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At least 91 records · Page 5Linked to original sources
USGS2004

Biochemical, histological and behavioural aspects of visual function during early development of rainbow trout

Retinal structure and concentration of retinoids involved in phototransduction changed during early development of rainbow trout Oncorhynchus mykiss, correlating with improvements in visual function. A test chamber was used to evaluate the presence of optokinetic or optomotor responses and to assess the functionality of the integrated cellular, physiological and biochemical components of the visual system. The results indicated that in rainbow trout optomotor responses start at 10 days post-hatch, and demonstrated for the first time that increases in acuity, sensitivity to low light as well as in motion detection abilities occur from this stage until exogenous feeding starts. The structure of retinal cells such as cone ellipsoids increased in length as photopic visual acuity improved, and rod densities increased concurrently with improvements in scotopic thresholds (2.2 log10 units). An increase in the concentrations of the chromophore all-trans-retinal correlated with improvements of all behavioural measures of visual function during the same developmental phase. ?? 2004 The Fisheries Society of the British Isles.

Journal of Fish Biology↗
USGS2009

Migratory behaviour and survival rates of wild northern Atlantic salmon Salmo salar post-smolts: Effects of environmental factors

To study smolt behaviour and survival of a northern Atlantic salmon Salmo salar population during river descent, sea entry and fjord migration, 120 wild S. salar were tagged with acoustic tags and registered at four automatic listening station arrays in the mouth of the north Norwegian River Alta and throughout the Alta Fjord. An estimated 75% of the post-smolts survived from the river mouth, through the estuary and the first 17 km of the fjord. Survival rates in the fjord varied with fork length (L F ), and ranged from 97??0 to 99??5% km -1 . On average, the post-smolts spent 1??5 days (36 h, range 11-365 h) travelling from the river mouth to the last fjord array, 31 km from the river mouth. The migratory speed was slower (1??8 L F s -1 ) in the first 4 km after sea entry compared with the next 27 km (3??0 L F s -1 ). Post-smolts entered the fjord more often during the high or ebbing tide (70%). There was no clear diurnal migration pattern within the river and fjord, but most of the post-smolts entered the fjord at night (66%, 2000-0800 hours), despite the 24 h daylight at this latitude. The tidal cycle, wind-induced currents and the smolts' own movements seemed to influence migratory speeds and routes in different parts of the fjord. A large variation in migration patterns, both in the river and fjord, might indicate that individuals in stochastic estuarine and marine environments are exposed to highly variable selection regimes, resulting in different responses to environmental factors on both temporal and spatial scales. Post-smolts in the northern Alta Fjord had similar early marine survival rates to those observed previously in southern fjords; however, fjord residency in the north was shorter. ?? 2009 The Fisheries Society of the British Isles.

Journal of Fish Biology↗
USGS2020

Behavioural responses of female lake trout Salvelinus namaycush to male chemical stimuli and prostaglandin F2α

Male olfactory cues may guide aggregation on spawning reefs, mate evaluation, and synchronized gamete release in lake trout Salvelinus namaycush, but a lack of information on the source and identity of the cues precludes direct tests of their function. Using a two-channel flume assay, we found female lake trout increased time spent in the channel treated with male-conditioned water, urine, and bile but not synthesized prostaglandin F2α. We suggest future efforts to characterize male olfactory cues focus on urine and postulate that bile acids contribute to its behavioural activity.

Journal of Fish Biology↗
USGS2020

Effect of water velocity and temperature on energy use, behaviour and mortality of pallid sturgeon Scaphirhynchus albus larvae

