Filters: Contacts: D.R. Smith (X)60 results (541ms)
Influence of waves and horseshoe crab spawning on beach morphology and sediment grain-size characteristics on a sandy estuarine beach
The effects of wave action and horseshoe crab spawning on the topography and grain-size characteristics on the foreshore of an estuarine sand beach in Delaware Bay, New Jersey, USA were evaluated using data collected over six consecutive high tides. Data were gathered inside and outside a 25 m long exclosure constructed to create a control area free of disturbance by crabs. The density of crabs in the swash zone outside the exclosure was 8??1 organisms m-2. The maximum depth of sediment activation on the upper foreshore where spawning occurred was 0??103 m during periods characterized by low significant wave heights: < 0??08 m. This depth is greater than the depth of activation by waves alone during moderate significant...
Categories: Publication; Types: Citation; Tags: Sedimentology
Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses...
Categories: Publication; Types: Citation; Tags: Natural Resource Modeling
Categories: Publication; Types: Citation; Tags: Colonial Waterbirds
Comparison of sediment grain size characteristics on nourished and un-nourished estuarine beaches and impacts on horseshoe crab habitat, Delaware Bay, New Jersey
This study was undertaken to determine whether nourished and un-nourished estuarine beaches have conspicuous differences in sediment size and sorting that could affect their value as habitat for horseshoe crabs. Comparisons are made of beach profiles and sediment samples gathered at 0.15 m and 0.30 m depths on the backshore, at spring tide elevation, neap tide elevation, and the lower foreshore on 5 un-nourished and 3 nourished beaches in Delaware Bay, where tidal range is <2.0 m. The backshore is at least 0.5 m higher on the recently nourished beaches than on a nearby un-nourished beach reworked by storm waves. Nourishing these beaches to elevations higher than natural overwash heights will restrict natural evolution...
Categories: Publication; Types: Citation; Tags: Zeitschrift fur Geomorphologie, Supplementband
Estimating Survival and Recruitment in a Freshwater Mussel Population Using Mark-recapture Techniques
We used a mark-recapture method and model averaging to estimate apparent survival, recruitment and rate of population growth in a native freshwater mussel population at a site on the Cacapon River, which is a tributary to the Potomac River. Over 2200 Elliptio complanata, E. fisheriana and Lampsilis cariosa were uniquely tagged over a period of 4 y. Recapture probabilities were higher in spring and summer than in winter except for L. cariosa which had a low probability of recapture regardless of time of year. All three species had high annual adult survival rates (>90%) with lower estimated survival of small (???55 mm) mussels (43%-69%). The variation in apparent survival over time was similar for all three species....
Categories: Publication; Types: Citation; Tags: American Midland Naturalist
A terrain-based paired-site sampling design to assess biodiversity losses from eastern hemlock decline
Biodiversity surveys are often hampered by the inability to control extraneous sources of variability introduced into comparisons of populations across a heterogenous landscape. If not specifically accounted for a priori, this noise can weaken comparisons between sites, and can make it difficult to draw inferences about specific ecological processes. We developed a terrain-based, paired-site sampling design to analyze differences in aquatic biodiversity between streams draining eastern hemlock (Tsuga canadensis) forests, and those draining mixed hardwood forests in Delaware Water Gap National Recreation Area (USA). The goal of this design was to minimize variance due to terrain influences on stream communities,...
Categories: Publication; Types: Citation; Tags: Environmental Monitoring and Assessment
Influence of eastern hemlock (Tsuga canadensis L.) on fish community structure and function in headwater streams of the Delaware River basin
Hemlock (Tsuga canadensis) forest of the eastern U.S. are in decline due to invasion by the exotic insect hemlock woolly adelgid (Adelges tsugae). Aquatic biodiversity in hemlock ecosystems has not been documented; thus the true impact of the infestation cannot be assessed. We compared ichthyofaunal assemblages and trophic structure of streams draining hemlock and hardwood forests by sampling first- and second-order streams draining 14 paired hemlock and hardwood stands during base flows in July 1997 at the Delaware Water Gap National Recreation Area of Pennsylvania and New Jersey. Over 1400 fish of 15 species and 7 families were collected, but hemlock and hardwood streams individually harbored only one to four...
Categories: Publication; Types: Citation; Tags: Ecology of Freshwater Fish
Assessment of sampling methods to estimate horseshoe crab (Limulus polyphemus L.) egg density in Delaware Bay
[No abstract available]
Categories: Publication; Types: Citation; Tags: Fishery Bulletin
Continuous monitoring of dissolved oxygen and total dissolved gas pressure based on head-space partial pressures
Categories: Publication; Types: Citation; Tags: Journal of the World Aquaculture Society
Hemlock stands contribute significantly to aquatic biodiversity Delaware Water Gap National Recreation Area
Categories: Publication; Types: Citation; Tags: ESP Newsletter; The News Bulletin of the Entomological Society of Pennsylvania
How to design an efficient large-area survey continues to be an interesting question for ecologists. In sampling large areas, as is common in environmental studies, adaptive sampling can be efficient because it ensures survey effort is targeted to subareas of high interest. In two-stage sampling, higher density primary sample units are usually of more interest than lower density primary units when populations are rare and clustered. Two-stage sequential sampling has been suggested as a method for allocating second stage sample effort among primary units. Here, we suggest a modification: adaptive two-stage sequential sampling. In this method, the adaptive part of the allocation process means the design is more flexible...
