Assateague Island National Seashore Research Articles

Comparing Wetland Elevation Change Using a Surface Elevation Table, Digital Level, and Total Station

The surface elevation table (SET) approach and two survey instruments, a digital level (DL) and a total station (TS), were used to evaluate elevation change at a 1-ha, micro-tidal, back-barrier salt marsh at Assateague Island National Seashore (Berlin, MD, USA) from 2016 to 2022. SET data were collected at 3 sampling stations along the perimeter of the plot, 36 pins per station, and the DL and TS data were collected adjacent to 36 stakes, four readings per stake, throughout the plot. The average elevation range of the marsh surface measurements at the SET stations was 2 cm, while the range was considerably greater within the larger 1-ha DL and TS sampling area (24 cm). The average elevation of the marsh surface only varied by 2 cm among the three methods. Elevation change trends of the three methods ranged from 2.8 to 3.5 mm year−1 and were not significantly different from each other. Despite differences in sample size and spatial distribution of measurements, these methods provided comparable measures of long-term trends in marsh surface elevation probably because the marsh at this site was structurally homogeneous with low topographic relief.

Analysis of Estrogenic Activity in Maryland Coastal Bays Using the MCF-7 Cell Proliferation Assay.

Contaminants of Emerging Concern (CECs) with estrogenic or estrogenic-like activity have been increasingly detected in aquatic environments and have been an issue of global concern due to their potential negative effects on wildlife and human health. This study used the MCF-7 cell proliferation assay (E-Screen) to assess the estrogenic activity profiles in Maryland Coastal Bays (MCBs), a eutrophic system of estuaries impacted by human activities. Estrogenic activity was observed in all study sites tested. Water samples from MCBs increased MCF-7 cell proliferation above the negative control from 2.1-fold at site 8, located in Sinepuxent Bay close to the Ocean City Inlet, to 6.3-fold at site 6, located in Newport Bay. The proliferative effects of the sediment samples over the negative control ranged from 1.9-fold at the Assateague Island National Seashore site to 7.7-fold at the Public Landing site. Moreover, elevated cell proliferation (p < 0.05) was observed when cells were co-exposed with 17ß-Estradiol (E2), while reduction in cell proliferation was observed when cells were co-exposed with the antagonist ICI 182, 780 suggesting that cell proliferative effects were primarily mediated by the estrogen receptor (ER). These results suggest the occurrence of some estrogenic or hormonal-like compounds in the MCBs and are consistent with our previous findings based on vitellogenin analyses.

Tidal and Hurricane Impacts on Saltmarshes in the Northeastern Coastal and Barrier Network: Theory and Empirical Results

The responses of marsh elevation in four National Parks affected by Hurricane Sandy were examined using empirical data from surface elevation tables (SET) and modeling. The parks examined were Fire Island National Seashore and Gateway National Recreational Area in New York; Cape Cod National Seashore, Massachusetts; and Assateague Island National Seashore, Maryland. Observed vertical accretion rates were compared with calculations made with the Marsh Equilibrium Model (MEM). MEM predicts vertical accretion resulting from the accumulation of organic material in soil and the capture of suspended inorganic material at the marsh surface. MEM simulations of a decade or more of marsh elevation change at 52 SET stations were generally consistent with observations. Park-specific averages of observed vertical accretion ranged from 0.16 ± 0.33 (± 1 SD) to 0.51 ± 0.21 cm/year, while the range of calculated rates was 0.15 ± 0.03 to 0.22 ± 0.05 cm/year, depending on the park. Grand means of observed and calculated rates were 0.36 ± 0.34 and 0.19 ± 0.06 cm/year, respectively. We defined a novel metric termed normalized elevation capital (NEC) that incorporates information about tide range and elevation capital. All but 2.3% of biomass collections from all the parks fell within 0 < NEC < 1. Consistent with marsh equilibrium theory, long-term vertical accretion rate tended to be greatest, 0.4 ± 0.2 cm/year, in the range 0.4 < NEC < 0.6 where vertical accretion is dominated by organic production. Average episodic accretion during the storm from mineral deposition also was greatest and positive, 0.6 ± 0.9 cm in the range 0.4 < NEC < 0.6. Finally, one marsh in Gateway NRA, restored by an application of sediment to NEC = 0.55–0.68, had post-treatment vertical accretion rates of 0.36 ± 0.31 cm/year, not statistically different from SET stations elsewhere in Gateway, 0.57 ± 0.54 cm/year. The sediment amendment placed restored sites in the range of NEC where theory predicts that biogenic accretion should dominate vertical accretion. Model simulations suggest that current rates of vertical accretion in the parks are close to their theoretical limits, and in the absence of new sediment, extant marsh communities in these parks are unlikely to survive continued acceleration of sea-level rise in the absence of periodic sediment renourishment.

