23-24, 1992) across the northern part of the Great Bahama Bank, thin laminated beds of carbonate mud were deposited in high-energy subtidal channels (4 m depth) through the ooid shoals of south Cat Cay and Joulters Cays. During our reconnaissance seven weeks later, we observed lime-mud beds exposed in the troughs of submarine oolite dunes and ripples. The mud layers were underlain and locally covered by ooid sand. The mud beds were lenticular and up to 5 cm thick. Their bases cast the underlying rippled surface. The layers were composed of soft silt- and sand-sized pellets and peloids and in some areas contained freshly preserved Thalassia blades and other organic debris along planes of lamination. The beds had a gelatinous consistency and locally had been penetrated by burrowers and plants. Layers of lime mud had also settled on bioturbated, plant-stabilized flats and in lagoonal settings but were quickly reworked and made unrecognizable by the burrowing of organisms. Thicker, more cohesive (and therefore older) mud beds and angular mud fragments associated with ooids from Joulters Cays have similar characteristics but lack fresh plant fragments. We infer that these older beds were similarly deposited and thus record the passage of previous hurricanes or tropical storms. Storm layers are preserved within channel sediments because migrating ooids prevent attack by the burrowing activity off organisms.

Florida↗

USGS2023

Shoreface sediment availability offshore of a rapidly migrating, mixed-energy barrier island

Less is known about sediment exchanges between shorefaces and mixed-energy barrier islands (MEBI) than between shorefaces and wave-dominated barrier islands. We used seismic stratigraphy from Cedar Island, Virginia, USA to understand the interplay between shoreface deposits and MEBI morphodynamics. Interpretations reveal that the shelf and shoreface are extensively dissected by breach and inlet channels. Shoreface morphology varies due to underlying lithology and variable rates of barrier retreat. Underlying lithology adjacent to breach channels affected their migration rates, thereby exerting controls on alongshore extent of shoreface erosion. Shoreface deposits reworked by a migrating breach have lower slopes than those reworked by a more stationary one. Elevated rates of barrier retreat in southern Cedar Island may cause flattening of the shoreface because rapid barrier island migration required increased onshore sediment fluxes. In summary, barrier breach pervasiveness at MEBI may play an outsized role on shoreface ravinement and morphology. Ultimately, analyses of shoreface architecture and morphology provide insight on the relative influences of inlets, geology, and sea-level rise on barrier island sediment fluxes, which could help inform coastal planners, improve parameterization of shoreface sediment flux, and further future studies of morphologic change at MEBI.

Virginia↗

USGS2012

Remote sensing of evapotranspiration for operational drought monitoring using principles of water and energy balance

Evapotranspiration (ET) is an important component of the hydrologic budget because it režects the exchange of mass and energy between the soil-water-vegetation system and the atmosphere. Prevailing weather conditions inžuence potential or reference ET through variables such as radiation, temperature, wind, and relativity humidity. In addition to these weather variables, actual ET (ETa) is also affected by land cover type and condition, as well as soil moisture. The dependence of ETa on land cover and soil moisture, and its direct relationship with carbon dioxide assimilation in plants, makes it an important variable for monitoring drought, crop yield, and biomass-a critical capability for decision makers interested in food security, grain markets, water allocation, and carbon sequestration (Bastiaanssen et al., 2005).

Book chapter↗

USGS2021

Quantifying energetic costs and defining energy landscapes experienced by grizzly bears

Animal movements are major determinants of energy expenditure and ultimately the cost–benefit of landscape use. Thus, we sought to understand those costs and how grizzly bears ( Ursus arctos ) move in mountainous landscapes. We trained captive grizzly bears to walk on a horizontal treadmill and up and down 10% and 20% slopes. The cost of moving upslope increased linearly with speed and slope angle, and this was more costly than moving horizontally. The cost of downslope travel at slower speeds was greater than the cost of traveling horizontally but appeared to decrease at higher speeds. The most efficient walking speed that minimized cost per unit distance was 1.19±0.11 m s −1 . However, grizzly bears fitted with GPS collars in the Greater Yellowstone Ecosystem moved at an average velocity of 0.61±0.28 m s −1 and preferred to travel on near-horizontal slopes at twice their occurrence. When traveling uphill or downhill, grizzly bears chose paths across all slopes that were ∼54% less steep and costly than the maximum available slope. The net costs (J kg −1 m −1 ) of moving horizontally and uphill were the same for grizzly bears, humans and digitigrade carnivores, but those costs were 46% higher than movement costs for ungulates. These movement costs and characteristics of landscape use determined using captive and wild grizzly bears were used to understand the strategies that grizzly bears use for preying on large ungulates and the similarities in travel between people and grizzly bears that might affect the risk of encountering each other on shared landscapes.