Categories: Publication; Types: Citation; Tags: Population Ecology
Presque Isle Bay, Lake Erie, was listed as an Area of Concern (AOC) by the International Joint Commission in part because of the high incidence of external tumor in brown bullheads. Verifying the source of the possible contaminant exposure is critical to addressing the AOC designation. We used telemetry tracking (n = 49 fish) to test the hypothesis that adult bullheads captured within the bay during spawning season do not exit the bay during the post-spawning summer and fall months. We analyzed genetic variation at 15 microsatellite loci for 112 adult fish from 5 locations, 4 inside the bay and 1 outside, in order to test for possible differences. Data from fixed-station receivers suggested fish did not leave Presque...
Categories: Publication; Types: Citation; Tags: Journal of Great Lakes Research
Petrology and geochemistry of late-stage intrusions of the A-type, mid-Proterozoic Pikes Peak batholith (Central Colorado, USA): Implications for petrogenetic models
The ~1.08 Ga anorogenic, A-type Pikes Peak batholith (Front Range, central Colorado) is dominated by coarse-grained, biotite ?? amphibole syenogranites and minor monzogranites, collectively referred to as Pikes Peak granite (PPG). The batholith is also host to numerous small, late-stage plutons that have been subdivided into two groups (e.g. Wobus, 1976. Studies in Colorado Field Geology, Colorado School of Mines Professional Contributions, Colorado): (1) a sodic series (SiO2= ~44-78 wt%; K/Na=0.32-1.36) composed of gabbro, diabase, syenite/quartz syenite and fayalite and sodic amphibole granite; and (2) a potassic series (SiO2= ~ 70-77 wt%; K/Na=0.95-2.05), composed of biotite granite and minor quartz monzonite....
Categories: Publication; Types: Citation; Tags: Precambrian Research
Immunomodulation and disease resistance in postyearling rainbow trout infected with Myxobolus cerebralis, the causative agent of whirling disease
Myxobolus cerebralis, the myxosporean parasite that causes whirling disease, has a number of deleterious effects on its salmonid host. Although it is well established that juvenile salmonids in the active stages of whirling disease mount an immune response to the pathogen, the occurrence and longevity of any related immunomodulatory effects are unknown. In this study, postyearling rainbow trout Oncorhynchus mykiss infected with M. cerebralis were examined for leukocyte functions and for resistance to Yersinia ruckeri, a bacterial pathogen of salmonids. Compared with uninfected controls, M. cerebralis-infected fish showed lower proliferative lymphocyte responses to four mitogens (concanavalin A, pokeweed mitogen,...
Categories: Publication; Types: Citation; Tags: Journal of Aquatic Animal Health
Virulence of Renibacterium salmoninarum isolates representing five origins was evaluated in eight salmonid hosts; four origins were of Lake Michigan and the fifth was of the Pacific Northwest. The species type strain, ATCC (American Type Culture Collection) 33209, was also included. Each isolate was grown in a kidney disease medium (KDM2) supplemented with 1 % ATCC 33209 culture metabolite; serial 10-fold dilutions were prepared, and groups of fish were challenged by intraperitoneal injection with 0.1 mL of each dilution. A 70-d observation period followed, and bacterial kidney disease (BKD) was diagnosed by the fluorescent antibody technique. Virulence of isolates was quantified as a dose lethal to 50% of fish...
Categories: Publication; Types: Citation; Tags: Journal of Aquatic Animal Health
Acoustic-tracking and radio-tracking of horseshoe crabs to assess spawning behavior and subtidal habitat use in delaware bay
This study used telemetry to determine spawning behavior and subtidal habitat use of horseshoe crabs Limulus polyphemus. We attached combined acoustic and radio transmitters to 12 gravid female horseshoe crabs at Ted Harvey Beach and 12 at North Bowers Beach (both on the western shore of Delaware Bay) over a 5-d period before peak spawning on the new moon. Horseshoe crabs were acoustically tracked and radio-tracked daily for 8 d during both high tides and during the incoming dominant (higher) high tide. All horseshoe crabs were relocated at least once, and 83% of females spawned from two to six times (x?? = 3.35, SE = 0.18). Of these females, 85% spawned on two to five consecutive nights (x?? = 3.31, SE = 0.59)....
Categories: Publication; Types: Citation; Tags: North American Journal of Fisheries Management
Categories: Publication; Types: Citation; Tags: Journal of Wildlife Management
Designing large-scale surveys of wildlife abundance and diversity using statistical sampling principles
Categories: Publication; Types: Citation; Tags: Transactions of the North American Wildlife and Natural Resources Conference
Spatial and temporal distribution of horseshoe crab (Limulus polyphemus) Spawning Delaware Bay: implications for monitoring
Categories: Publication; Types: Citation; Tags: Estuaries
Management and monitoring of the endangered Shenandoah salamander under climate change: Workshop report 10-12 April 2012
Here we report on a structured decision making (SDM) process to identify management strategies to ensure persistence of the federally endangered Shenandoah salamander (Plethodon shenandoah), given that it may be at increased extinction risk under projected climate change. The focus of this report is the second of two SDM workshops; in the first workshop, participants developed a prototype of the decision, including problem frame, management objectives and a suite of potential management strategies, predictive models to inform the decision and link alternatives with the objectives to identify potential solutions, and identified data needs to reduce key uncertainties in the decision. Participants in this second workshop...
Categories: Publication; Types: Citation; Tags: Natural Resource Report