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At least 1,261 records · Page 70Linked to original sources

USGS2007

The effects of acidic mine drainage from historical mines in the Animas River watershed, San Juan County, Colorado—What is being done and what can be done to improve water quality?

Historical production of metals in the western United States has left a legacy of acidic drainage and toxic metals in many mountain watersheds that are a potential threat to human and ecosystem health. Studies of the effects of historical mining on surface water chemistry and riparian habitat in the Animas River watershed have shown that cost-effective remediation of mine sites must be carefully planned. of the more than 5400 mine, mill, and prospect sites in the watershed, ∼80 sites account for more than 90% of the metal loads to the surface drainages. Much of the low pH water and some of the metal loads are the result of weathering of hydrothermally altered rock that has not been disturbed by historical mining. Some stream reaches in areas underlain by hydrothermally altered rock contained no aquatic life prior to mining. Scientific studies of the processes and metal-release pathways are necessary to develop effective remediation strategies, particularly in watersheds where there is little land available to build mine-waste repositories. Characterization of mine waste, development of runoff profiles, and evaluation of ground-water pathways all require rigorous study and are expensive upfront costs that land managers find difficult to justify. Tracer studies of water quality provide a detailed spatial analysis of processes affecting surface- and ground-water chemistry. Reactive transport models were used in conjunction with the best state-of-the-art engineering solutions to make informed and cost-effective remediation decisions. Remediation of 23% of the high-priority sites identified in the watershed has resulted in steady improvement in water quality. More than $12 million, most contributed by private entities, has been spent on remediation in the Animas River watershed. The recovery curve for aquatic life in the Animas River system will require further documentation and long-term monitoring to evaluate the effectiveness of remediation projects implemented.

Colorado, Montana↗

USGS2007

Sampling and monitoring for closure

An important aspect of planning a new mine or mine expansion within the modern regulatory framework is to design for ultimate closure. Sampling and monitoring for closure is a form of environmental risk management. By implementing a sampling and monitoring program early in the life of the mining operation, major costs can be avoided or minimized. The costs for treating mine drainage in perpetuity are staggering, especially if they are unanticipated. The Metal Mining Sector of the Acid Drainage Technology Initiative (ADTI-MMS), a cooperative government-industry-academia organization, was established to address drainage-quality technologies of metal mining and metallurgical operations. ADTI-MMS recommends that sampling and monitoring programs consider the entire mine-life cycle and that data needed for closure of an operation be collected from exploration through postclosure.

Reviews in Engineering Geology↗

USGS2013

Modeling volcano growth on the Island of Hawaii: Deep-water perspectives

Recent ocean-bottom geophysical surveys, dredging, and dives, which complement surface data and scientific drilling at the Island of Hawaii, document that evolutionary stages during volcano growth are more diverse than previously described. Based on combining available composition, isotopic age, and geologically constrained volume data for each of the component volcanoes, this overview provides the first integrated models for overall growth of any Hawaiian island. In contrast to prior morphologic models for volcano evolution (preshield, shield, postshield), growth increasingly can be tracked by age and volume (magma supply), defining waxing alkalic, sustained tholeiitic, and waning alkalic stages. Data and estimates for individual volcanoes are used to model changing magma supply during successive compositional stages, to place limits on volcano life spans, and to interpret composite assembly of the island. Volcano volumes vary by an order of magnitude; peak magma supply also varies sizably among edifices but is challenging to quantify because of uncertainty about volcano life spans. Three alternative models are compared: (1) near-constant volcano propagation, (2) near-equal volcano durations, (3) high peak-tholeiite magma supply. These models define inconsistencies with prior geodynamic models, indicate that composite growth at Hawaii peaked ca. 800–400 ka, and demonstrate a lower current rate. Recent age determinations for Kilauea and Kohala define a volcano propagation rate of 8.6 cm/yr that yields plausible inception ages for other volcanoes of the Kea trend. In contrast, a similar propagation rate for the less-constrained Loa trend would require inception of Loihi Seamount in the future and ages that become implausibly large for the older volcanoes. An alternative rate of 10.6 cm/yr for Loa-trend volcanoes is reasonably consistent with ages and volcano spacing, but younger Loa volcanoes are offset from the Kea trend in age-distance plots. Variable magma flux at the Island of Hawaii, and longer-term growth of the Hawaiian chain as discrete islands rather than a continuous ridge, may record pulsed magma flow in the hotspot/plume source.

