Brian P. Kennedy's research while affiliated with University of Idaho and other places

Publications (136)

Article
This study evaluates the influence of marine and freshwater conditions on the timing of river entry and upstream migration of sea trout (Salmo trutta) in the Grande River of Tierra del Fuego, Patagonia. We analysed the in-river catch-and-release records from a group of fishing lodges that dominate the Grande River fishery during January-April 2008...
Article
Effective species management often requires understanding patterns of movement and habitat use. A common approach in identifying where individuals reside relies upon chemical tracers from the environment that are incorporated into an individual's tissues. For fish, isotopes in their otoliths, specifically the portion of their otolith formed during...
Article
Full-text available
Ecological patterns are often fundamentally chronological. However, generalization of data is necessarily accompanied by a loss of detail or resolution. Temporal data in particular contain information not only in data values but in the temporal structure, which is lost when these values are aggregated to provide point estimates. Dynamic time warpin...
Preprint
Full-text available
Ecological patterns are often fundamentally chronological. However, generalization of data is necessarily accompanied by a loss of detail or resolution. Temporal data in particular contains information not only in data values but in the temporal structure, which is lost when these values are aggregated to provide point estimates. Dynamic Time Warpi...
Article
Volitional dispersal is a ubiquitous strategy characteristic of species across major faunal groups. Dispersal during the juvenile life stage is of interest because early performance can be critical for determining future success (survival/reproduction). For salmonids, dispersal can influence local density, competition, individual growth and surviva...
Article
Food availability and thermal regimes can largely govern growth opportunities in fishes. In temperate regions, streams can exhibit summer temperatures that exceed the optima for coolwater‐adapted species relative to the amount of available food, and therefore, spring and fall may confer better growing conditions, especially for larger size classes....
Article
Full-text available
Connecting maternal migratory behavior with the behavior and ecology of their progeny can reveal important details in the ecology of a population. One method for linking maternal migration to early juvenile life history is through maternal chemistry recorded in otoliths. Despite the wide use of maternal signatures to infer anadromy, the duration an...
Preprint
Full-text available
Connecting maternal migratory behavior with the behavior and ecology of their progeny can reveal important details in the ecology of a population. One method for linking maternal migration to early juvenile life-history is through maternal chemistry recorded in otoliths. Despite the wide use of maternal signatures to infer anadromy, the duration an...
Data
Clip4_TimbreTimbre transition used as positive control question in perceptual survey.
Data
Clip1_Full_SonificationAudio recording of full sonification using data from 45 individual fish.
Data
Clip7_IntermittentRandom, granular, intermittent sound used as negative control question in perceptual survey.
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Clip3_PitchPitch transition used as positive control question in perceptual survey.
Data
Q12_3Fish_VisualsSonification of three fish with accompanying visualization as seen by survey participants. The same audio was used for questions without visualizations.
Data
Q10_1Fish_VisualsSonification of a single fish with accompanying visualization as seen by survey participants. The same audio was used for questions without visualizations.
Data
Clip2_PanStereo panning sound transition used as positive control question in perceptual survey.
Article
Full-text available
The migration of Pacific salmon is an important part of functioning freshwater ecosystems, but as populations have decreased and ecological conditions have changed, so have migration patterns. Understanding how the environment, and human impacts, change salmon migration behavior requires observing migration at small temporal and spatial scales acro...
Data
Clip5_CrecendoLoudness transition used as positive control question in perceptual survey.
Data
Clip6_StaticRandom static used as negative control question in perceptual survey.
Data
Q11_2Fish_VisualsSonification of two fish with accompanying visualization as seen by survey participants. The same audio was used for questions without visualizations.
Article
Interactions among predators can have important consequences for lower trophic levels. Here, we use individual tag data on juvenile salmonids to quantify how their geographic, taxonomic, and life-history representation in the diets of great blue herons (Ardea herodias) changed after a pair of bald eagles (Haliaeetus leucocephalus) usurped the colon...
