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At least 847 records · Page 47Linked to original sources

USGS1999

Dietary effects of metals-contaminated invertebrates from the Coeur d'Alene River, Idaho, on cutthroat trout

Benthic macroinvertebrates with elevated concentrations of metals were collected from the Coeur d'Alene (CDA) River, Idaho, pasteurized, and fed to cutthroat trout Oncorhynchus clarki in the laboratory from start of feeding until 90 d posthatch. Invertebrates were collected from two sites known to contain elevated concentrations of metals: near Pinehurst in the South Fork of the CDA River and at Cataldo, approximately 5 km below the confluence of the South Fork and the North Fork. Invertebrates collected from a relatively clean site in the North Fork were used as a reference diet. We performed measurements of fish health that indicate reduced fitness of fish fed the South Fork and Cataldo diets. Effects measured were reduced feeding activity, increased number of macrophage aggregates and hyperplasia of cells in the kidney, degeneration of mucosal epithelium in the pyloric caecae, and metallothionein induction. These effects would likely reduce growth and survival of fish in the wild. Vacuolization of glial cells were also observed in fish fed the Cataldo diet. Metals in the water often exacerbated the histological effects observed. Although the invertebrates collected near Cataldo had lower concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) than the invertebrates from the South Fork, fish fed the Cataldo diet had equally high or higher concentrations of all metals except as by day 44. The Cataldo diet also caused the most deleterious effects on survival and growth. These findings are especially important for early life stage fish, whose diet consists wholly of benthic macroinvertebrates. Therefore, fish feeding on invertebrates in the CDA River below the Bunker Hill smelting complex are at risk of reduced fitness.

Transactions of the American Fisheries Society↗

USGS1992

Communications: Blood chemistry of laboratory-reared Golden trout

Golden trout Oncorhynchus aguabonita obtained from a wild stock as fertilized eggs were reared in the laboratory for 21 months. The laboratory-reared golden trout in our study reached sexual maturity earlier and grew more rapidly than wild golden trout do (according to the scientific literature). Male fish averaged 35.6 cm in total length and 426 g in weight, and females averaged 36.2 cm and 487 g. All golden trout were sexually mature when used for hematological analysis. The hematological profile (hematocrit, red blood cells, white blood cells, and thrombocytes) of golden trout was similar to that reported elsewhere for other trout species. Male and female golden trout did not have significantly different thrombocyte counts; however, the immobilization treatment used on the fish (anesthesia versus a blow to the head) resulted in significant treatment differences in thrombocyte numbers and interaction effect of sex in treatment for hematocrits. Gravid female golden trout had significantly higher plasma protein and calcium levels than did males. The ionic compositions of plasma (sodium, potassium, calcium, magnesium, copper, zinc, iron, and chloride) and gallbladder bile (calcium and chloride) were similar to those reported for other salmonids.

Journal of Aquatic Animal Health↗

USGS1997

Evaluation by enzyme-linked immunosorbent assay (ELISA) of Renibacterium salmoninarum bacterins affected by persistence of bacterial antigens

Rainbow trout Oncorhynchus mykiss were injected intraperitoneally with a bacterin containing killed Renibacterium salmoninarum cells delivered alone or in an oil-based adjuvant. We evaluated the relative abilities of the batterins to prevent the initiation or progression of infection in fish challenged by waterborne exposure to R. salmoninarum. Sixty-one days after vaccination, fish were held for 24 h in water containing either no bacteria or approximately 1.7 x 103, 1.7 x 105, or 5.3 x 106 live R. salmoninarum cells/mL. An enzyme-linked immunosorbent assay (ELISA) was used to monitor changes in the levels of R. salmoninarum antigen in live fish before and after the immersion challenges. High levels of R. salmoninarum antigens were detected by ELISA in kidney-spleen tissue homogenates from vaccinated fish immediately before the challenges. Levels of those antigens remained high in the tissues of unchallenged fish throughout the study. We found that the ELISA used in this study may be unsuitable for evaluating the efficacy of batterins because it did not distinguish antigens produced by the challenge bacteria during an infection from those of the bacterins. Groups of control and vaccinated fish also were injected with either 1.7 x 104 or 1.7 x 106 R. salmoninarum cells and served as R. salmoninarum virulence controls. Relative survival among the various subgroups in the injection challenge suggests that adverse effects might have been associated with the adjuvant used in this study. The lowest survival at both injection challenge levels was among fish vaccinated with bacteria in adjuvant.

