929 research outputs found
Remote Sensing Enhanced Motor Vehicle Emissions Control for Pollution Reduction in the Chicago Metropolitan Area: Siting and Issue Analysis
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Bioenergetics-based predator-prey relationships between piscivorous birds and juvenile salmonids in the Columbia River estuary
This dissertation focuses on the predator-prey relationship between two species of avian predators, Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus), and one of their important prey types, juvenile salmonids (Oncorhynchus spp.), in the Columbia River estuary of Oregon and Washington states during the period 1998 – 2007. I used a data-rich bioenergetics framework to estimate juvenile salmonid consumption by these two avian predators, assessed impacts to at-risk salmonid populations by estimating salmonid mortality rates due to avian predation, and estimated potential demographic benefits to salmonids if avian predation were reduced. The managed relocation of the Caspian tern colony from Rice Island to East Sand Island, lower in the Columbia River estuary, reduced tern predation on salmonids from over 11 million smolts consumed annually to 4 – 7 million, but those benefits accrued primarily to sub-yearling Chinook salmon (O. tshawytscha). Combined consumption of juvenile salmonids by Caspian terns and double-crested cormorants in the Columbia River estuary was ca. 7 – 15 million smolts per year during 2006-2007, causing an 8 – 17% mortality rate among smolts
migrating through the estuary, with higher mortality rates for steelhead (O. mykiss) and coho salmon (O. kisutch). Under a potential management scenario to reduce avian predation by both species, improvements in the average annual population growth rate (λ) of salmonids ranged from 0.4% for sub-yearling Chinook to 3.1% for coho. These improvements are generally less than what is possible from altered hydropower system operation within the Columbia Basin for salmonid populations that are more severely affected by dams. For a few salmonid populations, reduced avian predation might contribute to stabilizing the population (λ = 1), but would need to be part of a broader recovery strategy to ensure population growth and recovery (λ > 1).
Climate was an important factor modulating Caspian tern predation on salmonids, with greater consumption of smolts occurring in years of cooler ocean conditions and higher Columbia River flows. Climate did not contribute to variation in consumption of salmonids by cormorants, perhaps due to the larger effect of growth in the size of the cormorant colony during the study period. Due to current trends in colony size (terns: stable, cormorants: increasing) and the planned dispersal of a portion of the tern population, cormorant predation will likely be a more significant mortality factor for Columbia Basin salmonids in the future than will tern predation. A critical unknown factor remains; that is the degree to which reductions in avian predation on salmonids might be compensated for by other salmonid mortality factors
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Foraging ecology of caspian terns and double-crested cormorants in the Columbia River Estuary
A detailed understanding of the foraging ecology of species preying upon
threatened or endangered prey may contribute to identifying and evaluating
management options to reduce predation, when such management is deemed
appropriate. In the Columbia River estuary, Caspian terns (Sterna caspia) and
double-crested cormorants (Phalacrocorax auritus) have been identified as
significant predators on juvenile salmonids (Oncorhynchus spp.), many
populations of which are listed under the U.S. Endangered Species Act. In 1998
and 1999, we studied the foraging ecology of Caspian terns and double-crested
cormorants in the estuary using point count surveys. We also flew aerial strip transect surveys throughout the estuary for terns, and in 1999 we used
radiotelemetry to track tems during the chick-rearing period.
