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Results for “Journal of Biological Systems”

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At least 19 recordsLinked to original sources
USGS2011

Dynamics and spatio-temporal variability of environmental factors in Eastern Australia using functional principal component analysis

This paper introduces a new technique in ecology to analyze spatial and temporal variability in environmental variables. By using simple statistics, we explore the relations between abiotic and biotic variables that influence animal distributions. However, spatial and temporal variability in rainfall, a key variable in ecological studies, can cause difficulties to any basic model including time evolution. The study was of a landscape scale (three million square kilometers in eastern Australia), mainly over the period of 19982004. We simultaneously considered qualitative spatial (soil and habitat types) and quantitative temporal (rainfall) variables in a Geographical Information System environment. In addition to some techniques commonly used in ecology, we applied a new method, Functional Principal Component Analysis, which proved to be very suitable for this case, as it explained more than 97% of the total variance of the rainfall data, providing us with substitute variables that are easier to manage and are even able to explain rainfall patterns. The main variable came from a habitat classification that showed strong correlations with rainfall values and soil types. ?? 2010 World Scientific Publishing Company.

Journal of Biological Systems↗
USGS1986

Larval settlement into marine soft-sediment systems: Interactions with the meiofauna

The distribution and abundance of organisms exhibiting complex life cycles, like marine invertebrates, reflect ecological processes operating at all stages in the life history. Few studies have yet considered the mortality patterns of larvae and juveniles. To test whether the permanent meiofauna play a role in macrofaunal larval site-selection, and/or if permanent meiofaunal predators or competitors and disturbers are a significant source of mortality for newly settled macrofaunal juveniles, a series of manipulations of meiofauna were performed. Densities of (1) predatory turbellarians alone, and (2) other meiofauna, were increased in small boxes placed on a holding table in a shallow subtidal habitat. Natural settlement into meiofauna manipulations was examined approximately monthly for a year. Other experiments were conducted to examine the relative importance of site-selection and post-settlement mortality and to determine if settlement was density-dependent or density-independent. Densities of spionid, cirratulid, terebellid, capitellid, and maldanid polychaetes, oligochaetes, bivalves, and amphipods were all reduced by high densities of turbellarians, and sometimes by other meiofauna. Turbellarian predation was responsible for significant post-settlement mortality, but spionids, cirratulids, terebellids, and maldanids also appeared to avoid dense turbellarian treatments. Bivalve densities were reduced by high densities of other meiofauna, probably due to their sedimentary disturbance. Syllid polychaete densities were higher in turbellarian treatments, suggesting that they select for areas with high densities of their prey (small turbellarians). The effects of meiofauna on settlement and survival were greatest in spring and summer. The results of these experiments suggest larval settlement patterns and early juvenile survival should be considered in developing general models of life history and community structure for soft-sediment systems.

Journal of Experimental Marine Biology and Ecology↗
USGS2005

Geochemistry and the understanding of ground-water systems

Geochemistry has contributed significantly to the understanding of ground-water systems over the last 50 years. Historic advances include development of the hydrochemical facies concept, application of equilibrium theory, investigation of redox processes, and radiocarbon dating. Other hydrochemical concepts, tools, and techniques have helped elucidate mechanisms of flow and transport in ground-water systems, and have helped unlock an archive of paleoenvironmental information. Hydrochemical and isotopic information can be used to interpret the origin and mode of ground-water recharge, refine estimates of time scales of recharge and ground-water flow, decipher reactive processes, provide paleohydrological information, and calibrate ground-water flow models. Progress needs to be made in obtaining representative samples. Improvements are needed in the interpretation of the information obtained, and in the construction and interpretation of numerical models utilizing hydrochemical data. The best approach will ensure an optimized iterative process between field data collection and analysis, interpretation, and the application of forward, inverse, and statistical modeling tools. Advances are anticipated from microbiological investigations, the characterization of natural organics, isotopic fingerprinting, applications of dissolved gas measurements, and the fields of reaction kinetics and coupled processes. A thermodynamic perspective is offered that could facilitate the comparison and understanding of the multiple physical, chemical, and biological processes affecting ground-water systems.

