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At least 1,477 records · Page 82Linked to original sources
USGS2017

Experimental observations on the decay of environmental DNA from bighead and silver carps

Interest in the field of environmental DNA (eDNA) is growing rapidly and eDNA surveys are becoming an important consideration for aquatic resource managers dealing with invasive species. However, in order for eDNA monitoring to mature as a research and management tool, there are several critical knowledge gaps that must be filled. One such gap is the fate of eDNA materials in the aquatic environment. Understanding the environmental factors that influence the decay of eDNA and how these factors impact detection probabilities over time and space could have significant implications for eDNA survey design and data interpretation. Here we experimentally explore decay of eDNA associated with bighead carp ( Hypophthalmichthys nobilis ) biological waste collected from an aquaculture filtration system and with sperm collected from captive silver carp ( H. molitrix ), and how decay may be influenced by differing levels of water turbulence, temperature, microbial load, and pH. We found that the decay patterns of eDNA associated with both H. nobilis biological waste and H. molitrix milt significantly fit monophasic exponential decay curves. Secondly, we observed that the highest temperature we tested resulted in a decay half-life as much as 5.5× more rapid than the lowest temperature we tested. When we suppressed microbial loads in eDNA samples, we observed that overall losses of eDNA were reduced by about 2.5×. When we amended eDNA samples with pond water the half-life of eDNA was reduced by about 2.25×, despite relatively little apparent increase in the overall microbial load. This pattern indicated that species constituency of the microbial community, in addition to microbial load, might play a critical role in eDNA degradation. A shift in pH from 6.5 to 8.0 in the samples resulted in a 1.6× reduction in eDNA halflife. Water turbulence in our study had no apparent effect on eDNA decay. When we combined different temperature, pH, and microbial load treatments to create a rapid decay condition and a slow decay condition, and tracked eDNA decay over 91 days, we observed a 5.0× greater loss of eDNA by Day 5 under rapid decay conditions than under slow decay conditions. At the end of the trials, the differences in eDNA loss between the rapid decay and baseline and slow decay conditions were 0.1× and 3.3×, respectively. Our results strongly demonstrate the potential for environmental factors to influence eDNA fate and, thus, the interpretation of eDNA survey results.

Management of Biological Invasions↗
USGS2018

Exposure-related effects of Zequanox on juvenile lake sturgeon (Acipenser fulvescens) and lake trout (Salvelinus namaycush)

The environmental fate, persistence, and non-target animal impacts of traditional molluscicides for zebra, Dreissena polymorpha , and quagga, D. bugensis , mussel control led to the development of the biomolluscicide Zequanox. Although previous research has demonstrated the specificity of Zequanox, one study indicated sensitivity of salmonids and lake sturgeon, Acipenser fulvescens , following non-label compliant exposures to Zequanox. This study was conducted to evaluate sublethal and lethal impacts of Zequanox exposure on juvenile lake sturgeon and lake trout, Salvelinus namaycush , following applications that were conducted in a manner consistent with the Zequanox product label. Fish were exposed to 50 or 100 mg/L of Zequanox as active ingredient for 8 h and then held for 33 d to evaluate latent impacts. No acute mortality was observed in either species; however, significant latent mortality (P < 0.01, df = 9; 46.2%) was observed in lake trout that were exposed to the highest dose of Zequanox. Statistically significant (P < 0.03, df = 9), but biologically minimal differences were observed in the weight (range 20.17 to 21.49 g) of surviving lake sturgeon at the termination of the 33 d post-exposure observation period. Statistically significant (P < 0.05, df = 9) and biologically considerable differences were observed in the weight (range 6.19 to 9.55 g) of surviving lake trout at the termination of the 33 d post-exposure observation period. Histologic evaluation of lake trout gastrointestinal tracts suggests that the mode of action in lake trout is different from the mode of action that induces zebra and quagga mussel mortality. Further research could determine the sensitivity of other salmonid species to Zequanox and determine if native fish will avoid Zequanox treated water.

