Bombay Hook Research Articles

A surface porosity approach for eliminating artificial ponding in coastal salt marsh simulations

Hydrodynamic processes over marsh topography are significantly affected by surface defects such as cuts and rills on channel berms and platforms. These meter-scale features are often missing in the model representation due to the spatial resolution available from data sources, as well as incomplete resolution in the model grid itself. To minimize the artificial hydraulic isolation in the numerical models, we propose implementing an effective porosity algorithm on the marsh surface by considering the fine-scale topography over marsh depressions that control the drainage process. The modification is carried out to eliminate artificial ponding effects observed in model simulations in Bombay Hook National Wildlife Refuge, DE, USA using the original FVCOM code. Results from the revised and original FVCOM models are compared with pressure gauge data collected from an isolated depression in the marsh platform. The new implementations for proper wetting and drying are efficient and accurate for hydrodynamic modeling inside a complex salt-marsh system, which constitutes a major breakthrough in the context of increasing need for better understanding of physical and morphological changes in valuable coastal ecosystems. • A permeable-seabed technique is proposed to improve wetting and drying in artificial hydraulic depressions over salt marsh surfaces. • A new set of the formula is implemented in a widely used coastal ocean model FVCOM and tested the model performance in a salt marsh system. • The detailed comparison against the traditional approach showed a substantial improvement in the marsh flooding and draining accuracy.

Hydrodynamic modeling of a complex salt marsh system: Importance of channel shoreline and bathymetric resolution

Modeling hydrodynamics and sediment transport inside a multi-inlet wetland system is a challenging task due to constraints on model efficiency, accuracy and representation of physics, the scarcity of field data for model validation, and more importantly, the availability of high-resolution data sets of channel bathymetry. Lack of field data sets, model assumptions, and limitations often lead to wrong interpretation of the system’s nature. To correctly predict the changes in governing hydrodynamics and morphology of shallow wetland environments, it is essential to resolve the channel properties with the best possible accuracy. In this study, we consider the importance of two factors, numerical model grid resolution around channel shorelines, and bathymetry surveys, in improving the interior channel and mudflat hydrodynamics. Channel shoreline element size is observed to be an essential factor in time-varying channel volume estimation. Lower model resolution in channels inside a marsh can provide good agreement with in-situ surface elevation data, even though the channel surface-velocity phase lag, and velocity magnitude and asymmetry are inaccurate. A higher grid resolution at the channel berms and the high-density channel survey help define the time-varying lateral shoaling bathymetry, cross-section area, and bottom friction, and improve the corresponding model skill and tidal wave properties significantly. We have selected Bombay Hook National Wildlife Refuge, a rapidly eroding salt-marsh system in Delaware Bay, to compare model skills for different hypsometric conditions. Model performance is evaluated during two storm conditions; Hurricane Sandy (2012) and Hurricane Joaquin (2015), using tide gauges located on the marsh interior channels. • Poor grid resolution around marsh-channel berm creates artificial channel convergence and inaccurate tidal wave characteristics. • Topo-bathymetry field survey and bias correction improves channel hypsometry and numerical model reliability significantly. • Inaccurate channel bathymetry and inadequate resolution might lead to acceptable surface elevation but poor tidal velocity field. • The conventional grid generation methods based on sparse cross channel surveys is not sufficient for wetland models.

Additional U.S. collections of the Gulf Coast tick, <em>Amblyomma maculatum</em> (Acari: Ixodidae), from the State of Delaware, the first reported field collections of adult specimens from the State of Maryland, and data regarding this tick from surveillance of migratory songbirds in Maryland

