Using GPS telemetry to validate least-cost modeling of gray squirrel ( Sciurus carolinensis) movement within a fragmented landscape

In Britain, the population of native red squirrels Sciurus vulgaris has suffered population declines and local extinctions. Interspecific resource competition and disease spread by the invasive gray squirrel Sciurus carolinensis are the main factors behind the decline. Gray squirrels have adapted to the British landscape so efficiently that they are widely distributed. Knowledge on how gray squirrels are using the landscape matrix and being able to predict their movements will aid management. This study is the first to use global positioning system (GPS) collars on wild gray squirrels to accurately record movements and land cover use within the landscape matrix. This data were used to validate Geographical Information System (GIS) least-cost model predictions of movements and provided much needed information on gray squirrel movement pathways and network use. Buffered least-cost paths and least-cost corridors provide predictions of the most probable movements through the landscape and are seen to perform better than the more expansive least-cost networks which include all possible movements. Applying the knowledge and methodologies gained to current gray squirrel expansion areas, such as Scotland and in Italy, will aid in the prediction of potential movement areas and therefore management of the invasive gray squirrel. The methodologies presented in this study could potentially be used in any landscape and on numerous species

Oscillations of Dynamic Topography in the Eastern Equatorial Pacific

For 14 months in 1980–81, surface dynamic height was monitored with inverted echo sounders at five sites from 0 to 9°N along 110°W. These records show that the SEC/NECC equatorial current system was well-developed during the boreal summer and fall, but weak and irregular during winter and spring when westward flow associated with the NEC extended as far south as 6°N. Superimposed on the mean dynamic topography of this region are energetic 20-to-80-day oscillations, longer periods being associated with higher latitudes. Near the equatorial ridge (∼5°N), these oscillations have predominantly monthly periods, and amplitude of ∼10 dyn cm comparable to the mean dynamic-height difference across the NECC. The broad in-phase meridional extent of these monthly oscillations implies that the principal mode of ridge variation is vertical undulation rather than meridional meandering, producing large in-phase monthly modulations in transport of the SEC and NECC. Oscillations or the equatorial ridge are correlated with propagating ∼1000-km wavelength sea surface temperature (SST) wave patterns observed in satellite infrared imagery. Passage of a northerly SST crest on the equatorial front at 110°W corresponds to a dynamic height minimum on the equatorial ridge. The relative phase and trochoidal shape of these crests is explained kinematically by superposition of the observed mean and oscillatory dynamic-height fields

Fundamental‐mode basin oscillations in the Japan/East Sea

We present observational evidence from coastal tide station and bottom pressure data that basin‐mode oscillations are frequently excited in the Japan/East Sea (JES). The fundamental basin‐mode is a Kelvin‐wave‐like oscillation consisting of a single amphidromic system around which the high water propagates counter‐clockwise. Its period is about 6.7 hours and its coastal wavelength is equivalent to the circumference of the JES. The relative amplitudes of the observed oscillations agree with Rikiishi\u27s 1986 model results except for stations near the Korea Strait where the closed boundary in the model produces unrealistically high amplitudes. The basin oscillation amplitude varies on synoptic time scales (2–17 days) and exhibits seasonal variations. The optimal wind direction to generate basin‐mode oscillations is along 60°/240° T

The Residual GEM technique and its application to the southwestern Japan/East Sea

The standard gravest empirical mode (GEM) technique for utilizing hydrography in concert with integral ocean measurements performs poorly in the southwestern Japan/East Sea (JES) because of a spatially variable seasonal signal and a shallow thermocline. This paper presents a new method that combines the U.S. Navy\u27s Modular Ocean Data Assimilation System (MODAS) static climatology (which implicitly contains the mean seasonal signal) with historical hydrography to construct a “residual GEM” from which profiles of such parameters as temperature (T) and specific volume anomaly (δ) can be estimated from measurements of an integral quantity such as geopotential height or acoustic echo time (τ). This is called the residual GEM technique. In a further refinement, sea surface temperature (SST) measurements are included in the profile determinations. In the southwestern JES, profiles determined by the standard GEM technique capture 70% of the T variance and 64% of the δ variance, while the residual GEM technique using SST captures 89% of the T variance and 84% of the δ variance. The residual GEM technique was applied to optimally interpolated τ measurements from a two-dimensional array of pressure-gauge-equipped inverted echo sounders moored from June 1999 to July 2001 in the southwestern JES, resulting in daily 3D estimated fields of T and δ throughout the region. These estimates are compared with those from direct measurements and good agreement is found between them

South Atlantic mass transports obtained from subsurface float and hydrographic data