Wyoming↗

USGS2004

Holocene reef development where wave energy reduces accommodation

Analyses of 32 drill cores obtained from the windward reef of Kailua Bay, Oahu, Hawaii, indicate that high wave energy significantly reduced accommodation space for reef development in the Holocene and produced variable architecture because of the combined influence of sea-level history and wave exposure over a complex antecedent topography. A paleostream valley within the late Pleistocene insular limestone shelf provided accommodation space for more than 11 m of vertical accretion since sea level flooded the bay 8000 yr BP. Virtually no net accretion (<1 m) took place on surrounding Pleistocene substrates shallower than 10 m. Holocene reef accretion ocurred in three stages: (1) an early stage of catch-up framestone development in water depths of 11-17 m, (2) an intermediate stage characterized by either no accretion or by the pile-up of fore-reef-derived rubble (rudstone) and sparse bindstone, and (3) a final stage of catch-up bindstone accretion in depths > 6 m. Coral framestone accreted at rates of 2.5-6.0 mm/yr in water depths > 11 m during the early Holocene; it abruptly terminated at ~4500 yr BP because of wave scour as sea level stabilized. More than 4 m of rudstone derived from the upper fore reef accreted at depths of 6 to 13 m below sea level between 4000 and 1500 yr BP coincident with late Holocene relative sea-level fall. Variations in the thickness, composition, and age of these reef facies across spatial scales of 10-1000 m within Kailua Bay illustrate the importance of antecedent topography and wave-related stress in reducing accommodation space for reef development set by sea level. Although accommodation space of 6 to 17 m has existed through most of the Holocene, the Kailua reef has been unable to catch up to sea level because of persistent high wave stress.

Hawai'i↗

USGS2002

Energy resource potential of natural gas hydrates

The discovery of large gas hydrate accumulations in terrestrial permafrost regions of the Arctic and beneath the sea along the outer continental margins of the world's oceans has heightened interest in gas hydrates as a possible energy resource. However, significant to potentially insurmountable technical issues must be resolved be fore gas hydrates can be considered a viable option for affordable supplies of natural gas. The combined information from Arctic gas hydrate studies shows that, in permafrost regions, gas hydrates may exist at subsurface depths ranging from about 130 to 2000 m. The presence of gas hydrates in offshore continental margins has been inferred mainly from anomalous seismic reflectors, known as bottom-simulating reflectors, that have been mapped at depths below the sea floor ranging from about 100 to 1100 m. Current estimates of the amount of gas in the world's marine and permafrost gas hydrate accumulations are in rough accord at about 20,000 trillion m 3 . Disagreements over fundamental issues such as the volume of gas stored within delineated gas hydrate accumulations and the concentration of gas hydrates within hydrate-bearing strata have demonstrated that we know little about gas hydrates. Recently, however, several countries, including Japan, India, and the United States, have launched ambitious national projects to further examine the resource potential of gas hydrates. These projects may help answer key questions dealing with the properties of gas hydrate reservoirs, the design of production systems, and, most important, the costs and economics of gas hydrate production.

American Association of Petroleum Geologists Bulle↗

USGS2015

Seasonally-dynamic presence-only species distribution models for a cryptic migratory bat impacted by wind energy development

Understanding seasonal distribution and movement patterns of animals that migrate long distances is an essential part of monitoring and conserving their populations. Compared to migratory birds and other more conspicuous migrants, we know very little about the movement patterns of many migratory bats. Hoary bats ( Lasiurus cinereus ), a cryptic, wide-ranging, long-distance migrant, comprise a substantial proportion of the tens to hundreds of thousands of bat fatalities estimated to occur each year at wind turbines in North America. We created seasonally-dynamic species distribution models (SDMs) from 2,753 museum occurrence records collected over five decades in North America to better understand the seasonal geographic distributions of hoary bats. We used 5 SDM approaches: logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy and consolidated outputs to generate ensemble maps. These maps represent the first formal hypotheses for sex- and season-specific hoary bat distributions. Our results suggest that North American hoary bats winter in regions with relatively long growing seasons where temperatures are moderated by proximity to oceans, and then move to the continental interior for the summer. SDMs suggested that hoary bats are most broadly distributed in autumn—the season when they are most susceptible to mortality from wind turbines; this season contains the greatest overlap between potentially suitable habitat and wind energy facilities. Comparing wind-turbine fatality data to model outputs could test many predictions, such as ‘risk from turbines is highest in habitats between hoary bat summering and wintering grounds’. Although future field studies are needed to validate the SDMs, this study generated well-justified and testable hypotheses of hoary bat migration patterns and seasonal distribution.

PLoS ONE↗

USGS2016

Differences in energy expenditures and growth dilution explain higher PCB concentrations in male summer flounder

Comparison of polychlorinated biphenyl (PCB) concentrations between the sexes of mature fish may reveal important behavioral and physiological differences between the sexes. We determined whole-fish PCB concentrations in 23 female summer flounder Paralichthys dentatus and 27 male summer flounder from New Jersey coastal waters. To investigate the potential for differences in diet or habitat utilization between the sexes, carbon and nitrogen stable isotope ratios were also determined. In 5 of the 23 female summer flounder, PCB concentrations in the somatic tissue and ovaries were determined. In addition, we used bioenergetics modeling to assess the contribution of the growth dilution effect to the observed difference in PCB concentrations between the sexes. Whole-fish PCB concentrations for females and males averaged 87 and 124 ng/g, respectively; thus males were 43% higher in PCB concentration compared with females. Carbon and nitrogen stable isotope ratios did not significantly differ between the sexes, suggesting that diet composition and habitat utilization did not vary between the sexes. Based on PCB determinations in the somatic tissue and ovaries, we predicted that PCB concentration of females would increase by 0.6%, on average, immediately after spawning due to release of eggs. Thus, the change in PCB concentration due to release of eggs did not explain the higher PCB concentrations observed in males. Bioenergetics modeling results indicated that the growth dilution effect could account for males being 19% higher in PCB concentration compared with females. Thus, the bulk of the observed difference in PCB concentrations between the sexes was not explained by growth dilution. We concluded that a higher rate of energy expenditure in males, stemming from greater activity and a greater resting metabolic rate, was most likely the primary driver for the observed difference in PCB concentrations between the sexes.

New Jersey↗