Journal of Aquatic Animal Health↗

USGS1998

Elicitation of macrophages from the peritoneal cavity of channel catfish

Four chemicals were evaluated for elicitation of macrophages in peritoneal cavities of 250–300‐g healthy channel catfish Ictalurus punctatus. Cellular exudates were collected at 3, 5, 7, 10, 14, and 20 d following intraperitoneal injections with squalene, Freund's incomplete adjuvant (FIA), goat serum, thioglycollate, or as a control, phosphate‐buffered saline. Injection with either squalene or FIA induced significantly greater ( P ⩽ 0.0001) macrophage recruitment than the other chemicals. The effectiveness of squalene and FIA was compared further by macrophage collection daily for 7 d. Squalene and FIA elicited similarly high macrophage responses ( P ⩽ 0.0450), the highest being 3.43 × 10 6 macrophages/mL (SE, 2.4 × 10 6 ) at 99% purity at day 2 and 2.1 × 10 6 macrophages/mL (SE, 0.7 × 10 6 ) at day 14 at 80% purity, respectively. In both experiments, the time after injection was not statistically significant, nor was there an interaction between time and chemicals. The occurrence of cells other than macrophages decreased with time to yield macrophage recoveries of 47–99% for squalene and 30–80% for FIA. Two subsets of macrophages were observed by means of flow cytometry. As demonstrated by chemiluminescence, the squalene‐elicited cells produced high‐energy oxygen compounds important to the phagocytic process.

Journal of Aquatic Animal Health↗

USGS2000

Correlation of transforming growth factor-β messenger RNA (TGF-β mRNA) expression with cellular immunoassays in Triamcinolone-treated captive hybrid striped bass

Assessing fish immune status with molecular markers has been hampered by a lack of specific reagents. A quantitative polymerase chain reaction (PCR) method (reverse transcription quantitative–competitive PCR, RT-qcPCR) for measuring transforming growth factor-β (TGF-β) transcription from a broad range of teleost fish has recently been developed. The quantitative PCR now permits monitoring production of this important immunosuppressive cytokine in response to immunomodulating agents and conditions. We examined anterior kidney and spleen mononuclear cells from hybrid striped bass (female striped bass Morone saxatilis × male white bass M. chrysops ) for production of TGF-β messenger RNA (mRNA) in response to administration of the synthetic glucocorticoid triamcinolone. We also compared TGF-β transcription with anterior kidney macrophage bactericidal activity and splenic lymphocyte blastogenesis. Anterior kidney mononuclear cell TGF-β mRNA levels decreased, whereas bactericidal activity increased. Spleen TGF-β mRNA levels did not change significantly, and splenic lymphocyte pokeweed mitogen stimulation index increased in triamcinolone-treated fish. Since triamcinolone is used therapeutically as a suppressive immunomodulator, the enhanced immune functions indicated by the cellular immunoassays were unexpected; however, the inverse response of TGF-β production and macrophage bactericidal activity was consistent with the known relationship between TGF-β and macrophage activation in mammals. Induced immunomodulation in hybrid striped bass was detectable by both traditional cellular immunoassays and the new RT-qcPCR for TGF-β.

Journal of Aquatic Animal Health↗

USGS2001

Evaluation of commercially prepared transport systems for nonlethal detection of Aeromonas salmonicida in salmonid fish

In vitro studies indicated that commercially prepared transport systems containing Amies, Stuart's, and Cary-Blair media worked equally well in sustaining the viability of the fish pathogen Aeromonas salmonicida, which causes furunculosis. The bacterium remained viable without significant increase or decrease in cell numbers for as long as 48 h of incubation at 18-20??C in Stuart's transport medium; consequently, obtaining mucus samples in such tubes were comparable to on-site detection of A. salmonicida by dilution plate counts on Coomassie Brilliant Blue agar. In three different assays of 100 samples of mucus from Atlantic salmon Salmo salar infected subclinically with A. salmonicida, dilution counts conducted on-site proved more reliable for detecting the pathogen than obtaining the samples in the transport system. In the on-site assays, dilution counts detected the pathogen in 34, 41, and 22 samples, whereas this was accomplished in only 15, 15, and 3 of the respective samples when the transport system was used. In an additional experiment, Arctic char Salvelinus alpinus sustaining a frank epizootic of furunculosis were sampled similarly. Here, too, dilution counts were more predictive of the prevalence of A. salmonicida and detected the pathogen in 46 mucus samples; in comparison, only 6 samples collected by using the transport system were positive. We also observed that the transport system supported the growth of the normal mucus bacterial flora. Particularly predominant among these were motile aeromonads and Pseudomonas fluorescens. In studies of mixed culture growth, two representatives of both of the latter genera of bacteria outgrew A. salmonicida - in some cases, to the total exclusion of the pathogen itself.