Assessment of Salt Marsh Change on Assateague Island National Seashore Between 1962 and 2016

Salt marshes provide extensive ecosystem services, including high biodiversity, denitrification, and wave attenuation. In the mid-Atlantic, sea level rise is predicted to affect salt marsh ecosystems severely. This study mapped the entirety of Assateague Island with Very High Resolution satellite imagery and object-based methods to determine an accurate salt marsh baseline for change analysis. Topobathy-metric light detection and ranging was used to map the salt marsh and model expected tidal effects. The satellite imagery, collected in 2016 and classified at two hierarchical thematic schemes, were compared to determine appropriate thematic richness. Change analysis between this 2016 map and both a manually delineated 1962 salt marsh extent and image classification of the island from 1994 determined rates off change. The study found that from 1962 to 1994, salt marsh expanded by 4.01 ha/year, and from 1994 to 2016 salt marsh was lost at a rate of -3.4 ha/ year. The study found that salt marsh composition, (percent vegetated salt marsh) was significantly influenced by elevation, the length of mosquito ditches, and starting salt marsh composition. The study illustrates the importance of remote sensing monitoring for understanding site-specific changes to salt marsh environments and the barrier island system.

Benthic Habitat Morphodynamics-Using Remote Sensing to Quantify Storm-Induced Changes in Nearshore Bathymetry and Surface Sediment Texture at Assateague National Seashore

This study utilizes repeated geoacoustic mapping to quantify the morphodynamic response of the nearshore to storm-induced changes. The aim of this study was to quantitatively map the nearshore zone of Assateague Island National Seashore (ASIS) to determine what changes in bottom geomorphology and benthic habitats are attributable to storm events including hurricane Sandy and the passage of hurricane Joaquin. Specifically, (1) the entire domain of the National Parks Service offshore area was mapped with side-scan sonar and multibeam bathymetry at a resolution comparable to that of the existing pre-storm survey, (2) a subset of the benthic stations were resampled that represented all sediment strata previously identified, and (3) newly obtained data were compared to that from the pre-storm survey to determined changes that could be attributed to specific storms such as Sandy and Joaquin. Capturing event specific dynamics requires rapid response surveys in close temporal association of the before and after period. The time-lapse between the pre-storm surveys for Sandy and our study meant that only a time and storm integrated signature for that storm could be obtained whereas with hurricane Joaquin we could identify impacts to the habitat type and geomorphology more directly related to that particular storm. This storm impacts study provides for the National Park Service direct documentation of storm-related changes in sediments and marine habitats on multiple scales: From large scale, side-scan sonar maps and interpretation of acoustic bottom types, to characterize as fully as possible habitats from 1 to 10 m up to many kilometer scales, as well as from point benthic samples within each sediment stratum and these results can help guide management of the island resources.