Management of Biological Invasions↗
USGS2023

Natives bite back: Depredation and mortality of invasive juvenile Burmese pythons (Python bivittatus) in the Greater Everglades Ecosystem

Burmese pythons (Python bivittatus Kuhl, 1820) are one of the world’s largest snake species, making them a highly successful and biologically damaging invasive predator in the Greater Everglades Ecosystem, Florida, USA. Though we have knowledge of python diet within this system, we understand very little of other interactions with native species. Effects native species have on invasive pythons, especially in the juvenile size class, are of particular interest as the prevalence of mortalities would inform potential population growth and trophic dynamics with native prey species. Native ophiophagous predators in Florida feed on smaller native snake species and it is unknown if they consistently recognize similarly sized juvenile invasive pythons as prey items. Using radiotelemetry, we found at least four native species within Big Cypress National Preserve that were implicated in juvenile python deaths, including three Florida cottonmouths (Agkistrodon conanti Gloyd, 1969), five American alligators (Alligator mississippiensis Daudin, 1802), one hispid cotton rat (Sigmodon hispidus Say and Ord, 1825), and three mesomammals. One mortality was the result of an attempt to subdue a prey item 106% the size of the python, constituting the largest predator:prey size ratio ever reported in this size class. This finding may indicate that phenotypic variation in individual juvenile pythons includes behavior that could be maladaptive within the novel Florida environment. Here we describe some of the first confirmed cases of non-anthropogenic mortality in juvenile Burmese pythons in Florida and present evidence that invasive pythons in this size class are now being incorporated into the diets of native species in its invasive range Burmese pythons (Python bivittatus Kuhl, 1820) are one of the world’s largest snake species, making them a highly successful and biologically damaging invasive predator in the Greater Everglades Ecosystem, Florida, USA. Though we have knowledge of python diet within this system, we understand very little of other interactions with native species. Effects native species have on invasive pythons, especially in the juvenile size class, are of particular interest as the prevalence of mortalities would inform potential population growth and trophic dynamics with native prey species. Native ophiophagous predators in Florida feed on smaller native snake species and it is unknown if they consistently recognize similarly sized juvenile invasive pythons as prey items. Using radiotelemetry, we found at least four native species within Big Cypress National Preserve that were implicated in juvenile python deaths, including three Florida cottonmouths (Agkistrodon conanti Gloyd, 1969), five American alligators (Alligator mississippiensis Daudin, 1802), one hispid cotton rat (Sigmodon hispidus Say and Ord, 1825), and three mesomammals. One mortality was the result of an attempt to subdue a prey item 106% the size of the python, constituting the largest predator:prey size ratio ever reported in this size class. This finding may indicate that phenotypic variation in individual juvenile pythons includes behavior that could be maladaptive within the novel Florida environment. Here we describe some of the first confirmed cases of non-anthropogenic mortality in juvenile Burmese pythons in Florida and present evidence that invasive pythons in this size class are now being incorporated into the diets of native species in its invasive range.

Florida↗
USGS2023

Identifying research in support of the management and control of dreissenid mussels in the western United States

On February 9–10, 2022, the Pacific States Marine Fisheries Commission, U.S. Fish and Wildlife Service, U.S. Geological Survey, and Washington State University hosted a workshop to establish research priorities that support the implementation of action items listed in a current invasive species management plan, the Quagga and Zebra Mussel Action Plan (QZAP) 2.0, that are intended to limit the establishment and spread of quagga and zebra mussels in the western United States. The workshop focus was on developing research priorities for the thematic areas that are addressed in QZAP 2.0: 1) early detection monitoring, 2) prevention and containment, 3) control and management, and 4) rapid response. In addition, research priorities were developed for a fifth thematic area that addressed dreissenid mussel biology. Forty scientists participated in the two-day workshop. Prior to the workshop, participants were asked to review and rank research priorities that were established for a previous version of the QZAP and to offer suggestions on emerging research priorities. During the workshop, subject matter experts presented information describing current knowledge of research and information associated with the thematic areas of early detection monitoring, prevention and containment, rapid response, control and management, and biology in the context of strategies and actions listed in QZAP 2.0. The rankings of previous research priorities and suggestions of emerging priorities were then reviewed, and a revised list of research priorities was formed. The list of research priorities is presented by thematic area.

Management of Biological Invasions↗
USGS2012

Are all intertidal wetlands naturally created equal? Bottlenecks, thresholds and knowledge gaps to mangrove and saltmarsh ecosystems

Intertidal wetlands such as saltmarshes and mangroves provide numerous important ecological functions, though they are in rapid and global decline. To better conserve and restore these wetland ecosystems, we need an understanding of the fundamental natural bottlenecks and thresholds to their establishment and long-term ecological maintenance. Despite inhabiting similar intertidal positions, the biological traits of these systems differ markedly in structure, phenology, life history, phylogeny and dispersal, suggesting large differences in biophysical interactions. By providing the first systematic comparison between saltmarshes and mangroves, we unravel how the interplay between species-specific life-history traits, biophysical interactions and biogeomorphological feedback processes determine where, when and what wetland can establish, the thresholds to long-term ecosystem stability, and constraints to genetic connectivity between intertidal wetland populations at the landscape level. To understand these process interactions, research into the constraints to wetland development, and biological adaptations to overcome these critical bottlenecks and thresholds requires a truly interdisciplinary approach.