Journal of Aquatic Animal Health↗

USGS2003

Morphometric and histopathological parameters of gonadal development in adult common carp from contaminated and reference sites in Lake Mead, Nevada

This study examined the hypothesis that exposure to sublethal concentrations of contaminants alters the gonadal condition of feral common carp Cyprinus carpio . Adult common carp in Lake Mead, Nevada, were collected from a contaminated site (Las Vegas Bay) that receives municipal and industrial effluent and from a reference site (Overton Arm) with a relatively low level of contamination. Fish were sampled seven times over a 1-year period extending over two separate spawning seasons. Morphometric and histopathological parameters of gonadal and germ cell development were determined. In males, the pattern of seasonal changes in the gonadosomatic index (GSI) was similar between the sites and showed no clear association with site-specific seasonal temperature profiles. However, Las Vegas Bay males had consistently lower GSI values and, on one of the sampling dates, a lower proportion of sperm relative to other germ cell stages (determined histologically). Further, Las Vegas Bay males had a higher incidence of gonadal macrophage aggregates, which are putative tissue biomarkers of contaminant exposure in fishes. In females, seasonal GSI profiles, the frequency of fish with postovulatory follicles (an index of spawning activity), and the timing of new follicle recruitment all showed differences between sites, but these differences generally matched differences in water temperature profile. Also, the peak size-frequency of full-grown follicles did not differ between sites, and estimates of fecundity for the second spawning season indicated that females from the reference site unexpectedly produced a lower number of gametes. Overall, site differences in gonadal condition were observed in carp of both sexes but they seemed to be associated with site differences in contaminant levels only in males. The apparent lack of association between contaminant level and gonadal condition in female carp from mildly mesotrophic Lake Mead may indicate a lack of contaminant effects in females or a confounding effect of the higher nutrient loads in the Las Vegas Bay environment.

Nevada↗

USGS2011

Capture-related stressors impair immune system function in sablefish

The sablefish Anoplopoma fimbria is a valuable North Pacific Ocean species that, when not targeted in various commercial fisheries, is often a part of discarded bycatch. Predictions of the survival of discarded fish are dependent on understanding how a fish responds to stressful conditions. Our objective was to describe the immunological health of sablefish exposed to capture stressors. In laboratory experiments designed to simulate the capture process, we subjected sablefish to various stressors that might influence survival: towing in a net, hooking, elevated seawater and air temperatures, and air exposure time. After stress was imposed, the in vitro mitogen-stimulated proliferation of sablefish leukocytes was used to evaluate the function of the immune system in an assay we validated for this species. The results demonstrated that regardless of fishing gear type, exposure to elevated seawater temperature, or time in air, the leukocytes from stressed sablefish exhibited significantly diminished proliferative responses to the T-cell mitogen, concanavalin A, or the B-cell mitogen, lipopolysaccharide. There was no difference in the immunological responses associated with seawater or air temperature. The duration and severity of the capture stressors applied in our study were harsh enough to induce significantly elevated levels of plasma cortisol and glucose, but there was no difference in the magnitude of levels among stressor treatments. These data suggest that immunological suppression occurs in sablefish subjected to capture-related stressors. The functional impairment of the immune system after capture presents a potential reason why delayed mortality is possible in discarded sablefish. Further studies are needed to determine whether delayed mortality in discarded sablefish can be caused by increased susceptibility to infectious agents resulting from stressor-mediated immunosuppression.

