Average Rate Of Movement Research Articles

Spatial ecology of wolverines at the southern periphery of distribution

AbstractWolverines (Gulo gulo) in the conterminous United States have experienced range contraction, are uncommon, and have been designated as warranted for protection under the United States Endangered Species Act. Data from the southern edge of the wolverine's circumpolar distribution is sparse, and development of effective conservation strategies would benefit from a more complete understanding of the species' ecology. We captured and radio‐monitored 30 wolverines in the Greater Yellowstone Ecosystem (GYE), tested for seasonal habitat selection by elevation band, and examined a suite of spatial characteristics to clarify our understanding of the wolverine's niche. Wolverines in GYE selected for areas >2,600 m latitude‐adjusted elevation (LAE;n = 2,257 wolverine locations [12 F, 6 M]). Wolverines avoided areas <2,150 m LAE, including during winter when the vast majority of ungulates are pushed to these elevations by deep snow. Wolverine home ranges were large relative to body size, averaging 303 km2for adult females and 797 km2for adult males (n = 13 [8 F, 5 M] and 33 wolverine‐years). Resident adults fit with Global Positioning System (GPS) collars used an area >75% the size of their multi‐year home range in an average of 32 days (n = 7 [5 F, 2 M]). Average movement rates of 1.3 km/2‐hr indicated that both sexes move distances equivalent to the diameter of their home range every 2 days or the circumference of their home range in <1 week (n = 1,329 2‐hr movements,n = 12 individuals [7 F, 5 M]). This capability for movement, the short time‐frame over which home ranges were developed, and a lack of home range overlap by same sex adults (${\bar {x}} = 2.1\%\;{\rm overlap}$, 90% CI = 0.0–4.8%,n = 22 pairs) suggested territoriality. We estimated wolverine density to be 3.5/1,000 km2of area >2,150 m LAE (95% CI = 2.8–9.6). Dispersal movements extended to at least 170 km for both sexes (n = 5 F, 2 M). At the southern edge of distribution, where suitable and unsuitable conditions exist in close proximity, wolverines selected high‐elevation areas near alpine tree‐line where a mix of forest, meadow, and boulder fields were present, deep snow‐cover existed during winter, and low temperatures near freezing can occur throughout the year. Persistence in these areas where the growing season is brief requires large home ranges that are regularly patrolled, a social system that provides exclusive access to resources, and low densities. These characteristics, along with low reproductive rates, are prevalent throughout the species range, indicating that wolverines are specialists at exploiting a cold, unproductive niche where interspecific competition is limited. The vulnerability inherent in occupying this unproductive niche was likely influential in previous declines within the conterminous United States and will remain a factor as wolverines encounter modern human influences. Conserving wolverines in the conterminous United States will require collaborative management over a large geographic scale. © 2011 The Wildlife Society.

The effect of fluoride on orthodontic tooth movement in humans. A two- and three-dimensional evaluation

Abstract Aims: The aim of the present study was to determine whether high and low fluoride concentrations in drinking water affected the early stages of tooth movement when heavy and light orthodontic forces were applied for 4 weeks. A further aim was to compare and evaluate the resulting two-dimensional (2-D) and three-dimensional (3-D) orthodontic tooth movement. Methods: The sample consisted of 96 maxillary upper first premolars from 48 patients who required premolar extractions as part of their orthodontic treatment. Patients were selected from two different cities in Turkey with low and high fluoride concentrations of 0.05 and 2 ppm, respectively. The patient sample was divided into four groups according to the magnitude of force applied to the first premolars and the concentration of fluoride in the public water supply; Group 1, High fluoride intake (≥ 2 ppm)-Heavy force (225 g); Group 2, Low fluoride intake (≤ 0.05 ppm)-Heavy force; Group 3, High fluoride intake-Light force (25 g); and Group 4, Low fluoride intake-Light force. A light or heavy buccal tipping orthodontic force was applied to the upper first premolars for 4 weeks. The first three palatal rugae were used for the superimposition of patient casts in a 2-D and 3-D evaluation of generated movements. Results: It was found that heavy force application and fluoride intake increased the average rate of tooth movement. It was further shown that age was negatively correlated with tooth movement in the 2-D and 3-D measurements. Conclusions: The average rate of tooth movement was found to be greater in the heavy force and high fluoride intake group (Group 1HH). Age was negatively correlated with orthodontic tooth movement. Two- and three-dimensional methods were accurate for the assessment of tooth movement after four weeks of buccal tipping force application when the palatal rugae were used for superimposition.