Hydrogeology Journal↗
USGS1988

Monitoring wildlife habitat: A critique of approaches

Naturalists have long recognized that wildlife cannot exist in a natural state without adequate habitat. Habitat monitoring is an effort to monitor the physical conditions that provide life support for the species, given the underlying assumption that if the habitat is available the species will respond and fill that habitat with viable populations. Techniques for habitat monitoring are varied and depend on the species involved, geographical area, and resources available. At a very gross level, habitat monitoring may be little more than the monitoring of major vegetative associations: time series analysis of aerial photography is an excellent mechanism to monitor the changes in hectares of specified vegetative associations, which are surrogate measures of habitat. One approach uses population monitoring to determine habitat availability. Unfortunately, many researchers fail to recognize that population levels may or may not reflect habitat quality or habitat availability. Another approach is to monitor species richness or species diversity. Finally, the habitat components that compose quality habitat for a species or species group can be used for monitoring. This approach results in the identification of important habitat attributes that can be measured independent of the presence of the species. A thorough understanding of the biological system being monitored is paramount to the development of sound monitoring study design.

Statistical Journal of the United Nations ECE↗
USGS2007

Spatial and temporal variability in oceanographic and meteorologic forcing along Central California and its implications on nearshore processes

In the past two decades, the understanding of the important large-scale phenomena (El Niño, upwelling, California current, etc) that drive physical, chemical, and biological processes along the US West Coast has greatly improved. However, the ability to predict the influence of annual and inter-annual events on a regional scale still remains limited. High-resolution hourly data from 6 National Oceanographic and Atmospheric Administration (NOAA) buoys deployed since the early 1980's off Central California were analyzed to improve our understanding of spatial and temporal variability of oceanographic and meteorologic forcing along the coastline. Seasonal to inter-annual trends in wave height, wave period, sea level barometric pressure, sea-surface temperature, and wind direction were identified, as were significant departures in these trends during El Niño and La Niña periods. The results suggest there are increasing wave heights and wave periods, decreasing sea level barometric pressures and variability in sea-surface temperatures, and increasingly variable winds off Central California between 1980 and 2002. The impact of these climatic trends on coastal physical, geological and biologic processes will also be addressed.

California↗
USGS2014

Extensive feeding on sockeye salmon Oncorhynchus nerka smolts by bull trout Salvelinus confluentus during initial outmigration into a small, unregulated and inland British Columbia river

Stomach contents were collected and analysed from 22 bull trout Salvelinus confluentus at the edge of the Chilko Lake and Chilko River in British Columbia, Canada, during spring outmigration of sockeye salmon Oncorhynchus nerka smolts. Twenty of the 22 (>90%) stomachs contained prey items, virtually all identifiable prey items were outmigrant O. nerka smolts and stomach contents represented a large portion (0·0–12·6%) of estimated S. confluentus mass. The results demonstrate nearly exclusive and intense feeding by S. confluentus on outmigrant smolts, and support recent telemetry observations of high disappearance rates of O. nerka smolts leaving large natural lake systems prior to entering high-order unregulated river systems.

Journal of Fish Biology↗
USGS2001

Growth rate responses of Missouri and lower Yellowstone river fishes to a latitudinal gradient

Growth rate coefficients estimated for channel catfish Ictalurus punctatus, emerald shiners Notropis atherinoides, freshwater drums Aplodinotus grunniens, river carpsuckers Carpiodes carpio and saugers Stizostedion canadense collected in 1996-1998 from nine river sections of the Missouri and lower Yellowstone rivers at two life-stages (young-of-the-year and age 1 + years) were significantly different among sections. However, they showed no river-wide latitudinal trend except for age 1 + years emerald shiners that did show a weak negative relation between growth and both latitude and length of growing season. The results suggest growth rates of fishes along the Missouri River system are complex and could be of significance in the management and conservation of fish communities in this altered system. ?? 2001 The Fisheries Society of the British Isles.