Transactions of the American Fisheries Society↗

USGS2006

Comparison of methods used to diagnose generalized inflammatory disease in manatees (Trichechus manatus latirostris)

Manatees ( Trichechus manatus latirostris ) are afflicted with inflammatory and infectious disease secondary to human interaction, such as boat strike and entanglement, as well as “cold stress syndrome” and pneumonia. White-blood-cell count and fever, primary indicators of systemic inflammation in most species, are insensitive in diagnosing inflammatory disease in manatees. Acute phase-response proteins, such as haptoglobin and serum amyloid A, have proven to be sensitive measures of inflammation/infection in domestic large animal species. This study assessed diagnosis of generalized inflammatory disease by different methods including total white-blood-cell count, albumin: globulin ratio, gel electrophoresis analysis, C-reactive protein, alpha 1 acid glycoprotein, haptoglobin, fibrinogen, and serum amyloid A. Samples were collected from 71 apparently healthy and 27 diseased animals during diagnostic medical examination. Serum amyloid A, measured by ELISA, followed by albumin:globulin ratio, measured by plasma gel electrophoresis, were most sensitive in diagnosing inflammatory disease, with diagnostic sensitivity and specificity of approximately 90%. The reference interval for serum amyloid A is <10–50 μg/ml with an equivocal interval of 51–70 μg/ml. The reference interval for albumin:globulin ratio by plasma gel electrophoresis is 0.7–1.1. Albumin: globulin ratio, calculated using biochemical techniques, was not accurate due to overestimation of albumin by bromcresol green dye-binding methodology. Albumin:globulin ratio, measured by serum gel electrophoresis, has a low sensitivity of 15% due to the lack of fibrinogen in the sample. Haptoglobin, measured by hemoglobin titration, had a reference interval of 0.4–2.4 mg/ml, a diagnostic sensitivity of 60%, and a diagnostic specificity of 93%. The haptoglobin assay is significantly affected by hemolysis. Fibrinogen, measured by heat precipitation, has a reference interval of 100–400 mg/dl, a diagnostic sensitivity of 40%, and a diagnostic specificity of 95%.

Journal of Zoo and Wildlife Medicine↗

USGS2001

Geographic deaggregation of seismic hazard in the United States

The seismic hazard calculations for the 1996 national seismic hazard maps have been geographically deaggregated to assist in the understanding of the relative contributions of sources. These deaggregations are exhibited as maps with vertical bars whose heights are proportional to the contribution that each geographical cell makes to the ground-motion exceedance hazard. Bar colors correspond to average source magnitudes. We also extend the deaggregation analysis reported in Harmsen et al. (1999) to the western conterminous United States. In contrast to the central and eastern United States (CEUS); the influence of specific faults or characteristic events can be clearly identified. Geographic deaggregation for 0.2-sec and 1.0-sec pseudo spectral acceleration (SA) is performed for 10% probability of exceedance (PE) in 50 yr (475-yr mean return period) and 2% PE in 50 yr (2475-yr mean return period) for four western U.S. cities, Los Angeles, Salt Lake City, San Francisco, and Seattle, and for three central and eastern U.S. cities, Atlanta, Boston, and Saint Louis. In general, as the PE is lowered, the sources of hazard closer to the site dominate. Larger, more distant earthquakes contribute more significantly to hazard for 1.0-sec SA than for 0.2-sec SA. Additional maps of geographically deaggregated seismic hazard are available on the Internet for 120 cities in the conterminous United States (http://geohazards. cr.usgs.gov/eq/) for 1-sec SA and for 0.2-sec SA with a 2% PE in 50 yr. Examination of these maps of hazard contributions enables the investigator to determine the distance and azimuth to predominant sources, and their magnitudes. This information can be used to generate scenario earthquakes and corresponding time histories for seismic design and retrofit. Where fault density is lower than deaggregation cell dimensions, we can identify specific faults that contribute significantly to the seismic hazard at a given site. Detailed fault information enables investigators to include rupture information such as source directivity, radiation pattern, and basin-edge effects into their scenario earthquakes used in engineering analyses.