Hawai'i↗

USGS1955

Development of the hydrosphere and atmosphere, with special reference to probable composition of the early atmosphere

A satisfactory hypothesis of the development of the hydrosphere and atmosphere depends upon evidence from many sciences and the solution of many other fundamental problems of earth history. But because it is so closely related to many other problems, any progress toward unravelling the history of the hydrosphere and atmosphere limits the range of permissible speculation about such distantly related questions as the origin of the solar system, continents, mountains, and living organisms. Several hypotheses of the source of the earth’s air and waters are examined for their consistency with established principles and observed geologic evidence, and special attention is given to the probable composition of the early atmosphere. Hypotheses of the origin of the atmosphere and hydrosphere fall into two chief categories: (1) that all air and water of the earth are residual from a dense primitive atmosphere that once enveloped a molten globe; or (2) that they have accumulated at the earth’s surface by leakage from the interior. The quantities of water, carbon dioxide, organic carbon, nitrogen, sulfur, etc., that have been or are now part of the earth’s atmosphere and hydrosphere may be estimated within reasonable limits of uncertainty and these “excess” volatiles afford a basis for testing chemical consequences of the alternative hypotheses. Several writers have suggested that the primitive atmosphere may have been composed largely of CH 4 and NH 3 . However, the equilibrium constants for reactions of these and other gases, combined with the evidence of the “excess” volatiles, indicate that CO 2 and N 2 are much more likely. The stabilities of methane and ammonia depend upon the presence of free hydrogen; and the escape rate of hydrogen from the earth is such that methane probably could have persisted in significant amounts in the early atmosphere no more than 10 6 to 10 8 years. For all but a relatively brief period at the very beginning of earth history, the atmosphere probably contained CO 2 and N 2 rather than CH 4 and NH 3 . When the consequences of a dense atmosphere of CO 2 and N 2 (but with almost no free O 2 or H 2 ) are examined, it is found that several chemical effects (such as the quantity of rocks that would have to be weathered, of sodium dissolved in sea water, and of CaCO 3 deposited on the sea floor very early in early history) are not borne out by the observed geologic record. From this and other lines of evidence it seems extremely improbable that the present atmosphere and hydrosphere are residual from any such dense primitive atmosphere. Instead, it seems likely that the atmosphere and hydrosphere have accumulated gradually during geologic time by the escape of water vapor, CO 2 , CO, N 2 , and other volatiles from intrusive and extrusive rocks that have risen more or less continuously from the deep interior of the earth. The amount of free oxygen in the early atmosphere is a separate problem that cannot be solved until the evidence of the earliest rocks has been appraised more fully. Current hypotheses of the origin of life appear to require a reducing atmosphere, yet it seems likely that oxygen has been accumulating from the photodissociation of water vapor ever since the earth was formed. The oxidation of ferrous iron and sulfides in the earliest sediments may have kept the oxygen content very low, and life may have begun in local reducing environments.

GSA Special Papers↗

USGS2013

Spatio-temporal variability in movement, age, and growth of mountain whitefish ( Prosopium williamsoni ) in a river network based upon PIT tagging and otolith chemistry

Connectivity of river networks and the movements among habitats can be critical for the life history of many fish species, and understanding of the patterns of movement is central to managing populations, communities, and the landscapes they use. We combined passive integrated transponder tagging over 4 years and strontium isotopes in otoliths to demonstrate that 25% of the mountain whitefish ( Prosopium williamsoni ) sampled moved between the Methow and Columbia rivers, Washington, USA. Seasonal migrations downstream from the Methow River to the Columbia River to overwinter occurred in autumn and upstream movements in the spring. We observed migration was common during the first year of life, with migrants being larger than nonmigrants. However, growth between migrants and nonmigrants was similar. Water temperature was positively related to the proportion of migrants and negatively related to the timing of migration, but neither was related to discharge. The broad spatio-temporal movements we observed suggest mountain whitefish, and likely other nonanadromous fish, require distant habitats and also suggests that management and conservation strategies to keep connectivity of large river networks are imperative.