Natural reproduction of pallid sturgeon Scaphirhynchus albus has been limited for decades and a recruitment bottleneck is hypothesized to occur during the larval stage of development. In this study, we evaluated the effects of water velocity and temperature on the swimming activity, energy use, settling behaviour and mortality of endogenously feeding larvae. The swimming activity of drifting sturgeon larvae ( i.e. , fish exhibiting negative rheotaxis) increased at low water velocity. In subsequent experiments, we observed greater energy depletion and resultant mortality of larvae in no-flow environments (0 cm s −1 ) compared to tanks with water velocity ranging from 3.5 to 8.3 cm s −1 . The growth rate of drifting larvae was positively related to water temperature (18.7–23.3°C), but reduced growth rate at low water temperature (18.7°C) resulted in protracted development that extended average drift duration by ~4 days compared to larvae reared at 23.3°C. This study provides evidence that cooler summer water temperatures, characteristic of present-day conditions in the upper Missouri River, can reduce larval development and extend both the drift duration and distance requirements of S. albus . Moreover, if dispersed into low velocity environments, such as in reservoir headwaters, larvae may experience increased mortality owing to a mismatch between early life stage drift requirements and habitat conditions in the river. Manipulation of water releases to increase seasonal water temperature below dams may aid survival of S. albus larvae by shortening the time and distance spent drifting.

Journal of Fish Biology↗
USGS1999

Behaviour and ecology of sea ducks

In November 1995... a full-day symposium on the biology of sea ducks was held. The papers in this volume were presented at this symposium. It is hoped that by synthesizing this information, more informed management decisions for sea ducks may emerge. The symposium contents help to emphasize the seriousness of some conservation issues facing sea ducks, notably the possible endangerment of the eastern population of Barrow's Goldeneye and the dwindling number of eider ducks in the Nearctic, while also providing new data on the behaviour and habitat use of this beautiful group of ducks.

Occasional Paper of the Canadian Wildlife Service↗
USGS2002

Behavioural and physiological response of trout to winter habitat in tailwaters in Wyoming, USA

Fisheries managers have often suggested that survival of trout during the winter is a major factor affecting population densities in many stream ecosystems in the Rocky Mountains. In Wyoming, trout population reductions from fall to spring in excess of 90% have been documented in some reservoir tailwaters. Though biologists have surmised that these reductions were the result of either mortality or emigration from some river sections, the specific mechanisms have not been defined and the factors leading to the trout loss are unknown. This is a review of four studies that were conducted or funded between 1991 and 1998 by the Wyoming Game and Fish Department to understand the extent of overwinter losses, identify some of the mechanisms leading to those conditions and develop management strategies to help avoid those impacts. Winter studies were conducted on tailwater fisheries in the Green, North Platte, Bighorn and Shoshone rivers to document trout population dynamics, assess physical habitat availability, evaluate trout movement and habitat selection, and understand the relationships between food availability and bioenergetic relationships. Results indicate that winter trout losses are extreme in some years, that trout movement and habitat selection are affected by supercooled flows, and that mortality is probably not directly due to starvation. The combination of physiological impairment with frequently altered habitat availability probably leads to indirect mortality from predators and other factors. Copyright ?? 2002 John Wiley & Sons, Ltd.

Hydrological Processes↗
USGS1977

Uranium and coexisting element behaviour in surface waters and associated sediments with varied sampling techniques used for uranium exploration

Optimum sampling methods in surface water and associated sediments for use in uranium exploration are being studied at thirty sites in Colorado, New Mexico, Arizona and Utah. For water samples, filtering is recommended to increase sample homogeneity and reproducibility because for most elements studied water samples which were allowed to remain unfiltered until time of analysis contained higher concentrations than field-filtered samples of the same waters. Acidification of unfiltered samples resulted in still higher concentrations. This is predominantly because of leaching of the elements from the suspended fraction. U in water correlates directly with Ca, Mg, Na, K, Ba, B, Li and As. In stream sediments, U and other trace elements are concentrated in the finer size fractions. Accordingly, in prospecting, grain size fractions less than 90 μm (170 mesh) should be analyzed for U. A greater number of elements (21) show a significant positive correlation with U in stream sediments than in water. Results have revealed that anomalous concentrations of U found in water may not be detected in associated sediments and vice versa. Hence, sampling of both surface water and coexisting sediment is strongly recommended.