Bulletin of the Seismological Society of America↗

USGS2011

Fault displacement hazard for strike-slip faults

In this paper we present a methodology, data, and regression equations for calculating the fault rupture hazard at sites near steeply dipping, strike-slip faults. We collected and digitized on-fault and off-fault displacement data for 9 global strikeslip earthquakes ranging from moment magnitude M 6.5 to M 7.6 and supplemented these with displacements from 13 global earthquakes compiled byWesnousky (2008), who considers events up to M 7.9. Displacements on the primary fault fall off at the rupture ends and are often measured in meters, while displacements on secondary (offfault) or distributed faults may measure a few centimeters up to more than a meter and decay with distance from the rupture. Probability of earthquake rupture is less than 15% for cells 200 m??200 m and is less than 2% for 25 m??25 m cells at distances greater than 200mfrom the primary-fault rupture. Therefore, the hazard for off-fault ruptures is much lower than the hazard near the fault. Our data indicate that rupture displacements up to 35cm can be triggered on adjacent faults at distances out to 10kmor more from the primary-fault rupture. An example calculation shows that, for an active fault which has repeated large earthquakes every few hundred years, fault rupture hazard analysis should be an important consideration in the design of structures or lifelines that are located near the principal fault, within about 150 m of well-mapped active faults with a simple trace and within 300 m of faults with poorly defined or complex traces.

Bulletin of the Seismological Society of America↗

USGS2010

Multistate modeling of habitat dynamics: Factors affecting Florida scrub transition probabilities

Many ecosystems are influenced by disturbances that create specific successional states and habitat structures that species need to persist. Estimating transition probabilities between habitat states and modeling the factors that influence such transitions have many applications for investigating and managing disturbance-prone ecosystems. We identify the correspondence between multistate capture-recapture models and Markov models of habitat dynamics. We exploit this correspondence by fitting and comparing competing models of different ecological covariates affecting habitat transition probabilities in Florida scrub and flatwoods, a habitat important to many unique plants and animals. We subdivided a large scrub and flatwoods ecosystem along central Florida's Atlantic coast into 10-ha grid cells, which approximated average territory size of the threatened Florida Scrub-Jay (Aphelocoma coerulescens), a management indicator species. We used 1.0-m resolution aerial imagery for 1994, 1999, and 2004 to classify grid cells into four habitat quality states that were directly related to Florida Scrub-Jay source-sink dynamics and management decision making. Results showed that static site features related to fire propagation (vegetation type, edges) and temporally varying disturbances (fires, mechanical cutting) best explained transition probabilities. Results indicated that much of the scrub and flatwoods ecosystem was resistant to moving from a degraded state to a desired state without mechanical cutting, an expensive restoration tool. We used habitat models parameterized with the estimated transition probabilities to investigate the consequences of alternative management scenarios on future habitat dynamics. We recommend this multistate modeling approach as being broadly applicable for studying ecosystem, land cover, or habitat dynamics. The approach provides maximum-likelihood estimates of transition parameters, including precision measures, and can be used to assess evidence among competing ecological models that describe system dynamics. ?? 2010 by the Ecological Society of America.

Ecology↗

USGS2006

Dietary exposure of mink (Mustela vison) to fish from the Housatonic River, Berkshire County, Massachusetts, USA: Effects on organ weights and histology and hepatic concentrations of polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalence

The effects of feeding ranch mink ( Mustela vison ) diets containing polychlorinated biphenyl (PCB)-contaminated fish (88 gold fish [ Carassius auratus ] weighing a total of 70.3 kg and 16 carp [ Cyprinus carpio ] weighing a total of 77.3 kg) collected from the Housatonic River (HR; Berkshire County, MA, USA) in October 1999 on organ weights and histology and hepatic concentrations of total PCBs (ΣPCBs) and 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalence (TEQ) were evaluated. Diets contained 0.22 to 3.54% HR fish, which provided 0.34 to 3.7 μg ΣPCBs/g feed (3.5-69 pg TEQ/g feed). Female mink were fed the diets eight weeks before breeding through weaning of kits at six weeks of age. Offspring were maintained on their respective diets for an additional 180 d. The dietary concentration of PCBs that caused a decrease in kit survival (3.7 μg ΣPCBs/g feed [69 pg TEQ/g]) resulted in a maternal hepatic concentration of 3.1 μg ΣPCBs/g wet weight (218 pg TEQ/g). Organ weights were not consistently affected. Mandibular and maxillary squamous cell proliferation was apparent in 31-week-old juveniles exposed to as low as 0.96 (xg ΣPCBs/g feed (9.2 pg TEQ/g). Juveniles in this treatment group had a liver concentration of 1.7 μg ΣPCBs/g wet weight (40 pg TEQ/g). Because inclusion of PCB-contaminated fish, which comprised approximately 1% of the diet, resulted in mandibular and maxillary squamous cell proliferation, it is possible that consumption of up to 30-fold that quantity of HR fish, as could be expected for wild mink, would result in more severe lesions characterized by loss of teeth, thus impacting survivability.

