Network analysis to inform invasive species spread among lakes     

ESCOBAR Luis E.  ROMERO-ALVAREZ Daniel  LARKIN Daniel J.  PHELPS Nicholas B. D. 《海洋湖沼学报（英文）》2019,(3):1037-1041

Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.  相似文献   

Network analysis to inform invasive species spread among lakes     

ESCOBAR Luis E.  ROMERO-ALVAREZ Daniel  LARKIN Daniel J.  PHELPS Nicholas B. D. 《海洋湖沼学报（英文）》2019,(3):1037-1041

Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.  相似文献   

An iron-bearing wave-dominated siliciclastic shelf: Facies analysis and palaeogeographic implications (Silurian-Lower Devonian Sierra Grande Formation,Southern Argentina)     

Luis A. Spalletti 《Geological Journal》1993,28(2):137-148

The Sierra Grande Formation (Silurian-Early Devonian) consists of quartz arenites associated with clast supported conglomerates, mudstones, shales and ironstones. Eight sedimentary facies are recognized: cross-stratified and massive sandstone, plane bedded sandstone, ripple laminated sandstone, interstratified sandstone and mudstone, laminated mudstone and shale, oolitic ironstone, massive conglomerate and sheet conglomerate lags. These facies are interpreted as shallow marine deposits, ranging from foreshore to inner platform environments. Facies associations, based on vertical relationships among lithofacies, suggest several depositional zones: (a) beach to upper shoreface, with abundant plane bedded and massive bioturbated sandstones; (b) upper shoreface to breaker zone, characterized by multistorey cross-stratified and massive sandstone bodies interpreted as subtidal longshore-flow induced sand bars; (c) subtidal, nearshore tidal sand bars, consisting of upward fining sandstone sequences; (d) lower shoreface zone, dominated by ripple laminated sandstone, associated with cross-stratified and horizontal laminated sandstone, formed by translatory and oscillatory flows; and (e) transitional nearshore-offshore and inner platform zones, with heterolithic and pelitic successions, and oolitic ironstone horizons. Tidal currents, fair weather waves and storm events interacted during the deposition of the Sierra Grande Formation. However, the relevant features of the siliciclastics suggest that fair weather and storm waves were the most important mechanisms in sediment accumulation. The Silurian-Lower Devonian platform was part of a continental interior sag located between southern South America and southern Africa. The Sierra Grande Formation was deposited during a second order sea level rise, in which a shallow epeiric sea flooded a deeply weathered low relief continent.  相似文献   

The First Mesozoic Heterodactyl Bird from China   总被引：1，自引：1，他引：0  

ZHANG Zihui HOU Lianhai HASEGAWA Yoshikasu Jingmai O＇CONNOR Larry D. MARTIN Luis M. CHIAPPE 《《地质学报》英文版》2006,80(5):631-635

1 Introduction Enantiornithines were the dominant birds nearly worldwide throughout the entire span of the Cretaceous (Chiappe, 1995; Feduccia, 1996). The adaptive radiation of opposite birds is little known besides the disparity of rostral morphology in Boluochia (Zhou, 1995), Longipteryx (Zhang et al., 2001), Longirostravis ( Hou et al., 2004), and the presence of stomach contents that reflect a diversity of diets. Like the structure of rostrum, differentiation of the locomotor apparatu…  相似文献   

Late Miocene evaporite geochemistry of Lorca and Fortuna basins (Eastern Betics,SE Spain): Evidence of restriction and continentalization     

Javier García-Veigas  Luis Gibert  Dioni I. Cendón  David Artiaga  Hugo Corbí  Jesús M. Soria  Tim K. Lowenstein  Enrique Sanz 《Basin Research》2020,32(5):916-948

The Lorca and Fortuna basins are two intramontane Neogene basins located in the eastern Betic Cordillera (SE Spain). During the Late Tortonian—Early Messinian, marine and continental evaporites precipitated in these basins as a consequence of increased marine restriction and isolation. Here we show a stratigraphic correlation between the evaporite records of these basins based on geochemical indicators. We use SO₄ isotope compositions and Sr isotopic ratios in gypsum, and halite Br contents to characterize these units and to identify the marine or continental source of the waters feeding the evaporite basins. In addition, we review the available chronological information used to date these evaporites in Lorca (La Serrata Fm), including a thick saline deposit, that we correlate with the First Evaporitic Group in Fortuna (Los Baños Fm). This correlation is also supported by micropalaeontological data, giving a Late Tortonian age for this sequence. The Second Evaporitic Group, (Chicamo Fm), and the Third Evaporitic Group (Rambla Salada Fm) developed only in Fortuna during the Messinian. According to the palaeogeographical scheme presented here, the evaporites of the Lorca and Fortuna basins were formed during the Late Tortonian—Early Messinian, close to the Betic Seaway closure. Sulphate isotope compositions and Sr isotopic ratios of the Ribera Gypsum Mb, at the base of the Rambla Salada Fm (Fortuna basin), match those of the Late Messinian selenite gypsum beds in San Miguel de Salinas, in the near Bajo Segura basin (40 km to the East), and other Messinian Salinity Crisis gypsum deposits in the Mediterranean. According to these geochemical indicators and the uncertainty of the chronology of this unit, the assignment of the Rambla Salada Fm to the MSC cannot be ruled out.  相似文献   