Biological Reviews↗
USGS1993

Proceedings of the symposium on the management of prairie dog complexes for the reintroduction of the black-footed ferret

The workshop featured a review of current knowledge in the biology of prairie dogs in the context of managing black-footed ferret habitat. The review addressed two main components. The first consisted of a series of papers on prairie dog habitat and biology. The second component of the workshop was a summary of the participants' discussion about managing prairie dog complexes. This discussion was based on the previously identified papers and profited from the participants' expertise on the ecology of black-footed ferrets and prairie dogs. The report provides current and comprehensive information about management of habitat for prairie dogs and black-footed ferrets and is a useful guide for agencies and individuals that manage black-footed ferrets.

Biological Report↗
USGS2012

A history of herpetologists and herpetology in the U.S. Department of the Interior

The U.S. Department of the Interior (DOI) has a long and distinguished history of employing herpetologists to conduct basic and applied research to better manage amphibian and reptile populations on public lands and even outside the boundaries of the United States. This history extends back over 125 years with roots in the U.S. Biological Survey, the Fish and Wildlife Service, the Bureau of Land Management, the National Park Service and later, the National Biological Service. In more recent times, the DOI employed more professional herpetologists than any single organization in the world, especially in the U.S. Geological Survey. In 1938, Henry Fitch was the first Interior scientist hired who conducted substantial herpetological research. William and Lucille Stickel of the Fish and Wildlife Service conducted herpetological research throughout the period from the 1940s-1980s but most DOI herpetologists were hired from 1975-80 with another hiring spike from 2000-2005. The former spike was congruent with early versions of the Endangered Species Act while the latter reflected growing recognition of global amphibian decline and the creation of the Amphibian Research and Monitoring Initiative in DOI. Collectively, these herpetologists produced hundreds of books, scientific publications and other scholarly publications, many of which are classics in the literature. In addition, many have served as officers and on the boards of numerous scientific societies particularly those specializing in amphibian and reptile research. The DOI shows a continuing commitment to funding herpetological research by hiring young scientists to replace the aging ranks of herpetologists who started their careers in the 1970s. This commitment is critical given the global decline of both amphibians and reptiles, including those found on public lands in the United States.

Herpetological Conservation and Biology↗
USGS2008

Book review: The ecology and behavior of amphibians

This state‐of‐the‐art book has made its timely emergence amid a crisis of global magnitude: that of population declines, range reductions, and extinctions of numerous species of amphibians. A clear understanding of the fundamental concepts in amphibian biology is crucial to the success of any conservation effort. This volume compiles the information necessary to acquire that basic understanding. It is a comprehensive synthesis of both traditional and contemporary facets of amphibian biology, spanning a breadth of topics ranging from phylogeny, physiology, behavior, population and community ecology, and conservation. As such, it undoubtedly takes its place among contemporary volumes as the single, authoritative source for basic topics relevant to amphibian life. Review info: The Ecology and Behavior of Amphibians. By Kentwood D. Wells, 2007. ISBN: 978-0-226-89334-1, 1148 pp.

The Quarterly Review of Biology↗
USGS2001

The interplay of species concepts, taxonomy, and conservation: lessons from the Hawaiian avifauna

The Hawaiian Islands, with their unique geological history and geographic position, provide an excellent natural laboratory in which to evaluate currently competing biological (BSC) and phylogenetic (PSC) concepts of the species. Although the BSC as historically applied in archipelagic situations is shown to be flawed in producing overlumped polytypic species, it nevertheless remains the preferable concept for most practical purposes. A review of the taxonomic history and species limits in Hawaiian birds under both concepts reveals that, when properly applied, the BSC yields a species total remarkably close to that produced under the PSC, contrary to what many proponents of the latter have supposed. We propose that the widespread adoption of the PSC for conservation purposes is potentially harmful. The PSC trivializes the species taxon and introduces new problems of deciding when a population becomes diagnosable, the possibility that species could appear and disappear in a reticulate fashion, and the likelihood that genetically diagnosable but phenotypically identical, and therefore not field identifiable, populations could be ranked as species. All of these problems negatively impact such things as constructing credible and politically defensible lists of endangered species, the prioritization of limited conservation resources, and the gathering of field data. We contend the BSC is arguably a more rational concept that better supports the activities of both scientific and nonprofessional observers. Biological species limits in oceanic archipelagoes worldwide need to be reevaluated using modern concepts and technologies before rational conservation decisions can be made.

