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Research about Maryland

Source-linked reports with geographic coverage including Maryland.

At least 181 records · Page 10Linked to original sources
USGS2005

Atlantic Flyway review: Region IV, Piedmont-Coastal Plain, Fall 2004: Robbins Nest, Laurel, MD (390-0765)

The continuing decline in migratory species is depressing. For a 'migration station' to report Northern Cardinal as the species most commonly banded during the autumn months came as a real shock, especially when the cardinal was so far ahead of second-place catbird. I caught twice as many cardinals as all sparrows combined (including juncos), and the total for cardinals came within ten birds of the total for all warblers combined. Warblers comprised only 16.8% of this fall's catch, compared with an average of 21.7% for the previous five years. Hurricanes Bonnie and Frances passed to the east of us and Charles and Ivan to the west, but none was followed by a landfall of migrants. Last year I reported the sharp drop in Tufted Titmice and Carolina Chickadees locally and the small number of returns from prior years. This year, after no overwintering titmice, numbers have returned to nearly normal, but chickadee numbers are still only half normal. I recaptured cardinals from each year back to 1999, but the only other birds more than two years old were a Carolina Wren and two titmice banded in the autumn of 2000.

Maryland↗
USGS2005

Toward predicting barrier island vulnerability: Simple models for dune erosion

The objective of this study is to quantify the accuracy of two engineering models for dune erosion (SBEACH and EDUNE), and to determine which of the two models is best suited for predicting barrier island vulnerability due to extreme storm events. The first model, SBEACH, computes sediment transport using empirically derived equations from two large wave tank experiments. The second model, EDUNE, theoretically relates excess wave energy dissipation in the surf zone to sediment transport. The first mechanism for model comparison is sensitivity testing, which describes the response of the model to empirical, physical, and hydrodynamic variables. Through sensitivity tests, it is possible to determine if responses to physical variables (e.g. grain size) and hydrodynamic variables (e.g. wave height) are consistent with theoretical expectations, and whether the function of each variable is properly specified within the governing equations. With respect to empirical parameters, model calibrations are performed on multiple study sites in order to determine whether or not the empirical parameters are properly constrained. Finally, error statistics are generated on four study sites in order to compare model accuracy. Cross-shore profiles of dune elevation are extracted from coastal lidar (light detecting and ranging) surveys flown before and after the impact of major storm events. Three study sites are taken from 1998 lidar surveys of Assateague Island, MD in response to two large northeasters that produced significant erosion along the Assateague shoreline. Two additional study sites are obtained from 2003 lidar surveys of Hatteras Island, NC in response to erosion caused by Hurricane Isabel. Error statistics generated on these study sites suggest that the models are statistically equivalent in their ability to hindcast dune erosion due to extreme storm events.

Maryland↗
USGS2004

Tumor prevalence and biomarkers of exposure in brown bullhead (Ameiurus nebulosus) from Back River, Furnace Creek, and Tuckahoe River, Maryland

Brown bullheads ( Ameiurus nebulosus ) were collected from 2 locations near Baltimore, Maryland, Back River and Furnace Creek, and 1 (reference) location, Tuckahoe River, to compare the prevalence of tumors (liver and skin) and visible skin lesions (fin erosion and abnormal barbels). Cytochrome P450 activity measured as ethoxyresorufin- O -deethylase, biliary PAH-like fluorescent metabolites, and fillet contaminant concentrations were determined as indicators of exposure in a randomly selected subset of the fish. There were no significant differences in liver tumor prevalence: Back River = 8% (4/50), Furnace Creek = 0% (0/50), and Tuckahoe River = 2.6% (1/39; p = 0.20, extension of Fisher’s exact test). Skin tumor prevalence was as follows: Furnace Creek = 12% (6/50), Back River = 8% (4/50), and Tuckahoe River = 0% (0/39; p = 0.063). In the Back River fish, there was a 40% (20/50) prevalence of fin erosion and a 28% (14/50) prevalence of abnormal (shortened, clubbed, or missing) barbels. Fin erosion was not observed in the other collections, and only 10% (5/50) of the Furnace Creek fish had abnormal barbels ( p < 0.001 for both lesions). There were statistically significant differences in mean EROD activity, with levels in Furnace Creek and Back River fish approximately twice that found in Tuckahoe River fish. There were also significant differences in mean benzo(a)pyrene-like bile metabolite concentrations: the lowest mean was in the Tuckahoe River fish, 8 times higher in Furnace Creek fish, and 13 times higher in Back River fish. Of the 3 groups, the Back River bullheads appear to be most adversely affected by contaminant exposure because they had the highest prevalence of liver tumors, fin erosion, and abnormal barbels.