Article
Full-text available
Riverscapes are complex, landscape-scale mosaics of connected river and stream habitats embedded in diverse ecological and socioeconomic settings. Social–ecological interactions among stakeholders often complicate natural-resource conservation and management of riverscapes. The management challenges posed by the conservation and restoration of wild...
Article
Full-text available
In territorial stream salmonids, asymmetric competition can perpetuate individual size differences over time, but the extent to which this is manifested can be environmentally mediated. Here we study the variation in juvenile steelhead (Oncorhynchus mykiss) growth rates to identify the conditions (population density and water temperature) under whi...
Article
A paradox in managing threatened and endangered species is the increased need for documenting population status, which in many instances requires capturing and handling individuals. Electrofishing is a widely used method for sampling fish in small streams, but the potential for detrimental effects call for its careful use. Methods that reduce expos...
Article
We studied the potential effects of predicted climate change on the energetic demands of juvenile steelhead (Oncorhynchus mykiss) and their consequences for local population size and structure in Idaho, USA. Projected increases in water temperature incurred on average a 10% higher energetic cost by 2040 (range 7.0%–12.5% among study reaches in the...
Article
Recent declines of anadromous salmonids in the Pacific Northwest have prompted a need to understand the factors limiting populations across habitats and life stages. In the weeks following emergence from the spawning gravel, juvenile salmonids have limited swimming capacity and can be particularly vulnerable to predation by piscivores, such as scul...
Article
Anadromous salmonids can display considerable movement within their natal streams prior to outmigration, reflecting behavioural responses to biotic and abiotic conditions. Here we quantify dispersal and site fidelity in juvenile steelhead (Oncorhynchus mykiss) over four weeks in the fall, their consequences for individual growth rates, and how habi...
Conference Paper
Decades of decline in Pacific Lamprey (Entosphenus tridentatus) within the Columbia River Basin have increased attention on regional restoration efforts as well as highlighted the need for basic ecological and life history information. Pacific Lampreys are culturally important to the Nez Perce Tribe, who have been translocating adults into local sp...
Article
Full-text available
Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world’s largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some o...
Article
Full-text available
Self-thinning patterns are frequently used to describe density dependence in populations on timescales shorter than the organism's life span and have been used to infer carrying capacity of the environment. Among mobile animals, this concept has been used to document density dependence in stream salmonids, which compete over access to food and spac...
Research
Full-text available
Hegg JC, Giarrizzo T, Kennedy BP (2015) Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management. bioRxiv (in-review, PloS One) pre-print: 1–37. DOI: http://dx.doi.org/10.1101/018671.
Preprint
Full-text available
Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world's largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some o...
Article
Physical habitat characteristics can affect the abundance and distribution of organisms, and are frequently used to predict the standing crop of stream fish for purposes of understanding their ecology and better direct management. However, the spatial scale of the investigation and the resolution of the data can affect the outcome of such analyses....
Article
Full-text available
Complex life histories render anadromous fishes particularly susceptible to environmental and anthropogenic change. Adult Pacific Lampreys Entosphenus tridentatus migrating in the Columbia River and its tributaries must ascend a series of dams to reach interior spawning sites. While considerable research has focused on improving dam passage for lam...
Conference Paper
In steelhead (Oncorhynchus mykiss), individual variation in the costs and benefits associated with migration leads to differing migratory strategies for maximization of individual lifetime fitness. While genetics play a role in determining the occurrence of migration, juvenile steelhead migratory behavior is highly plastic in response to conditions...
Article
Understanding ecological effects of altered stream flows is an essential objective. In a comparative field study of juvenile steelhead trout (Oncorhynchus mykiss) that compared natural- and reduced-flow sites, we used mark–recapture modelling and information theory to quantify spatially and temporally explicit patterns of density, specific growth r...
Article
Across taxa, it is generally accepted that there are fitness advantages to rapid growth early in life. For stream-dwelling salmonids, however, high temperatures and associated energetic costs during the summer growing season might offset or even prevent the competitive advantage of large body size. Our overall objective was to understand the relati...