Terns and cormorants generally used habitat in relation to availability,
with tidal flats and deep water channels both important foraging habitats, while
tributaries, sloughs, and areas near ocean jetties were less important. Higher
densities of cormorants were observed foraging in locations with pile dikes and/or
pilings in 1999. More terns foraged in the freshwater portion of the estuary in
1998, than in 1999, when some tems nested on East Sand Island in the marine
zone of the estuary. During the latter half of both seasons, use of upriver foraging
sites became less prevalent for both terns and cormorants and use of sites in the
marine and mixing zone more prevalent. Terns were observed foraging 50 km
from the Rice Island colony (where all terns nested in 1998, and most did in
1999); however, 5% of foraging occurred 27 km from this colony in both
years. In 1999, we compared the foraging ecology of radio-tagged Caspian terns
raising young at the main estuary colony on Rice Island, in the freshwater zone of
the estuary, to tems raising young at a newly restored colony site at East Sand
Island in the marine zone. Early in the chick-rearing period, radio-tagged terns
nesting at Rice Island (river km 34) foraged close to the colony in the freshwater
zone of the estuary, while terns nesting on East Sand Island (river km 8) foraged
in the marine or estuarine mixing zones close to that colony. Late in the chick-rearing period, Rice Island terns shifted their foraging to the marine and mixing
zones lower in the estuary; East Sand Island terns continued to forage in these
areas. Tern diets at each colony corresponded to foraging location (freshwater
zone vs. marine/mixing zone) of radio-tagged individuals: Rice Island terns relied
heavily on juvenile salmonids (71% of identified prey) early in chick-rearing but
this declined late in chick-rearing (46%). East Sand Island terns relied less upon
salmonids (42% and 16%, respectively), instead utilizing marine fishes such as
anchovy (Engraulis mordax) and herring (Clupea pallasi). Throughout chickrearing,
Rice Island terns foraged farther from the colony (median distance: 12.3
km during early chick-rearing and 16.9 km during late chick-rearing) than did
East Sand Island terns (9.6 and 7.7 km, respectively). Colony attendance
decreased for terns at both sites from similar high levels during early chickrearing
(60-70% of daylight hours) to lower levels (40-50%) during late chickrearing,
with attendance decreasing significantly more at Rice Island. We conclude that Caspian terns and double-crested cormorants are
generalist foragers and make use of the forage fish resources most available near
the breeding colony. Predation rates on salmonids should decline if terns are
attracted to colony sites, such as East Sand Island, where alternative prey are
readily available. Precluding cormorant roosting at pile dikes and pilings, if
feasible, might reduce consumption of salmonids, but additional studies would be
required for verification
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Research, Monitoring, and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid-Columbia River, 2006 Final Season Summary.
This study investigates predation by piscivorous waterbirds on juvenile salmonids (Oncorhynchus spp.) from throughout the Columbia River Basin. During 2006, study objectives in the Columbia River estuary, work funded by the Bonneville Power Administration, were to (1) monitor and evaluate previous management initiatives to reduce Caspian tern (Hydroprogne caspia) predation on juvenile salmonids (smolts); (2) measure the impact of double-crested cormorant (Phalacrocorax auritus) predation on smolt survival, and assess potential management options to reduce cormorant predation; and (3) monitor large colonies of other piscivorous waterbirds in the estuary (i.e., glaucous-winged/western gulls [Larus glaucescens/occidentalis]) to determine the potential impacts on smolt survival. Study objectives on the mid-Columbia River, work funded by the Walla Walla District of the U.S. Army Corps of Engineers, were to (1) measure the impact of predation by Caspian terns and double-crested cormorants on smolt survival; and (2) monitor large nesting colonies of other piscivorous waterbirds (i.e., California gulls [L. californicus], ring-billed gulls [L. delawarensis], American white pelicans [Pelecanus erythrorhynchos]) on the mid-Columbia River to determine the potential for significant impacts on smolt survival. Our efforts to evaluate system-wide losses of juvenile salmonids to avian predation indicated that Caspian terns and double-crested cormorants were responsible for the vast majority of smolt losses to avian predators in the Columbia Basin, with most losses occurring in the Columbia River estuary. In 2006, East Sand Island in the Columbia River estuary supported the largest known breeding colonies of Caspian terns and double-crested cormorants in the world. The Caspian tern colony on East Sand Island consisted of about 9,200 breeding pairs in 2006, up slightly (but not significantly so) from the estimate of colony size in 2005 (8,820 