Post 3.9 Ma fault activity within the West Antarctic rift system: onshore evidence from Gandalf Ridge, Mount Morning eruptive centre, southern Victoria Land, Antarctica

AbstractA hawaiite dyke dated at 3.88 ± 0.05 Ma from the Mount Morning eruptive centre intrudes a diamictite deposit at Gandalf Ridge in the southern Ross Sea. The dyke has been dextrally offset up to 6 m horizontally by faults interpreted as the onshore continuation of the West Antarctic rift system (WARS) fault array. Felsic dykes emplaced during the Miocene are also present at Gandalf Ridge. The offset of the Miocene dykes is equivalent to the offset on the hawaiite dyke, suggesting that at this locality movement on faults within WARS has been restricted to a period more recent than c. 3.88 Ma. Over this period the minimum average rate of movement on these faults within WARS is 0.0015 mm yr-1.

Daily and hourly movement of male desert‐dwelling elephants

AbstractThe daily and hourly movements of eight male desert‐dwelling elephants of various ages (12–45 years old) were determined hourly by global positioning system (GPS)/telemetry collars during the wet, cold dry and hot dry seasons of 2006 in northwest Namibia. The average daily movement in the wet season was greater than that observed during either the cold dry or the hot dry seasons. A similar difference was also observed for the movement rates, with the highest average rate of hourly movement recorded during the wet season. The diurnal movements (both distance and rate) were greater than those in the nocturnal hours during the wet season, whilst during the cold dry and hot dry season the reverse was true. The daily cycle of movement also changed seasonally, with greatest movement rates observed during the wet season between 11.00–20.00 hours, during the cold dry season between 14.00–21.00 hours; and between 04.00–11.00 hours during the hot dry season. Periods of decreased movement rates were observed between 09.00–10.00 and 02.00–03.00 hours in the wet season; 03.00–06.00 and 11.00–13.00 hours in the cold dry season; and 01.00–03.00 and 12.00–14.00 hours during the hot dry season.

Spatial and temporal segregation allows coexistence in a hybrid zone among two Mediterranean vipers (Vipera aspis and V. latastei)

Abstract Mediterranean vipers are ecologically very similar. When in contact, they constitute an exceptional model to study the effects of competitive interactions and niche segregation mechanisms. In High Ebro, distinct methodologies (random visual encounter, road sampling and radio-tracking surveys, captive maintenance, standardized transects and ad hoc field observations) were used to compare ecological traits (diet, micro-habitat, activity, reproductive and demographic) of V. aspis, V. latastei and hybrids among both species and determine competitive advantages of each form. Diet preferences were similar but few differences were found in feeding frequency and annual variation in diet consumption. Males of the three forms compete for areas with similar characteristics but differences were found mainly during summer. Significant differences in average movement rates and home range size were found among males. Fecundity and new-borns fitness were lower in V. aspis than in V. latastei, whereas hybrids had intermediate values. Male and female adult hybrids were more abundant than parental forms, whereas female and juvenile V. latastei and juvenile hybrids had high road-mortality. The three forms seem to be competing intensely for resources but the segregation on the spatial and temporal axes of their niches could be reducing interspecific competition and allowing coexistence. The use of different resources probably confers reproductive and demographic advantages for V. latastei and hybrids, respectively. Moreover, reproductive fitness of hybrids suggests the occurrence of endogenous selection. Comparative thermal and genetic studies are needed to clarify the limiting factors of vipers and to establish a model of the hybrid zone.