Article
Full-text available
Recent advances in using naturally occurring isotopes to reconstruct movement patterns have revolutionized the study of migration and spatial patterns across taxa. Isoscape approaches utilize isotopic variation in the underlying geology to quantify migration pathways. Spatial patterns in the geology can be used to predict isotopic variation, such a...
Article
Full-text available
Human disturbances to ecosystems have created challenges to populations worldwide, forcing them to respond phenotypically in ways that increase their fitness under current conditions. One approach to examining population responses to disturbance in species with complex life histories is to study species that exhibit spatial patterns in their phenot...
Conference Paper
The self thinning hypothesis states that as individuals grow they require a larger fraction of the available resources, and this competition regulates population densities. Experiments in steelhead showed that competition caused increased mortality, lower and more variable growth rates, and increased emigration of smaller fish. Across a stream netw...
Conference Paper
Background/Question/Methods Understanding the distribution, abundance and relative performance of life history types is critical for development of passage for juvenile Chinook salmon in the Willamette Valley Basin (WVB), and an important element of the Willamette Valley Biological Opinion. Recent analyses of screw trap data suggest that juvenile...
Conference Paper
Background/Question/Methods When managing and conserving migratory populations, it is important to consider population parameters at each location or life history stage. For anadromous fish, the freshwater rearing phase can be important to population regulation and persistence. Both natural and anthropogenic factors can drive survival of rearing ju...
Article
The use of benthic barriers alone or in combination with other control methods could initiate the eradication of pioneer populations of Eurasian watermilfoil and facilitate maintenance of acceptable population levels in water bodies where the weed is widely established. We evaluated the effects of duration of geotextile fabric panel placement on sm...
Article
Full-text available
The resilience of organisms to large-scale environmental and climatic change depends, in part, upon the ability to colonize and occupy new habitats. While previous efforts to describe homing, or natal site fidelity, of migratory organisms have been hindered by the confounding effects of fragmented landscapes and management practices, realistic cons...
Conference Paper
The resilience of fish populations to large-scale environmental and climatic change depends, in part, upon their life history diversity. For migratory salmon adapting to disturbance-prone environments, this may have maintained selection for highly plastic behaviors. A fundamental challenge to understanding these migratory processes in contemporary...
Conference Paper
Pacific salmon populations have suffered declines and local extirpations in the Pacific Northwest over the last century as a result of physical and functional changes to their freshwater environments, yet persist in highly altered habitats. Life history variation in Pacific salmonids has been suggested as one factor that contributes to population r...
Conference Paper
Stream diversion projects are globally widespread and can have detrimental effects on salmonid rearing conditions. Withdrawals alter stream habitat conditions including temperature, hydrographs, velocities, connectivity, and habitat area. These alterations can then impact growth and survival of rearing salmonids. For anadromous populations, growth...
Conference Paper
As increasing urbanization and changing climates contribute to altered hydrologic regimes, there is increasing need to understand how stream water supply and temperature influences the energy requirements for growth of fishes. In hot and dry summer climates the scope of growth can be exceeded for cool- and coldwater species such as steelhead (Oncor...
Conference Paper
Temporal variation in anadromous salmon abundance has been shown to be strongly correlated to aspects of climate variability. Indeed, Chinook salmon production has been linked to water chemistry, hydrologic, and temperature regimes, all of which are very likely to be altered during the next 50 years because of continued changes in the Earth’s physi...
Conference Paper
Background/Question/Methods The resilience of organisms to large-scale environmental and climatic change depends, in part, upon the ability to colonize and occupy new habitats. However, a fundamental challenge to understanding dispersal and migratory processes for populations is our inability to follow the behavior of individuals over large spati...
