Schooling behaviour and environmental forcing in relation to anchoveta distribution: An analysis across multiple spatial scales   总被引：7，自引：4，他引：3  

Arnaud Bertrand  Franois Gerlotto  Sophie Bertrand  Mariano Gutirrez  Luis Alza  Andres Chipollini  Erich Díaz  Pepe Espinoza  Jesús Ledesma  Roberto Quesqun  Salvador Peraltilla  Francisco Chavez 《Progress in Oceanography》2008,79(2-4):264

The Peruvian anchovy or anchoveta (Engraulis ringens) supports the highest worldwide fishery landings and varies in space and time over many scales. Here we present the first comprehensive sub-mesocale study of anchoveta distribution in relation to the environment. During November 2004, we conducted a behavioural ecology survey off central Peru and used a series of observational and sampling tools including SST and CO₂ sensors, Niskin bottles, CTD probes, zooplankton sampling, stomach content analysis, echo-sounder, multibeam sonar, and bird observations. The sub-mesoscale survey areas were chosen from mesoscale acoustic surveys. A routine coast-wide (2000 km) acoustic survey performed just after the sub-mesoscale surveys, provided information at an even larger population scale. The availability of nearly concurrent sub-mesoscale, mesoscale and coast-wide information on anchoveta distribution allowed for a unique multi-scale synthesis. At the sub-mesoscale (100s m to km) physical processes (internal waves and frontogenesis) concentrated plankton into patches and determined anchoveta spatial distribution. At the mesoscale (10s km) location relative to the zone of active upwelling (and age of the upwelled water) and the depth of the oxycline had strong impacts on the anchoveta. Finally, over 100s km the size of the productive area, as defined by the upwelled cold coastal waters, was the determining factor. We propose a conceptual view of the relative importance of social behaviour and environmental (biotic and abiotic) processes on the spatial distribution of anchoveta. Our ecological space has two y-axis; one based on self-organization (social behaviour), and the other based on the environmental processes. At scales from the individual (10s cm), to the nucleus (m), social behaviour (e.g. the need to school) drives spatial organization. At scales larger than the school, environmental forces are the main driver of fish distribution. The conceptual ecosystem models presented in this paper may provide the final links needed to develop accurate forecasts of the spatial distribution of anchoveta over multiple scales.  相似文献   

Spatial proximity of age-0 walleye pollock (Theragra chalcogramma) to zooplankton near the Pribilof Islands, Bering Sea, Alaska     

Swartzman  G.; Brodeur  R.; Napp  J.; Hunt  G.; Demer  D.; Hewitt  R. 《ICES Journal of Marine Science》1999,56(4):545-560

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Laboratory examination of linearity in rainfall–runoff relationships     

Arie Ben-Zvi 《水文科学杂志》2020,65(10):1794-1801

ABSTRACT

Certain rainfall–runoff models, e.g. the unit hydrograph, assume linear relationships between the variables. These are proportionality of runoff discharges to (net) rainfall depth and linear summations of discharges resulting from (net) rainfalls during different time intervals or over different sectors of a watershed. This study examines the validity of these assumptions by use of an extensive two-dimensional laboratory experimentation. The results indicate that proportionality would be found under high rainfall intensity through a long duration. Spatial summations would more likely yield correct discharges in cases where rainfall duration is equal to, or is longer than, the time of concentration. Temporal summations may yield correct discharges when rainfall duration is longer than one half of the time of concentration. Here, the time of concentration is determined at the beginning of gradual approach of the discharge towards the equilibrium state.  相似文献   

中国潮汐汉道研究的进展   总被引：14，自引：0，他引：14  

张忍顺 《地球科学进展》1994,9(4):45-49

潮汐汊道（ｔｉｄａｌｉｎｌｅｔ）是一种重要的海岸类型。本世纪７０年代，在欧美等国成为研究热点。８０年代，我国不少海岸学家加入这一研究行列。分析了潮汐汊道及其与其它潮汐海岸类型如潮汐河口、潮流冲刷槽等在学术概念上的差异与重合，评述了中国潮汐汊道研究的进展，重点介绍有代表性的研究成果，提出了今后我国应优先研究的主要课题。  相似文献   

RADIAL GROWTH OF HUASHAN PINE AND ITS RESPONSE TO CLIMATE   总被引：4，自引：0，他引：4  

Shao Xuemei  Wu Xiangding 《地理学报(英文版)》1994,(Z2)