Study of soil mass movement in harvested areas of Caspian Forest, northern Iran

Mass movements and landslides are important factors that have contributed to the destruction of natural mountainous forests in northern Iran. The phenomenon is compounded by road construction and other human-induced development projects. Factors mainly attributed to soil instability in such areas are topography; hydro-geology, geology, and pedology. The Chafroud forest district located in western Guilan was selected as the study area chiefly because of its high incidence of landmass movement and landslides. Areas with higher mass movement rates were selected (showing an average movement rate of 80~100 cm during the seven months of from August 2005 to March 2006) for further assessment of mass movement type and rate, as related to soil type and mechanical features. Leveling operations and soil mechanical tests including Atterberg limits pertaining to liquid, plastic, shrinkage limits, and related indices, soil grading, and texturing were carried out. Results revealed that the main movement type was landslides caused by a combination of high moisture content in a fine-grained soil texture which prevented drainage. The most amount of landslide occurred in winter that assume the winter rainfall has saturated the clay soil of the regions and eventually increased the landslide. The natural water content of the soil in the sliding region increases with the increase of soil depth. This fact indicates that water content at depth is higher than the surface water content. Hence, scattered clay layers present at deeper levels contain higher amounts of water. Since clay loses its water content slowly, high water content in deeper layers results in instability of the soil structure and, consequently, results in landslides creating a higher level of damage.

56 years of solifluction measurements in the abisko mountains, northern sweden – analysis of temporal and spatial variations of slow soil surface movement

.Solifluction movement rates from 1952 to 2008 for the Abisko region, northern Sweden, have been compiled and analysed through correlation tests and multiple regression. The temporal analysis is based on two datasets (Lobe11 & gridAB and Line B) from Kärkevagge. The dataset Lobe11 & gridAB show a strong correlation between movement rates and mean annual air temperature (MAAT) and MAAT is also identified as one of the significant contributing parameters in the multiple regression model. No significant correlations were found for the Line B dataset. The spatial analysis indicates generally higher movement rates in the western part of the region and at lower altitudes mainly between 700 and 900 m a.s.l., but the spatial variability is high. To reduce the influence of the temporal variation the data for the correlation tests of the spatial variations were divided into two parts: 1957 to 1980 and 1981 to 2008. The correlation analysis of the dataset 1957 to 1980 shows a significant negative correlation between annual average movement rates and permafrost probability and altitude. The dataset 1981 to 2008 shows a positive correlation between movement rates and wetness index. It is concluded that movement rates may increase with higher MAAT in the western part of the region (Kärkevagge), the spatial variability of movement rates within the region is very high and that altitude (and/or permafrost) together with wetness index are the main controls on the regional spatial variation. The study highlights the limitations in establishing statistical relationships between movement rates and climate using data from different field empirical studies.

Modeling the slowing of neurofilament transport along the mouse sciatic nerve

Neurofilaments are transported along axons in the slow component of axonal transport. The average rate of movement is generally quoted as several millimeters or tenths of a millimeter per day, but this rate is known to decrease while the neurofilaments are in transit due to spatial and temporal factors that are not understood. We have previously presented a stochastic model for neurofilament movement in vivo based on the transport kinetics of single neurofilaments observed by time-lapse fluorescence imaging in cultured neurons. The model took into account multiple velocity states and was only accessible through computational simulations. In simulations of the movement of a pulse of radiolabeled neurofilaments, this model generated a Gaussian wave which closely matched the experimental data. Here we present a simpler model with only three velocity states which is more amenable to analytical approaches. We show that the transport wave can be fully described by the mean and variance and we present analytical solutions for these cumulants in terms of the kinetic parameters of the model. We use the resulting expressions to examine the slowing of neurofilament transport in the mouse sciatic nerve. We show that the slowing is accompanied by an increase in the spread of the wave and that these changes are most readily explained by a change in the rate at which neurofilaments reverse their direction of movement. This suggests that the directionality of neurofilament transport in axons may be under spatial and/or temporal control and that alterations in the directionality of neurofilament transport could provide a mechanism for regulating the transport and distribution of these cytoskeletal polymers along axons.