Organic carbon dynamics in soils of Mid-Atlantic barrier island landscapes

Geomorphic processes associated with coastal wetlands often result in high carbon accumulation rates and relatively large carbon stocks. Barrier islands are an important component of coastal ecosystems and freshwater and brackish wetlands on these islands provide an important habitat for a number of animal and plant species. However, organic carbon dynamics in these landscapes have received relatively little attention. The objective of this study was to document the accumulation of organic carbon and understand the factors influencing soil carbon dynamics on barrier islands. Ten topographic transects were established on different landforms on Assateague Island National Seashore, MD, USA. Soil organic carbon stocks, aboveground carbon inputs, and decomposition rates were compared among landforms (representing differing degrees of landform stability and soil age) and drainage conditions. Soil organic carbon stocks (0–1.0 m) ranged from 0.49 to 18.8 kg C m−2, and increased in magnitude with soil age. Higher carbon stocks in the older soils were partly attributed to the increased time over which carbon had accumulated. Additionally, a shift from herbaceous dominated to forest dominated plant communities led to greater carbon inputs in older soils. Carbon stocks were also greater in the very poorly and poorly drained soils (relative to drier soils) where high levels of carbon inputs (plant biomass) exceed decomposition rates, which were slowed under anaerobic conditions. While rates of carbon accumulation (average 0.021 kg C m−2 yr−1) are somewhat low compared to other more productive systems, barrier island soils have the potential to store large amounts of organic carbon (relative to other soils) as organic-rich surface horizons are buried during overwash events.

Geometric Properties of the Third Metacarpal Bone: A Comparison Between Thoroughbred and Quarter Horse Racehorses

A frequent reason that Thoroughbred racehorses are killed during racing or training is fracture of the third metacarpal (the cannon bone). Determining the factors involved in these catastrophic cannon bone fractures is imperative to improving both horse and jockey safety. Though seemingly spontaneous, catastrophic cannon bone fractures generally result from the combination of mechanical forces commonly present in racing Thoroughbreds, and generally materialize in the distal lateral condyle of the cannon bone. Thoroughbreds, however, are not the only breed of racehorse to experience catastrophic fractures—Quarter Horses also exhibit specific patterns of injury in more proximal limb bones. Different fracture patterns in these two breeds of galloping racehorse may indicate different loading patterns of their limbs, which could be a product of varied training programs, or variance in breed morphology. The present analysis compares geometric properties of the third metacarpal in Thoroughbred and Quarter Horse racehorses, using feral Assateague Island ponies as an outgroup, in order to clarify the reasons for distinctive fracture patterns in different breeds of racehorses.Six cannon bones from each breed were obtained from New Bolton Center (Thoroughbreds), Oklahoma State University (Quarter Horses), and the Assateague Island National Seashore (Assateague Island ponies). Peripheral Quantitative Computed Tomography (pQCT) generated cross sections at 40% and 20% (distal) of bone length, and at the midpoint of the distal articular surface. Cross‐sectional areas, second moments of area, and section moduli were calculated for the two diaphyseal sections, and trabecular bone mineral density and total bone mineral density were determined for the distal articular section. Approximate body masses were estimated from proximal articular breadths using a published formula.Analysis of covariance (ANCOVA) revealed that although the overall strength of cannon bones in Thoroughbreds and Quarter Horses did not differ relative to body size, Thoroughbreds had relatively higher anteroposterior bending strength in the diaphysis than Quarter Horses, and relatively lower mediolateral bending strength. Thoroughbreds also had lower values of trabecular and total bone densities in the distal articular section, which is the region where lateral condyle fractures are generally incurred by Thoroughbreds but not Quarter Horses. Both Thoroughbreds and Quarter Horses had lower overall safety factors compared to feral Assateague Island ponies. Assateague Island ponies exhibited relatively stronger bone shafts and a higher trabecular density in the distal articular section. Results suggest that breed‐specific bone structure differences contribute to the greater incidence of fractures in domestic racehorses and, relatedly, the common location of fractures in Thoroughbreds.Support or Funding InformationFunded by the American Society of Mammalogists.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Land Cover Change Image Analysis for Assateague Island National Seashore Following Hurricane Sandy

The assessment of storm damages is critically important if resource managers are to understand the impacts of weather pattern changes and sea level rise on their lands and develop management strategies to mitigate its effects. This study was performed to detect land cover change on Assateague Island as a result of Hurricane Sandy. Several single-date classifications were performed on the pre and post hurricane imagery utilized using both a pixel-based and object-based approach with the Random Forest classifier. Univariate image differencing and a post classification comparison were used to conduct the change detection. This study found that the addition of the coastal blue band to the Landsat 8 sensor did not improve classification accuracy and there was also no statistically significant improvement in classification accuracy using Landsat 8 compared to Landsat 5. Furthermore, there was no significant difference found between object-based and pixel-based classification. Change totals were estimated on Assateague Island following Hurricane Sandy and were found to be minimal, occurring predominately in the most active sections of the island in terms of land cover change, however, the post classification detected significantly more change, mainly due to classification errors in the single-date maps used.