Washington↗

USGS2014

Effects of fine sediment, hyporheic flow, and spawning site characteristics on survival and development of bull trout embryos

Successful spawning is imperative for the persistence of salmonid populations, but relatively little research has been conducted to evaluate factors affecting early life-stage survival for bull trout ( Salvelinus confluentus ), a threatened char. We conducted a field experiment to assess the relationship between site-specific environmental factors and bull trout embryo survival and fry emergence timing. Survival from egg to hatch was negatively related to percent fine sediment (<1 mm) in the redd and positively related to the strength of downwelling at spawning sites. Survival of eggs to fry emergence was also negatively related to fine sediment, and the best statistical models included additional variables that described the rate of downwelling and intragravel flow within the incubation environment. Fry emerged at an earlier stage in development from redds with high percentages of fine sediment. Increased hydraulic conductivity via redd construction and selection of spawning sites with strong downwelling appear to enhance hyporheic flow rates and bull trout egg survival, but early life-stage success may ultimately be limited by intrusion of fine sediment into the incubation environment.

Oregon↗

USGS2019

Phenology of hatching, emergence, and end-of-season body size in young-of-year Coho Salmon in thermally contrasting streams draining the Copper River Delta, Alaska

Phenology can be linked to individual fitness, particularly in strongly seasonal environments where the timing of events have important consequences for growth, condition, and survival. We studied the phenology of Coho Salmon hatching and emergence in streams with contrasting thermal variability, but in close geographic proximity. Following emergence, we tracked body sizes of cohorts of young-of-year fish until the end of the growing season. Hatch and emergence timing occurred at the same time among streams with marked variability in thermal regimes. We demonstrate that this can be explained in part by the thermal units accumulated during embryo development. At the end of the first growing season there were some differences in body size, however overall fish size among streams were similar despite strong differences in thermal regimes. Collectively these results provide novel insights into the interactions between environmental variability and the early life-history stages of Coho Salmon furthering our understanding of the consequences of phenology on growth and survival for individuals within the critical first summer of life.

Alaska↗

USGS2025

Estimating drivers and identifying uncertainties in smallmouth bass population dynamics in an invaded river network

Smallmouth bass ( Micropterus dolomieu ) is an important recreational sportfish and destructive non-native species when introduced into freshwater habitats. There is therefore a need to understand the drivers of, and uncertainties in, smallmouth bass population dynamics for various management objectives. We combined long-term smallmouth bass catch-effort and early life history data from a non-native population in the Green River sub-basin of the upper Colorado River to develop a demographic model that links interannual variability in environmental conditions to recruitment in three river reaches. We used the model to quantify how hydrology, river temperature, and exploitation drive smallmouth bass population dynamics. Early life stages were influenced by timing of hatching and discharge. Dispersal of age-0 fish and density-dependent dynamics were identified as primary sources of uncertainty. Determining the true nature of density-dependent dynamics is important, as the impact of exploitation-based management actions is dependent on the strengths of any density-dependent feedbacks. Our model provides a framework to predict smallmouth bass population responses to future climate conditions, reservoir operations, and exploitation levels.

Utah↗

USGS2018

Annual cycle of White-winged Scoters (Melanitta fusca) in eastern North America: Migratory phenology, population delineation, and connectivity

Understanding full annual cycle movements of long-distance migrants is essential for delineating populations, assessing connectivity, evaluating crossover effects between life stages, and informing management strategies for vulnerable or declining species. We used implanted satellite transmitters to track up to 2 years of annual cycle movements of 52 adult female White-winged Scoters ( Melanitta fusca (Linnaeus, 1758)) captured in the eastern United States and Canada. We used these data to document annual cycle phenology; delineate migration routes; identify primary areas used during winter, stopover, breeding, and molt; and assess the strength of migratory connectivity and spatial population structure. Most White-winged Scoters wintered along the Atlantic coast from Nova Scotia to southern New England, with some on Lake Ontario. White-winged Scoters followed four migration routes to breeding areas from Quebec to the Northwest Territories. Principal postbreeding molting areas were in James Bay and the St. Lawrence River estuary. Migration phenology was synchronous regardless of winter or breeding origin. Cluster analyses delineated two primary breeding areas: one molting area and one wintering area. White-winged Scoters demonstrated overall weak to moderate connectivity among life stages, with molting to wintering connectivity the strongest. Thus, White-winged Scoters that winter in eastern North America appear to constitute a single continuous population.