Maryland↗
USGS2004

Nitrogen fluxes and retention in urban watershed ecosystems

Although the watershed approach has long been used to study whole-ecosystem function, it has seldom been applied to study human-dominated systems, especially those dominated by urban and suburban land uses. Here we present 3 years of data on nitrogen (N) losses from one completely forested, one agricultural, and six urban/suburban watersheds, and input-output N budgets for suburban, forested, and agricultural watersheds. The work is a product of the Baltimore Ecosystem Study, a long-term study of urban and suburban ecosystems, and a component of the US National Science Foundation's long-term ecological research (LTER) network. As expected, urban and suburban watersheds had much higher N losses than did the completely forested watershed, with N yields ranging from 2.9 to 7.9 kg N ha −1 y −1 in the urban and suburban watersheds compared with less than 1 kg N ha −1 y −1 in the completely forested watershed. Yields from urban and suburban watersheds were lower than those from an agricultural watershed (13-19.8 kg N ha −1 y −1 ). Retention of N in the suburban watershed was surprisingly high, 75% of inputs, which were dominated by home lawn fertilizer (14.4 kg N ha −1 y −1 ) and atmospheric deposition (11.2 kg N ha −1 y −1 ). Detailed analysis of mechanisms of N retention, which must occur in the significant amounts of pervious surface present in urban and suburban watersheds, and which include storage in soils and vegetation and gaseous loss, is clearly warranted.

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USGS2004

Role of manganese oxides in the exposure of mute swans (Cygnus olor) to Pb and other elements in the Chesapeake Bay, USA

The aims of this study are to estimate exposure of waterfowl to elements in contaminated sediments in the Chesapeake Bay and to consider the potential role of Mn in influencing bioavailability and exposure. Metal concentrations were measured in livers and digesta taken from mute swans living on the Aberdeen Proving Ground, whose sediment had elevated concentrations of Cu, S, Se, Zn, As, Co, Cr, Hg and Pb. Concentrations of only the first four of these elements were elevated in swan digesta. None of the concentrations detected in the digesta or livers of the swans was considered toxic, although the concentrations of Cu and Se were high compared to concentrations of these elements reported in other waterfowl. Lead was found to be scavenged by Mn and Fe oxides from the water and deposited on the surface of vegetation at a reference site. Under some environmental chemical conditions, this is an important route of exposure to Pb in waterfowl, not previously recognized.

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USGS2004

Deciphering multiple Mesoproterozoic and Paleozoic events recorded in zircon and titanite from the Baltimore Gneiss, Maryland: SEM imaging, SHRIMP U-Pb geochronology, and EMP analysis

The Baltimore Gneiss , exposed in antiforms in the eastern Maryland Piedmont, consists of a suite of felsic and mafic gneisses of Mesoproterozoic age. Zircons from the felsic gneisses are complexly zoned, as shown in cathodoluminescence imaging ; most zircon grains have multiple overgrowth zones, some of which are adjacent and parallel to elongate cores. Sensitive high-resolution ion microprobe ( SHRIMP ) analyses of oscillatory-zoned cores indicate that the volcanic protoliths of the felsic gneisses crystallized at ca. 1.25 Ga. These rocks were subsequently affected by at least three Mesoproterozoic growth events , at ca. 1.22, 1.16, and 1.02 Ga. Foliated biotite granite intruded the Baltimore Gneiss metavolcanic sequence at ca. 1075 Ma. The Slaughterhouse Granite (renamed herein) also is Mesoproterozoic , but extremely discordant U-Pb data from high-U, metamict zircons preclude calculating a precise age. The 1.25 Ga rocks of the Baltimore Gneiss are coeval with rocks emplaced in the Grenville Province during the Elzevirian orogeny, and the 1.22 Ga zircon overgrowths are coincident with a later stage of this event . Younger zircon overgrowths formed during the Ottawan phase of the Grenville orogeny. Backscattered electron imaging of titanites from felsic gneisses and foliated biotite granite reveals that many of the grains contain cores, intermediate mantles, and rims. Electron microprobe traverses across zoned grains show regular variations in composition. SHRIMP ages for titanite from the foliated biotite granite are 374 ± 8, 336 ± 8, and 301 ± 12 Ma. The ca. 374 Ma age suggests growth of titanite during a thermal event following the Acadian orogeny, whereas the late Paleozoic titanite growth ages may be due to greenschist-facies replacement reactions associated with Alleghanian metamorphism and deformation.