Hydric Soil Field Indicators for Use in Mid-Atlantic Barrier Island Landscapes

Hydric soils in Holocene-aged barrier island landscapes in the Mid-Atlantic region of North America lack morphologies typically associated with saturated and reducing conditions. Furthermore, many better drained (nonhydric) soils have low chroma colors due to parent material effects, making identification and delineation of wetlands problematic. Our objective was to develop field indicators that could be used to effectively recognize hydric soils in these environments. Soils along 10 topographic transects were evaluated at Assateague Island National Seashore, Maryland. Transects spanned a gradient of topographic positions from dune crests to interdunal swales. Water tables and reducing conditions were monitored to determine hydric status. Soil descriptions along each transect were used to identify morphological features indicative of soil wetness. Of 16 monitored and documented hydric soils, only five met recognized field indicators. Hydric soils were best identified by the presence of matrix colors with chromas less than 2 in mineral soils or the presence of at least 1 cm of muck (Oa horizon). On the basis these characteristics, we propose two new indicators restricted for use in Holocene-aged barrier island landscapes in the Mid-Atlantic region. These indicators will allow identification of hydric soils, improving the accuracy and ease of delineation of wetlands.

A Bayesian network approach to predicting nest presence of the federally-threatened piping plover (Charadrius melodus) using barrier island features

Sea-level rise and human development pose significant threats to shorebirds, particularly for species that utilize barrier island habitat. The piping plover (Charadrius melodus) is a federally-listed shorebird that nests on barrier islands and rapidly responds to changes in its physical environment, making it an excellent species with which to model how shorebird species may respond to habitat change related to sea-level rise and human development. The uncertainty and complexity in predicting sea-level rise, the responses of barrier island habitats to sea-level rise, and the responses of species to sea-level rise and human development necessitate a modeling approach that can link species to the physical habitat features that will be altered by changes in sea level and human development. We used a Bayesian network framework to develop a model that links piping plover nest presence to the physical features of their nesting habitat on a barrier island that is impacted by sea-level rise and human development, using three years of data (1999, 2002, and 2008) from Assateague Island National Seashore in Maryland. Our model performance results showed that we were able to successfully predict nest presence given a wide range of physical conditions within the model's dataset. We found that model predictions were more successful when the ranges of physical conditions included in model development were varied rather than when those physical conditions were narrow. We also found that all model predictions had fewer false negatives (nests predicted to be absent when they were actually present in the dataset) than false positives (nests predicted to be present when they were actually absent in the dataset), indicating that our model correctly predicted nest presence better than nest absence. These results indicated that our approach of using a Bayesian network to link specific physical features to nest presence will be useful for modeling impacts of sea-level rise or human-related habitat change on barrier islands. We recommend that potential users of this method utilize multiple years of data that represent a wide range of physical conditions in model development, because the model performed less well when constructed using a narrow range of physical conditions. Further, given that there will always be some uncertainty in predictions of future physical habitat conditions related to sea-level rise and/or human development, predictive models will perform best when developed using multiple, varied years of data input.

Assessment of Inundation Risk from Sea Level Rise and Storm Surge in Northeastern Coastal National Parks