Intr0ducti0nltiswell-knownthattl1eannualringSoftreeprovideuniqueinformationfOrdeductionofpastclimaticchange.ProPertiesoftreeringrsuchaswooddensityandringwidthvaryinresPOnsetoclimaticc0nditionsthatlimittreegrowth[7,l4].ByunderstandingtherelationsllipsbetweentreegroWthandclimatevariables,PaStclimaticvariationscanbederivedfromtree-ringdata.InChina,mostdendroclimaticstudieshavebeenconductedonclimaicallyextremesites[l2,l8,l9].TreesgrOwingonsuchsiteshavestrongandstraightfO~relationshipswithclim…  相似文献   

Relationship between stratigraphical variation in the morphology of Gabonella elongata and geochemical composition of the host sediments     

H. Ivert 《Cretaceous Research》1980,1(3):223-233

One hundred and sixty-two microspheric and 110 megalospheric specimens of the Late Cretaceous benthic foraminifer Gabonella elongata de Klasz and Meijer were picked from 13 borehole samples and analyzed for stratigraphical variation in four variables. Principal component and canonical variate analyses indicate a larger inter-level variation in the relative size of the final chamber in the microspheric generation than in the megalospheric. The morphometrical measurements were weighed against the concentration of 13 chemical elements determined at each level. The analyses indicate that G. elongata developed large tests in arenaceous sediments, whereas carbonaceous, argillaceous sediments seem to have resulted in small tests. Especially the microspheric generation tends to show greater reduction in growth in the ultimate chamber in carbonaceous, argillaceous sediments than in more arenaceous. This indicates that the genetically controlled growth pattern of the last chamber may be influenced by environmental factors such as agitation and clearness of the water.  相似文献   

Temporal variations in bedload transport rates: The effect of progressive bed armouring     

Basil Gomez 《地球表面变化过程与地形》1983,8(1):41-54

The quantitative bedload transport data that are presently available confirm that the generalized bedload transport rate-stream power relationship is applicable to natural streams. However, the bedload transport rate is not solely dependent upon hydraulic parameters, but also upon the inter-relationship between bed material characteristics and flow properties. Segregation of the surficial bed material, as expressed through the development of an armour coat, limits the availability of transportable material. Under such circumstances observed bedload transport rates are less than the predicted values. The effect which the development of an armoured surface has upon the bedload transport rate is described with reference to bedload and bed material sampling in the Borgne d'Arolla, Valais, Switzerland. The data refer to two periods when the resumption of baseflow conditions following flood events which were of a sufficient magnitude to transport all but the coarsest (0·3–0·5 m) particles on the streambed, provided the opportunity for the bed to adjust to a comparatively stable flow regime. Observed and predicted bedload transport rate-stream power relationships are compared. The theoretical relationship does not adequately describe conditions in some gravel-bed channels, since it fails to take into account the effect which armouring may have upon the supply of transportable material.  相似文献   

Embodiment and sexuality in cross-cultural research     

Linda Malam 《The Australian geographer》2004,35(2):177-183

In this paper, I reflect on the impact that my embodiment and the sexed subject positions that I took up at various moments in the field had on my research on cross-cultural sexual encounters between Thai men and tourist women. I explore the negotiation of sexed subjectivity and positionality and the implications that these negotiations had for research ethics in the project. The issue of research ethics is bound up in the conceptualisation of power relationships between researcher and researched. Here I argue that power is not necessarily already distributed between researcher and researched; rather, that power can shift in different contexts.  相似文献   

3-D density model of the crust of southern and central Finland obtained from joint interpretation of the SVEKALAPKO crustal P-wave velocity models and gravity data   总被引：1，自引：0，他引：1  

E. Kozlovskaya  S. Elo  S.-E. Hjelt  J. Yliniemi  M. Pirttijärvi  SVEKALAPKO Seismic Tomography Working Group 《Geophysical Journal International》2004,158(3):827-848

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山西北部沙棘群落优势种种间关系   总被引：8，自引：2，他引：8  

李晶  上官铁梁 《山地学报》2006,24(2):222-227

用X2检验、Jaccard关联指数及Pearson相关和Spearman秩相关系数对山西北部地区沙棘群落20个优势种群进行种间关系研究。结果表明:1)X2检验共有8个种对为显著正关联,2个种对为显著负关联;Pearson相关系数有10个种对为显著正相关,3个种对为显著负相关;Spearman秩相关系数有14个种对为显著正相关,7个种对为显著负相关。Spearman秩相关检验用于表征种间关联具有较高的灵敏度;2)草本层呈显著和极显著相关的种对最多,灌木与草本间呈显著和极显著相关的种对次之;3)灌木种群间均呈现负相关,表明沙棘群落尚处于动态演替之中。根据Spearman秩相关星座图,将20个优势种划分为4个生态种组,各生态种组内的种具有相似的生态适应性,而组间则表现出明显的差异性;灰栒子、小叶鼠李、灌木铁线莲对特殊生境有较强适应性,呈现独立分布格局。  相似文献