Journal of Fish Biology↗
USGS2020

Versatile combustion-amalgamation technique for the photometric determination of mercury in fish and environmental samples

Total mercury in a variety of substances is determined rapidly and precisely by direct sample combustion, collection of released mercury by amalgamation, and photometric measurement of mercury volatilized from the heated amalgam. Up to 0.2 g fish tissue is heated in a stream of O 2 (1.2 L/min) for 3.5 min in 1 tube of a 2-tube induction furnace. The released mercury vapor and combustion products are carried by the stream of O 2 through a series of traps (6% NaOH scrubber, water condenser, and Mg(ClO 4 ) 2 drying tube) and the mercury is collected in a 10 mm diameter column of 24 gauge gold wire (8 g) cut into 3 mm lengths. The resulting amalgam is heated in the second tube of the induction furnace and the volatilized mercury is measured with a mercury vapor meter equipped with a recorder-integrator. Total analysis time is approximately 8 min/sample. The detection limit is less than 0.002 μ g and the system is easily converted for use with other biological materials, water, and sediments.

Journal of the Association of Official Analytical ↗
USGS2018

Flow-ecology relationships are spatially structured and differ among flow regimes

In streams, hydrology is a predominant driver of ecological structure and function. Providing adequate flows to support aquatic life, or environmental flows, is therefore a top management priority in stream systems. Flow regime classification is a widely accepted approach for establishing environmental flow guidelines. However, it is surprisingly difficult to quantify relationships between hydrology and ecology (flow–ecology relationships) while describing how these relationships vary across classified flow regimes. Developing such relationships is complicated by several sources of spatial bias, such as autocorrelation due to spatial design, flow regime classification and other environmental or ecological sources of spatial bias. We used mixed moving‐average spatial stream network models to develop flow–ecology relationships across classified flow regimes and to assess spatial patterns of these relationships. We compared relationships between fish traits and life‐history strategies with hydrologic metrics across flow regimes and assessed whether spatial autocorrelation influenced these relationships. Trait–hydrology relationships varied between flow regimes and across all streams combined. Some relationships between traits and hydrologic metrics fit predictions based on life‐history theory, while others exhibited unexpected relationships with hydrology. Spatial factors described a large proportion of variability in fish traits and different patterns of spatial autocorrelation were observed in different flow regimes. Synthesis and applications. Further work is needed to understand why flow–ecology relationships vary across classified flow regimes and why these relationships may not fit predictions based on life‐history theories. Managers determining environmental flow standards need to be aware that different hydrologic metrics are often important drivers of fish trait diversity in different flow regimes. Flow–ecology relationships may therefore be confounded by spatial structure inherent in flow regime classification and much existing biological data. Complex patterns of spatial bias should be considered when managing stream systems within an environmental flows framework.

Journal of Applied Ecology↗
USGS1971

Trees and streams: The efficiency of branching patterns

Extending the analysis of branching patterns of the drainage net of rivers, originated by Horton, the relation of average numbers and lengths of tree branches to size of branch was investigated. Size of branch was defined by branch order, or its position in the hierarchy of tributaries. It was found that, as in river drainage nets, there is a definite logarithmic relation between branch order and lengths and numbers. This definite relation is quantitatively comparable, within limits, among river networks, tree branching systems, and several random-walk models in both two and three dimensions. Such a relation appears to be the most probable under the applicable constraints. Moreover the most probable arrangement appears to minimize the total length of all stems in the branching system within other constraints and so, to that extent, achieves a certain efficiency.