Murdukhayeva, A.; August, P.; Bradley, M.; LaBash, C., and Shaw, N., 2013. Assessment of inundation risk from sea level rise and storm surge in northeastern coastal national parks.Sea level rise and an increase in storm frequency and intensity are two major impacts expected to result from climate change in coastal ecosystems. Coastal national parks have many low-lying areas that are at risk from inundation resulting from these impacts. To help park managers meet their goal of preserving resources, we developed a methodology to evaluate risk of inundation from sea level rise and storm surge at sentinel sites, areas of importance for natural, cultural, and infrastructural resources. We selected the most recent, readily available, and appropriate geospatial tools, models, and data sets to conduct case studies of our coastal inundation risk assessments in two northeastern coastal national parks—Cape Cod National Seashore, MA, and Assateague Island National Seashore, MD/VA. We collected elevation data at sentinel sites using real-time kinematic global positioning system (RTK GPS) technology. We used three modeling approaches: modified bathtub modeling; the Sea Level Affecting Marshes Model (SLAMM); and the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model to assess the likelihood of inundation at sentinel sites. Cape Cod's sentinel sites, which in many cases occurred in high-elevation settings, were found to be less vulnerable to inundation than were Assateague Island's sentinel sites, which were distributed in low-lying areas along the barrier beach island. This inundation risk assessment methodology can be applied to other coastal areas and to the same coastal parks at different times as more accurate elevation data sets and updated sea level rise projections become available.

Impacts of driving on the beach: Case studies from Assateague Island and Padre Island National Seashores

There is mounting evidence that driving on the beach has a significant biophysical impact, and it has been suggested in a number of recent studies that driving on the beachface leads to a net loss of sediment from the beach-dune system. Identifying a conclusive link between beach driving and beach erosion is, however, complicated by the natural variability of the environment in both space and time, and it has proven difficult to distinguish the driving signal from this background noise. In this respect, the impacts of beach driving are not clear, making it difficult to develop appropriate management strategies to reduce the impact in either degree or extent. LiDAR data from both Padre Island National Seashore and Assateague Island National Seashore are used in the present study to determine if the differences in beach and dune morphology between restricted and open access sections of the beach are associated with beach driving. Results from Padre Island National Seashore suggest that beach driving does not affect the height and volume of the foredunes, but is responsible for a statistically significant decrease in the elevation of the dune crest and base compared to the control section of beach. The decrease in elevation is ascribed to the compaction and pulverization of seaweed wrack that accumulates along the Texas coast in the spring and summer months, and is responsible for the anchoring of sediment for the growth of new vegetation seaward of the foredune. At Assateague Island National Seashore, driving on the beach is shown to cause a statistically significant change in the beach-dune morphology, with smaller dunes set further back from the shoreline within the open access sections of the beach. Despite the changes in dune morphology at both sites, there is no statistically significant difference in beach-dune volume on either side of the beach access road, which suggests that driving on the beach does not lead to a net loss of sediment from the beach-dune system. Driving on the beach does, however, make the foredune at both sites susceptible to scarping and overwash during tropical storms and hurricanes.

Improving management of a mid-Atlantic coastal barrier island through assessment of habitat condition

To achieve desired environmental outcomes, environmental condition and trends need to be rigorously measured and communicated to resource managers, scientists, and a broader general audience. However, there is often a disconnect between responsive ecosystem monitoring and decision making for strategic long-term management. This project demonstrates how historical monitoring data can be synthesized and used for future planning and decision making, thereby closing the management feedback cycle. This study linked disparate datasets, collected for a variety of purposes and across multiple temporal and spatial scales, in order to assess and quantify current habitat conditions. The results inform integrated resource management decision-making at Assateague Island National Seashore (Maryland and Virginia, USA) by using ecological reference conditions to identify monitoring needs, areas of high vulnerability, and areas with potential for improved management. The approach also provides a framework that can be applied in the future to assess the effectiveness of these management decisions on the condition of island habitats, and is a replicable demonstration of incorporating diverse monitoring datasets into an adaptive management cycle.

Exploring Traditional Use and Association Through the Ethnographic Overview and Assessment for Assateague Island National Seashore

Assateague, a dynamic barrier island extending from just south of Ocean City, Maryland, to the northern portions of Virginia's eastern shore, was added to the National Park Service (NPS) system in 1965 (Mackintosh 1982) and now draws roughly 2 million visitors per year (Bentley 2008). Prior to the Seashore's establishment, however, the island and its environs drew a range of people from fishermen to land developers. While today's Eastern Shore communities continue many of their traditional lifeways related to the island, they now share its resources with tourists from around the world who are drawn to the seeming pristine beaches and famed wild ponies, managed today by two federal agencies (NPS and United States Fish and Wildlife Service [USFWS]).