Journal of Geochemical Exploration↗
USGS2025

Are behavioural ecotoxicity endpoints relevant at the population level? Evidence-based insights for environmental protection

A substantial body of evidence exists demonstrating that exposure to environmental contaminants can alter animal behavior. Moreover, methodological and technological advancements, as well as increasing standardization, mean that behavioral ecotoxicity studies are more rigorous and reliable than ever before. Despite this, behavioral data are still seldom used in the risk assessment and regulation of chemicals. This is partly due to a lack of clarity among some stakeholders about whether changes in behavior at the individual level result in population-level outcomes. To address this, we first consider the state of evidence within the field of behavioral ecotoxicology linking individual-level behavioral alterations with population-level consequences. We then assess the evidence from behavioral ecology and other neighboring fields that supports this link. Further, we evaluate whether some behavioral endpoints are more easily tied to population-level changes than others. In this regard, we propose combining insights from two complementary ecological frameworks─the functional trait framework and the limiting traits framework─to evaluate which behaviors should be prioritized in ecotoxicological research and regulatory efforts. We contend that the link between behavioral changes and population-level outcomes is evident, with behavioral endpoints representing a highly valuable yet so far underutilized line of evidence in applied environmental protection.

Environmental Science and Technology↗
USGS1962

Study of natural glasses through their behaviour as membrane electrodes

THE low-temperature chemical alteration of natural glass occurs in two stages: an initial stage in which it remains glassy but absorbs as much as 6 per cent water 1 , and a final stage in which devitrification to clay minerals, with release of silica, occurs 2,3 . During the first stage the composition of the glass may change, with gain of K 2 O and water and loss of Na 2 O (Smith, R. L., personal communication). This change is due to ion exchange.

Nature↗
USGS2009

Development and application of a mark-recapture model incorporating predicted sex and transitory behaviour

We developed an extension of Cormack-Jolly-Seber models to handle a complex mark-recapture problem in which (a) the sex of birds cannot be determined prior to first moult, but can be predicted on the basis of body measurements, and (b) a significant portion of captured birds appear to be transients (i.e. are captured once but leave the area or otherwise become ' untrappable'). We applied this methodology to a data set of 4184 serins (Serinus serinus) trapped in northeastern Spain during 1985-96, in order to investigate age-, sex-, and time-specific variation in survival rates. Using this approach, we were able to successfully incorporate the majority of ringings of serins. Had we eliminated birds not previously captured (as has been advocated to avoid the problem of transience) we would have reduced our sample sizes by >2000 releases. In addition, we were able to include 1610 releases of birds of unknown (but predicted) sex; these data contributed to the precision of our estimates and the power of statistical tests. We discuss problems with data structure, encoding of the algorithms to compute parameter estimates, model selection, identifiability of parameters, and goodness-of-fit, and make recommendations for the design and analysis of future studies facing similar problems.

Bird Study↗
USGS2018

The ecology of movement and behaviour: a saturated tripartite network for describing animal contacts

Ecologists regularly use animal contact networks to describe interactions underlying pathogen transmission, gene flow, and information transfer. However, empirical descriptions of contact often overlook some features of individual movement, and decisions about what kind of network to use in a particular setting are commonly ad hoc . Here, we relate individual movement trajectories to contact networks through a tripartite network model of individual, space, and time nodes. Most networks used in animal contact studies (e.g. individual association networks, home range overlap networks, and spatial networks) are simplifications of this tripartite model. The tripartite structure can incorporate a broad suite of alternative ecological metrics like home range sizes and patch occupancy patterns into inferences about contact network metrics such as modularity and degree distribution. We demonstrate the model's utility with two simulation studies using alternative forms of ecological data to constrain the tripartite network's structure and inform expectations about the harder-to-measure metrics related to contact.

Proceedings of the Royal Society B: Biological Sci↗
USGS2009

Salinity effects on behavioural response to hypoxia in the non-native Mayan cichlid Cichlasoma urophthalmus from Florida Everglades wetlands

This study quantified the hypoxia tolerance of the Mayan cichlid Cichlasoma urophthalmus over a range of salinities. The species was very tolerant of hypoxia, using aquatic surface respiration (ASR) and buccal bubble holding when oxygen tensions dropped to <20 mmHg (c. 1??0 mg l -1 ) and 6 mmHg, respectively. Salinity had little effect on the hypoxia tolerance of C. urophthalmus, except that bubble holding was more frequent at the higher salinities tested. Levels of aggression were greatest at the highest salinity. The ASR thresholds of C. urophthalmus were similar to native centrarchid sunfishes from the Everglades, however, aggression levels for C. uropthalmus were markedly higher. ?? 2009 The Fisheries Society of the British Isles.