Journal of Theoretical Biology↗
USGS2018

High-precision 41K/39K measurements by MC-ICP-MS indicate terrestrial variability of δ41K

Potassium is a major component in continental crust, the fourth-most abundant cation in seawater, and a key element in biological processes. Until recently, difficulties with existing analytical techniques hindered our ability to identify natural isotopic variability of potassium isotopes in terrestrial materials. However, measurement precision has greatly improved and a range of K isotopic compositions has now been demonstrated in natural samples. In this study, we present a new technique for high-precision measurement of K isotopic ratios using high-resolution, cold plasma multi-collector mass spectrometry. We apply this technique to demonstrate natural variability in the ratio of 41 K to 39 K in a diverse group of geological and biological samples, including silicate and evaporite minerals, seawater, and plant and animal tissues. The total range in 41 K/ 39 K ratios is ca. 2.6‰, with a long-term external reproducibility of 0.17‰ (2, N=108). Seawater and seawater-derived evaporite minerals are systematically enriched in 41 K compared to silicate minerals by ca. 0.6‰, a result consistent with recent findings1, 2. Although our average bulk-silicate Earth value (-0.54‰) is indistinguishable from previously published values, we find systematic δ 41 K variability in some high-temperature sample suites, particularly those with evidence for the presence of fluids. The δ 41 K values of biological samples span a range of ca. 1.2‰ between terrestrial mammals, plants, and marine organisms. Implications of terrestrial K isotope variability for the atomic weight of K and K-based geochronology are discussed. Our results indicate that high-precision measurements of stable K isotopes, made using commercially available mass spectrometers, can provide unique insights into the chemistry of potassium in geological and biological systems.

Journal of Analytical Atomic Spectrometry↗
USGS2013

Comparing mechanisms of host manipulation across host and parasite taxa

Parasites affect host behavior in several ways. They can alter activity, microhabitats or both. For trophically transmitted parasites (the focus of our study), decreased activity might impair the ability of hosts to respond to final-host predators, and increased activity and altered microhabitat choice might increase contact rates between hosts and final-host predators. In an analysis of trophically transmitted parasites, more parasite groups altered activity than altered microhabitat choice. Parasites that infected vertebrates were more likely to impair the host’s reaction to predators, whereas parasites that infected invertebrates were more likely to increase the host’s contact with predators. The site of infection might affect how parasites manipulate their hosts. For instance, parasites in the central nervous system seem particularly suited to manipulating host behavior. Manipulative parasites commonly occupy the body cavity, muscles and central nervous systems of their hosts. Acanthocephalans in the data set differed from other taxa in that they occurred exclusively in the body cavity of invertebrates. In addition, they were more likely to alter microhabitat choice than activity. Parasites in the body cavity (across parasite types) were more likely to be associated with increased host contact with predators. Parasites can manipulate the host through energetic drain, but most parasites use more sophisticated means. For instance, parasites target four physiological systems that shape behavior in both invertebrates and vertebrates: neural, endocrine, neuromodulatory and immunomodulatory. The interconnections between these systems make it difficult to isolate specific mechanisms of host behavioral manipulation.

Journal of Experimental Biology↗
USGS2023

Integrated analysis shows how the effects of extreme flooding events propagate through fish communities to impact amphibians

Research Highlight: Davis, C. L., Walls, S. C., Barichivich, W. J., Brown, M. E., & Miller, D. A. (2022). Disentangling direct and indirect effects of extreme events on coastal wetland communities. Journal of Animal Ecology , https://doi.org/10.1111/1365-2656.13874 . Catastrophic events such as floods, hurricanes, winter storms, droughts and wildfires increasingly touch our lives either directly or indirectly. These events draw our attention to the seriousness of changes in climate not only to human well-being but also to the integrity of ecological systems upon which we depend. Understanding the impacts of extreme events on ecological systems requires the ability to characterize the cascading effects of environmental changes on the environments in which organisms live and the altered biological interactions produced. This scientific ambition represents no small challenge for the study of animal communities, which are typically difficult to census as well as dynamic in time and space. Davis et al. (2022) in a recent study in the Journal of Animal Ecology examined the amphibian and fish communities found in depressional coastal wetlands to better understand how they respond to major rainfall and flooding events. Data from the U.S. Geological Survey's Amphibian Research and Monitoring Initiative provided an 8-year record of observations as well as environmental measurements. For this study, the authors integrated techniques for assessing the dynamics of animal populations with a Bayesian implementation of structural equation modelling. Using their integrated methodological approach permitted the authors to reveal the direct and indirect effects of extreme weather events on co-occurring amphibian and fish communities while accounting for observational uncertainty and temporal variation in population-level processes. Their findings indicate that the most prominent effects of flooding on the amphibian community were caused by changes in the fish community that led to increased predation and resource competition. In their conclusions, the authors emphasize the importance of understanding networks of abiotic and biotic effects if we are to predict and mitigate the influence of extreme weather events.