This report describes collections of the Gulf Coast tick, Amblyomma maculatum Koch (Ixodida: Ixodidae), made during 2013 at the Bombay Hook National Wildlife Refuge (NWR), Delaware, and at two sites in Maryland: the Blackwater NWR and the Chester River Field Research Station (CRFRS). Ticks were collected via field drags, dry ice-baited traps, and/or from the human field researchers (collections of ticks crawling on clothing/boots) at Bombay Hook NWR and Blackwater NWR. A total of 21 A. maculatum were successfully collected at Bombay Hook NWR during May 28–30, 2013. Using a genus-specific quantitative real-time polymerase chain reaction (qPCR) assay and species-specific qPCR assays, a single male was found to be positive for the presence of Rickettsia parkeri DNA (a spotted fever group rickettsia). The repeated collection of this species in the adult stage at Bombay Hook NWR, the relatively large number collected (n=21), along with its continuity of presence pre- and post-winter, indicate that an established population may now exist at Bombay Hook NWR. A single adult female was collected from a field drag at Blackwater NWR on June 18, 2013; this specimen was negative for the presence of Rickettsia spp. DNA (including R. parkeri DNA). An adult male was collected on a researcher at CRFRS on August 8, 2013; this specimen was found to be positive for R. parkeri DNA. This report also summarizes data from 2008 to 2010 for A. maculatum collected during mist netting surveillance of migratory songbirds by the Foreman’s Branch Bird Observatory, located at CRFRS: a total of 104 immature A. maculatum were collected. The adult specimens of A. maculatum collected at Blackwater NWR and at CRFRS are regarded as representing the first documentation of adult field-collected A. maculatum within the state. Future sampling is needed at each location to determine if A. maculatum is firmly established, the prevalence of R. parkeri infection, and the epidemiological risk to humans.

Generating meshes for tidal wetland modeling using light detection and ranging (LiDAR) data

A high resolution model mesh was required to numerically simulate sediment transport in tidal marshes. The timing of flooding is dependent on the tidal marsh ground elevation, which requires accurate topographic elevation data. The tidal prism of the marsh is determined by the volume provided by tidal channels in the system. Hence, their location and bathymetry needed to be represented adequately. Due to the high spatial variability and inaccessibility of marshes, remote sensing techniques such as light detection and ranging (LiDAR) are a significant resource for elevation data. LiDAR measures the highest elevation of elements. To determine the bare ground elevation, filter techniques exist but are often inadequate to eliminate elevation errors that are introduced by the vegetation of marshes. We introduce a simple method to remove remaining vertical elevation errors in high resolution digital terrain models (DTMs) of vegetated marshes and present an approach to determine the bathymetry of tidal channels based on a limited number of cross-sectional measurements. Forcing polygons for mesh generation were extracted from the DTMs to assure an accurate spatial representation of the marsh. DTMs (2 × 2 m/1 × 1 m) derived from LiDAR data from the Blackbird Creek Reserve and Bombay Hook National Wildlife Refuge in Delaware, USA, were used.

Infection of the Gulf Coast tick, <i>Amblyomma maculatum</i> (Acari: Ixodidae), with <i>Rickettsia parkeri</i>: first report from the State of Delaware

The molecular detection of Rickettsia parkeri in a Gulf Coast tick, Amblyomma maculatum, collected in Delaware represents the first evidence of the human pathogen R. parkeri associated with A. maculatum in the state. A total of five adult (2 male and 3 female) Gulf Coast ticks were collected from tick drags conducted during a two-day sampling event (21–22 May 2012) at Bombay Hook National Wildlife Refuge, near Smyrna, Delaware. All specimens were tested for the presence of Rickettsia with a genus-specific quantitative real-time polymerase chain reaction (qPCR) assay; one of the female specimens tested positive. This specimen was then assessed for the presence of Rickettsia parkeri and Candidatus Rickettsia andeanae by two species-specific qPCR assays. The presence of R. parkeri DNA was detected, whereas Candidatus R. andeanae DNA was not.

