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At least 937 records · Page 52Linked to original sources
USGS2018

Influence of governance structure on green stormwater infrastructure investment

Communities are faced with the challenge of meeting regulatory requirements mandating reductions in water pollution from stormwater and combined sewer overflows (CSO). Green stormwater infrastructure and gray stormwater infrastructure are two types of water management strategies communities can use to address water pollution. In this study, we used long-term control plans from 25 U.S. cities to synthesize: the types of gray and green infrastructure being used by communities to address combined sewer overflows; the types of goals set; biophysical characteristics of each city; and factors associated with the governance of stormwater management. These city characteristics were then used to identify common characteristics of “green leader” cities—those that dedicated >20% of the control plan budget in green infrastructure. Five “green leader” cities were identified: Milwaukee, WI, Philadelphia, PA, Syracuse, NY, New York City, NY, and Buffalo, NY. These five cities had explicit green infrastructure goals targeting the volume of stormwater or percentage of impervious cover managed by green infrastructure. Results suggested that the management scale and complexity of the management system are less important factors than the ability to harness a “policy window” to integrate green infrastructure into control plans. Two case studies—Philadelphia, PA, and Milwaukee, WI—indicated that green leader cities have a long history of building momentum for green infrastructure through a series of phases from experimentation, demonstration, and finally—in the case of Philadelphia—a full transition in the approach used to manage CSOs.

Environmental Science and Policy↗
USGS2017

Spectrally monitoring the response of the biocrust moss Syntrichia caninervis to altered precipitation regimes

Climate change is expected to impact drylands worldwide by increasing temperatures and changing precipitation patterns. These effects have known feedbacks to the functional roles of dryland biological soil crust communities (biocrusts), which are expected to undergo significant climate-induced changes in community structure and function. Nevertheless, our ability to monitor the status and physiology of biocrusts with remote sensing is limited due to the heterogeneous nature of dryland landscapes and the desiccation tolerance of biocrusts, which leaves them frequently photosynthetically inactive and difficult to assess. To address this critical limitation, we subjected a dominant biocrust species Syntrichia caninervis to climate-induced stress in the form of small, frequent watering events, and spectrally monitored the dry mosses’ progression towards mortality. We found points of spectral sensitivity responding to experimentally-induced stress in desiccated mosses, indicating that spectral imaging is an effective tool to monitor photosynthetically inactive biocrusts. Comparing the Normalized Difference Vegetation Index (NDVI), the Simple Ratio (SR), and the Normalized Pigment Chlorophyll Index (NPCI), we found NDVI minimally effective at capturing stress in precipitation-stressed dry mosses, while the SR and NPCI were highly effective. Our results suggest the strong potential for utilizing spectroscopy and chlorophyll-derived indices to monitor biocrust ecophysiological status, even when biocrusts are dry, with important implications for improving our understanding of dryland functioning.

Scientific Reports↗
USGS2009

Distinct freshwater and seawater isoforms of Na+/K+-ATPase in gill chloride cells of Atlantic salmon

Gill Na(+)/K(+)-ATPase (NKA) in teleost fishes is involved in ion regulation in both freshwater and seawater. We have developed and validated rabbit polyclonal antibodies specific to the NKA alpha1a and alpha1b protein isoforms of Atlantic salmon (Salmo salar Linnaeus), and used western blots and immunohistochemistry to characterize their size, abundance and localization. The relative molecular mass of NKA alpha1a is slightly less than that for NKA beta1b. The abundance of gill NKA alpha1a was high in freshwater and became nearly undetectable after seawater acclimation. NKA alpha1b was present in small amounts in freshwater and increased 13-fold after seawater acclimation. Both NKA isoforms were detected only in chloride cells. NKA alpha1a was located in both filamental and lamellar chloride cells in freshwater, whereas in seawater it was present only as a faint background in filamental chloride cells. In freshwater, NKA alpha1b was found in a small number of filamental chloride cells, and after seawater acclimation it was found in all chloride cells on the filament and lamellae. Double simultaneous immunofluorescence indicated that NKA alpha1a and alpha1b are located in different chloride cells in freshwater. In many chloride cells in seawater, NKA alpha1b was present in greater amounts in the subapical region than elsewhere in the cell. The combined patterns in abundance and immunolocalization of these two isoforms can explain the salinity-related changes in total NKA and chloride cell abundance. The results indicate that there is a freshwater and a seawater isoform of NKA alpha-subunit in the gills of Atlantic salmon and that they are present in distinct chloride cells.