Hawaii↗
USGS2002

Introduction

The Arctic National Wildlife Refuge in northeastern Alaska is one of 16 refuges in Alaska and 539 refuges nationwide within the National Wildlife Refuge System administered by the U.S. Fish and Wildlife Service. First established as the Arctic National Wildlife Range in 1960 by Public Land Order 2214, it initially had a three-fold purpose to preserve unique wildlife, wilderness, and recreation values on 8.9 million acres. In 1980, the Arctic National Wildlife Range was expanded to the southwest and renamed the Arctic National Wildlife Refuge (also called the Arctic Refuge in this report) when the U.S. Congress passed the Alaska National Interest Lands Conservation Act (ANILCA), Public Law 96-487 (94 Stat. 2371). This legislation also designated almost all of the original Arctic National Wildlife Range as wilderness, and it directed the Secretary of the Interior to conduct studies evaluating both the biological resources and the potential petroleum reserves of 1.5 million acres (titled the 1002 Area) on the coastal plain of the Arctic Refuge. In April 1982, the Arctic Refuge staff completed a report summarizing the then current state of knowledge on the fish, wildlife, and their habitats present on the coastal plain of the Arctic Refuge (U.S. Fish and Wildlife Service 1982). From 1982 to 1985, field investigations of biological resources of the 1002 Area were carried out by a number of investigators, and annual reports summarized the results (Garner and Reynolds 1983, 1984, 1985, 1986, 1987). These reports and other resources were used to prepare a Department of the Interior report to Congress: Arctic National Wildlife Refuge, Alaska Coastal Plain Resource Assessment - Report and Recommendation to the Congress of the United States and Final Environmental Impact Satement (Clough et al., 1987).

Alaska, Northwest Territories, Yukon Territory↗
USGS1997

Hazard assessment of inorganics, individually and in mixtures, to two endangered fish in the San Juan River, New Mexico

Acute toxicity tests were conducted for 96 h with larval Colorado squawfish ( Ptychocheilus lucius ) and razorback sucker ( Xyrauchen texanus ) in a reconstituted water quality simulating the San Juan River near Shiprock, New Mexico, to determine biological effect concentrations. Tests were conducted with arsenate, copper, selenate, selenite, zinc, and five mixtures of seven to nine inorganics simulating environmental mixtures reported for sites along the San Juan River (Ojo Amarillo Canyon, Gallegos Canyon, Hogback East Drain, Mancos River, and McElmo Creek). Razorback suckers were significantly more sensitive to arsenate, selenate, selenite, Hogback East Drain mixture, and Ojo Amarillo Canyon mixture than were Colorado squawfish. For both species, the Gallegos Canyon mixture had synergistic toxicity, the Mancos River and McElmo Creek mixtures had additive toxicity, and the Ojo Amarillo Canyon mixture had antagonistic toxicity. The Hogback East Drain mixture had additive toxicity to Colorado squawfish, but synergistic toxicity to razorback suckers. The major toxic component in the five mixtures was copper. Comparison of biological effect concentrations (i.e., 96-h LC 50 ) with environmental water concentrations from the San Juan River resulted in a ratio of <100, which revealed a high potential hazard for copper and all five environmental mixtures. The high hazard ratios suggest inorganic contaminants could adversely affect larval Colorado squawfish and razorback suckers in the San Juan River at sites receiving elevated inorganics such as from nonpoint discharges and irrigation return flows.

New Mexico↗
USGS1998

Modelling of instream flow needs: The link between sediment and aquatic habitat

Instream flows are needed to remove undesirable accumulations of sediment. Fines and sand accumulate on and in gravels during periods of low flow and must be removed (flushed) periodically in order for the gravel to continue as suitable habitat for aquatic animals. Sediment of all sizes can also fill pools in the river and must be removed in order to maintain pool habitat. A new technique relates the sizes of sediment important in the biological process to the size transported as wash, suspended and bed loads. The technique has a biological component, a hydraulic component and a selection component that links the two. The technique was used to determine the instream flows needed to maintain habitat for Colorado squawfish in the Gunnison River in western Colorado. Flows included a flushing flow to remove course sand form the riffles where Colorado squawfish spawn, to remove fines and sand from the river in general, to remove gravel from pools, and to scour side channels. The Gunnison River has a mean discharge of 73 m 3 /s and the flows of both sediment and water in the river have been modified by the construction of reservoirs and by major diversions for irrigation. The flows needed to maintain the spawning habitat for the Colorado squawfish by removing fines and sand from the riffles is 355 m 3 /s, to remove sand and fines from the river is 354 m 3 /s, to remove gravel from pools is 484 m 3 /s and to scour side channels is 210 m 3 /s. The flow required to maintain the riffles during spawning is 210 m 3 /s. These flushing flows are not required each year but they are required periodically (usually not less than once in every 3 years); and the maintenance flow is needed every year.