Journal of Animal Ecology↗
USGS2009

Web GIS in practice VII: stereoscopic 3-D solutions for online maps and virtual globes

Because our pupils are about 6.5 cm apart, each eye views a scene from a different angle and sends a unique image to the visual cortex, which then merges the images from both eyes into a single picture. The slight difference between the right and left images allows the brain to properly perceive the 'third dimension' or depth in a scene (stereopsis). However, when a person views a conventional 2-D (two-dimensional) image representation of a 3-D (three-dimensional) scene on a conventional computer screen, each eye receives essentially the same information. Depth in such cases can only be approximately inferred from visual clues in the image, such as perspective, as only one image is offered to both eyes. The goal of stereoscopic 3-D displays is to project a slightly different image into each eye to achieve a much truer and realistic perception of depth, of different scene planes, and of object relief. This paper presents a brief review of a number of stereoscopic 3-D hardware and software solutions for creating and displaying online maps and virtual globes (such as Google Earth) in "true 3D", with costs ranging from almost free to multi-thousand pounds sterling. A practical account is also given of the experience of the USGS BRD UMESC (United States Geological Survey's Biological Resources Division, Upper Midwest Environmental Sciences Center) in setting up a low-cost, full-colour stereoscopic 3-D system.

International Journal of Health Geographics↗
USGS2020

At Palmyra Atoll, the fish‐community environmental DNA signal changes across habitats but not with tides

At Palmyra Atoll, the environmental DNA (eDNA) signal on tidal sand flats was associated with fish biomass density and captured 98%–100% of the expected species diversity there. Although eDNA spilled over across habitats, species associated with reef habitat contributed more eDNA to reef sites than to sand‐flat sites, and species associated with sand‐flat habitat contributed more eDNA to sand‐flat sites than to reef sites. Tides did not disrupt the sand‐flat habitat signal. At least 25 samples give a coverage >97.5% at this diverse, tropical, marine system.

Journal of Fish Biology↗
USGS2009

Indicators of biodiversity and ecosystem services: A synthesis across ecosystems and spatial scales

According to the Millennium Ecosystem Assessment, common indicators are needed to monitor the loss of biodiversity and the implications for the sustainable provision of ecosystem services. However, a variety of indicators are already being used resulting in many, mostly incompatible, monitoring systems. In order to synthesise the different indicator approaches and to detect gaps in the development of common indicator systems, we examined 531 indicators that have been reported in 617 peer-reviewed journal articles between 1997 and 2007. Special emphasis was placed on comparing indicators of biodiversity and ecosystem services across ecosystems (forests, grass- and shrublands, wetlands, rivers, lakes, soils and agro-ecosystems) and spatial scales (from patch to global scale). The application of biological indicators was found most often focused on regional and finer spatial scales with few indicators applied across ecosystem types. Abiotic indicators, such as physico-chemical parameters and measures of area and fragmentation, are most frequently used at broader (regional to continental) scales. Despite its multiple dimensions, biodiversity is usually equated with species richness only. The functional, structural and genetic components of biodiversity are poorly addressed despite their potential value across habitats and scales. Ecosystem service indicators are mostly used to estimate regulating and supporting services but generally differ between ecosystem types as they reflect ecosystem-specific services. Despite great effort to develop indicator systems over the past decade, there is still a considerable gap in the widespread use of indicators for many of the multiple components of biodiversity and ecosystem services, and a need to develop common monitoring schemes within and across habitats. Filling these gaps is a prerequisite for linking biodiversity dynamics with ecosystem service delivery and to achieving the goals of global and sub-global initiatives to halt the loss of biodiversity. ?? 2009 Oikos.

Oikos↗