Journal of Experimental Biology↗
USGS2024

Experimental changes in food and ectoparasites affect dispersal timing in juvenile burrowing owls

Natal dispersal is a key demographic trait that affects population dynamics, and intraspecific variation in dispersal affects gene flow among populations and source-sink dynamics. However, relatively little is known about the selective pressures and trade-offs that animals face when departing their natal area due to the logistical difficulties associated with monitoring animals during this critical life stage. We used a randomized block design to examine the selective pressure that influence dispersal timing in juvenile burrowing owls ( Athene cunicularia ) by experimentally altering both food and ectoparasites at 135 nests. We also examined the effects of local food abundance, ectoparasite loads, and parental departure on natal dispersal timing. Juvenile burrowing owls varied widely in natal dispersal timing, and phenotypic plasticity in dispersal timing was evident in juvenile owls’ response to our experimental treatments, local conditions, and their parents’ departure from the natal area. Moreover, juveniles responded differently than their parents to experimental manipulation of food and ectoparasite loads. Juveniles typically dispersed shortly after their parents departed the natal area, but delayed dispersing more than 2 weeks after parental departure if they did not receive experimental food supplements during a low-food year. In contrast, the experimental food supplements did not affect the migratory departure decisions of adult owls in either year. Juveniles at nests treated for ectoparasites initiated dispersal at a younger age (and prior to adults in the high-food year) compared to juveniles at control nests. In contrast, parents at nests treated for ectoparasites departed later than parents at control nests. Our results suggest that unfavorable conditions (low food or high ectoparasite loads) caused juveniles to delay dispersal, but prompted adults to depart sooner. Our results highlight the extent of intraspecific variation in natal dispersal timing, and demonstrate that ecological conditions affect dispersal decisions of parents and offspring differently, which can create important trade-offs that likely affect life history strategies and responses to climatic changes.

Washington↗
USGS1986

Transport of chloride ion in a water-unsaturated soil exhibiting anion exclusion

Miscible displacement techniques were used to create Cl - concentration profiles in unsaturated laboratory columns of Delhi sand (Typic Xeropsamments), each having a nearly uniform water content. The three steady flow rates used resulted in three different, average water contents. Chloride concentrations near the top of the column were smaller and penetration of Cl - in the column was deeper than expected assuming that Cl - is a noninteracting solute. Such observations indicate the presence of anion exclusion. This interpretation is further substantiated by chloride and tritium breakthrough curves obtained from a saturated column of the same soil. The saturated experiments show that tritium occupies the entire measured pore volume of the column, but that Cl - is restricted to a smaller pore volume. The formulation of the conventional convection-dispersion theory for solute transport in soil which includes anion exclusion resulted in model calculations that fitted the unsaturated Cl - concentration profiles quite well. The dispersion coefficients obtained for the unsaturated profiles increase with water velocity and are lower than those previously reported for comparable water velocities in the same but saturated soil. The dispersivity of the unsaturated soil is also smaller than that reported for the saturated soil. For the experimental conditions used, the effective Cl - exclusion volume was found to be independent of water content and velocity and occupied about ten percent of the unsaturated water content.

Soil Science Society of America Journal↗
USGS2017

Large carnivore science: non-experimental studies are useful, but experiments are better

We recently described the following six interrelated issues that justify questioning some of the discourse about the reliability of the literature on the ecological roles of large carnivores (Allen et al. In press): 1. The overall paucity of available data, 2. The reliability of carnivore population sampling techniques, 3. The general disregard for alternative hypotheses to top-down forcing, 4. The lack of applied science studies, 5. The frequent use of logical fallacies, 6. The generalisation of results from relatively pristine systems to those substantially altered by humans.