Inter-annual variability in Delaware Bay brackish marsh vegetation, USA

Reports of sudden marsh browning, or even dieback, suggest that the many heretofore “healthy” coastal marshes have reached some tipping point with respect to sea level rise, necessitating better and more widespread monitoring. In this paper, we examine spatial and temporal variations in marsh vegetation cover, substrate wetness, and sediment exposure for mesohaline to oligohaline marshes in Delaware Bay over a 15-year period (1993–2008) using three spectral indices (the Normalized Difference Vegetation Index, the Normalized Difference Water Index, and the Normalized Difference Soil Index) based on Landsat Thematic Mapper and Enhanced Thematic Mapper + imagery. In general, degrading marsh areas show low percentages of vegetation cover compared to bare marsh substrate, and substrate wetness tends to be high. But this characterization is not consistent from one year to the next, and in marshes that are in incipient stages of degradation, apparent vegetation health can improve substantially for a few years. Detailed transect data collected from July to September in an area of Bombay Hook National Wildlife Refuge, where little marsh loss was evident, document considerable variability in vegetation dynamics. The marshes along the transect kept pace with the major transgressive pulse of the 1990s, but as the rate of sea level rise decreased after 2000, vegetation vigor fell, especially in 2004, the year after Hurricane Isabel. The years of maximum vegetation cover, 2003 and 2005, coincided with short-term, sea level high stands and/or very wet and cooler summers. We theorize that after keeping up with the dramatic rise in sea level during the 1990s, marsh surface elevations in these microtidal systems are now too high to allow adequate flushing of sulfides and low dissolved oxygen waters except for high precipitation events or short-term sea level rises. If this situation were to continue, it could affect the “health” of marshes that otherwise were accommodating high rates of sea level rise well.

The input of foraminiferal infaunal populations to sub-fossil assemblages along an elevational gradient in a salt marsh: application to sea-level studies in the mid-Atlantic coast of North America

The suitability of marsh sites for sea-level studies was examined based on a field study along a transect from high to low marsh. Living foraminifera at Bombay Hook (Delaware, USA) are considered to be shallow infaunal (i.e., uppermost 10 cm). Peak concentrations were found at 1–10 cm in the high marsh, 1–5 cm in the intermediate marsh, and 3–5 cm in the low marsh. However, sporadic deep infaunal inputs in the low marsh could significantly contribute to the sub-fossil assemblage. In the upper 10 cm buried (death + sub-fossil) and living assemblages showed a strong correlation, and the seasonal pattern of the buried assemblage paralleled the living one, suggesting that the buried assemblage reflected the most recent reproductive inputs. The cumulative standing crop of each dominant species was used to estimate their contribution to the buried assemblage in order to assess if the community is vertically homogeneous and, therefore, if the infaunal production causes differential sub-surface enrichment. The results showed that a “shallow” (0–5 cm) infaunal contribution is able to explain much of the sub-fossil assemblage beneath the surface in the high and intermediate marsh plots. However, in the low marsh plot, the deep infaunal contribution was greatest and significantly affected the sub-fossil assemblage. Therefore, modern analogues for sea-level studies in mid-Atlantic North American marshes should include the uppermost 5 cm. The interval proposed for the high and intermediate marsh is thin enough that epifaunal species are not underrepresented and encompasses only ~8 years (based on burial rates) providing a high temporal resolution.

INTERANNUAL VARIATION OF MARSH FORAMINIFERAL ASSEMBLAGES (BOMBAY HOOK NATIONAL WILDLIFE REFUGE, SMYRNA, DE): DO FORAMINIFERAL ASSEMBLAGES HAVE A MEMORY?