Climatology of Surface Cyclone Tracks Associated with Large Central and Eastern U.S. Snowstorms, 1950–2000

Abstract The 241 largest snowstorms over the eastern two-thirds of the United States during 1950–2000 exhibited considerable temporal variability ranging from 1 storm in three winters to 10 storms in 1993/94. The peak decadal frequency was 55 storms (1950s), and the minimum was 45 storms (1970s and 1980s). The east–north-central region experienced the greatest number of large snowstorms (148) followed by the west–north-central (136) and central (133) regions. Regional trends were different. Assessment of surface cyclone tracks associated with the large snowstorms identified three primary tracks: one was located from the leeward side of the south-central Rocky Mountains east-northeast toward the Great Lakes; a second was from the lower Mississippi River basin northeastward toward the Great Lakes; and a third was along the coastal mid-Atlantic region northeast toward Maine. Temporal differences in the frequency of certain surface cyclone tracks were related to the decadal trends in regional large snowstorm occurrence. The minimum surface pressure associated with these storms ranged from 959 to 1013 hPa with more than 67% of all storms having a minimum surface pressure between 980 and 999 hPa. The average orthogonal distance from the storm track to the heavy snow region was 201 km. The average rate of cyclone movement ranged from less than 483 to more than 1930 km day−1, with more than 57% of storms moving between 805 and 1287 km day−1.

Slow mass movement in the Kangchenjunga Area, Eastern Nepal Himalaya

The rates of the accumulated and continuous displacement of solifluction lobes in the Kangchenjunga area, eastern Nepal Himalaya, were determined using glass fiber tubes and a strain probe. Ground temperature, precipitation and soil moisture were monitored at two sites, whose altitude differed by approximately 100 m, to understand the solifluction process. The average movement rate of the glass fiber tubes on a 31° slope at altitudes of 5412–5414 m a.s.l. was approximately 11 mm/year, being almost threefold greater than that observed on a 22° slope at 5322–5325 ma.s.l. There was no significant difference in the depth of displacement at these sites. The continuous displacement measurement near the ground surface at 5414 m showed permanent downslope movement from early July. Such movement may be attributed to additional moisture supply during the monsoon season. The amplitude of the displacement cycle was highest at the ground surface, and decreased to virtually zero at and below 20 cm in depth. Probable factors leading to the relatively slow rates of downslope displacement at the surface and depth at the studied altitudes are the lack of concurrence of the freeze–thaw cycles and the high moisture condition in the soil, and the low moisture retention capacity of the soil because of steep slopes and superficial desiccation. The rate of displacement may be more pronounced at altitudes above 5600 m because of the freeze–thaw cycles during the summer season.

Movements and Habitat Selection of Raccoon Dogs (Nyctereutes procyonoides) in a Mosaic Landscape

To test how interindividual variation in response to resource availability might reveal mechanisms leading to interpopulation variation across the geographic range of a species, we investigated movement patterns and use of space by 18 radiocollared raccoon dogs (Nyctereutes procyonoides viverrinus) in a mixed landscape of agriculture and forestry that is widely distributed in Japan, and that is a typical landscape for raccoon dogs. We tested the idea that the behavior of raccoon dogs, as ecological generalists, is sufficiently plastic for individual movement patterns to match habitat variation in this landscape. Home ranges averaged 111 ha (95% kernel estimate), much larger than previously reported for this species in Japan, and varied greatly among individuals (23–228 ha). Home ranges were 62.5% larger in autumn than in other seasons, and 33.5% larger for subadults than for adults. Average movement rate tended to be higher in autumn (mean rate = 297 m/h), and lowest in winter (mean rate = 204 m/h). Within the population, some individuals occupied home ranges that were predominantly seminatural (we refer to these animals as “mountain type”), whereas those of others were dominated by heavily managed habitats (these we term “village type”). Within their home ranges, the types showed preferences for the habitats that were most prevalent there. Mountain-type individuals showed a preference for herbaceous habitat, whereas the village-type individuals used cropland disproportionately. Activity, as measured by the proportion of fixes designated active, tended to be lower in home ranges where cropland was predominant, and the magnitude of preference for cropland increased with its availability with the home range, suggesting a functional response to habitat availability. The fractal dimension of movement trails was more complex in seminatural areas than in agricultural land, possibly reflecting greater spatial regularity of agricultural habitat.