Canadian Journal of Zoology↗

USGS2010

Environmental drivers of fish functional diversity and composition in the Lower Colorado River Basin

Freshwater conservation efforts require an understanding of how natural and anthropogenic factors shape the present-day biogeography of native and non-native species. This knowledge need is especially acute for imperiled native fishes in the highly modified Lower Colorado River Basin (LCRB), USA. In the present study we employed both a taxonomic and functional approach to explore how natural and human-related environmental drivers shape landscape-scale patterns of fish community composition in the LCRB. Our results showed that hydrologic alteration, watershed land use, and regional climate explained 30.3% and 44.7% of the total variation in fish community taxonomic and functional composition, respectively. Watersheds with greater dam densities and upstream storage capacity supported higher non-native functional diversity, suggesting that dams have provided additional "niche opportunities" for non-native equilibrium life-history strategists by introducing new reservoir habitat and modifying downstream flow and thermal regimes. By contrast, watersheds characterized by greater upstream land protection, lower dam densities, and higher variation in spring and summer precipitation supported fish communities with a strong complement of native species (opportunistic-periodic strategists). In conclusion, our study highlights the utility of a life-history approach to better understand the patterns and processes by which fish communities vary along environmental gradients.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2011

Nutrient fluxes and the recent collapse of coastal California salmon populations

Migratory salmon move nutrients both in and out of fresh waters during the different parts of their life cycle. We used a mass-balance approach to quantify recent changes in phosphorus (P) fluxes in six coastal California, USA, watersheds that have recently experienced dramatic decreases in salmon populations. As adults, semelparous Chinook ( Oncorhynchus tshawytscha ) and coho ( Oncorhynchus kisutch ) salmon imported 8.3 and 10.4 times more P from the ocean, respectively, than they exported as smolts, while iteroparous steelhead (i.e., sea-run rainbow trout, Oncorhynchus mykiss ) imported only 1.6 times more than they exported as kelts and smolts. Semelparous species whose life histories led them to import more nutrients were also the species whose populations decreased the most dramatically in California in recent years. In addition, the relationship between import and export was nonlinear, with export being proportionally more important at lower levels of import. This pattern was driven by two density-dependent processes — smolts were larger and disproportionately more abundant at lower spawner abundances. In fact, in four of our six streams we found evidence that salmon can drive net export of P at low abundance, evidence for the reversal of the "conveyor belt" of nutrients.

California↗

USGS2012

Estimating westslope cutthroat trout ( Oncorhynchus clarkii lewisi ) movements in a river network using strontium isoscapes

We used natural variation in the strontium concentration (Sr:Ca) and isotope composition ( 87 Sr: 86 Sr) of stream waters and corresponding values recorded in otoliths of westslope cutthroat trout ( Oncorhynchus clarkii lewisi ) to examine movements during their life history in a large river network. We found significant spatial differences in Sr:Ca and 87 Sr: 86 Sr values (strontium isoscapes) within and among numerous spawning and rearing streams that remained relatively constant seasonally. Both Sr:Ca and 87 Sr: 86 Sr values in the otoliths of juveniles collected from nine natal streams were highly correlated with those values in the ambient water. Strontium isoscapes measured along the axis of otolith growth revealed that almost half of the juveniles had moved at least some distance from their natal streams. Finally, otolith Sr profiles from three spawning adults confirmed homing to natal streams and use of nonoverlapping habitats over their migratory lifetimes. Our study demonstrates that otolith geochemistry records movements of cutthroat trout through Sr isoscapes and therefore provides a method that complements and extends the utility of conventional tagging techniques in understanding life history strategies and conservation needs of freshwater fishes in river networks.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1975