Food Webs↗
USGS2010

Re-analysis of a banding study to test the effects of an experimental increase in bag limits of mourning doves

In 1966-1971, eastern US states with hunting seasons on mourning doves (Zenaida macroura) participated in a study designed to estimate the effects of bag limit increases on population survival rates. More than 400 000 adult and juvenile birds were banded and released during this period, and subsequent harvest and return of bands, together with total harvest estimates from mail and telephone surveys of hunters, provided the database for analysis. The original analysis used an ANOVA framework, and resulted in inferences of no effect of bag limit increase on population parameters (Hayne 1975). We used a logistic regression analysis to infer that the bag limit increase did not cause a biologically significant increase in harvest rate and thus the experiment could not provide any insight into the relationship between harvest and annual survival rates. Harvest rate estimates of breeding populations from geographical subregions were used as covariates in a Program MARK analysis and revealed an association between annual survival and harvest rates, although this relationship is potentially confounded by a latitudinal gradient in survival rates of dove populations. We discuss methodological problems encountered in the analysis of these data, and provide recommendations for future studies of the relationship between harvest and annual survival rates of mourning dove populations.

Journal of Applied Statistics↗
USGS2017

Experimental investigation on thermochemical sulfate reduction in the presence of 1-pentanethiol at 200 and 250 °C: Implications for in situ TSR processes occurring in some MVT deposits

Organic sulfur compounds are ubiquitous in natural oil and gas fields and moderate-low temperature sulfide ore deposits. Previous studies have shown that organic sulfur compounds are important in enhancing the rates of thermochemical sulfate reduction (TSR) reactions, but the details of these reaction mechanisms remain unclear. In order to assess the extent of sulfate reduction in the presence of labile sulfur species at temperature conditions near to those where TSR occurs in nature, we conducted a series of experiments using the fused silica capillary capsule (FCSS) method. The tested systems containing labile sulfur species are MgSO 4 + 1-pentanethiol (C 5 H 11 SH) + 1-octene (C 8 H 16 ), MgSO 4 + 1-octene (C 8 H 16 ), MgSO 4 + 1-pentanethiol (C 5 H 11 SH), 1-pentanethiol (C 5 H 11 SH)+H 2 O, and MgSO 4 + 1-pentanethiol (C 5 H 11 SH) + ZnBr 2 systems. Our results show that: (1) intermediate oxidized carbon species (ethanol and acetic acid) are formed during TSR simulation experiments when 1-pentanethiol is present; (2) in the presence of ZnBr 2 , 1-pentanethiol can be oxidized by sulfate to CO 2 at 200 °C, which is within the temperature range observed in natural TSR; and (3) the precipitation of sulfide minerals may significantly promote the rate of TSR, indicating that the rates of in situ TSR reactions in ore deposits could be much faster than previously thought. This may be important for understanding the possibility of in situ TSR as a mechanism for the precipitation of metal sulfides in some ore deposits. These findings provide important experimental evidence for understanding the role of organic sulfur compounds in TSR reactions and the pathway of TSR reactions initiated by organic sulfur compounds under natural conditions.