Horizontal and vertical movements of unionid mussels in a lowland river

AbstractFreshwater mussels are important constituents of freshwater ecosystems, yet much of their basic biology remains to be examined. The behavior of 3 species of unionid mussels (Unio tumidus, Unio pictorum, and Anodonta anatina) was examined in the lowland River Spree (Germany). Mussels were marked individually, and their positions on the sediment surface and depth below the sediment surface were recorded weekly between May and October 2004. The average rate of horizontal movement was 11 ± 15 cm/wk (mean ± 1 SD). The direction of the movements seemed erratic; however, a significant net shoreward displacement of ~17 cm, possibly caused by rising water levels, was observed during the study. A surprisingly high percentage of the mussels (74 ± 7%) was burrowed entirely in the sediment to depths as great as 20 cm during the summer. Smaller mussels and individuals not infested by the zebra mussel, Dreissena polymorpha, burrowed deeper in the sediments than larger or infested mussels. Burrowing reduced infes...

Using geochemical fingerprinting to determine transpressive fault movement history: Application to the New Zealand Alpine Fault

Geochemical fingerprinting of conglomerate clasts from depocenters adjacent to a strike‐slip fault, and of source areas on the opposite side of the fault, provides a method of determining fault movement history in instances where potential piercing points have been removed by erosion or buried in pull‐apart or down‐warp basins. Our example demonstrating this method is the Neogene Maruia Basin adjacent to the New Zealand Alpine Fault, the on‐land Australian‐Pacific plate boundary, which shows Permian Pelorus‐Caples terrane offset by 480 km. Twenty‐six sandstone and schist conglomerate clasts from the Maruia Basin Rappahannock Group were analyzed for major elements and 18 trace elements by X‐ray fluorescence and compared to similar analyses from potential regional source areas. Significant source terranes, the Caples Group and the Torlesse terrane were identified, both located southeast of the fault. Dextral movement on the fault provided a conveyor belt of material to the Maruia Basin, first supplying (at ∼11.5 Ma) Caples sandstone, then Caples schist followed by Torlesse schist (from ∼9.5 Ma), which translates to an average Neogene movement rate of 36–37 mm yr−1. The increase in metamorphic grade reflects accelerated exhumation of source rocks as they passed through a restraining bend adjacent to the Maruia Basin and from later regional uplift from a change in the Australian Pacific plate motion vector and more transpressive movement from ∼5 Ma. This robust method of geochemical fingerprinting could be readily applied to determining movement history of transpressive faults of other regions.

Slow mass movement in the Kangchenjunga area, eastern Nepal Himalaya

Abstract The rates of the accumulated and continuous displacement of solifluction lobes in the Kangchenjunga area, eastern Nepal Himalaya, were determined using glass fiber tubes and a strain probe. Ground temperature, precipitation and soil moisture were monitored at two sites, whose altitude differed by approximately 100 m, to understand the solifluction process. The average movement rate of the glass fiber tubes on a 31° slope at altitudes of 5412–5414 m a.s.l. was approximately 11 mm/year, being almost threefold greater than that observed on a 22° slope at 5322–5325 ma.s.l. There was no significant difference in the depth of displacement at these sites. The continuous displacement measurement near the ground surface at 5414 m showed permanent downslope movement from early July. Such movement may be attributed to additional moisture supply during the monsoon season. The amplitude of the displacement cycle was highest at the ground surface, and decreased to virtually zero at and below 20 cm in depth. Probable factors leading to the relatively slow rates of downslope displacement at the surface and depth at the studied altitudes are the lack of concurrence of the freeze–thaw cycles and the high moisture condition in the soil, and the low moisture retention capacity of the soil because of steep slopes and superficial desiccation. The rate of displacement may be more pronounced at altitudes above 5600 m because of the freeze–thaw cycles during the summer season.