Article
Landscape-scale patterns of freshwater fish diversity and assemblage structure remain poorly documented in many areas of Central America, while aquatic ecosystems throughout the region have been impacted by habitat degradation and hydrologic alterations. Diadromous fishes may be especially vulnerable to these changes, but there is currently very li...
Article
Abstract –  Understanding population regulation in juvenile salmonids requires distinguishing the effects of intrinsic (size, behaviour) and extrinsic (food, competition) factors. To examine the relative influence of these variables on juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Salmon River drainage (ID, USA), we examined diel differ...
Conference Paper
American Shad (Alosa sapidissima) were introduced to the Sacramento River, CA in 1871. Since then, they have expanded their range from southern California to southeast Alaska. Initially, the Columbia River population remained at low levels, but increased after dam construction improved spawning and rearing conditions. The number of adult shad passi...
Conference Paper
Background/Question/Methods The emergence and maintenance of life history strategies in salmon populations is the combined result of variation in individual migratory behaviors and fluctuating environmental conditions. It is therefore of fundamental interest to understand how different migratory strategies confer fitness advantages to individuals w...
Article
We measured summer microhabitat use, availability, and selection by age-0 Chinook salmon Oncorhynchus tshawytscha in the Big Creek drainage, Idaho. Age-0 fish selected for low-velocity (0-25 cm/s), moderate-depth (40-80 cm) habitats that were located within 80 cm of cover. Pools (52%) and runs (38.5%) were the most commonly used habitat types, whil...
Article
Riparian forest buffers may play a critical role in moderating the impacts of deforestation on tropical stream ecosystems, but very few studies have examined the ecological effects of riparian buffers in the tropics. To test the hypothesis that riparian forest buffers can reduce the impacts of deforestation on tropical stream biota, we sampled fish...
Article
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis. Does common genetic variation at human TH alter autonomic activity and predispose to cardiovascular disease? We undertook systematic polymorphism discovery at the TH locus, and then tested variants for contributions to sympathetic function and blood pressure. We re...
Article
1. Few studies have evaluated the effectiveness of riparian buffers in the tropics, despite their potential to reduce the impacts of deforestation on stream communities. We examined macroinvertebrate assemblages and stream habitat characteristics in small lowland streams in southeastern Costa Rica to assess the impacts of deforestation on benthic c...
Article
Realistic population models and effective conservation strategies require a thorough understanding of mechanisms driving stage-specific mortality. Mortality bottlenecks for many species occur in the juvenile stage and are thought to result from limitation on food or foraging habitat during a "critical period" for growth and survival. Without a way...
Article
Full-text available
1. In large deep oligotrophic lakes, the shallow nearshore waters may provide the most important habitat for animals to feed and breed, and it is this area of the lake where humans are most likely to have initial impacts as the shoreline is developed. Nutrients in fertilizers, sediments and sewage effluents are likely to be rapidly intercepted by n...
Article
1 In postganglionic sympathetic neurones and adrenal chromaffin cells, catecholamines are co-stored in vesicles with soluble peptides, including chromogranin A (CgA) and neuropeptide Y (NPY), which are subject to exocytotic co-release with catecholamines. 2 Plasma catecholamine, CgA and NPY responses to stimulators and inhibitors of sympatho-adrena...
Article
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis. Does common genetic variation at human TH alter autonomic activity and predispose to cardiovascular disease? We undertook systematic polymorphism discovery at the TH locus and then tested variants for contributions to sympathetic function and blood pressure. We res...
Article
Chromogranin A, coreleased with catecholamines by exocytosis, is cleaved to the catecholamine release-inhibitory fragment catestatin. We identified a natural nonsynonymous variant of catestatin, Gly364Ser, that alters human autonomic function and blood pressure. Gly364Ser heterozygotes and controls underwent physiological and biochemical phenotypin...
Article
Albumin excretion marks early glomerular injury in hypertension. This study investigated heritability of albumin excretion in twin pairs and its genetic determination by adrenergic pathway polymorphism. Genetic associations used single nucleotide polymorphisms at adrenergic pathway loci spanning catecholamine biosynthesis, storage, catabolism, rece...