Environmental Toxicology and Chemistry↗

USGS2008

Utilization of protein expression profiles as indicators of environmental impairment of smallmouth bass (Micropterus dolomieu) from the Shenandoah River, Virginia, USA

The Shenandoah River (VA, USA), the largest tributary of the Potomac River (MD, USA) and an important source of drinking water, has been the site of extensive fish kills since 2004. Previous investigations indicate environmental stressors may be adversely modulating the immune system of smallmouth bass ( Micropterus dolomieu ) and other species. Anterior kidney (AK) tissue, the major site of blood cell production in fish, was collected from smallmouth bass at three sites along the Shenandoah River. The tissue was divided for immune function and proteomics analyses. Bactericidal activity and respiratory burst were significantly different between North Fork and mainstem Shenandoah River smallmouth bass, whereas South Fork AK tissue did not significantly differ in either of these measures compared with the other sites. Cytotoxic cell activity was highest among South Fork and lowest among North Fork AK leukocytes. The composite two‐dimension gels of the North Fork and mainstem smallmouth bass AK tissues contained 584 and 591 spots, respectively. South Fork smallmouth bass AK expressed only 335 proteins. Nineteen of 50 proteins analyzed by matrix‐assisted laser desorption ionization‐time of flight were successfully identified. Three of the four identified proteins with increased expression in South Fork AK tissue were involved in metabolism. Seven proteins exclusive to mainstem and North Fork smallmouth bass AK and expressed at comparable abundances serve immune and stress response functions. The proteomics data indicate these fish differ in metabolic capacity of AK tissue and in the ability to produce functional leukocytes. The variable responses of the immune function assays further indicate disruption to the immune system. Our results allow us to hypothesize underlying physiological changes that may relate to fish kills and suggest relevant contaminants known to produce similar physiological disruption.

Virginia↗

USGS2009

A simplified method for correcting contaminant concentrations in eggs for moisture loss.

We developed a simplified and highly accurate method for correcting contaminant concentrations in eggs for the moisture that is lost from an egg during incubation. To make the correction, one injects water into the air cell of the egg until overflowing. The amount of water injected corrects almost perfectly for the amount of water lost during incubation or when an egg is left in the nest and dehydrates and deteriorates over time. To validate the new method we weighed freshly laid chicken (Gallus gallus) eggs and then incubated sets of fertile and dead eggs for either 12 or 19 d. We then injected water into the air cells of these eggs and verified that the weights after water injection were almost identical to the weights of the eggs when they were fresh. The advantages of the new method are its speed, accuracy, and simplicity: It does not require the calculation of a correction factor that has to be applied to each contaminant residue.

Environmental Toxicology and Chemistry↗

USGS2005

Terlinguacreekite, Hg2+3O2 Cl2, a new mineral species from the Perry pit, Mariposa mine, Terlingua mining district, Brewster County, Texas, U.S.A