Ore Geology Reviews↗
USGS1998

A borehole-to-surface electromagnetic survey

The results of a limited field trial confirm the usefulness of borehole-to-surface electromagnetic (EM) measurements for monitoring fluid extraction. A vertical EM profiling experiment was done at the University of California Richmond Field Station, where we simulated a brine spill plume by creating a saline water injection zone at a depth of 30 m. The data acquisition mode was analogous to the reverse vertical seismic profiling (VSP) configuration used for seismic measurements in that the EM transmitter traversed the PVC-cased borehole used for fluid injection and extraction while the receivers were deployed on the surface. The EM measurements were made at 9.6 kHz with an accuracy of 1% in signal amplitude and 1??in signal phase. Observations were taken at 5-m intervals along two intersecting profiles that were centered on the injection well and extended for 60 m on either side of it. The presence of the injected salt water, at the expected 30 m depth, was indicated clearly by differences between the pre-extraction and postextraction data. A limited amount of numerical modeling showed that the experimental data were consistent with the presence of two superposed saline plumes. The uppermost of these, located at 26 m depth, was 2 m thick and had an area of 30 m2. The lower plume, located at 30 m, is the major cause of the observed anomally, as it has an areal extent of 120 m2 and a thickness of 3 m. Surprisingly, the measurements were very sensitive to the presence of cultural surficial conductivity anomalies. These spurious effect were reduced by spatial filtering of the data prior to interpretation.The results of a limited field trial confirm the usefulness of borehole-to-surface electromagnetic (EM) measurements for monitoring fluid extraction. A brine spill plume is simulated by creating a saline water injection zone at a depth of 30 m. The data acquisition mode was analogous to the reverse vertical seismic profiling (VSP) configuration used for seismic measurements in that the EM transmitter traversed the polyvinyl chloride-cased borehole used for fluid injection and extraction while the receivers were deployed on the surface. Observations were taken at 5-m intervals along two intersecting profiles that were centered on the injection well and extended for 60 m on either side of it.

Geophysics↗
USGS2011

An experimental analysis of harmful algae-zooplankton interactions and the ultimate defense

W We examined effects of the invasive, toxigenic haptophyte Prymnesium parvum on grazing rates, feeding behaviors, and life‐history characteristics of clonal lineages of three daphniid zooplankton species. Grazing experiments revealed similar clearance rates for P. parvum and a common green alga. Behavioral observations revealed no significant effects of P. parvum on daphniid feeding behaviors after 30 min, but major declines in appendage beat rates after 1 h. Chronic exposure (10 d) to P. parvum resulted in severe reductions in daphniid growth rates, age at first reproduction, fecundity, and survivorship at densities as low as 7750 cells mL −1 . Thus, in addition to direct fish mortality during P. parvum blooms of 50,000–200,000 cells mL −1 , the entire food web of an invaded system may be subjected to potentially severe negative consequences even at nonbloom densities of P. parvum .

Limnology and Oceanography↗
USGS1989

Use of experimental ecosystems in regulatory decision making

Tiered testing for the effects of chemicals on aquatic ecosystems has begun to include tests at the ecosystem level as a component in pesticide regristration. Because such tests are expensive, regulators and industry need to know what additional information they can gain from such tests relative to the costs of the simpler single-species toxicity bioassays. Requirements for ecosystem-level testing have developed because resource managers have not fully understood the implications of potential damage to resources without having evaluations of the predicted impacts under field conditions. We review approaches taken in the use of experimental ecosystems, discuss benefits and limitations of small- and large-scale ecosystem tests, and point to correlative approaches between laboratory and field toxicity testing. Laboratory experimental ecosystems (microcosms) have been successfully used to measure contaminant bioavailability, to determine routes of uptake in moderately complex aquatic systems, and to isolate factors modifying contaminant uptake into the biota. Such factors cannot be as readily studied in outdoor experimental ecosystems because direct cause-and-effect relations are often confounded and difficult to isolate. However, laboratory tests can be designed to quantify the relations among three variables: known concentrations of Stressors; specific sublethal behavioral, biochemical, and physiological effects displayed by organisms; and responses that have been observed in ecosystem-level analyses. For regulatory purposes, the specificity of test results determines how widely they can be applied. Ecotoxicological research should be directed at attempts to identify instances where single-species testing would be the appropriate level of analysis for identifying critical ecological endpoints and for clarifying relationships between ecosystem structure and function, and where it would be inadequate for a given level of analysis.

