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At least 991 records · Page 55Linked to original sources
USGS2015

Survival and recovery rates of mottled ducks banded in Texas and Louisiana

The Western Gulf Coast population of the mottled duck (Anas fulvigula) is dependent on the Gulf coastal marsh to complete its entire life cycle. Band recovery data can be used to monitor mottled duck populations by estimating annual survival, indexing harvest rate, and assessing movements. Band returns from hunting seasons 1997–2013 were used to evaluate factors influencing annual survival, recovery rates, and movements of mottled ducks in Texas and Louisiana. For banding years of 1997–2013, 58,349 normal, wild mottled ducks were banded and released in Texas and Louisiana. Since 2002, 86% of mottled duck bandings have occurred on the Chenier Plain of Texas and Louisiana. Hunters shot, recovered, and reported 7,061birds with bands during this period. Direct recovery rates were greater for juveniles than adults but changed little since the 1970s. Estimates of annual survival did not differ between Texas and Louisiana, but did among years and between sex and age classes. Adult male and juvenile female mottled ducks had the greatest and lowest annual survival rates, respectively. Recovery of birds banded on the Chenier Plain was four times greater for birds banded in Texas and harvested in Louisiana than banded in Louisiana and harvested in Texas. Much of the current inference of results from banding mottled ducks is limited to the Chenier Plain. To monitor the entire Western Gulf Coast population of mottled ducks, managers can consider expanding operational banding operations with annual quotas, which would improve survival and recovery estimates and allow for inference beyond the Chenier Plain region.

Louisiana, Texas↗
USGS2019

A 4000-year history of debris flows in north-central Washington State, U.S.A.: Preliminary results from trenching and surficial geologic mapping at the Pope Creek fan

Long-term records of the magnitude and frequency of debris flows on fans are rare, but such records provide critical information needed for debris-flow hazard and risk assessments. This study explores the history of debris flows on a fan with seasonally inhabited cabins at Pope Creek along the Entiat River about 48 km upstream from the town of Entiat, Washington. Motivation for this study was provided by the Duncan Fire, a wildfire which burned the Pope Creek basin in 2014 and resulted in debris flows and water-dominated floods on the fan between August 2014 and October 2016. We excavated and mapped seven 6-m long (2.4 m deep) trenches, mapped deposits on the surface of the fan, and constrained the ages of deposits using radiocarbon dating and the computer program OxCal. Preliminary results indicate that there have been at least 10 debris-flow events (DFEs) since 4000 cal yr BP. The mean recurrence interval between events was 433 +/-44 years, but intervals range from 724 to 20 years. The four most recent events have the shortest recurrence intervals. The largest event had an estimated sediment volume of 97,000 m3 and occurred at about 285 cal yr BP (1665 AD) during the Little Ice Age. The most recent debris-flow event that was triggered by rainstorms following the Duncan Fire was about 8x smaller than the largest event. These results may indicate that the largest DFE was triggered by an exceptional meteorological event that occurred during a cool, wet time, and that smaller DFEs were triggered by less exceptional meteorological events that occurred following wildfires.