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USGS2004

Modeling abundance effects in distance sampling

Distance-sampling methods are commonly used in studies of animal populations to estimate population density. A common objective of such studies is to evaluate the relationship between abundance or density and covariates that describe animal habitat or other environmental influences. However, little attention has been focused on methods of modeling abundance covariate effects in conventional distance-sampling models. In this paper we propose a distance-sampling model that accommodates covariate effects on abundance. The model is based on specification of the distance-sampling likelihood at the level of the sample unit in terms of local abundance (for each sampling unit). This model is augmented with a Poisson regression model for local abundance that is parameterized in terms of available covariates. Maximum-likelihood estimation of detection and density parameters is based on the integrated likelihood, wherein local abundance is removed from the likelihood by integration. We provide an example using avian point-transect data of Ovenbirds ( Seiurus aurocapillus ) collected using a distance-sampling protocol and two measures of habitat structure (understory cover and basal area of overstory trees). The model yields a sensible description (positive effect of understory cover, negative effect on basal area) of the relationship between habitat and Ovenbird density that can be used to evaluate the effects of habitat management on Ovenbird populations.

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USGS2004

Barrier island morphodynamic classification based on lidar metrics for north Assateague Island, Maryland

In order to reap the potential of airborne lidar surveys to provide geological information useful in understanding coastal sedimentary processes acting on various time scales, a new set of analysis methods are needed. This paper presents a multi-temporal lidar analysis of north Assateague Island, Maryland, and demonstrates the calculation of lidar metrics that condense barrier island morphology and morphological change into attributed linear features that may be used to analyze trends in coastal evolution. The new methods proposed in this paper are also of significant practical value, because lidar metric analysis reduces large volumes of point elevations into linear features attributed with essential morphological variables that are ideally suited for inclusion in Geographic Information Systems. A morphodynamic classification of north Assategue Island for a recent 10 month time period that is based on the recognition of simple patterns described by lidar change metrics is presented. Such morphodynamic classification reveals the relative magnitude and the fine scale alongshore variation in the importance of coastal changes over the study area during a defined time period. More generally, through the presentation of this morphodynamic classification of north Assateague Island, the value of lidar metrics in both examining large lidar data sets for coherent trends and in building hypotheses regarding processes driving barrier evolution is demonstrated

Maryland↗
USGS2004

Invasive herbivory: resident Canada geese and the decline of wild rice along the tidal Patuxent River

While concern grows over the increasing numbers of exotic mute swans ( Cygnus olor ) on the Chesapeake Bay, less attention seems to be given to the highly familiar and native Canada goose ( Branta canadensis ) which has over time developed unprecedented nonmigratory, or resident, populations. Although nuisance flocks of Canada geese have been well advertised at city parks, athletic fields, and golf courses over the past three decades, recent expansion of populations to an estimated one million birds in the Atlantic Flyway, and to over 100,000 in Maryland, carries a threat of broader ecological consequences.

Maryland↗
USGS2004

Atlantic Flyway review: Region IV - Fall 2003: Patuxent powerline right-of-way (390-0764)

The station was operated on fewer days than usual in 2003, opening a bit later, closing a week early, and missing several good days in September through mid-October, when the manager/lead bander was conducting research on migrating birds in Lower Delmarva. As a result, capture totals for many species are not comparable to other years, and totals for several species, including House Wren, Northern Parula, Nashville Warbler, Blackthroated Green Warbler, Bay-breasted Warbler, American Redstart, Connecticut Warbler, and Common Yellowthroat, set record lows. Fifty-three birds banded in previous years were captured, all of species that either nest or. winter here. Included were a record high 16 Gray Catbirds, nine of which were hatching-year (HY) birds when banded. Six return Red-eyed Vireos were captured, again far fewer than during the station's first 20 years of operation; the oldest, an adult when banded in Aug 1998, was last captured in Aug 2000. Other highlights were captures of a Cerulean Warbler (HY male), a Marsh Wren, an American Tree Sparrow, and a Northern Saw-whet Owl with a meadow jumping mouse ( Zapus hudsonius ) in its talons. Special thanks to Danny Bystrak, who operated the station on many mornings during my absence. Thanks also to Marty Barron, Murray Efford, Cecilia Leumas, Woody Martin, Diann Prosser, Mike Quinlan, Gemma Radko, Jack Saba, and John Sauer, who provided regular or occasional assistance. Sara Campbell, assistant of Dr. Peter Marra at the Smithsonian Environmental Research Center, collected blood samples from over 500 birds to test for exposure to West Nile Virus. Results are not yet available.