Mean total (barotropic + baroclinic) mass transports of the oceanic top 1000 dbar are estimated for two regions of the South Atlantic between 18°S and 47°S. These transports are obtained by using Gravest Empirical Mode (GEM) fields calculated from historical hydrography with temperature and position data from quasi-isobaric subsurface floats deployed from 1992 through 2001. The float-GEM-estimated total mass transports reveal a Brazil Current with a southward flow of 20.9 Sv at 30°S and 46 Sv at 35°S (1 Sverdrup, Sv = 106 m3 s–1). Two recirculation cells are identified in the southwest corner of the subtropical gyre north of 40°S, one centered at 48°W, 37°S recirculating 28.5 Sv and another centered at 40°W, 38°S recirculating 13.9 Sv. The South Atlantic Current (SAC) flows eastward with 50 Sv at 30°W and splits into two branches in the east, one north of 38°S transporting 19 Sv and one south of 41°S transporting 31 Sv. Of the 39.7 Sv of SAC transport that comes from the Malvinas Current/Antarctic Circumpolar Current (ACC) system in the western basin, only 8.7 Sv flow with the northern branch and the remaining 31 Sv flow as the southern branch out of the South Atlantic rejoining the ACC directly (20.6 Sv) or interacting with the Agulhas Current Retroflection (10.4 Sv). From the northern branch, only 4.7 Sv of Malvinas Current/ACC origin and 10.3 Sv of Brazil Current origin (a total of 15 Sv) stays in the South Atlantic forming the Benguela Current, recirculating within the subtropical gyre. The Agulhas Current Retroflection reaches westward as far as 10°E with a transport of 48 Sv. In terms of mean total transport, the cold-water route carries 4.7 Sv in the upper 1000 dbar whereas the warm-water route carries 8.5 Sv. However, considering the interaction between waters from both origins, there is a total of 19.1 Sv of waters entering the Cape Basin from the Pacific Ocean and 18.5 Sv from the Indian Ocean

Gulf Stream and wind‐induced current variability on the Georgia continental shelf, winter 1978

Low‐frequency longshore current fluctuations on the continental shelf off Georgia and their relationships with local atmospheric forcing and Gulf Stream displacement were examined for a 3‐month period from January to April 1978. (Acoustic travel time and bottom pressure measurements at a station on the continental slope were used to determine the depth of the main thermocline, as an indicator of Gulf Stream displacement.) On the middle shelf, current variability was dominated by local wind forcing at periods longer than 2 days, with very little Gulf Stream influence. Longshore wind stress was the main driving force at periods longer than 4 days, while cross‐shore wind contributed at shorter periods. In contrast, on the outer shelf, current fluctuations in the upper layer were highly coherent with Gulf Stream displacement at a 12‐day period, and marginally coherent with longshore wind at a 6‐day period. Linear regression analysis showed that Gulf Stream and local wind forcing accounted for most of the fluctuations in the upper layer over the shelf break for time scales greater than 5 days and at around 2 days. A low multiple coherence window at 2.8–5 days was probably due to Gulf Stream frontal eddies. In the lower layer over the shelf break the current fluctuations had a character intermediate between the upper layer currents (Gulf Stream dominated) and mid‐shelf currents (wind dominated)

Second‐mode internal tides in the East China Sea deduced from historical hydrocasts and a model

From historical hydrocasts in the Okinawa Trough region of the East China Sea (ECS), acoustic echo time from 700 dbar to the surface shows a tight relationship with temperature (T) except near the 100–200‐dbar layer. This is caused by 2nd‐ or higher‐mode baroclinic variations. Significant out‐of‐phase correlation between upper and lower layer T from the hydrocasts confirms that 2nd‐mode variations are strong. Furthermore, the 2nd‐mode variations are dominant during the ebb tide period, which suggests they are caused by 2nd‐mode internal tides (ITs) generated at the continental shelf break. For comparison, we investigate historical hydrocasts southeast of the Ryukyu Islands, where no significant 2nd‐mode variations are found. A model simulating the M2 IT agrees qualitatively with these observations: it predicts relatively strong 2nd‐mode IT energy in the ECS, but weak energy in the region southeast of the Ryukyu Islands

Effect of Hydrodynamics on Sediment Transport near a Coastal Inlet

River, Estuarine and Coastal Dynamic

Animated PowerPoint Presentations For Teaching Operations And Supply Chain Management: Perceived Value And Electronic Exchange Of Files

This paper presents the innovation of sharing animated PowerPoint presentations used in teaching operations and supply chain management techniques and concepts through an international electronic exchange. The plan for the exchange is presented and discussed. The potential benefits to faculty and students of using PowerPoint animations in operations and supply chain management classes are discussed. Evidence of these benefits is also provided. Readers are provided with information about how to join the exchange