Differential single-frequency GPS monitoring of the La Valette landslide (French Alps)

Recently, Global Positioning System (GPS) surveying techniques have been increasingly employed to monitor landslide movement. Here we present an application of GPS to monitor the La Valette landslide, located in the Ubaye Valley in the southern French Alps. This complex landslide is composed by an upper rotational part, a central part with generally translational movement and a lower part, which occasionally transforms into mud flows during intense rainfall events. Displacement rates average a few centimeters per month, with velocity peaks of some centimeters per day during periods of strong activity. GPS data presented in this study were acquired with two single-frequency GPS receivers Magellan connected to multipath-resistant antennas. The data were processed with the Magellan software MSTAR. Nine points have been set in the studied area, seven of them in the moving area, one in a stable area near the landslide and one on the facing slope, which is used as reference point. For each observation, one GPS receiver is placed on the reference point for the whole day and the second one is placed on each monitored point for 1-h sessions. The distance between the base and monitored point ranges from 480 to 1660 m. Eight survey campaigns were made between October 2000 and October 2002, to follow the evolution of the surface displacements. The maximum cumulative 3-D displacement observed in the area was about 21 m during the period in the center part of the landslide, corresponding to an average rate of movement of about 3 cm/day. The accuracy achieved during the GPS measurements has been evaluated to be about 2.4 cm in E–W direction, about 11 cm in N–S direction and about 7.4 cm in elevation in the worst case. The GPS results have been compared with traditional surveying techniques (EDM) carried out on the same site by RTM Service (Restauration des Terrains en Montagne). The velocities obtained by the two methods are similar. The advantage of the GPS technique is the collection of data for the three spatial coordinates ( x, y, z) of each point, which allow to calculate the 3-D displacement vector. These measurements have been combined with SAR interferometric data in order to analyse the temporal evolution of the different landslide sectors.

Ultrasonic tracking of Greenland sharks, Somniosus microcephalus, under Arctic ice

Six Greenland sharks, Somniosus microcephalus (Bloch and Schneider, 1801), 190–355 cm fork length, were tracked under land-fast sea ice off northern Baffin Island (73.2°N; 85.3°W) between 16 and 28 May 1999, using ultrasonic telemetry. The sharks were tracked continuously for periods of 5.5–13.0 h, with the tracks of two individuals lasting 31.4 and 42.8 h, respectively, each with an interval when the track was lost. Several sharks dove after release and moved along the ocean bottom for the duration of the tracking period, while others varied their movements regarding course and depth. Two sharks made repeated visits to within 11 m of the ice–water interface from deeper water. The tracked sharks exhibited no apparent depth or temperature preferences, and pooled data indicated that sharks remained deep during the morning and gradually moved into shallower depths through the afternoon and night. Rates of descent (average=0.099 m s−1) were significantly greater than rates of ascent (average=0.058 m s−1) for all sharks, and the average rate of horizontal movement over ground was estimated as 0.215 m s−1. Based on the movements of tracked sharks and information contained in the literature, S. microcephalus may prey on seals in areas covered by land-fast sea ice.

Strains and displacements in the Mam Tor landslip, Derbyshire, England

The spectacular Mam Tor landslip, near Castleton, Derbyshire, formed over 3000 years ago on an oversteepened slope left after the last ice age. A section of the Namurian Edale mudstones and overlying Mam Tor sandstones has collapsed, leaving an 80 m high scar on the eastern side of Mam Tor. The slip is about 750 m long and nearly 300 m wide and has the old main road from Manchester to Sheffield built across it. The slipped mass is in a state of year-on-year creep motion, which over the 190 years since the construction of the highway has led to extensive damage to the road, culminating in its closure in 1979. Since 1996 we have carried out annual monitoring by electronic distance measurement of the movement of a network of some 30 stations on the slipped mass. The average movement rate of the whole mass is about 10 cm a −1 , with the central region moving significantly faster, at almost 50 cm a −1 . Thus substantial readjustments of mass are taking place within the landslip. Local vertical displacements are systematically related to horizontal offsets, and the ratio of the two allows inference of the local attitude of the basal slip surface. The development of surface morphological features (pressure ridges and irregular topography, shear offsets on the highway, bulging of the road surface) reflects the lateral variations in displacement rate. Comparison of our survey of the present-day road position with that recorded in the topographical survey of 1880 shows a total 40 m downhill displacement of the highway over 122 years. This is consistent with extrapolation of our measured displacement rates back to 1880. Displacement rates within this period are, however, clearly higher than during the past 3000 years. There is a fairly clear correlation between vertical and horizontal displacement rates and annual variations in rainfall, with accelerated displacements following winter rainfall above a critical threshold level. Using survey points to define nodal points of a network of triangles, we have analysed the distribution of strain within the slipped mass. This revealed a pattern of continuous strain variations comparable with that found in flowing glaciers. In the lower part of the slip, horizontal strains are contractional and triangle areas are decreasing, causing some uplift of the ground relative to the general downhill flow on the basal slip surface. In the uphill part, strains are extensional and triangle areas are increasing. The new data allow an estimate of the time-dependent rheological behaviour of the sheared mudstone in the basal shear zone. The shear stress vs. shear strain rate relationship is very non-linear, with significant shear strain rates occurring only at shear stress levels within 10% of that required for rapid (catastrophic) shearing.