Washington↗
USGS2015

Mercury and methylmercury in reservoirs in Indiana

Mercury (Hg) is an element that occurs naturally, but evidence suggests that human activities have resulted in increased amounts being released to the atmosphere and land surface. When Hg is converted to methylmercury (MeHg) in aquatic ecosystems, MeHg accumulates and increases in the food web so that some fish contain levels which pose a health risk to humans and wildlife that consume these fish. Reservoirs unlike natural lakes, are a part of river systems that are managed for flood control. Data compiled and interpreted for six flood-control reservoirs in Indiana showed a relation between Hg transport, MeHg formation in water, and MeHg in fish that was influenced by physical, chemical, and biological differences among the reservoirs. Existing information precludes a uniform comparison of Hg and MeHg in all reservoirs in the State, but factors and conditions were identified that can indicate where and when Hg and MeHg levels in reservoirs could be highest. As part of a statewide monitoring network for Hg and MeHg in Indiana streams, 66 water samples were collected from four reservoir tailwater sites (downstream near the dams) on a quarterly schedule for 5 years. The reservoirs were Brookville Lake, Cagles Mill Lake, J. Edward Roush Lake, and Mississinewa Lake. Particulate-bound Hg concentrations were significantly lower in tailwater samples than in samples from free-flowing streams in the statewide network. (Free-flowing streams were not affected by dams and were not upstream from these reservoirs.) These data indicated the reduced flow velocity of water upstream from dams was allowing particulate-bound Hg to settle out of the water in the reservoir pools. The concentration ratios of MeHg to Hg were significantly higher in the tailwater samples than in samples from free-flowing streams, and the MeHg to Hg ratios were significantly higher in summer than in other seasons. To evaluate the conditions related to MeHg formation, pools of three reservoirs (Brookville Lake, Monroe Lake, and Patoka Lake) were investigated during summer hydrologic conditions. Water temperature and dissolved oxygen were measured from the water surface to the lake bottom at 10 to 17 transects across each reservoir to identify three thermal strata, defined by water temperature, dissolved oxygen concentration, and depth. Depth-specific water samples were collected from these thermal strata throughout each reservoir, from the headwaters to the dam and from the tailwater. Mercury concentrations higher than 0.04 nanogram per liter (ng/L) were detected in all 53 samples, and MeHg concentrations higher than 0.04 ng/L were detected in 53 percent of the samples. The investigation found a zone of water below 8 or 9 meters, with temperatures less than 18 degrees Celsius and dissolved oxygen less than 3.5 milligrams per liter, extending through nearly half the reservoir area in Monroe Lake and Patoka Lake. This zone had abundant dissolved MeHg and concentration ratios of dissolved MeHg to Hg that ranged from 25 to 82 percent. This zone also had water with pH less than 7 and decreased dissolved sulfate, conditions indicating sulfate reduction by microorganisms that promoted a high potential for the conversion of Hg to MeHg. Reservoir outflow came from this zone at Monroe Lake and contributed to a tailwater concentration ratio for dissolved MeHg to Hg of 56 percent. Reservoir outflow at Patoka Lake was not from this zone, and dissolved MeHg was not detected in the tailwater. In contrast, samples from the summer pool at Brookville Lake had no MeHg detections even though Hg was detected, probably because the water pH higher than 7 inhibited sulfate reduction and did not promote the conversion of Hg to MeHg. Mercury and MeHg concentrations and the concentration ratios of MeHg to Hg in water varied among the six reservoirs in Indiana, and the differences were related to a combination of factors that could apply to other reservoirs. In areas with moderate to high rates of atmospheric Hg wet and dry deposition, Hg runoff and transport to streams and reservoirs was potentially highest for reservoirs with heavily forested watersheds in steep terrains of near-surface bedrock. Methylmercury concentrations and concentration ratios of MeHg to Hg were highest for reservoirs with the longest summer pools and highest inflow-to-outflow retention times, where water-chemistry conditions favoring sulfate reduction promoted conversion of Hg to MeHg. Methylmercury (reported as Hg) in fish-tissue samples collected for the State fish consumption advisory program was used to describe MeHg food-web accumulation and magnification in the reservoirs. The highest percentages of fish-tissue samples with Hg concentrations that exceeded the criterion of 0.30 milligram per kilogram for protection of human health were from Monroe Lake (38 percent) and Patoka Lake (33 percent). A review of the number and size of fish species caught from these two reservoirs resulted in two implications for fish consumption by humans. First, the highest numbers of fish harvested for potential human consumption were species more likely to have MeHg concentrations lower than the human-health criterion (crappie, bluegill, and catfish). Second, although largemouth bass were likely to have MeHg concentrations higher than the human-health criterion, they were caught and released more often than they were harvested. However, the average size largemouth bass (in both reservoirs) and above-average size walleye (in Monroe Lake) that were harvested for potential human consumption were likely to have MeHg concentrations higher than the human-health criterion.

Indiana↗
USGS2013

Factors related to occurrence and distribution of selected bacterial and protozoan pathogens in Pennsylvania streams

The occurrence and distribution of fecal indicator bacteria (FIB) and bacterial and protozoan pathogens are controlled by diverse factors. To investigate these factors in Pennsylvania streams, 217 samples were collected quarterly from a 27-station water-quality monitoring network from July 2007 through August 2009. Samples were analyzed for concentrations of Escherichia coli (EC) and enterococci (ENT) indicator bacteria, concentrations of Cryptosporidium oocysts and Giardia cysts, and the presence of four genes related to pathogenic types of EC ( eae A, stx 2, stx 1, rfb O157 ) plus three microbial source tracking (MST) gene markers that are also associated with pathogenic ENT and EC ( esp , LTIIa, STII). Water samples were concurrently analyzed for basic water chemistry, physical measures of water quality, nutrients, metals, and a suite of 79 organic compounds that included hormones, pharmaceuticals, and antibiotics. For each sample location, stream discharge was measured by using standardized methods at the time of sample collection, and ancillary sample site information, such as land use and geological characteristics, was compiled. Samples exceeding recreational water quality criteria were more likely to contain all measured pathogen genes but not Cryptosporidium or Giardia (oo)cysts. FIB and Giardia density and frequency of eae A gene occurrence were significantly related to season. When discharge at a sampling location was high (>75th percentile of daily mean discharge), there were greater densities of FIB and Giardia , and the stx2 , rfb O157 , STII, and esp genes were found more frequently than at other discharge conditions. Giardia occurrence was likely related to nonpoint sources, which are highly influential during seasonal overland transport resulting from snowmelt and elevated precipitation in late winter and spring in Pennsylvania. When MST markers of human, swine, or bovine origin were present, samples more frequently carried the eae A, stx 2, stx 1, and rfb O157 genes, but no genes were related exclusively to an individual MST marker. The human source pharmaceuticals (HSPs) acetaminophen and caffeine were correlated with Giardia , and the presence of HSPs proved to be more useful than MST markers in distinguishing the occurrence of Giardia . The HSPs caffeine and carbamazepine were correlated with the sum total of pathogen genes detected in a sample, demonstrating the value of using HSPs as an indicator of fecally derived pathogens. Sites influenced by urban land use with less forest were more likely to have greater FIB and Giardia densities and sum of the array of pathogen genes. Sites dominated by shallow carbonate bedrock in the upstream catchment were likely to have greater FIB densities and higher sum totals of pathogen genes but no correlation with Giardia detection. Our study provides a range of specific environmental, chemical, geologic, and land-use variables related to occurrence and distribution of FIB and selected bacterial and protozoan pathogens in Pennsylvania streams. The information presented could be useful for resource managers in understanding bacterial and protozoan pathogen occurrence and their relation to fecal indicator bacteria in similar settings.