Environmental Management↗
USGS2012

Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome

White-nose syndrome (WNS) is an emerging disease of hibernating bats associated with cutaneous infection by the fungus Geomyces destructans ( Gd ), and responsible for devastating declines of bat populations in eastern North America. Affected bats appear emaciated and one hypothesis is that they spend too much time out of torpor during hibernation, depleting vital fat reserves required to survive the winter. The fungus has also been found at low levels on bats throughout Europe but without mass mortality. This finding suggests that Gd is either native to both continents but has been rendered more pathogenic in North America by mutation or environmental change, or that it recently arrived in North America as an invader from Europe. Thus, a causal link between Gd and mortality has not been established and the reason for its high pathogenicity in North America is unknown. Here we show that experimental inoculation with either North American or European isolates of Gd causes WNS and mortality in the North American bat, Myotis lucifugus . In contrast to control bats, individuals inoculated with either isolate of Gd developed cutaneous infections diagnostic of WNS, exhibited a progressive increase in the frequency of arousals from torpor during hibernation, and were emaciated after 3–4 mo. Our results demonstrate that altered torpor-arousal cycles underlie mortality from WNS and provide direct evidence that Gd is a novel pathogen to North America from Europe.

Proceedings of the National Academy of Sciences↗
USGS2025

The interface between rare plant management and genetics: Conserving Pitcher’s thistle (Cirsium pitcheri) in the Great Lakes region, USA

Background and Aims Tools showing best conservation practices are becoming critical for rare plant conservation as populations become isolated through habitat fragmentation and changing ecosystem processes. We illustrate the importance of reintroduction and assisted gene flow, using reintroduction of the USA federally threatened Pitcher’s thistle ( Cirsium pitcheri ), a monocarpic perennial endemic to the western Great Lakes sand dunes. We evaluate the success of experimental reintroductions of this species into its dynamic coastal environment and address fundamental issues for rare plant reintroduction, including questions of maintenance of genetic diversity, founder size, introduction methods and assisted gene flow effectiveness. Methods In 1994 we initiated experimental reintroductions at three new locations along a habitat successional gradient using 4200 seeds collected from 54 maternal lines. At each site, seed sources were distributed among replicate blocks that were split by sowing method (sowing vs broadcasting) to examine establishment success. We monitored population demography for 30 years, assessing genetic variation in 2009 and regionally from 1997 to 2014. Key Results Two of three populations persisted for 30 years from a single-seeding founder event. Reintroduction populations had greater expected heterozygosity than regional native populations. Despite persistence, moderate inbreeding coefficients showed that reintroduction populations have not achieved an effective size to reduce the likelihood of inbreeding depression. However, the mid-successional reintroduction had the lowest kinship of all populations sampled, indicating a healthy restoration. Seed sowing produced three times as many seedlings as broadcasting, but seed source did not affect germination success. Persistence has been facilitated by local migration to suitable habitat patches, an important metapopulation process. Conclusions Seeds can be an effective method for reintroducing monocarpic plants in high-quality habitats. However, low numbers of reproductive adults and moderate inbreeding illustrate the need for repeated additions of plants or seed to reduce inbreeding to improve rare plant genetic evolutionary potential.

Indiana↗
USGS1988

Tunnel-construction methods and foraging path of a fossorial herbivore, Geomys bursarius

The fossorial rodent Geomys bursarius excavates tunnels to find and gain access to belowground plant parts. This is a study of how the foraging path of this animal, as denoted by feeding-tunnel systems constructed within experimental gardens, reflects both adaptive behavior and constraints associated with the fossorial lifestyle. The principal method of tunnel construction involves the end-to-end linking of short, linear segments whose directionalities are bimodal, but symmetrically distributed about 0°. The sequence of construction of left- and right-directed segments is random, and segments tend to be equal in length. The resulting tunnel advances, zigzag-fashion, along a single heading. This linearity, and the tendency for branches to be orthogonal to the originating tunnel, are consistent with the search path predicted for a "harvesting animal" (Pyke, 1978) from optimal-foraging theory. A suite of physical and physiological constraints on the burrowing process, however, may be responsible for this geometric pattern. That is, by excavating in the most energy-efficient manner, G. bursarius automatically creates the basic components to an optimal-search path. The general search pattern was not influenced by habitat quality (plant density). Branch origins are located more often than expected at plants, demonstrating area-restricted search, a tactic commonly noted in aboveground foragers. The potential trade-offs between construction methods that minimize energy cost and those that minimize vulnerability to predators are discussed.