pairs). There has not been a statistically significant change in the size of the Caspian tern colony on East Sand Island since 2000. Tern nesting success averaged 0.72 fledglings per breeding pair in 2006, significantly higher than in 2005 (0.37 fledglings per breeding pair), a year of poor ocean conditions. Despite the presumably higher availability of marine forage fishes in 2006, the proportion of juvenile salmonids in diets of Caspian terns (32% of prey items) averaged higher than in 2005 (23% of prey items) and 2004 (18% of prey items). Steelhead smolts were particular vulnerable to predation by East Sand Island terns in 2006, with predation rates as high as 20% on particular groups of PIT-tagged fish reaching the estuary. Consumption of juvenile salmonids by terns nesting at the East Sand Island colony in 2006 was approximately 5.3 million smolts (95% c.i. = 4.4-6.2 million), significantly higher than the estimated 3.6 million smolts consumed in 2005, but still roughly 7 million fewer smolts consumed compared to 1998 (when all terns nested on Rice Island in the upper estuary). Caspian terns nesting on East Sand Island continue to rely primarily on marine forage fishes as a food supply, even in 2005 when availability of marine forage fishes declined due to poor ocean conditions. Further management of Caspian terns to reduce losses of juvenile salmonids would be implemented under the Caspian Tern Management Plan for the Columbia River Estuary; the Records of Decision (RODs) authorizing implementation of the plan were signed in November 2006. The ROD lists as the management goal the redistribution of approximately half of the East Sand Island Caspian tern colony to alternative colony sites in interior Oregon and San Francisco Bay, California (USFWS 2006). Implementation of the management plan is stalled, however, because of the lack of appropriated funds
Oxygen ion dynamics in the Earth's ring current: Van Allen probes observations
Oxygen (O+) enhancements in the inner magnetosphere are often observed during geomagnetically active times, such as geomagnetic storms. In this study, we quantitatively examine the difference in ring current dynamics with and without a substantial O+ ion population based on almost 6 years of Van Allen Probes observations. Our results have not only confirmed previous finding of the role of O+ ions to the ring current but also found that abundant O+ ions are always present during large storms when sym-H < -60 nT without exception, whilst having the pressure ratio () between O+ and proton (H+) larger than 0.8 and occasionally even larger than 1 when L < 3. Simultaneously, the pressure anisotropy decreases with decreasing sym-H and increasing L shell. The pressure anisotropy decrease during the storm main phase is likely related to the pitch angle isotropization processes. In addition, we find that increases during the storm main phase and then decreases during the storm recovery phase, suggesting faster buildup and decay of O+ pressure compared to H+ ions, which are probably associated with some species dependent source and/or energization as well as loss processes in the inner magnetosphere.Accepted manuscrip
A Method to have Multi-Layer Thermal Insulation Provide Damage Detection
Design and testing of a multi-layer thermal insulation system that also provides debris and micrometeorite damage detection is presented. One layer of the insulation is designed as an array of passive open-circuit electrically conductive spiral trace sensors. The sensors are a new class of sensors that are electrically open-circuits that have no electrical connections thereby eliminating one cause of failure to circuits. The sensors are powered using external oscillating magnetic fields. Once electrically active, they produce their own harmonic magnetic fields. The responding field frequency changes if any sensor is damaged. When the sensors are used together in close proximity, the inductive coupling between sensors provides a means of telemetry. The spiral trace design using reflective electrically conductive material provides sufficient area coverage for the sensor array to serves as a layer of thermal insulation. The other insulation layers are designed to allow the sensor s magnetic field to permeate the insulation layers while having total reflective surface area to reduce thermal energy transfer. Results of characterizing individual sensors and the sensor array s response to punctures are presented. Results of hypervelocity impact testing using projectiles of 1-3.6 millimeter diameter having speeds ranging from 6.7-7.1 kilometers per second are also presented
BLOOD FLOW RESTRICTION DOES NOT AFFECT ACUTE MEASURES OF POWER AND FATIGUE DURING MAXIMAL CYCLING AMONG WOMEN