Quantification of erosion patterns in the Brahmaputra–Jamuna River using geographical information system and remote sensing techniques

AbstractThere is significant evidence of frequent and rapid erosion and fast rates of bank line retreat along the river Brahmaputra–Jamuna within Bangladesh. This study is aimed at quantifying the actual rates of bank erosion along the river based on time series analysis of satellite images and historical maps. Analysis shows that the erosion rates in the Brahmaputra–Jamuna River were 160 m year−1 between 1973 and 1992, indicating the severity of erosion hazard along the river. This study also revealed the fact that the river has migrated westwards at an average movement rate of 50 m year−1 during the period of 1830–1992. In 1830, the river had an average width of 6·2 km, but by 1992 the average width had increased to 10·6 km. The channel has widened at an average rate of 27 m year−1 during 1830–1914. After that, it has widened at an average rate of 65 m year−1. The average width of the river has increased about 130 m year−1 since 1973. Analysis of the Landsat images shows that, over the whole river, riverine islands most often persist from 1 to 7 years, but 30% have lasted for 14 years or more. Accretion has taken place in the middle and lower reaches north of the east bank and in the extreme north of the west bank between 1973 and 1992. The rate of accretion is not comparable with the rate of bank erosion of the Brahmaputra–Jamuna River. Copyright © 2003 John Wiley & Sons, Ltd.

The Impact of Biomedical Bleeding on Horseshoe Crab, Limulus polyphemus, Movement Patterns on Cape Cod, Massachusetts

The purpose of this study was to determine if bleeding, for biomedical purposes, influenced the behavior of horseshoe crabs, Limulus polyphemus. In the summer of 2001, ten bled and ten control (unbled) female horseshoe crabs were tracked for 26 days using acoustic telemetry in a small estuary on Cape Cod, Massachusetts. All but three crabs, two bled and one control, were located during the study period. No mortality was observed in the control group, while 20% mortality was observed within the bled group. There was no significant difference in the average rate of movement or in the spatial distribution within the estuary between the two groups. However, a difference was detected in the movement patterns. Horseshoe crabs from the bled group had a random direction of movement compared to the directional movement pattern of the control group, suggesting that the bled crabs experienced more disorientation.

Relationship of the faulting to the creep movement of Iwakura landslide in Saga, Japan.

A huge creep type slow moving landslide was identified near Saga City of Kyushu Island in 1999. It has been evidenced that this landslide was activating through out several years since the quarry was opened up at the bottom of the valley. Quantitative and qualitative analyses were implemented to investigate the rate of movement, to demarcate the extent of the affected area and to find the major cause of this sliding.Periodical monitoring together with field and laboratory investigations has been carried out for nearly 2 years . Analysis of the extensometer measurement data, results of the surface displacement monitoring survey and the surface geological and structural investigation revealed that this sliding is taking place along the fault planes. Stereographic projection data combined with the sur-face movement monitoring suggested that the sliding is taking place in three directions along the fault planes and along the inter-section of two extensive fault planes sub-parallel to the slope concerned. Subsequent borehole drilling and the pipe strain gauge installation confirmed the location of the slip surface at 27 m and 29 m below the surface along these faults . The average move-ment rate of this sliding mass has been approximated to 6 cm/day, which has occasionally increased to a value more than 12 cm/day, just after heavy rainfall.