Pennsylvania↗
USGS1998

Mapping global grassland ecosystems: A comparison of four data sets

Grassland ecosystems have broad global geographic distribution, occurring in tropical and temperate latitudes and from near sea level to high mountain slopes. The author lists the areas by continent of the world's grasslands as depicted in four global land cover data sets. Grasslands, by definition, include regions where the dominant vegetative cover is herbaceous. Functionally, they include managed rangelands and pastures. These ecosystems have been experiencing alterations such as changes in productivity, desertification, influx of exotic species, and conversion to agriculture. Some of the largest temperate grassland areas have been subjected to broad-scale land use conversion. For example, the central plains of North America have been largely converted into the "world's most productive dryland wheat region". Grassland regions exhibit sensitivity to changes in environmental conditions. For example, the boundaries between grasslands and other vegetation types, as well as between different grassland types, on the North American plains are subject to change based on factors such as available exhibit sensitivity to changes in moisture, precipitation, length of growing season, or maximum temperature within the growing season. In global climate change scenarios, there are predicted changes for such environmental factors, however the magnitude and location for the changes are as yet unclear. In some cases, climate changes coupled with the human-induced changes of grasslands are expected to intensify such processes as desertification or degradation.

Conference Paper↗
USGS2005

Developing ecological criteria for prescribed fire in South Florida pine rockland ecosystems

The pine rocklands of South Florida, characterized by a rich herbaceous flora with many narrowly endemic taxa beneath an overstory of south Florida slash pine (Pinus elliottii var. densa), are found in three areas: the Miami Rock Ridge of southeastern peninsular Florida, the Lower Florida Keys, and slightly elevated portions of the southern Big Cypress National Preserve. Fire is an important element in these ecosystems, since in its absence the pine canopy is likely to be replaced by dense hardwoods, resulting in loss of the characteristic pineland herb flora. Prescribed fire has been used in Florida Keys pine forests since the creation of the National Key Deer Refuge (NKDR), with the primary aim of reducing fuels. Because fire can also be an effective tool in shaping ecological communities, we conducted a 4-year research study which explored a range of fire management options in NKDR. The intent of the study was to provide the Fish and Wildlife Service and other land managers with information regarding when and where to burn in order to perpetuate these unique forests. In 1998 we initiated a burning experiment in a randomized complete block design. Three treatments were to be carried out in a single well-defined block in each of two characteristic understory types during each year from 1998 through 2000. One understory type was characterized by a relatively sparse shrub layer and a well-developed herb layer ('open'), and the second had a dense shrub layer and poorly developed herb layer ('shrubby'). The three burn treatments were: (a) summer burn, (b) winter burn, and (c) no burn, or control. Three 1- ha plots were established in each block, and randomly assigned to the three treatments. Though the first year experimental burns were carried out without incident, constraints posed by external factors, including nationwide and statewide prohibitions on prescribed burning due to wildfires in other regions, delayed the experimental burns and precluded collection of postburn data on one third of the burns. Ultimately we burned only eleven plots, three in winter and eight in summer, over a four-year period from 1998 to 2001. Vegetation was sampled in a stratified, nested design within 18 plots. Trees were sampled in a 1.0-ha plot, shrubs in twenty 50-m2 circular (radius 4 m) subplots within the tree plot, and the herb layer in four circular 1-m2 quadrats (radius 0.57 m) within each subplot. The amount of fuel in the shrub layer was estimated by applying regression models to plant dimensional data, and ground layer fuel was estimated by a harvest method. The effects of Key deer herbivory on regeneration of the understory pine rockland plant community after fire was studied by monitoring inside and outside exclosures established within two of the six blocks. Pine trees constituted more than half (53.3%) of the biomass, but understory fine fuels comprised a surprisingly high proportion of total aboveground biomass. In the three blocks in which paired summer and winter burns were successfully conducted, the summer burns were more intense than the winter burns as judged by our indicators of fire intensity. Because of the differences in fire intensity between seasons, it was not possible to say whether observed differences in vegetation response between summer and winter burns were due to season or to fire intensity. The mortality of South Florida slash pine trees was greater after the summer burn than the winter burn in each block, but other vegetation responses were rarely as consistent. For instance, Metopium showed less recovery after summer burns in two blocks and after the winter burn in the third block. Moreover, there were instances in which alternative growth stages of the same species responded differently. Adult palms succumbed more frequently to summer than winter burns, and mortality of Coccothrinax exceeded that of Thrinax. In contrast, small palms recovered more readily after summer burns than winter burns. High in

Florida↗
USGS2012

Atmospheric inputs to watersheds of the Luquillo Mountains in eastern Puerto Rico: Chapter D in Water quality and landscape processes of four watersheds in eastern Puerto Rico