Journal of Fish Biology↗
USGS2008

Congruent population structure inferred from dispersal behaviour and intensive genetic surveys of the threatened Florida scrub-jay ( Aphelocoma cœrulescens )

The delimitation of populations, defined as groups of individuals linked by gene flow, is possible by the analysis of genetic markers and also by spatial models based on dispersal probabilities across a landscape. We combined these two complimentary methods to define the spatial pattern of genetic structure among remaining populations of the threatened Florida scrub-jay, a species for which dispersal ability is unusually well-characterized. The range-wide population was intensively censused in the 1990s, and a metapopulation model defined population boundaries based on predicted dispersal-mediated demographic connectivity. We subjected genotypes from more than 1000 individual jays screened at 20 microsatellite loci to two Bayesian clustering methods. We describe a consensus method for identifying common features across many replicated clustering runs. Ten genetically differentiated groups exist across the present-day range of the Florida scrub-jay. These groups are largely consistent with the dispersal-defined metapopulations, which assume very limited dispersal ability. Some genetic groups comprise more than one metapopulation, likely because these genetically similar metapopulations were sundered only recently by habitat alteration. The combined reconstructions of population structure based on genetics and dispersal-mediated demographic connectivity provide a robust depiction of the current genetic and demographic organization of this species, reflecting past and present levels of dispersal among occupied habitat patches. The differentiation of populations into 10 genetic groups adds urgency to management efforts aimed at preserving what remains of genetic variation in this dwindling species, by maintaining viable populations of all genetically differentiated and geographically isolated populations.

Florida↗
USGS2012

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread.

Ecology Letters↗
USGS2019

Individual behaviour and resource use of thermally stressed brook trout Salvelinus fontinalis portend the conservation potential of thermal refugia

Individual aggression and thermal refuge use were monitored in brook trout Salvelinus fontinalis in a controlled laboratory to determine how fish size and personality influence time spent in forage and thermal habitat patches during periods of thermal stress. On average, larger and more exploratory fish initiated more aggressive interactions and across all fish there was decreased aggression at warmer temperatures. Individual personality did not explain changes in aggression or habitat use with increased temperature; however, larger individuals initiated comparatively fewer aggressive interactions at warmer temperatures. Occupancy of forage patches generally declined as ambient stream temperatures approached critical maximum and fish increased thermal refuge use, with a steeper decline in forage patch occupancy observed in larger fish. These findings suggest that larger individuals may be more vulnerable to stream temperature rise. Importantly, even at thermally stressful temperatures, all fish periodically left the thermal refuge to forage. This indicates that the success of refugia at increasing population survival during periods of stream temperature rise may depend on the location of thermal refugia relative to forage locations within the larger habitat mosaic. These results provide insights into the potential for thermal refugia to improve population survival and can be used to inform predictions of population vulnerability to climate change.

Journal of Fish Biology↗
USGS2017

Spatial mismatch between sea lamprey behaviour and trap location explains low success at trapping for control

Crucial to the management of invasive species is understanding space use and the environmental features affecting space use. Improved understanding of space use by invasive sea lamprey ( Petromyzon marinus ) could help researchers discern why trap success in large rivers is lower than needed for effective control. We tested whether manipulating discharge nightly could increase trap success at a hydroelectric generating station on the St. Marys River. We quantified numbers of acoustically tagged sea lampreys migrating up to, and their space use at, the hydroelectric generating station. In 2011 and 2012, 78% and 68%, respectively, of tagged sea lampreys reached the generating station. Sea lampreys were active along the face, but more likely to occur at the bottom and away from the traps near the surface, especially when discharge was high. Our findings suggest that a low probability of encountering traps was due to spatial (vertical) mismatch between space use by sea lamprey and trap locations and that increasing discharge did not alter space use in ways that increased trap encounter. Understanding space use by invasive species can help managers assess the efficacy of trapping and ways of improving trapping success.

Canadian Journal of Fisheries and Aquatic Sciences↗