Inter Simple Sequence Repeats (ISSR) Reveal Genetic Variation Among Mid-Atlantic Populations of Threatened Amaranthus pumilus and Phylogenetic Relationships

Abstract Amaranthus (Amaranthaceae) is a globally distributed plant genus composed of both weedy and cultivated species. While there have been previous attempts to resolve phylogenetic relationships within the genus, little attention has been placed on systematic relationships of the federally threatened coastal species Amaranthus pumilus Raf., endemic to eastern United States barrier islands, nor on genetic variability within the genus. In the present study, single primer ISSRs were employed to measure both genetic diversity and the phylogenetic position of A. pumilus. Leaf tissue samples were taken from wild populations on Fenwick Island, Delaware and from wild and propagated populations on Assateague Island National Seashore, Maryland. Genetic variation was detected among and within A. pumilus populations, though variability was low. Fenwick populations exhibited the highest genetic variability (h = 0.1016), while on Assateague the wild A. pumilus population had higher variability (0.0340) than the p...

Pedigrees and the Study of the Wild Horse Population of Assateague Island National Seashore

ABSTRACT Recently, a number of papers have addressed the use of pedigrees in the study of wild populations, highlighting the value of pedigrees in conservation management. We used pedigrees to study the horses (Equus caballus) of Assateague Island National Seashore, Maryland, USA, one of a small number of free‐ranging animal populations that have been the subject of long‐term studies. This population grew from 28 in 1968 to 175 in 2001, causing negative impacts on the island ecosystem. To minimize these effects, an immunocontraception program was instituted, and horse numbers are slowly decreasing. However, there is concern that this program may negatively affect the genetic health of the herd. We found that although mitochondrial DNA diversity is low, nuclear diversity is comparable to that of established breeds. Using genetic data, we verified and amended maternal pedigrees that had been primarily based on behavioral data and inferred paternity using genetic data along with National Park Service records of the historic ranges of males. The resulting pedigrees enabled us to examine demography, founder contributions, rates of inbreeding and loss of diversity over recent generations, as well as the level of kinship among horses. We then evaluated the strategy of removing individuals (using nonlethal means) with the highest mean kinship values. Although the removal strategy increased the retained diversity of founders and decreased average kinship between individuals, it disproportionately impacted sizes of the youngest age classes. Our results suggest that a combined strategy of controlled breeding and immunocontraception would be more effective than removing individuals with high mean kinships in preserving the long‐term health and viability of the herd.

Monitoring seasonal bat activity on a coastal barrier island in Maryland, USA

Research on effects of wind turbines on bats has increased dramatically in recent years because of significant numbers of bats killed by rotating wind turbine blades. Whereas most research has focused on the Midwest and inland portions of eastern North America, bat activity and migration on the Atlantic Coast has largely been unexamined. We used three long-term acoustic monitoring stations to determine seasonal bat activity patterns on the Assateague Island National Seashore, a barrier island off the coast of Maryland, from 2005 to 2006. We recorded five species, including eastern red bats (Lasiurus borealis), big brown bats (Eptesicus fuscus), hoary bats (Lasiurus cinereus), tri-colored bats (Perimyotis subflavus), and silver-haired bats (Lasionycteris noctivagans). Seasonal bat activity (number of bat passes recorded) followed a cosine function and gradually increased beginning in April, peaked in August, and declined gradually until cessation in December. Based on autoregressive models, inter-night bat activity was autocorrelated for lags of seven nights or fewer but varied among acoustic monitoring stations. Higher nightly temperatures and lower wind speeds positively affected bat activity. When autoregressive model predictions were fitted to the observed nightly bat pass totals, model residuals>2 standard deviations from the mean existed only during migration periods, indicating that periodic increases in bat activity could not be accounted for by seasonal trends and weather variables alone. Rather, the additional bat passes were attributable to migrating bats. We conclude that bats, specifically eastern red, hoary, and silver-haired bats, use this barrier island during migration and that this phenomenon may have implications for the development of near and offshore wind energy.

