Patterns of fish movement at a desert river confluence

Quantifying fish movements in river networks helps identify critical habitat needs and how they change with environmental conditions. Some of the challenges in tracking fish movements can be overcome with the use of passive integrated transponder (PIT) tagging and antennas. We used PIT technology to test predictions of movement behaviour for four fish species at a mainstem–tributary confluence zone in an arid‐land river system. Specifically, we focused on the McElmo Creek tributary confluence with the San Juan River in south‐western Utah, USA. We quantified variation in species occurrences at this confluence zone from May 2012 to December 2015 relative to temporal and environmental conditions. We considered occurrences among species relative to tagging origins (tributary versus mainstem), season and time of day. Generally, fishes tagged in the focal tributary were more likely to be detected compared to fish tagged in the mainstem river or other tributaries. Additionally, adults were most likely to be detected across multiple years compared to subadults. Based on a Random Forests model, the best performing environmental variables for predicting seasonal detections included mainstem discharge during run‐off season (razorback sucker Xyrauchen texanus), tributary discharge during monsoon season (Colorado pikeminnow Ptychocheilus lucius) and mainstem water temperature (flannelmouth sucker Catostomus latipinnis and channel catfish Ictalurus punctatus). The variable responses by endemic and introduced fishes indicate tributary habitats provide several key functions within a fish community including spawning, rearing, foraging and refuge.     

Fractals and search paths in mammals

The fractal index by Katz and George (1985) for thecharacterization of planar curves is applied to wolf search pathsrecorded by radio-telemetry. All the sets of paths studied showspatial patterns whose complexity is between a straight line anda true random walk. Females fractal dimensions show significantchanges throughout the year, depending on the state of their lifecycle (normal, breeding and wandering). There are alsodifferences between males and females, but not between adults andnon-adults. The results are discussed with regard to wolffood-search strategies.     

Active bleb formation is abated in Lytechinus variegatus red spherule coelomocytes after disruption of acto‐myosin contractility

Red spherule coelomocytes are immune cells in the sea urchin Lytechinus variegatus that have been characterized as motile O₂ transport cells. Video microscopy of living red spherule coelomocytes reveals a constitutive, dynamic array of cellular morphologies and movements. Cells continuously send out and retract membrane blebs all over the cell surface as part of their normal cellular physiology. Disruption of microtubules by perfusion with either nocodazole or taxol had no effect on bleb formation or motility. Perfusion with cytochalasin B abated bleb formation and revealed cells that exhibited multiple small spheres attached by short membrane extensions. Attenuation of blebbing and intracellular organelle motility were restored by washing out with cytochalasin B. Treatment with phalloidin also abated bleb formation and revealed a smooth, spherical cellular morphology. The effects of phalloidin were completely reversible after washout. Red spherule coelomocytes treated with blebbistatin rounded up with an irreversible retraction of blebs into surface blebs that were greatly reduced in size, number and motility. Normal cell surface bleb formation and intracellular organelle motility were not restored after washout of the drug. These results indicate that the acto‐myosin contractile mechanism contributes to the dynamics of constitutive cell surface membrane blebbing in invertebrate immune cells.     

Agreement between two inertial sensor gait analysis systems for lameness examinations in horses

Gait analysis is gaining popularity for quantification of lameness and 2 commonly used inertial sensor systems assess trunk movement symmetry: can these be used interchangeably in multi‐centre studies? We compared head and pelvic movement symmetry between 2 inertial sensor gait analysis systems in 13 horses equipped simultaneously with the 2 systems. The first system quantified dorsoventral movement in the local reference frame (System A) and the second system global vertical movement (System B). Widths of limits of agreement were calculated employing a well established regression method dealing with systematically changing differences over the range of measured values. Widths of limits of agreement between Systems A and B were narrower for pelvic movement than head movement. For head movement, they ranged from 6.4 to 6.9 mm for in‐hand trot and from 7.3 to 9.7 mm on the lunge and for pelvic movement from 2.5 to 4.4 mm in‐hand and from 3.6 to 5.3 mm on the lunge. Widths of limits of agreement between the 2 investigated inertial sensor gait analysis systems are of comparable magnitude (some equivalent, some marginally higher) to the currently proposed thresholds of 6 mm for head and 3 mm for pelvic movement used in lameness investigations. Differences in measurements with 2 different systems (A and B) obtained from the same horse falling within the reported values should not be seen as a sign of a change in lameness.     