Journal of Mammalogy↗
USGS2003

Investigation of the possible connection of rock and soil geochemistry to the occurrence of high rates of neurodegenerative diseases on Guam and a hypothesis for the cause of the diseases

High incidences of neurodegenerative diseases, mainly dementia, parkinsonism, and amyotrophic lateral sclerosis, occur on the island of Guam (Koerner, 1952; Kurland and Mulder, 1954). The occurrence and description of the diseases and a summary of the investigations can be found in Perl (1997). The diseases have been more prevalent along the southern coast, particularly the small villages of Umatac, Merizo, and Inarajan (Reed and Brody, 1975; Roman, 1996; and Perl, 1997) (fig. 1), and referred to as the southern villages in this report. Tertiary volcanic rocks underlie most of the southern part of the island, including these villages. The northern part of Guam, with lower incidences of the diseases, consists of carbonate rocks. Epidemiological studies beginning in the early 1950’s failed to show the cause to be genetic etiology (Plato and others, 1986; Zhang and others, 1990). In recent studies, the search for pathogenic mechanisms has shifted to environmental factors. Excesses or deficiencies of various elements from dietary sources including drinking water can have an effect on human health. These deficiencies or excesses can usually be attributed to the geochemical composition of the rocks and derived soils that underlie the area. An example is the high concentration of Se in soil associated with the occurrence of selenosis in adults (Mills, 1996). Yase (1972) suggested that the neurodegenerative diseases on Guam may be related to accumulation of trace elements such as manganese and aluminum, both of which may cause neurodegeneration. It has been suggested that a deficiency in calcium and magnesium in the soil and water along with readily available aluminum could be connected to the occurrence of the diseases (Gajdusek, 1982; Yanagihara and others, 1984; Garruto and others, 1989). Some of the studies investigated metal exposure, particularly aluminum and manganese, and deficiencies in calcium and magnesium (Garruto and others, 1984). Aluminum has been shown to have neurotoxic effects (MacDonald and Martin, 1988), and aluminum has been implicated in the pathogenesis of Alzheimer’s disease and similar dementia by Perl and others (1982). Studies of soils developed on volcanic rocks on Guam and other islands by McLachlan and others (1989) found that soils on Guam averaged 42-fold higher yield of elutable aluminum than soils developed on volcanic rocks on Jamaica or Palau. They did not detect unusually high dietary aluminum or low dietary calcium, but concluded that the soils and possibly the dusts of Guam might be a major source of aluminum entering the body of the inhabitants. This study was conducted to investigate the geochemistry of the soils and rocks of the volcanic southern part of the island of Guam, particularly in the vicinity of the three southern villages (Umatac, Merizo, and Inarajan) with high incidences of the diseases. In addition to total chemical analyses of the soils and rocks, various extractions of soils were carried out. Both excesses and deficiencies of various elements were looked for. Because soluble aluminum in the soil was shown by McLachlan and others (1989) to be unusually high, water-soluble extractions as well as sequential extractions of the soils were carried out. In addition, elements such as aluminum found in dust can traverse the nose-brain barrier in experimental animals (Sunderman, 2000) and respiratory epithelium is known to contain the highest concentration of aluminum in the human body (Tipton and others, 1957). The availability of elements, particularly aluminum from human inhalation of dust, derived from soil, was investigated. The available elements were determined by extractions of soils using a simulated lung-fluid extraction. In order to compare the results of the chemical data of rocks and soils from Guam to other rocks and soils elsewhere, samples of similar rocks and soils were collected in the western United States and similar analyses to those for the Guam samples carried out. The complete chemical analyses of the soils, rocks, and streambed sediments as well as descriptions of the methods used can be found in Miller and others (2002).

Open-File Report↗
USGS1964

Sea-water systems for experimental aquariums; a collection of papers

This volume was created to provide a source of information on design, construction, and operation of experimental aquarium facilities. The idea developed out of our own frustrated search for published material on sea-water supply systems when we were planning facilities for the new Sandy Hook Marine Laboratory. We found that we had to spend many weeks visiting laboratories and many months corresponding with aquarists to obtain the information we needed. It became clear, as a result of this, that nearly everyone who has built a sea-water system has experienced similar difficulties.