Article
C-reactive protein (CRP) both reflects and participates in inflammation, and its circulating concentration marks cardiovascular risk. Here we sought to understand the role of heredity in determining CRP secretion. CRP, as well as multiple facets of the metabolic syndrome, were measured in a series of 229 twins, both monozygotic (MZ) and dizygotic (...
Article
The Rho/Rho kinase (ROCK) pathway is implicated in experimental hypertension. We, therefore, explored the role of ROCK2 genetic variation in human blood pressure (BP) regulation, exploiting the advantages of a human twin sample to probe heritability. The focus of this work is the common nonsynonymous variant at ROCK2: Thr431Asn. Cardiovascular and...
Article
Obstructive sleep apnea (OSA) is characterized by noradrenergic activation. Nasal continuous positive airway pressure (CPAP) is the treatment of choice and has been shown to effectively reduce elevated norepinephrine (NE) levels. This study examined whether the reduction in NE after CPAP is due to an increase in NE clearance and/or a decrease of NE...
Article
Full-text available
The secretory prohormone chromogranin A (CHGA) is overexpressed in essential hypertension, a complex trait with genetic predisposition, while its catecholamine release-inhibitory fragment catestatin is diminished, and low catestatin predicts augmented adrenergic pressor responses. These findings from studies on humans suggest a mechanism whereby di...
Article
We compared the success of using naturally occurring stable isotopes of N, C, and Sr as markers for the rearing locations of juvenile salmon. We analyzed the isotopic signatures (δ 15 Na ndδ 13C in muscle and scales and 87 Sr/86Sr in otoliths) of >200 juvenile Atlantic salmon (Salmo salar) from 12 tributaries of the Connecticut River, USA. Young sa...
Article
Tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, has a common tetranucleotide repeat polymorphism, (TCAT)(n). We asked whether variation at (TCAT)(n) may influence the autonomic nervous system and its response to environmental stress. To understand the role of heredity in such traits, we turned to a human twin study des...
Article
Summary 1. Establishing reliable estimates of consumption is necessary for understanding the physiology, bioenergetics and trophic relationships of organisms. For fish, the inability to measure consumption directly prevents a mechanistic understanding of habitat- foraging relationships. Building upon established models for 137 caesium (Cs) mass bal...
Article
alpha2-Adrenergic blockade responses suggest adrenergic dysfunction in hypertension. alpha2-Blockade is also used to treat autonomic dysfunction. However, pharmacokinetic determinants of yohimbine disposition are not understood. We evaluated alpha2-blockade with intravenous yohimbine in 172 individuals. Specific cytochrome P450 (CYP) isoform-mediat...
Article
Essential hypertension is characterized by alterations in autonomic nervous system activity, in particular baroreflex sensitivity or baroreceptor slope. Baroreceptor slope can be tested in humans by evaluating the heart rate responses to induced changes in blood pressure. Baroreceptor slope is already deranged even in the hypertension family histor...
Article
Insomnia predicts cardiovascular and non-cardiovascular disease mortality. This study evaluated EEG sleep, nocturnal sympathetic activity, and daytime measures of immune function in subjects with primary insomnia (n = 17) and patients with current major depression (n = 14) as compared to controls (n = 31). Insomniacs showed disordered sleep continu...
Article
Full-text available
Stimulation of chromaffin cell secretion in vitro triggers not only secretion but also resynthesis of just released catecholamines and chromogranin A, the precursor of the catecholamine release-inhibitory, nicotinic cholinergic antagonist peptide catestatin. Does stimulus-transcription coupling occur in vivo? And does catestatin antagonize secretio...
Article
This study examined the effects of hypertension and an acute psychological stressor on white blood cells and their expression of CD62L and CD11a. Seventeen mild hypertensive and 23 normotensive volunteers were studied prior to and following a standardized laboratory public speech. In response to the speech, all subjects increased the number of circ...