Research Article| April 01, 2002 INTERANNUAL VARIATION OF MARSH FORAMINIFERAL ASSEMBLAGES (BOMBAY HOOK NATIONAL WILDLIFE REFUGE, SMYRNA, DE): DO FORAMINIFERAL ASSEMBLAGES HAVE A MEMORY? Scott P. Hippensteel; Scott P. Hippensteel Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. 1Present address: Department of Geography and Earth Sciences, 9201 University City Boulevard, University of North Carolina, Charlotte, NC 28223-0001. Search for other works by this author on: GSW Google Scholar Ronald E. Martin; Ronald E. Martin 2 Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. 2Corresponding author: Phone: 302-831-6755; Fax: 302-831-4158; E-mail: Daddy@Strauss.Udel.Edu Search for other works by this author on: GSW Google Scholar Daria Nikitina; Daria Nikitina Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. Search for other works by this author on: GSW Google Scholar James E. Pizzuto James E. Pizzuto Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. Search for other works by this author on: GSW Google Scholar Author and Article Information Scott P. Hippensteel 1Present address: Department of Geography and Earth Sciences, 9201 University City Boulevard, University of North Carolina, Charlotte, NC 28223-0001. Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. Ronald E. Martin 2 Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. Daria Nikitina Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. James E. Pizzuto Department of Geology, University of Delaware, Newark, DE 19716 U.S.A. 2Corresponding author: Phone: 302-831-6755; Fax: 302-831-4158; E-mail: Daddy@Strauss.Udel.Edu Publisher: Cushman Foundation for Foraminiferal Research Received: 12 Dec 2000 Accepted: 07 May 2001 First Online: 03 Mar 2017 Online ISSN: 1943-264X Print ISSN: 0096-1191 © 2002 Journal of Foraminiferal Research Journal of Foraminiferal Research (2002) 32 (2): 97–109. https://doi.org/10.2113/0320097 Article history Received: 12 Dec 2000 Accepted: 07 May 2001 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Scott P. Hippensteel, Ronald E. Martin, Daria Nikitina, James E. Pizzuto; INTERANNUAL VARIATION OF MARSH FORAMINIFERAL ASSEMBLAGES (BOMBAY HOOK NATIONAL WILDLIFE REFUGE, SMYRNA, DE): DO FORAMINIFERAL ASSEMBLAGES HAVE A MEMORY?. Journal of Foraminiferal Research 2002;; 32 (2): 97–109. doi: https://doi.org/10.2113/0320097 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract Seasonal reproduction and preservation of foraminifera were monitored for three years at Bombay Hook National Wildlife Refuge (Smyrna, DE). Cluster analysis of “seasonally artificially time-averaged” (SATA) assemblages indicates that assemblages reflect the most recent test inputs, and that test inputs record subtle variations in porewater chemistry related to rates of sulfate reduction, pyrite oxidation, and vertical differentiation of geochemical gradients. Changes in geochemical gradients are caused by interannual variation of rainfall: more rainfall damps pyrite oxidation and weakens geochemical gradients, whereas less rainfall allows more pyrite oxidation and strengthens vertical gradients. Geochemical overprinting of assemblages related to rainfall tended to occur during the summer and early fall. Therefore, as assemblages pass into the historical layer, they may have a “memory” of the most recent test inputs and environmental conditions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Artificial time-averaging of marsh foraminiferal assemblages: linking the temporal scales of ecology and paleoecology

Multiple regression models were developed for seasonal test inputs to, and preservation of, marsh foraminiferal assemblages for a two-year period at Bombay Hook National Wildlife Refuge (BHNWR; Smyrna, Delaware). Seasonal assemblages were quite variable and yielded poor regression models. However, signal/noise ratios were amplified using artificially time-averaged (ATA) assemblages, in which separate dead and live abundances of the most abundant species were summed for all seasons. Regression models that used ATA species abundances to retrodict original sample depths accounted for up to ~99% (p < 0.0001) and ~91% (p < 0.023) of the variation of dead and live ATA assemblages, respectively, and usually retrodicted sample depths within 2–3 cm of actual depths.Artificially time-averaged assemblages were also used to extract multidecadal- to centennial-scale sea-level signals from near-surface assemblages at BHNWR formed during the past few centuries. The BHNWR sea-level curve closely resembles one previously published for marshes in Clinton, Connecticut (also based on foraminifera). The technique of artificial time-averaging therefore links the temporal scales of ecology and paleobiology by extracting high-resolution paleoenvironmental signals preserved in the fossil record.