Terlinguacreekite, ideally Hg 2+ 3 O 2 Cl 2 , has a very pronounced subcell that is orthorhombic, space-group choices Imam , Imcm , Ima 2 and I 2 cm , with unit-cell parameters refined from powder data: a 6.737(3), b 25.528(10), c 5.533(2) Å, V 951.6(6) Å 3 , a:b:c 0.2639:1:0.2167, Z = 8. The true symmetry, supercell unit-cell parameters, and details regarding the crystal structure are unknown. The strongest nine lines of the X-ray powder-diffraction pattern [ d in Å ( I )(subcell hkl )] are: 5.413(30)(011), 4.063(80)(121), 3.201(50)(080), 3.023(50)(161), 2.983(60)(240), 2.858(30)(211), 2.765(50)(002), 2.518(100b)(091, 251) and 2.026(30)(242). The mineral is found in an isolated area measuring approximately 1 × 0.5 m in the lower level of the Perry pit, Mariposa mine, Terlingua mining district, Brewster County, Texas (type locality), as mm-sized anhedral dark orange to reddish orange crusts of variable thickness on calcite, and rarely as 0.5 mm-sized aggregates of crystals of the same color. It has also been identified at the McDermitt mine, Humboldt County, Nevada, U.S.A., where it occurs with kleinite and calomel in silicified volcanic rocks and sediments. Terlinguacreekite is a secondary phase, most probably formed from the alteration of primary cinnabar or native mercury. At Terlingua, most crusts are thin, almost cryptocrystalline, with no discernable forms, and are resinous and translucent to opaque. Crystals are up to 0.2 mm in length, subhedral, acicular to prismatic, elongation [001], with a maximum length-to-width ratio of 4:1. They are vitreous, transparent, and some crystals have brightly reflecting faces, which may be {010} and {110}. The streak is yellow, and the mineral is brittle with an uneven fracture, no observable cleavage, and is soft, nonfluorescent under both long- and short-wave ultraviolet light. D (calc.) is 9.899 g/cm 3 (empirical formula). Material from the McDermitt mine is reversibly photosensitive, and turns from vivid orange to black in strong light. In reflected plane-polarized light, it is bluish grey, with very weak (in air) to distinct (in oil) bireflectance, nonpleochroic, and distinctly anisotropic, with colors masked by ubiquitous yellowish orange to orange internal reflections. Measured values of reflectance obtained in air and in oil are tabulated. Averaged results of electron-microprobe analysis give HgO 92.03, Cl 9.54, Br 1.22, sum 102.79, less O = Cl + Br 2.28, total 100.51 wt.%. The empirical formula is Hg 2+ 3.00 O 2.00 (Cl 1.90 Br 0.11 ) ∑2.01 , based on O + Cl + Br = 4 atoms per formula unit. The mineral name recalls the creek that flows through the Terlingua mining district and into the Rio Grande River.

Texas↗

USGS2011

Halloysite nanotubes and bacteria at the saprolite-bedrock interface, Rio Icacos watershed, Puerto Rico

Quartz diorite bedrock underlying the Luquillo Mountains of eastern Puerto Rico undergoes weathering at one of the fastest documented rates for granitic rocks in the world. Although tropical temperatures and precipitation promote rapid weathering in this location, increased bacterial densities in the regolith immediately above the bedrock suggest that microorganisms contribute to mineral weathering as well. Deep saprolite and saprock samples were obtained at the bedrock interface in an upland location (Guaba Ridge) in the Rio Icacos watershed for examination by environmental scanning electron microscopy (ESEM). In ESEM images, mineral nanotubes were observed to occur frequently in association with coccus- and rod-shaped structures resembling bacteria. These nanotubes (50–140-nm width and 150–2700-nm length) were identified as halloysite using transmission electron microscopy. Observations of multiple nanotubes on the surfaces of an individual cell are consistent with the cell's exterior functional groups interacting with Si in pore water to facilitate halloysite nucleation. We propose that one mechanism by which bacteria contribute to the rapid weathering of quartz diorite minerals in this regolith is by lowering the free energy for secondary mineral formation. The presence of bacterial surfaces may result in more rapid removal of Si from solution, thereby increasing the dissolution rates of primary minerals.

Puerto Rico↗

USGS2005

The stability and Raman spectra of ikaite, CaCO 3 ·6H 2 O, at high pressure and temperature

Raman analyses of single crystals of ikaite, CaCO 3 ·6H 2 O, synthesized in a diamond-anvil cell at ambient temperature yield spectra from 0.14 to 4.08 GPa; the most intense peaks are at 228 and 1081 cm −1 corresponding to E g (external) and A 1 g (internal) modes of vibrations in CO 2− 3 ions, respectively. These are in good agreement with Raman spectra previously published for ikaite in powder form at ambient temperature and pressure. Visual observations of a sample consisting initially of a mixture of calcite + water in a hydrothermal diamond-anvil cell yielded a P-T phase diagram up to 2 GPa and 120 °C; the boundary for the reaction ikaite ↔ aragonite + water has a positive slope and is curved convexly toward the aragonite + water field similar to typical melt curves. This curvature can be explained in terms of the Clapeyron equation for a boundary between a solid phase and a more compressible liquid phase or largely liquid phase assemblage.

American Mineralogist↗