Dieldrin in the diet of channel catfish ( Ictalurus punctatus ): uptake and effect on growth

Fingerling channel catfish (Ictalurus punctatus) were given diets containing 0, 0.4, 0.8, or 4.0 I?g dieldrin/g of food (dry weight) for 210 days, followed by a dieldrin-free diet for 56 days. Catfish receiving 4.0 I?g dieldrin/g food gained about 17% less weight than the control fish in 210 days and about 35% less weight during the last 126 days of the 210-day period. No growth differences were attributable to the ingestion of 0.4 or 0.8 I?g dieldrin/g of feed. Mortality during the experiment was random and not appreciable. Dieldrin accumulations were characterized by an immediate rapid rise of residue levels in the tissues, followed by a period during which concentrations were relatively stable. Residues in tissues decreased rapidly after dieldrin was withdrawn from the diet. Dieldrin half-life was 9.6 days (mean for the three groups). Theoretical residue concentrations calculated from the growth, feeding, and half-life data were similar to the empirical concentrations, although the theoretical values were consistently the higher. The recoverable concentration accounted for 25.7% (mean of the three treatments) of the theoretical concentration.

Journal of the Fisheries Research Board of Canada↗

USGS1976

Antimycin: Uptake, distribution, and elimination in brown bullheads (Ictalurus nebulosus)

Radioactive antimycin was readily taken up in bile and tissues of brown bullheads ( Ictalurus nebulosus ) exposed to 0.045 μg/ml of 14 C-antimycin for as long as 48 h. Bile contained the most and blood the least radioactivity at all sampling periods. The highest concentration of 14 C-antimycin in muscle was 0.12 μg/g, after 12 h of exposure. The average amount of 14 C-antimycin per fish was 0.94 μg/g. The 14 C-antimycin concentration decreased with the elapse of time in the muscle and in samples of combined head, skin, and viscera. The concentration of l4 C-antimycin in the exposure solution decreased from 0.045 μg/ml to 0.015 μg/ml after 12 h and 0.010 μg/ml after 48 h. The initial half-life of 14 C-antimycin in the exposure solution was about 6.5 h. A second group of fish was exposed to 0.045 μg/ml of l4 C-antimycin for 48 h and then transferred to antimycin-free, flowing water for up to 96 h. The 14 C-activity decreased in muscle tissue from 0.11 μg/g to 0.05 μg/g in 96 h. Half-life of 14 C-antimycin was about 75 h in muscle and 61 h in the combined head, skin, and viscera.

Journal of the Fisheries Research Board of Canada↗

USGS1987

Recent changes in Lake Michigan's fish community and their probable causes, with emphasis on the role of the alewife (Alosa pseudoharengus)

Deepwater ciscoes ( Coregonus spp.) or "chubs" of Lake Michigan far surpassed those of Lake Huron in yield, population density, and resilience following severe depletion in the 1960s and 1970s, when the bloater ( C . hoyi ) composed more than 90% of the stocks. The population decline of bloaters in recent decades was mainly attributed to exploitation, to the depression of chub recruitment (e.g. from inferred predation on early life stages) by nonendemic alewives ( Alosa pseudoharengus ) and rainbow smelt ( Osmerus mordax ), and to complications arising from extreme female predominance that was best documented for Lake Michigan. The various interactions between bloaters and the nonendemic species, which were intensified after the loss of large predators to sea lamprey ( Petromyzon marinus ), would help to explain why a stock–recruitment relation was not shown for the Lake Michigan bloater. We hypothesize that reproductive inefficiency caused by a shift to strong female predominance in the bloater depresses recruitment and thus helps to regulate abundance. However, the low resilience that sex imbalance seems to impart makes the stock unstable when exploited. It should therefore be exploited conservatively during such periods. Also, the sex ratio and its direction of change appear to be important qualifiers when surplus production is estimated from stock size.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2012

Geologic controls on sediment distribution and transport pathways around the Chandeleur Islands, LA., USA