While it is known that blood flow restriction (BFR) can positively affect training and rehabilitation progression timelines, the physiological basis of this intervention is not fully understood. The purpose of this study was to determine the short-term impact of BFR upon power and fatigue performance measures during maximal cycling. In this study, maximal cycling was assessed using the Wingate Anaerobic Test (WAnT). Using a counterbalanced design, fourteen female participants completed standardized BFR and non-BFR protocols while completing the WAnT. No statistically-significant differences (p ≤ 0.05) were found between conditions for measures of peak power (PP), low power (LP) or fatigue index (FI). These findings suggest that BFR had no statistically-significant acute effect on these performance measures commonly assessed during the WAnT
THE EFFECTS OF BLOOD FLOW RESTRICTION ON MEASURES OF GROSS MOTOR COORDINATION DURING THE WINGATE ANAEROBIC TEST
To date little research has addressed the impact of blood flow restriction (BFR) training upon gross motor coordination measures (GMCM) during a wide variety of maximal activities. The purpose of this study was to assess the effects of BFR on GMCM exhibited during maximal cycling. The performance of 14 females between the ages of eighteen and thirty-five were analyzed during the Wingate Anaerobic Test (WAnT). The participants completed the test under two conditions, using BFR and without. Results showed statistically significant differences (p ≤ 0.05) between conditions for dependent variables assessed throughout this common 30 second test of maximal cycling. These findings suggest that BFR negatively influenced GMCM exhibited during the WAnT
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Nutritional stress affects corticosterone deposition in feathers of Caspian tern chicks
Stressful environmental conditions affect the adrenocortical function of developing animals, which can have consequences
for their fitness. Discovery of the avian stress hormone corticosterone (CORT) in feathers has the potential to broaden the
application of endocrine research in ecological and evolutionary studies of wild birds by providing a long-term measure
of CORT secretion. Mechanisms of CORT deposition in feathers are not well known and few studies have related feather
CORT to circulating plasma CORT during feather growth. Our objective was to experimentally test the validity of
using feather CORT as a measure of CORT secretion in developing birds experiencing nutritional stress. Caspian tern
Hydroprogne caspia chicks were fed ad libitum or restricted (35% less than ad libitum) diets for four weeks. We measured
CORT in feathers from these chicks to examine the relationship between feather CORT concentrations and nutritional
limitation, circulating plasma CORT, and feather development. We found that feather CORT was higher in controls fed
ad libitum than in restricted individuals, despite higher levels of plasma CORT in restricted chicks compared to controls.
Feather mass and growth rates were strongly and positively related to feather CORT concentrations in both treatments.
This is the first experimental study to show that feather CORT concentrations can be lower in response to nutritional
stress, even when plasma CORT concentrations are elevated. Our results indicate that CORT deposition in feathers may be
confounded when feather mass and growth rates are compromised by nutritional stress. We conclude that feather CORT
can be used for assessing nutritional stress in growing birds, but the direction of response depends on how strongly stress
affects feather development
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Developing Nondestructive Techniques for Managing Conflicts Between Fisheries and Double-Crested Cormorant Colonies
Double-crested cormorants (Phalacrocorax auritus) have been identified as the source of significant mortality to juvenile salmonids (Oncorhynchus spp.) in the Columbia River Basin. Management plans for reducing the size of a large colony on East Sand Island (OR, USA) in the Columbia River estuary are currently being developed. We evaluated habitat enhancement and social attraction as nondestructive techniques for managing cormorant nesting colonies during 2004–2007. We tested these techniques on unoccupied plots adjacent to the East Sand Island cormorant colony. Cormorants quickly colonized these plots and successfully raised young. Cormorants also were attracted to nest and raised young on similar plots at 2 islands approximately 25 km from East Sand Island; 1 island had a history of successful cormorant nesting whereas the other was a site where cormorants had previously nested unsuccessfully. On a third island with no history of cormorant nesting or nesting attempts, these techniques were unsuccessful at attracting cormorants to nest. Our results suggest that some important factors influencing attraction of nesting cormorants using these techniques include history of cormorant nesting, disturbance, and presence of breeding cormorants nearby. These techniques may be effective in redistributing nesting cormorants away from areas where fish stocks of conservation concern are susceptible to predation, especially if sites with a recent history of cormorant nesting are available within their foraging or dispersal range.Keywords: salmonids, social attraction, Phalacrocorax auritus, predation, habitat enhancement, cormoran
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