Maryland↗
USGS2004

Atlantic Flyway review: Region IV - Fall 2003: Robbins Nest, Laurel, MD (390-0765)

The most notable finding at this station in 2003 was the sharp decline in recaptures of previously banded birds and most especially a Crash in the chickadee and titmouse populations. In the autumn of 2001, I recaptured 36 birds banded in previous autumns, but I caught only 24 returns in 2002 and 17 in 2003, a 33% drop each year. In 2002, Tufted Titmouse was my fourth most common species (19 caught) and Carolina Chickadee (15)was in seventh place. This year, I had only four titmice and six chickadees, declines of 79% and 60%. Until now, only the migratory species have been of concern. We suspect West Nile virus is responsible. However, the oldest bird we recaptured this year was Blue Jay 723-42798, banded as HY in 1993, a species known to be especially vulnerable to West Nile. Half of this year's returns were cardinals, the oldest of which was only four years of age. My birds/100nh continues to drop each year without any noticeable change in surrounding habitat. The only banded migrant known to have remained here for more than a week was a Swainson's Thrush that weighed 31.9 g on 4 Oct and 41.6 g nine days later, an increase of 30%.

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USGS2003

Population dynamics of Microtus pennsylvanicus in corridor-linked patches

Corridors have become a key issue in the discussion of conservation planning: however, few empirical data exist on the use of corridors and their effects on population dynamics. The objective of this replicated, population level, capture-re-capture experiment on meadow voles was to estimate and compare population characteristics of voles between (1) corridor-linked fragments, (2) isolated or non-linked fragments, and (3) unfragmented areas. We conducted two field experiments involving 22600 captures of 5700 individuals. In the first, the maintained corridor study, corridors were maintained at the time of fragmentation, and in the second, the constructed corridor study, we constructed corridors between patches that had been fragmented for some period of time. We applied multistate capture-recapture models with the robust design to estimate adult movement and survival rates, population size, temporal variation in population size, recruitment, and juvenile survival rates. Movement rates increased to a greater extent on constructed corridor-linked grids than on the unfragmented or non-linked fragmented grids between the pre- and post-treatment periods. We found significant differences in local survival on the treated (corridor-linked) grids compared to survival on the fragmented and unfragmented grids between the pre- and post-treatment periods. We found no clear pattern of treatment effects on population size or recruitment in either study. However, in both studies, we found that unfragmented grids were more stable than the fragmented grids based on lower temporal variability in population size. To our knowledge, this is the first experimental study demonstrating that corridors constructed between existing fragmented populations can indeed cause increases in movement and associated changes in demography, supporting the use of constructed corridors for this purpose in conservation biology.

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USGS2003

Methodological refinements in the determination of 146 polychlorinated biphenyls, including non-ortho- and mono-ortho-substituted PCBs, and 26 organochlorine pesticides as demonstrated in heron eggs

A method for the determination of 146 polychlorinated biphenyls (PCBs), including four non-ortho- and eight mono-ortho-substituted congeners, and 26 chlorinated pesticides is described. The method consists of ultrasonic extraction, Florisil cleanup, HPLC fractionation over porous graphitic carbon (PGC), and final determination with GC/ECD, GC/MS, or both. Two PCB congeners (PCB 30 and PCB 161) and two polybromobiphenyls (2,4‘,5-tribromobiphenyl and 3,3‘,4,4‘-tetrabromobiphenyl) were used as surrogate standards to evaluate the analytical efficiency. Four PCB congeners, PCB 14 and PCB 159 for the first fraction, PCB 61 for the second fraction, and PCB 204 for the third fraction, were used as internal standards to monitor the GC performance. The retention behavior of PCBs and pesticides on the PGC column are discussed. The method was found to be reproducible, effective, and reliable under the operational conditions proposed and was applied successfully to the analysis of individual PCBs and chlorinated pesticides in black-crowned night heron ( Nycticorax nycticorax ) egg samples.