Regulated Rivers: Research & Management↗
USGS2016

Processes of multibathyal aragonite undersaturation in the Arctic Ocean

During 3 years of study (2010–2012), the western Arctic Ocean was found to have unique aragonite saturation profiles with up to three distinct aragonite undersaturation zones. This complexity is produced as inflow of Atlantic-derived and Pacific-derived water masses mix with Arctic-derived waters, which are further modified by physiochemical and biological processes. The shallowest aragonite undersaturation zone, from the surface to ∼30 m depth is characterized by relatively low alkalinity and other dissolved ions. Besides local influence of biological processes on aragonite undersaturation of shallow coastal waters, the nature of this zone is consistent with dilution by sea-ice melt and invasion of anthropogenic CO 2 from the atmosphere. A second undersaturated zone at ∼90–220 m depth (salinity ∼31.8–35.4) occurs within the Arctic Halocline and is characterized by elevated p CO 2 and nutrients. The nature of this horizon is consistent with remineralization of organic matter on shallow continental shelves bordering the Canada Basin and the input of the nutrients and CO 2 entrained by currents from the Pacific Inlet. Finally, the deepest aragonite undersaturation zone is at greater than 2000 m depth and is controlled by similar processes as deep aragonite saturation horizons in the Atlantic and Pacific Oceans. The comparatively shallow depth of this deepest aragonite saturation horizon in the Arctic is maintained by relatively low temperatures, and stable chemical composition. Understanding the mechanisms controlling the distribution of these aragonite undersaturation zones, and the time scales over which they operate will be crucial to refine predictive models.

Journal of Geophysical Research: Oceans↗
USGS2020

A weight-of-evidence approach for defining thermal sensitivity in a federally endangered species

1. Managing for threatened and endangered species under changing environmental conditions is a challenge faced by resource managers worldwide. Lack of basic knowledge of the biology and habitat requirements of these species can contribute to this difficulty, but is confounded by the limitations of working with rare (i.e. few individuals) species or unrefined methods for evaluating stress. 2. A weight of evidence approach was used to evaluate the thermal biology of the federally endangered dwarf wedgemussel ( Alasmidonta heterodon ), utilizing cumulative results from multiple experimental assessments, co-occurring species, and their host fish to begin defining thermal limits and optimal conditions for the species. 3. Results suggest that dwarf wedgemussel and its host fish are thermally sensitive species compared to other Atlantic-slope mussels, with lower critical thermal maximum and selection of reduced temperatures during choice experiments. 4. Physiological studies resulted in lack of statistical significance primarily due to low power which was a function of sample size, one unavoidable problem when studying rare species. Given these limitations, thermal choice and CTM may be more useful endpoints than physiological processes such as clearance and respiration rates when dealing with sample size limitations. 5. These results suggest that management strategies that avoid exposing dwarf wedgemussel and its thermally sensitive host fish to extreme temperatures could be important for species conservation.

New Jersey, Pennsylvania↗
USGS2016

Biomarkers reveal sea turtles remained in oiled areas following the Deepwater Horizon oil spill

Assessments of large-scale disasters, such as the Deepwater Horizon oil spill, are problematic because while measurements of post-disturbance conditions are common, measurements of pre-disturbance baselines are only rarely available. Without adequate observations of pre-disaster organismal and environmental conditions, it is impossible to assess the impact of such catastrophes on animal populations and ecological communities. Here, we use long-term biological tissue records to provide pre-disaster data for a vulnerable marine organism. Keratin samples from the carapace of loggerhead sea turtles record the foraging history for up to 18 years, allowing us to evaluate the effect of the oil spill on sea turtle foraging patterns. Samples were collected from 76 satellite-tracked adult loggerheads in 2011 and 2012, approximately one to two years after the spill. Of the 10 individuals that foraged in areas exposed to surface oil, none demonstrated significant changes in foraging patterns post spill. The observed long-term fidelity to foraging sites indicates that loggerheads in the northern Gulf of Mexico likely remained in established foraging sites, regardless of the introduction of oil and chemical dispersants. More research is needed to address potential long-term health consequences to turtles in this region. Mobile marine organisms present challenges for researchers to monitor effects of environmental disasters, both spatially and temporally. We demonstrate that biological tissues can reveal long-term histories of animal behavior and provide critical pre-disaster baselines following an anthropogenic disturbance or natural disaster.