Twenty years of precipitation-chemistry data from the National Atmospheric Deposition Program site at El Verde, Puerto Rico, demonstrate that three major sources control the composition of solutes in rain in eastern Puerto Rico. In order of importance, these sources are marine salts, temperate contamination from the Northern Hemisphere, and Sahara Desert dust. Marine salts are a source of roughly 82 percent of the ionic charge in precipitation; marine salt inputs are greatest in January. Evaluation of 15 years of U.S. Geological Survey data for four watersheds in eastern Puerto Rico suggests that large storms, including hurricanes, are associated with exceptionally high chloride concentrations in stream waters. Some of these storms were missed in sampling by the National Atmospheric Deposition Program, and therefore its data on the marine contribution likely underestimate chloride. The marine contribution is a weak source of acidity. Temperate contamination contributes about 10 percent of the ionic charge in precipitation; contaminants are primarily nitrate, ammonia, and sulfate derived from various manmade and natural sources. Peak deposition of temperate contaminants is during January, April, and May, months in which strong weather fronts arrive from the north. Temperate contamination, a strong source of acidity, is the only component that is increasing through time. Sahara Desert dust provides 5 percent of the ionic charge in precipitation; it is strongly seasonal, peaking in June and July during times of maximum dust transport from the Sahara and sub-Saharan regions. This dust contributes, on average, enough alkalinity to neutralize the acidity in June and July rains.

Professional Paper↗
USGS2020

Post-fire vegetation response in a repeatedly burned low-elevation sagebrush steppe protected area provides insights about resilience and invasion resistance

Sagebrush steppe ecosystems are threatened by human land-use legacies, biological invasions, and altered fire and climate dynamics. Steppe protected areas are therefore of heightened conservation importance but are few and vulnerable to the same impacts broadly affecting sagebrush steppe. To address this problem, sagebrush steppe conservation science is increasingly emphasizing a focus on resilience to fire and resistance to non-native annual grass invasion as a decision framework. It is well-established that the positive feedback loop between fire and annual grass invasion is the driving process of most contemporary steppe degradation. We use a newly developed ordinal zero-augmented beta regression model fit to large-sample vegetation monitoring data from John Day Fossil Beds National Monument, USA, spanning 7 years to evaluate fire responses of two native perennial foundation bunchgrasses and two non-native invasive annual grasses in a repeatedly burned, historically grazed, and inherently low-resilient protected area. We structured our model hierarchically to support inferences about variation among ecological site types and over time after also accounting for growing-season water deficit, fine-scale topographic variation, and burn severity. We use a state-and-transition conceptual diagram and abundances of plants listed in ecological site reference conditions to formalize our hypothesis of fire-accelerated transition to ecologically novel annual grassland. Notably, big sagebrush ( Artemisia tridentata ) and other woody species were entirely removed by fire. The two perennial grasses, bluebunch wheatgrass ( Pseudoroegneria spicata ) and Thurber's needlegrass ( Achnatherum thurberianum ) exhibited fire resiliency, with no apparent trend after fire. The two annual grasses, cheatgrass ( Bromus tectorum ) and medusahead ( Taeniatherum caput-medusae ), increased in response to burn severity, most notably medusahead. Surprisingly, we found no variation in grass cover among ecological sites, suggesting fire-driven homogenization as shrubs were removed and annual grasses became dominant. We found contrasting responses among all four grass species along gradients of topography and water deficit, informative to protected-area conservation strategies. The fine-grained influence of topography was particularly important to variation in cover among species and provides a foothold for conservation in low-resilient, aridic steppe. Broadly, our study demonstrates how to operationalize resilience and resistance concepts for protected areas by integrating empirical data with conceptual and statistical models.

Oregon↗
USGS1982

Assessing mesquite-grass vegetation condition from Landsat

Landsat multispectral scanner (MSS) band values, band ratios, and vegetation index models were compared with selected rangeland vegetation parameters collected at six test sites within the honey mesquitellotebushlmixed grass association in north-central Texas. The comparisons at four dates showed that two vegetation index models, TV16 and GVI, are highly correlated (P = 0.01) with green yield, green cover, and plant moisture content. The green vegetation index (GVZ) developed by Kauth and Thomas (1976), was highly correlated and superior to other models in relationship to wet green yield, dry green yield, and cured vegetation cover. TV16, developed by Rouse et al. (1974), was more highly correlated with green vegetation cover and vegetation moisture content. Both TV16 and GVI are superior to other models in their relationship with green cover. None of the Landsat MSS parameters tested was significantly correlated with dry total yield, percent bare ground, or moisture of the soil measured at the surface or at a 20 cm depth. I t is concluded that Landsat MSS data are sensitive to seasonal changes in vegetation growth conditions and inherent ecological differences within a relatively unqorm vegetationlsoil system.

Texas↗
USGS1999

Growth, smoltification, and smolt-to-adult return of spring chinook salmon from hatcheries on the Deschutes river, Oregon

The relationship between smoltification and smolt-to-adult return (SAR) of spring chinook salmon Oncorhynchus tshawytscha from the Deschutes River, Oregon, was examined for four release groups in each of three successive years. Fish were reared, marked with coded wire tags, and released from Round Butte Hatchery, Pelton Ladder rearing facility, and Warm Springs National Fish Hatchery. Smolt releases occurred in nearly the same place at similar times, allowing a direct comparison of SAR to several characters representing smolt quality. Return rates varied significantly among facilities, varying over an order of magnitude each year. The highest average SAR was from Pelton Ladder, the lowest was from Warm Springs. Each of the characters used as metrics of smoltification - fish size, spring growth rate (February-April), condition factor, plasma hormone concentration (thyroxine, cortisol, and insulin-like growth factor-I [IGF-I]), stress challenge, gill Na+,K+-ATPase activity, and liver glycogen concentration - varied significantly among facilities and seasonally within hatchery groups. However, only spring growth rate, gill ATPase activity, and plasma IGF-I concentration showed significant relationships to SAR. These characters and SAR itself were consistently lower for fish released from Warm Springs Hatchery than for fish from Round Butte Hatchery and Pelton Ladder. This demonstrates that differences in the quality of fish released by facilities may have profound effects on subsequent survival and suggests that manipulations of spring growth rate may be used to influence the quality of smolts released from facilities.