Geophysical surveys around the Chandeleur Islands provide the necessary data to map the thickness and distribution of the Holocene deposit associated with this barrier island system. This system rests uncomformably on St. Bernard Delta deposits of the Mississippi Delta plain and is thinnest under the central part of the island chain and thickest at the northern and southern ends. The zone of divergence in the bidirectional littoral transport system coincides with the thin central part. An estimate of northward littoral transport rate based on lithosome age and the volume of sediment that has accumulated at the northern end of the transport cell suggests the average transport rate over the life of the system is greater than present day fair-weather estimates. This difference may be attributed to changes in transport rates through the life of the system, to changes in the rate of sea-level rise or to storms playing a more dominant role than fair-weather waves in littoral transport.

Louisiana↗

USGS2005

Laboratory agonistic interactions demonstrate failure of an introduced crayfish to dominate two imperiled endemic crayfishes

Following its introduction into the St. Francis River drainage, Missouri, U.S.A., the woodland crayfish, Orconectes hylas has expanded its range there; simultaneously populations of two imperiled endemic species, the Big Creek crayfish, O. peruncus, and the St. Francis River crayfish, O. quadruncus have declined therein. In seeking a basis for this decline, our study objective was to test whether the outcome of aggressive inter-specific interactions would favor O. hylas. We studied agonistic encounters between size-matched pairs of same-sex individuals of the introduced and the endemic species in a laboratory setting, first with juveniles and then with adults. Within each life stage, we conducted four sets of laboratory experiments, with approximately 20 trials in each set: (1) O. hylas males versus O. peruncus males, (2) O. hylas males versus O. quadruncus males, (3) O. hylas females versus O. peruncus females, and (4) O. hylas females versus O. quadruncus females. In addition, these same four experiment sets were repeated using larger adult O. hylas crayfish matched with smaller-sized adult endemics, mimicking the mismatch in adult sizes that occurs in the wild. Within each experiment, every trial was analysed to quantify the frequency of occurrence of three initiation behaviors and to determine the overall outcome of the trial. Results did not show O. hylas (juveniles or adults) to be behaviorally dominant over either endemic species. Orconectes hylas displayed the majority of one of the initiation behaviors significantly more often than did the endemic species in only two of the twelve experiments. Because direct aggressive interaction was not demonstrated to be the mechanism whereby O. peruncus and O. quadruncus are being replaced by O. hylas, other life history and ecological factors will require investigation. ?? Koninklijke Brill NV, 2005.

Crustaceana↗

USGS2016

Habitat use and growth of the western painted crayfish Orconectes palmeri longimanus

Identifying ontogenetic shifts in habitat use by aquatic organisms is necessary for improving conservation strategies; however, our ability to designate life stages based on surrogate metrics (i.e., length) is questionable without validation. This study identified growth patterns of age-0 western painted crayfish Orconectes palmeri longimanus (Faxon, 1898) reared in the laboratory, provided support for field-based designations of age-0 lengths, and identified microhabitat factors important to adult and juvenile presence from field collections. Two growth periods of a laboratory crayfish population were described using a broken line model: a rapid, early-growth period (weeks 2-20, slope = 0.81 ± 0.03SE), and a slower, late-growth period (weeks 22-50, slope = 0.13 ± 0.03SE). A smoothed curve was generated to represent the size distribution of juveniles from our laboratory population to determine the probability that an age-0 crayfish from our laboratory population had a carapace length (CL) similar to that found in previous field studies using onset of maturity (22.4 mm CL). We determined that the probability of the age-0 crayfish in our summer laboratory population exceeding 22.4 mm CL was 0.06. The threshold between the lower 0.95 and upper 0.05 probabilities was 22.9 mm CL, confirming previous field observations of onset at maturity. We used this threshold to identify juveniles and adults from our field collections, and found that both life stages were positively associated with coarse substrate and negatively associated with water depth. Adults, however, were negatively related to gravel, whereas juveniles showed a positive relationship. This result is reflective of the relationship between crayfish body size and refuge use within the interstitial spaces of substrates, whereby adult crayfish are unable to seek refuge in the small interstitial spaces of gravel.

Journal of Crustacean Biology↗