Coastal 3-D Morphological Change Analysis Using LiDAR Series Data: A Case Study of Assateague Island National Seashore

This article presents our observation and analysis results of coastal three-dimensional morphological changes using U.S. Geological Survey (USGS), National Aeronautics and Space Administration (NASA), and National Oceanic and Atmospheric Administration (NOAA) light detection and range (LiDAR) data. The study area is located in Assateague Island National Seashore, along a 63 km stretch of Assateague Island on the Eastern Shore of Virginia and Maryland. Digital elevation models from LiDAR data over various time intervals, e.g., year-to-year (1996–1997–1997–1998–1998–2000), season-to-season (September, January), and multiyear (1996–2000), were created to test our analysis methods. Six sections in our study area were partitioned in accordance with their historical changes and coastal conditions. Three profiles of each section were extracted from the digital elevation models, and the spatial patterns and volumetric amounts of erosion and deposition of each section on a cell-by-cell basis were calculated. The means of volumetric net change per unit area (m3/m2) of each section were derived. With the analysis of the deposition, erosion, or no change of the study area, the spatial patterns of three-dimensional morphological change pattern can be traced in both detailed and broad extent over varying time periods and frequencies. The analyzed results discovered that the two ends of the island experienced the most significant erosion and deposition, with the changes gradually decreasing toward the middle of the island. The south end of the island had the largest amount of erosion (16,274 m3). The recommendation for light LiDAR data collection frequency is also made.

Seawater and Shellfish (Geukensia demissa) Quality Along the Western Coast of Assateague Island National Seashore, Maryland: An Area Impacted by Feral Horses and Agricultural Runoff

We evaluated the quality of seawater and ribbed mussels (Gukensia demissa) at six sites along the West Coast of Assateague Island National Seashore (ASIS), a barrier island popular with tourists and fishermen. Parameters evaluated were summertime temperature, pH, salinity, dissolved oxygen, total phosphorus, total ammonia nitrogen, and nitrite levels for seawater and total heterotrophic plate counts and total Vibrionaceae levels for the ribbed mussels. Approximately 150 feral horses (Equus caballus) are located on ASIS and, combined with agricultural runoff from animals and croplands, local wildlife, and anthropogenic inputs, contribute to nutrient loads affecting water and shellfish quality. The average monthly dissolved oxygen for June was 2.65 mg L(-1), below the minimum acceptable threshold of 3.0 mg L(-1). Along Chincoteague Bay, total phosphorus generally exceeded the maximum level of 0.037 mg L(-1), as set by the Maryland Coastal Bays Program management objective for seagrasses, with a high of 1.92 mg L(-1) in June, some 50-fold higher than the recommended threshold. Total ammonia nitrogen approached levels harmful to fish, with a maximum recorded value of 0.093 mg L(-1). Levels of total heterotrophic bacteria spiked to 9.5 x 10(6) cells g(-1) of mussel tissue in August in Sinepuxent Bay, leading to mussels which exceeded acceptable standards for edible bivalves by 19-fold. An average of 76% of the bacterial isolates were in the Vibrionaceae family. Together, these data suggest poor stewardship of our coastal environment and the need for new intervention strategies to reduce chemical and biological contamination of our marine resources.

Bats of Assateague Island National Seashore, Maryland

ABSTRACT As significant nocturnal insectivores, bats are an integral part of many ecosystems. Determining bat species composition in an area is a critical first step in managing for this important resource. Little information exists concerning the bat species composition of Maryland's Coastal Plain, which is located on the northern periphery of the geographic ranges of five bat species occurring in the southeastern United States. We conducted mist net surveys for bats at Assateague Island National Seashore, a barrier island on Maryland's coast, in summer 2005 and summer and autumn 2006. In 2005 we captured 133 bats representing three species, including two big brown bats (Eptesicus fuscus), 129 eastern red bats (Lasiurus borealis) and two purported Seminole bats (L. seminolus). In 2006 we captured 60 eastern red bats in summer and autumn combined. We used Anabat II bat detectors to conduct long-term acoustic monitoring on the island year round and documented three additional bat species, including silver-...