Oregon↗
USGS2009

Modeling utilization distributions in space and time

W. Van Winkle defined the utilization distribution (UD) as a probability density that gives an animal's relative frequency of occurrence in a two-dimensional (x, y) plane. We extend Van Winkle's work by redefining the UD as the relative frequency distribution of an animal's occurrence in all four dimensions of space and time. We then describe a product kernel model estimation method, devising a novel kernel from the wrapped Cauchy distribution to handle circularly distributed temporal covariates, such as day of year. Using Monte Carlo simulations of animal movements in space and time, we assess estimator performance. Although not unbiased, the product kernel method yields models highly correlated (Pearson's r - 0.975) with true probabilities of occurrence and successfully captures temporal variations in density of occurrence. In an empirical example, we estimate the expected UD in three dimensions (x, y, and t) for animals belonging to each of two distinct bighorn sheep {Ovis canadensis) social groups in Glacier National Park, Montana, USA. Results show the method can yield ecologically informative models that successfully depict temporal variations in density of occurrence for a seasonally migratory species. Some implications of this new approach to UD modeling are discussed. ?? 2009 by the Ecological Society of America.

Ecology↗
USGS1999

Selected nutrients and pesticides in streams of the eastern Iowa basins, 1970-95

Water-quality data from 17 surface-water monitoring sites were compiled for 1970 through 1995 and analyzed to determine historical waterquality conditions and possible trends in the Eastern Iowa Basins study unit as part of the U.S. Geological Survey's National Water-Quality Assessment Program. The Eastern Iowa Basins encompasses the Wapsipinicon, Cedar, Iowa, and Skunk River Basins and covers about 19,500 square miles. Seven of the monitoring sites were sampled by the Iowa Department of Natural Resources, three sites by the Minnesota Pollution Control Agency, three sites by the University of Iowa Institute for Hydraulic Research, and four sites by the U.S. Geological Survey. Water-quality analyses typically consisted of nitrate, ammonia, total nitrogen, and total phosphorus, with limited analyses available for organic nitrogen, dissolved phosphorus, dissolved orthophosphate, and water-soluble pesticides. Long-term historical nutrient and pesticide data were not available for the Wapsipinicon River Basin. Median concentrations for total nitrogen ranged from 4.6 to 9.4 milligrams per liter, and maximum concentrations of total nitrogen ranged from 4.6 to 31 milligrams per liter. The majority of nitrogen transported in surface waters of the Eastern Iowa Basins study unit is in the form of nitrate (nitrogen). Median concentrations of total phosphorus ranged from less than 0.10 to 0.66 milligram per liter, and maximum concentrations of total phosphorus ranged from less than 0.10 to 5.4 milligrams per liter. Nitrate varied seasonally. Median concentrations of nitrate were largest during the spring and the winter (6.0 to 7.0 milligrams per liter) compared to the summer and fall (2.0 to 4.0 milligrams per liter). Concentrations of nitrate greater than 10 milligrams per liter typically occurred during spring runoff. Median ammonia concentrations generally were highest during the winter (approximately 0.3-0.5 milligram per liter) compared to the spring and summer when ammonia concentrations were often close to the detection limit (0.01 milligram per liter). In general, the median concentrations of total phosphorus varied less than 0.1 milligram per liter between seasons. The statistical analysis of the nutrient data typically indicated a strong positive correlation of nitrate with streamflow. Total phosphorus concentrations with streamflow showed greater variability than nitrate, perhaps reflecting the greater potential of transport of phosphorus on sediment rather than in the dissolved phase as with nitrate. Ammonia and ammonia plus organic nitrogen showed no correlation with streamflow or a weak positive correlation. Seasonal variations and the relations of nutrients and pesticides to streamflow generally corresponded with nonpoint‑source loadings, although possible point sources for nutrients were indicated by the data at selected monitoring sites. Statistical trend tests for concentrations and loads were computed for nitrate, ammonia, and total phosphorus. Trend analysis indicated decreases for ammonia and total phosphorus concentrations at several sites and increases for nitrate concentrations at other sites in the study unit.