Winter Movements and Habitat Use by Greater Snow Geese

We studied local movements, feeding patterns, and roost site use of 38 female greater snow geese (Chen caerulescens atlantica) radiomarked at Bombay Hook National Wildlife Refuge on the Delmarva (Del.-Md.-Va.) Peninsula from October 1990 to March 1991. In early (Oct-Nov), mid- (Dec-Jan), and late (Feb-Mar) seasons, mean distances traveled by marked birds from roosts to feed (5, 11, and 4 km) and between roosts (4, 23, and 11 km) differed seasonally (P 0.05), but use of tidal saltmarsh differed seasonally (P 50% from early (27.9%) to late (12.1%) season. Seasonal differences in use of harvested corn (P < 0.0078) were evident as geese fed heavily in cornfields in early (56.5%) and mid-(46.2%) seasons, but use decreased in late season (32.8%). Use of small grain fields (green vegetation) for feeding differed seasonally (P < 0.0001) as they were used little in early season (5.7%) but became the most important feeding habitat in late season (34.6%). Overall, radiomarked snow geese used a variety of habitats and dispersed widely over the Delmarva Peninsula and into New Jersey and Pennsylvania. Provision of green vegetation in fall (e.g., small grains) may help satisfy dietary needs of geese and reduce local destruction of tidal saltmarsh habitat by feeding geese, but this likely will increase winter survival and ultimately lead to an increased population size. Therefore, the complex issue of habitat management on and near the refuge will be particularly important as the greater snow goose population continues to increase.

Dynamics of fat and protein reserves during winter and spring migration in greater snow geese

We studied the dynamics of fat and protein reserves in greater snow geese (Chen caerulescens atlantica) during winter and spring migration, and examined the influence of a recent expansion of their staging grounds and change in habitat use on fat and protein storage. We collected 63 geese during the winter of 1989–1990 at Bombay Hook National Wildlife Refuge in Delaware, 158 geese in spring 1989 and 1990 at Lake Saint-Pierre and Cap-Saint-Ignace along the St. Lawrence River in southern Quebec, and 17 geese at the end of the 1990 migration on By lot Island, N.W.T. In both sexes, protein reserves did not change in winter but fat declined from a peak in December to a low point in early March, just before spring migration. Geese collected 3 weeks later at Lake Saint-Pierre (800 km north) had considerably larger fat reserves (90% larger in females and 40% in males). Geese accumulated large fat reserves at both sites along the St. Lawrence River. Although geese staged for a shorter period at Lake Saint-Pierre (a recently used area), males stored as much fat as those staging at Cap-Saint-Ignace and females only slightly less. A small amount of protein was stored between late winter and the end of staging. Spring conditioning of geese along the St. Lawrence River seems to have improved over the past decade. We found weak evidence that larger females stored more fat. The cost of migrating from the St. Lawrence to Arctic nesting grounds (2900 km) is considerable, as half of the fat reserves accumulated in spring were used for the migration. There is no evidence of fat or protein storage between the St. Lawrence estuary and the Arctic nesting grounds.

Lead Poisoning in Canada Geese in Delaware

483 geese died at the Bombay Hook Wildlife Refuge between November 1965 and April 1966. All but one goose had enough lead in the liver to indicate lead poisoning as the cause of death. Delaware waterfowl biologists have estimated that perhaps as many as 2000-4000 geese succumbed to what appears to be lead poisoning during the winter of 1965-66. 9 references, 3 figures, 2 tables.

Straw Infusion Attractiveness to Gravid Female Culex salinarius1

Results of replicated field-plot studies and observations at Bombay Hook Refuge. Del., from 1959 to 1964 indicated that certain chemical factors of apparent protein origin are responsible for the pronounced attractiveness of straw infusion to gravid females of Culex salinarius Coquillett. Physical factors such as cover or shelter proved less significant. These chemical attractant substances were isolated by treating concentrated straw infusion with 10% trichloracetic acid. Subsequently, water suspensions of the acid-free residues were field tested against straw infusion, natural habitat, and tap water. Field observations and experimental data showed that the trichloracetic acid extract actively attracted more ovipositing females of C. salinarius than did the straw infusion, whereas natural habitat and tap water attracted relatively insignificant numbers. These findings suggest the means by which mosquito oviposition site selection takes place and provide a basis for understanding the ecological distribution of larvae. Although further chemical definition of the attractant substance is needed before it can have practical application, the results of this work may lead to the development of an oviposition “lurc” applicable to highly selective control measures.