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USGS2003

Medieval Warm Period, Little Ice Age and 20th century temperature variability from Chesapeake Bay

We present paleoclimate evidence for rapid (< 100 years) shifts of ~2-4 o C in Chesapeake Bay (CB) temperature ~2100, 1600, 950, 650, 400 and 150 years before present (years BP) reconstructed from magnesium/calcium (Mg/Ca) paleothermometry. These include large temperature excursions during the Little Ice Age (~1400-1900 AD) and the Medieval Warm Period (~800-1300 AD) possibly related to changes in the strength of North Atlantic thermohaline circulation (THC). Evidence is presented for a long period of sustained regional and North Atlantic-wide warmth with low-amplitude temperature variability between ~450 and 1000 AD. In addition to centennial-scale temperature shifts, the existence of numerous temperature maxima between 2200 and 250 years BP (average ~70 years) suggests that multi-decadal processes typical of the North Atlantic Oscillation (NAO) are an inherent feature of late Holocene climate. However, late 19th and 20th century temperature extremes in Chesapeake Bay associated with NAO climate variability exceeded those of the prior 2000 years, including the interval 450-1000 AD, by 2-3 o C, suggesting anomalous recent behavior of the climate system.

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USGS2003

Type A influenza virus surveillance in free-flying, nonmigratory ducks residing on the eastern shore of Maryland

Virus surveillance in free-flying, nonmigratory ducks living on the eastern shore of Maryland indicated that influenza A viruses were introduced into the area or that the prevalence of endemic infections increased between July 15 and August 27, 1998. Cloacal swabs collected between May 28 and July 15, 1998, were negative for influenza A virus recovery (0/233), whereas 13.9% (29/209) of swabs collected between August 27 and September 2, 1998, were positive for influenza A virus recovery. Five hemagglutinin subtypes (H2, H3, H6, H9, and H12), six neuraminidase subtypes (N1, N2, N4, N5, N6, and N8), and nine HA-NA combinations were identified among 29 influenza A isolates. Interestingly, 18 of the 29 isolates initially appeared to contain two or more HA and/or NA subtypes. The free-flying, nonmigratory ducks served as excellent sentinels for the early detection of type A influenza viruses in the southern half of the Atlantic Migratory Waterfowl Flyway during the earliest phase of the yearly southern migration.

Avian Diseases↗
USGS2003

The difference between the potentiometric surfaces of the upper Patapsco aquifer, September 1990 and September 1999 in southern Maryland

This report presents a map showing the change in the potentiometric surface of the Upper Patapsco aquifer in the Upper Patapsco Formation of Cretaceous age in Southern Maryland for September 1990 and September 1999. The map, based on water-level measurements in 37 wells, shows that the potentiometric surface during the 9- year period ranged from a decline of 1 foot in the northernmost part of the study area, which is near the outcrop of the aquifer, to a decline of 22 feet at LaPlata, which is near the southwesternmost part of the study area.

Maryland↗
USGS2003

Bog iron formation in the Nassawango Watershed, Maryland

Introduction Bog iron deposits occur at a number of localities in the Pocomoke River basin. The most extensive deposits are situated along Nassawango Creek northwest of Snow Hill, a town on the Pocomoke River. After the discovery of these deposits an iron furnace was built in 1830 on the west side of Nassawango Creek, five miles northwest of Snow Hill, at a location known as the Furnace. The furnace exclusively smelted bog iron obtained along Nassawango Creek for a mile or so north of the furnace site; iron was produced from 1830 to 1850 at a rate of approximately 700 tons per year. Smelting technology of that period used mollusc shells for lime flux and locally burned charcoal for fuel; they were unable to remove phosphorous and the iron was rendered brittle when cold ("cold short") because of the high phosphorous content inherited from the ore. For that reason, and because of the limited size of the deposits and the discovery of the much larger and higher quality ore deposits in other parts of the country, production ceased about 1850. The bog iron deposits have been forming throughout the Holocene and are still forming today. Singewald (1911) stated, that their chief interest today lies in the fact that the deposits are now forming and at such a rate as to be observable. "Deposits which were once exhausted are again workable after an interval of a few years" (for more on rate of formation of bog ore at different locations see Starkey, 1962 and Moore, 1910). In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite (FeO(OH)). The ores in the Nassawango, in addition to goethite and other ferric oxyhydroxides, contain a significant amount of magnetite.

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