Iowa, Minnesota↗
USGS2005

Insectivory versus piscivory in Black Terns: Implications for food provisioning and growth of chicks

The Black Tern (Chlidonias niger) is known for insectivory in their breeding range, but they are piscivorous in winter and feed some fish to chicks. Fish have potentially high value for chick provisioning because of their larger mass, but the relative value of fish and insect diets for chick growth is unknown. In 1999-2000, we documented use of fish and insects for provisioning chicks at four Black Tern colonies in Maine and examined chick growth rates at two colonies (Douglas Pond and Carlton Pond) that differed in fish and insect use. Deliveries of fish and insects to broods were documented using video cameras and observations from blinds, while concurrently measuring chick growth in nest enclosures. Fish use was substantial (>25% of deliveries) at three of four colonies. Fish comprised 29% of items and 56% of metabolizable energy delivered to chicks at Douglas Pond compared to 13% of items and 22% of metabolizeable energy at Carlton Pond. Food delivery rate was inversely related to the proportion of large fish. In brood diets at Douglas and Carlton Ponds and increased with brood age at Carlton Pond only, apparently due to high insect use. Chick growth rate did not vary with respect to fish and insect composition of diets. It is concluded that adults were able to raise chicks through age 12 d at comparable growth rates with insect-or fish-dominated diets. Use of fish may be more energy efficient for adults, and the capability to use both fish and insects may reduce potential variability in food availability during the breeding season.

Waterbirds↗
USGS2013

Geology, water-quality, hydrology, and geomechanics of the Cuyama Valley groundwater basin, California, 2008--12

To assess the water resources of the Cuyama Valley groundwater basin in Santa Barbara County, California, a series of cooperative studies were undertaken by the U.S. Geological Survey and the Santa Barbara County Water Agency. Between 2008 and 2012, geologic, water-quality, hydrologic and geomechanical data were collected from selected sites throughout the Cuyama Valley groundwater basin. Geologic data were collected from three multiple-well groundwater monitoring sites and included lithologic descriptions of the drill cuttings, borehole geophysical logs, temperature logs, as well as bulk density and sonic velocity measurements of whole-core samples. Generalized lithologic characterization from the monitoring sites indicated the water-bearing units in the subsurface consist of unconsolidated to partly consolidated sand, gravel, silt, clay, and occasional cobbles within alluvial fan and stream deposits. Analysis of geophysical logs indicated alternating layers of finer- and coarser-grained material that range from less than 1 foot to more than 20 feet thick. On the basis of the geologic data collected, the principal water-bearing units beneath the monitoring-well sites were found to be composed of younger alluvium of Holocene age, older alluvium of Pleistocene age, and the Tertiary-Quaternary Morales Formation. At all three sites, the contact between the recent fill and younger alluvium is approximately 20 feet below land surface. Water-quality samples were collected from 12 monitoring wells, 27 domestic and supply wells, 2 springs, and 4 surface-water sites and were analyzed for a variety of constituents that differed by site, but, in general, included trace elements; nutrients; dissolved organic carbon; major and minor ions; silica; total dissolved solids; alkalinity; total arsenic and iron; arsenic, chromium, and iron species; and isotopic tracers, including the stable isotopes of hydrogen and oxygen, activities of tritium, and carbon-14 abundance. Of the 39 wells sampled, concentrations of total dissolved solids and sulfate from 38 and 37 well samples, respectively, were greater than the U.S. Environmental Protection Agency’s secondary maximum contaminant levels. Concentrations greater than the maximum contaminant levels for nitrate were observed in five wells and were observed for arsenic in four wells. Differences in the stable-isotopic values of hydrogen and oxygen among groundwater samples indicated that water does not move freely between different formations or between different zones within the Cuyama Valley. Variations in isotopic composition indicated that recharge is derived from several different sources. The age of the groundwater, expressed as time since recharge, was between 600 and 38,000 years before present. Detectable concentrations of tritium indicated that younger water, recharged since the early 1950s, is present in parts of the groundwater basin. Hydrologic data were collected from 12 monitoring wells, 56 domestic and supply wells, 3 surface-water sites, and 4 rainfall-gaging stations. Rainfall in the valley averaged about 8 inches annually, whereas the mountains to the south received between 12 and 19 inches. Stream discharge records showed seasonal variability in surface-water flows ranging from no-flow to over 1,500 cubic feet per second. During periods when inflow to the valley exceeds outflow, there is potential recharge from stream losses to the groundwater system Water-level records included manual quarterly depth-to-water measurements collected from 68 wells, time-series data collected from 20 of those wells, and historic water levels from 16 wells. Hydrographs of the manual measurements showed declining water levels in 16 wells, mostly in the South-Main zone, and rising water levels in 14 wells, mostly in the Southern Ventucopa Uplands. Time-series hydrographs showed daily, seasonal, and longer-term effects associated with local pumping. Water-level data from the multiple-well monitoring sites indicated seasonal fluctuations as great as 80 feet and water-level differences between aquifers as great as 40 feet during peak pumping season. Hydrographs from the multiple-well groundwater monitoring sites showed vertical hydraulic gradients were upward during the winter months and downward during the irrigation season. Historic hydrographs showed water-level declines in the Southern-Main, Western Basin, Caliente Northern-Main, and Southern Sierra Madre zone ranging from 1 to 7 feet per year. Hydrographs of wells in the Southern Ventucopa Uplands zone showed several years with marked increases in water levels that corresponded to increased precipitation in the Cuyama Valley. Investigation of hydraulic properties included hydraulic conductivity and transmissivity estimated from aquifer tests performed on 63 wells. Estimates of horizontal hydraulic conductivity ranged from about 1.5 to 28 feet per day and decreased with depth. The median estimated hydraulic conductivity for the older alluvium was about five times that estimated for the Morales Formation. Estimates of transmissivity ranged from 560 to 163,400 gallons per day per foot and decreased with depth. The median estimated transmissivity for the younger alluvium was about three times that estimated for the older alluvium. Geomechanical analysis included land-surface elevation changes at five continuously operating global positioning systems (GPS) and land-subsidence detection at five interferometric synthetic aperture radar (InSAR) reference points. Analysis of data collected from continuously operating GPS stations showed the mountains to the south and west moved upward about 1 millimeter (mm) annually, whereas the station in the center of the Southern-Main zone moved downward more than 7 mm annually, indicating subsidence. It is likely that this subsidence is inelastic (permanent) deformation and indicates reduced storage capacity in the aquifer sediments. Analysis of InSAR data showed local and regional changes that appeared to be dependent, in part, on the time span of the interferogram, seasonal variations in pumping, and tectonic uplift. Long-term InSAR time series showed a total maximum detected subsidence rate of approximately 12 mm per year at one location and approximately 8 mm per year at a second location, while short-term InSAR time series showed maximum subsidence of about 15 mm at one location and localized maximum uplift of about 10 mm at another location.