Research Report↗
USGS2008

Impacts of short-term acid and aluminum exposure on Atlantic salmon (Salmo salar) physiology: A direct comparison of parr and smolts

Episodic acidification resulting in increased acidity and inorganic aluminum (Al i ) is known to impact anadromous salmonids and has been identified as a possible cause of Atlantic salmon population decline. Sensitive life-stages such as smolts may be particularly vulnerable to impacts of short-term (days–week) acid/Al exposure, however the extent and mechanism(s) of this remain unknown. To determine if Atlantic salmon smolts are more sensitive than parr to short-term acid/Al, parr and smolts held in the same experimental tanks were exposed to control (pH 6.3–6.6, 11–37 μg l −1 Al i ) and acid/Al (pH 5.0–5.4, 43–68 μg l −1 Al i ) conditions in the lab, and impacts on ion regulation, stress response and gill Al accumulation were examined after 2 and 6 days. Parr and smolts were also held in cages for 2 and 6 days in a reference (Rock River, RR) and an acid/Al-impacted tributary (Ball Mountain Brook, BMB) of the West River in Southern Vermont. In the lab, losses in plasma Cl − levels occurred in both control parr and smolts as compared to fish sampled prior to the start of the study, however smolts exposed to acid/Al experienced additional losses in plasma Cl − levels (9–14 mM) after 2 and 6 days, and increases in plasma cortisol (4.3-fold) and glucose (2.9-fold) levels after 6 days, whereas these parameters were not significantly affected by acid/Al in parr. Gill Na + ,K + -ATPase (NKA) activity was not affected by acid/Al in either life-stage. Both parr and smolts held at BMB (but not RR) exhibited declines in plasma Cl − , and increases in plasma cortisol and glucose levels; these differences were significantly greater in smolts after 2 days but similar in parr and smolts after 6 days. Gill NKA activity was reduced 45–54% in both life-stages held at BMB for 6 days compared to reference fish at RR. In both studies, exposure to acid/Al resulted in gill Al accumulation in parr and smolts, with parr exhibiting two-fold greater gill Al than smolts after 6 days. Our results indicate that smolts are more sensitive than parr to short-term acid/Al. Increased sensitivity of smolts appears to be independent of a reduction in gill NKA activity and greater gill Al accumulation. Instead, increased sensitivity of smolts is likely a result of both the acquisition of seawater tolerance while still in freshwater and heightened stress responsiveness in preparation for seawater entry and residence.

Aquatic Toxicology↗
USGS2005

Hormonal control of sulfate uptake by bronchial cartilage of coho salmon: Role of IGF-I

The direct hormonal control of sulfate uptake by cartilage matrix of coho salmon was examined by exposing branchial cartilage to 1 μCi · ml −1 35 SO 4 for 48 hours at 15°C in a defined medium. Sulfate uptake occurred primarily in cartilage (rather than bone) and the amount of specific uptake was similar in epibranchial and ceratobranchial cartilages. Intact and hypophysectomized coho salmon starved for 22 days had equivalent in vitro sulfate uptake, which in both cases were 30% of the uptake seen in branchial cartilage of fed, intact controls. In branchial cartilage from starved coho salmon, in vitro exposure to recombinant bovine insulin-like growth factor I (rbIGF-I) at 1, 10, 100, and 1,000 ng · ml −1 caused a dose-dependent increase in sulfate uptake, with a maximum 3-fold increase over control at 1,000 ng · ml −1 rbIGF-I. Coho salmon insulin (1, 10, 100, and 1,000 ng · ml −1 ) resulted in a maximum 30% increase in sulfate uptake at the highest dose. Growth hormone and triiodo-L-thyronine had no direct effect on in vitro sulfate uptake. The results indicate that IGF-I has direct effects on coho salmon cartilage and may be an important regulator of growth in salmon and other teleosts.

Journal of Experimental Zoology↗