陕西省南部地区土壤粘粒特性研究

陕西南部土壤粘粒特性的研究发现,陕西省南部北亚热带湿润地区,发育在第四纪下蜀黄土母质上的土壤粘粒含量高,粘化层不明显,粘土矿物以伊利石和蒙脱石为主,粘粒铁富集明显;发育在基岩风化物母质上的土壤粘化层明显,粘土矿物以蒙脱石、蛭石为主,且有一定量的高岭石,粘粒中铝富集强烈。中山区暖温带湿润地区的土壤,粘粒含量较低,粘土矿物以伊利石、绿泥石为主,粘粒中铁、铝富集均不明显,元素的淋溶迁移较弱。     

历史时期鄂尔多斯沙化的气候因素作用分析

本文根据历史资料,以鄂尔多斯历史时期气候波动对沙化进退过程影响为主线,提出了本区沙化孕育的环境不仅是冷干时期,而在暖干时期沙化也会发展。人类活动是沙化进退的诱导和加强因素,并且随着全球气候变暖,人为活动的的加剧,本区沙化有加强的趋势。     

Designing satellite tagging studies: estimating and optimizing data recovery

Satellite telemetry is used routinely to collect and transmit movement, behaviour and environmental data from free‐ranging animals. Satellite tags (hereafter SATs) are essential for collecting in situ data from animals where manual retrieval of a data logger is impossible. The collected data is fundamental for scientific and many management applications. However, the amount of data a SAT can transmit is limited by its battery life, transmission opportunities, bandwidth and satellite coverage. When designing a SAT study, these factors should be taken into account to ensure that limited transmissions are utilized as effectively as possible. In this paper we present a theoretical discussion of the factors that influence the data transmission and present tools for designing effective SAT studies. We calculate the optimal sampling period for the tag given its expected lifetime and regional variation in satellite coverage. Taking these factors into account allows prediction of the expected number of tags required to meet targets for a deployment. These methods are applied to a case study of a highly migratory pelagic fish tagged with popup archival satellite tags (PSATs). Our findings will be useful for SAT study design in general and demonstrate an approach which can reduce the ad hoc nature of SAT deployments.     

Otolith chemistry indicates walleye movement and entrainment in a large serial reservoir system

Understanding fish movement in impounded river systems is important for fisheries management. Otolith chemistry was used to examine walleye Sander vitreus (Mitchill) intra‐ and inter‐reservoir movement in four Missouri River impoundments. Age‐0 individuals were reclassified with 75%–93% accuracy to known natal sites, allowing for reliable evaluation of movement patterns of age‐1 and older fish. Nearly half of walleye occupied the same location annually (i.e. site residency) between 2009 and 2010. In 2011, during the largest flood on record since 1898, downstream movement (49% of age‐1 and older fish) exceeded upstream movement (7%) and site residency (33%) across the study area. After the flood, most walleye moved downstream within reservoirs (45%) or were site residents (37%). Entrainment occurred most frequently during the flood year and was proportionally greatest in downstream reservoirs. Otolith chemistry is useful for understanding walleye movement and entrainment and is a tool for fisheries management with applications such as informing reservoir water releases, harvest regulations and habitat protection and rehabilitation within and outside the Missouri River reservoir system.     

三氯生对红白鲫运动行为的影响

利用视频跟踪系统研究三氯生(TCS)对红白鲫运动行为的影响。将红白鲫(red-white crucian carp)暴露在5种不同浓度的TCS(0.50、0.60、0.70、0.80和0.90 mg/L)水体中,视频记录5 min内红白鲫的运动轨迹(运动轨迹线、摆动次数)、游动速度和垂直穿梭次数的变化。同时,进行TCS(0.60、0.69 mg/L)对红白鲫的14 d暴露实验,暴露实验结束后,2 min内监测上述指标。结果显示:短期TCS暴露,红白鲫的运动轨迹条数、摆动次数、垂直穿梭次数、运动速率显著增加;暴露14 d后的红白鲫上述运动行为学指标显著降低。结果表明:在一定浓度范围内,TCS能够改变红白鲫的运动行为。