California↗
USGS2019

Simulation of water availability in the Southeastern United States for historical and potential future climate and land-cover conditions

A study was conducted by the U.S. Geological Survey (USGS), in cooperation with the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (GCPO LCC) and the Department of the Interior Southeast Climate Adaptation Science Center, to evaluate the hydrologic response of a daily time step hydrologic model to historical observations and projections of potential climate and land-cover change for the period 1952–2099. The model simulations were used to compute the potential changes in hydrologic response and streamflow statistics across the Southeastern United States, using historical observations of climate and streamflow. Thirteen downscaled general circulation models with four representative concentration pathways were used to represent a range of potential future changes in climate (a total of 45 future simulations) from the Coupled Model Intercomparison Project Phase 5. The streamflow statistics were selected to describe streamflow conditions that may be most useful in defining the suitability for each river or stream to support sustaining populations of priority aquatic species across the GCPO LCC. An application of the Precipitation-Runoff Modeling System (included as part of the USGS National Hydrologic Model) was used to develop the hydrologic simulations. The results showed increases in air temperature across the study area, with the highest increases occurring in the northern part of the study area during July to September. The results showed a mix of increases and decreases in precipitation accumulation across the study area and across seasons, with decreases in precipitation accumulation across all seasons for the southwestern part of the study area. Actual evapotranspiration decreased for the southeastern part of the study area and increased for the northwestern part of the study area. The results showed general decreases in runoff across the study area, with increases in runoff in areas surrounding large metropolitan regions where potential future increases in impervious area occur. Results from a statistical analysis (Kolmogorov-Smirnov test) showed that the downscaled general circulation models generally have more skill in producing historical streamflow statistics in the duration and magnitude categories and less skill in producing historical streamflow statistics in the frequency, rate of change, and timing categories for this study area. The potential changes in the streamflow statistics and the results of the Kolmogorov-Smirnov test are available through the GCPO LCC Conservation Planning Atlas, an online science-based mapping platform built specifically for land managers and planners.

Alabama, Arkansas, Florida, Georgia, Illinois, Kan↗
USGS2010

Limiting factors of four rare plant species in `Ōla`A Forest of Hawai'i Volcanoes National Park