Ecological Applications↗
USGS2015

Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata

Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. Additionally, we investigated ontogenetic shifts by incorporating the unsexed juveniles into the male and female datasets. In general, male color traits were isometric (i.e., color scaled with body size), while females and juvenile color traits were hypoallometric, growing in size more slowly than the increase in body size. When we included unsexed juveniles in our male and female datasets, our linear regression analyses found all relationships to be hypoallometric and our model selection analysis found support for nonlinear models describing the relationship between body size and color patterns, suggestive of an ontogenetic shift in coloration traits for both sexes at maturity. Although color is critical for many species' biology and therefore under strong selective pressure in many other species, our results are likely explained by an epiphenomenon related to the different selection pressures on body size and growth rates between juveniles and adults and less attributable to the evolution of color patterns themselves.

Ecology and Evolution↗
USGS2016

Baseline glucocorticoids are drivers of body mass gain in a diving seabird

Life-history trade-offs are influenced by variation in individual state, with individuals in better condition often completing life-history stages with greater success. Although resource accrual significantly impacts key life-history decisions such as the timing of reproduction, little is known about the underlying mechanisms driving resource accumulation. Baseline corticosterone (CORT, the primary avian glucocorticoid) mediates daily and seasonal energetics, responds to changes in food availability, and has been linked to foraging behavior, making it a strong potential driver of individual variation in resource accrual and deposition. Working with a captive colony of white-winged scoters ( Melanitta fusca deglandi ), we aimed to causally determine whether variation in baseline CORT drives individual body mass gains mediated through fattening rate (plasma triglycerides corrected for body mass). We implanted individuals with each of three treatment pellets to elevate CORT within a baseline range in a randomized order: control, low dose of CORT, high dose of CORT, then blood sampled and recorded body mass over a two-week period to track changes in baseline CORT, body mass, and fattening rates. The high CORT treatment significantly elevated levels of plasma hormone for a short period of time within the biologically relevant, baseline range for this species, but importantly did not inhibit the function of the HPA (hypothalamic&ndash;pituitary&ndash;adrenal) axis. Furthermore, an elevation in baseline CORT resulted in a consistent increase in body mass throughout the trial period compared to controls. This is some of the first empirical evidence demonstrating that elevations of baseline CORT within a biologically relevant range have a causal, direct, and positive influence on changes in body mass.

Ecology and Evolution↗
USGS2017

Ad hoc instrumentation methods in ecological studies produce highly biased temperature measurements

In light of global climate change, ecological studies increasingly address effects of temperature on organisms and ecosystems. To measure air temperature at biologically relevant scales in the field, ecologists often use small, portable temperature sensors. Sensors must be shielded from solar radiation to provide accurate temperature measurements, but our review of 18 years of ecological literature indicates that shielding practices vary across studies (when reported at all), and that ecologists often invent and construct ad hoc radiation shields without testing their efficacy. We performed two field experiments to examine the accuracy of temperature observations from three commonly used portable data loggers (HOBO Pro, HOBO Pendant, and iButton hygrochron) housed in manufactured Gill shields or ad hoc, custom‐fabricated shields constructed from everyday materials such as plastic cups. We installed this sensor array (five replicates of 11 sensor‐shield combinations) at weather stations located in open and forested sites. HOBO Pro sensors with Gill shields were the most accurate devices, with a mean absolute error of 0.2°C relative to weather stations at each site. Error in ad hoc shield treatments ranged from 0.8 to 3.0°C, with the largest errors at the open site. We then deployed one replicate of each sensor‐shield combination at five sites that varied in the amount of urban impervious surface cover, which presents a further shielding challenge. Bias in sensors paired with ad hoc shields increased by up to 0.7°C for every 10% increase in impervious surface. Our results indicate that, due to variable shielding practices, the ecological literature likely includes highly biased temperature data that cannot be compared directly across studies. If left unaddressed, these errors will hinder efforts to predict biological responses to climate change. We call for greater standardization in how temperature data are recorded in the field, handled in analyses, and reported in publications.

Ecology and Evolution↗