Three endangered or candidate endangered plant species native to `Ōla`a Forest ( Cyrtandra giffardii , ha`iwale; Phyllostegia floribunda , a mint with no common name; and Sicyos alba , `ānunu) were studied for more than 2 years to determine their stand structures, short-term mortality rates, patterns of reproductive phenology, success of fruit production, seed germination rates in the greenhouse, presence of soil seed bank, and survival of both natural and planted seedlings. The role of rodents as seed predators was evaluated for S. alba using seed offerings in open and closed stations. A 4th endangered species at a remote site in `Ōla`a ( Cyrtandra tintinnabula ) was visited to determine its stand structure and mortality rate. Cyrtandra giffardii displayed a stable population structure with many adults and few small or very large plants; the monitored population had a mortality rate of 7.3% over 3 years. Mortality of plantings from 2003-2004 in a re-introduced population of Phyllostegia floribunda was 21.4%. The stand structure of C. tintinnabula indicated a relatively stable population with both small and large plants present and a short-term mortality rate between visits of 14.5- 17.0%. Four groups of S. alba vines were monitored; 3 of these have persisted in place for at least 15 years. All species monitored had annual patterns of flower and fruit phenology, although male inflorescences of S. alba showed a subannual pattern. Successful transition of flowers to fruit was high for P. floribunda (51.5%), moderate for C. giffardii (23.3%) and undetermined for S. alba . High percentage viability was demonstrated for seeds of P. floribunda and S. alba (78.5-100% positive to strongly positive in tetrazolium tests), but seed viability was not tested for C. giffardii . Greenhouse germination rates were high for P. floribunda (88.0-92.0%), but variable and relatively low for C. giffardii (0-19.3%) and S. alba (4.0-11.1% in 2007 and 0 in 2008). No soil seed bank was detected for S. alba in 3 seasonal samplings, but P. floribunda was found to have a viable seed bank in April that persisted from at least the previous summer. Rodent predation of S. alba seeds was 93.3% in fruit offerings in accessible bait stations. Mortality of natural seedlings was high for both P. floribunda (90.2%) and S. alba (69.7%). Planted seedlings of P. floribunda produced flowers and fruit in their first year, and reproduction was higher in sunny plots than in shady plots. Mortality was high in both planting treatments, and survival rates did not differ significantly in sun and shade (χ 2 =0.48, df = 1, p = 0.490). Three planted seedlings of S. alba survived for 12-16 months but did not reproduce. Floral visitors were observed at C. giffardii and P. floribunda using digital video cameras and recorders. In almost 200 hours of observation, no visitors entered the flowers of C. giffardii , although 1 very small insect, either a micro-wasp (Hymenoptera) or fly (Diptera) was seen on the exterior of a corolla. In almost 300 hours of video observation, 3 floral visitors were identified at P. floribunda flowers. Honeybees ( Apis mellifera ) were likely pollinators, as they contacted both anthers and stigma of flowers. The mean visitation rate of honeybees was 0.003 visit/flower/hour, and visit duration ranged from 2 to 17 seconds. Fruit flies (Drosophilidae of undetermined species) crawled around flower interiors, but did not seem to forage for either nectar or pollen. Fruit fly mean visitation rate was 0.006 visit/flower/hour, and visit duration was 28 to 1,424 seconds. The 3rd observed insect visitor was an endemic geometrid moth caterpillar ( Lophoplusia giffardi ), which was seen feeding on foliage and flowers of P. floribunda . In conclusion, 2 of the 3 regularly-monitored rare plant species of `Ōla`a Forest appeared to have more than 1 limiting factor inhibiting the natural increase in their populations, while for P. floribunda the most important factor was high seedling mortality. Most plants of the monitored C. giffardii population appeared to be hybrids, probably with the more common species C. lysiosepala . Seed germination rates were low, and natural seedlings were not observed. Pollinators were not seen in many hours of observation, indicating that cross pollination is a rare or uncommon event. The re-introduced population of P. floribunda had relatively low mortality, and reproduction was successful with high rates of fruit formation from abundant flowers. Seed germination rates were high, and a soil seed bank was detected. Natural seedling recruitment was observed, but high seedling mortality indicated that this life stage was the most vulnerable in the species. The population of S. alba was small and the vine life form precluded an accurate estimate of the number of adult plants in `Ōla`a Forest. Natural dormancy was likely a factor in the observed low rate of seed germination. No soil seed bank was detected, and alien rodents were implicated as seed predators. Natural recruitment was observed at multiple sites in `Ōla`a, but seedling mortality was high. The cause of seedling mortality was not identified.

Hawaii↗
USGS2024

Seismic velocity changes from repetitive seismicity at Mauna Loa prior to and during its 2022 eruption

Mauna Loa’s short-lived eruption from late November to early December 2022 marked the culmination of nearly a decade of elevated seismic activity and geodetic inflation. The volcano has been monitored by a network of permanent, short period and broadband seismometers. I used the continuous waveform data from that network starting in 2012 to generate a catalog of seismicity that enhances the US Geological Survey Hawaiian Volcano Observatory’s public seismic catalog with four times the number of earthquakes, which were then grouped by waveform similarity. Analysis of subtle delays in the timing of arrivals of scattered waves between pairs of earthquakes in this catalog yields a history of small changes in the shallow seismic velocity structure of the volcano. Seismic velocities have been shown at other volcanoes to change during unrest and eruption. My results show a decrease in seismic velocity centered on the summit beginning in September 2022, corresponding to the onset of a vigorous precursory swarm of seismic activity and shallow inflation. During the eruption itself, I observe large changes due likely to dike opening along the northeast rift zone and deflation of the summit reservoir. However, seismic velocity changes associated with non-volcanic sources such as ground shaking from large earthquakes and meteorological influences at seasonal and diurnal time scales are also observed, and these dominate the velocity changes prior to the eruption. Proper accounting of these effects will be a requirement for use in real-time monitoring, and this work serves as a starting point in that endeavor for Mauna Loa.

Hawaii↗
USGS2001

Progression of natural attenuation processes at a crude oil spill site: II. Controls on spatial distribution of microbial populations

A multidisciplinary study of a crude-oil contaminated aquifer shows that the distribution of microbial physiologic types is strongly controlled by the aquifer properties and crude oil location. The microbial populations of four physiologic types were analyzed together with permeability, pore-water chemistry, nonaqueous oil content, and extractable sediment iron. Microbial data from three vertical profiles through the anaerobic portion of the contaminated aquifer clearly show areas that have progressed from iron-reduction to methanogenesis. These locations contain lower numbers of iron reducers, and increased numbers of fermenters with detectable methanogens. Methanogenic conditions exist both in the area contaminated by nonaqueous oil and also below the oil where high hydrocarbon concentrations correspond to local increases in aquifer permeability. The results indicate that high contaminant flux either from local dissolution or by advective transport plays a key role in determining which areas first become methanogenic. Other factors besides flux that are important include the sediment Fe(II) content and proximity to the water table. In locations near a seasonally oscillating water table, methanogenic conditions exist only below the lowest typical water table elevation. During 20 years since the oil spill occurred, a laterally continuous methanogenic zone has developed along a narrow horizon extending from the source area to 50–60 m downgradient. A companion paper [J. Contam. Hydrol. 53, 369–386] documents how the growth of the methanogenic zone results in expansion of the aquifer volume contaminated with the highest concentrations of benzene, toluene, ethylbenzene, and xylenes.

Journal of Contaminant Hydrology↗