Climatic regimes and the recruitment rate of anchoveta, Engraulis ringens, off Peru   总被引：2，自引：0，他引：2  

Sandra M. Cahuin  Luis A. Cubillos  Miguel iquen  Rubn Escribano 《Estuarine, Coastal and Shelf Science》2009,84(4):591-597

The recruitment rate of Peruvian anchoveta, Engraulis ringens, was studied to test the hypothesis that long-term environmental variation (regime shifts) had a significant impact on density-dependent processes governing the anchovy recruitment during the period 1963–2004. On the basis of previous defined regimes and turning points for the Humboldt Current System, we identified two groups of years for increased recruitment of anchoveta (1963–1971 and 1986–2004), and one unfavorable period (1972–1985). A common intercept and significantly different slopes were found when the recruitment rate was plotted as a function of the spawning stock biomass during those groups of years, suggesting that density-dependent effects on recruitment were affected during different climate regimes. The favorable (unfavorable) regime was characterized by higher (lower) zooplankton volumes, and with a higher frequency of colder (warmer) waters. Dome-shaped relationships between recruitment rate, spawning stock biomass and SST, were detected with a Generalized Additive Model for the favorable regime. Thus, recruitment could be explained by non-linear effects of environmental variables. Ultimately, climatic regimes are affecting the density-dependent effects on recruitment of anchoveta and the mechanisms involved may be associated with changes in the carrying capacity of the spawning habitat of anchoveta off Peru, which in turn are related with the effects of cold and warm regimes.  相似文献   

The response of vegetation at the end of the last glacial period (MIS 3 and MIS 2) in littoral areas of NW Iberia     

Luis Gómez‐Orellana  Pablo Ramil‐Rego  Castor Muñoz Sobrino 《Boreas: An International Journal of Quaternary Research》2013,42(3):729-744

This paper describes and discusses the palaeobotanical data obtained from organic levels of two exposed deposits on the Atlantic shore of the northwestern Iberian Peninsula. Radiocarbon dating assigns these levels to a period of marine regression at the end of MIS 3 and the beginning of the Last Glacial Maximum. The pollen record shows an initial predominance of tree taxa (mainly deciduous, including the presence of Fagus far from its current limit), followed by an episode of partial forest retraction related to the end of MIS 3 and the beginning of the Last Glacial Maximum. However, the presence of numerous tree taxa in the record, even during the cold intervals associated with Heinrich events, points to the existence of sheltered refugia for these species during this period, in keeping with the conclusions of recent reviews of the vegetation dynamics of this region for the Lateglacial and the Holocene.  相似文献   

Groundwater contamination with arsenic and other trace elements in an area of the pampa,province of Córdoba,Argentina   总被引：1，自引：0，他引：1  

Hugo B. Nicolli  Jose M. Suriano  Miguel A. Gomez Peral  Luis H. Ferpozzi  Omar A. Baleani 《Environmental Geology》1989,14(1):3-16

A geochemical study of groundwater of the pampa in the province of Córdoba, Argentina, was performed; the area covered approximately 10,000 km².Physical-chemical parameters, dissolved solids, and seven trace elements were determined in 60 selected water samples. Systematic and accurate measurements of arsenic, flourine, and vanadium were performed for the first time. Three trace element contaminants not reported earlier were found: an important one, selenium, and two others of less known effects, uranium and molybdenum.Eighty-four percent of the water analyzed showed arsenic contents over 0.05 mg/L, maximum contaminant level established by the U.S. Environmental Protection Agency (1982). The frequency distribution of trace elements was analyzed, and its fit to the lognormal distribution was proved by means of the Pearson and Kolmogorov-Smirnov test; the geographic distribution of the seven trace elements was mapped and its correlation with the anion-cation composition of the water was studied.The maximum arsenic, fluorine, vanadium, and uranium contents were found in the western part of the area under study, in waters containing dominant alkali metals in the cation composition. Maximum selenium and antimony contents were found in the eastern part of the area, while molybdenum distribution does not show any relationship with the other two groups. In addition, the geographic distribution of the trace elements seems to be related to the subsurface structure, which has been inferred using interactive digital analysis of Landsat imagery. The movements of the subsoil have disturbed surface and subsurface drainage influencing the water salinity and trace element contents.In order to investigate the origin of the contamination, 54 loess samples were collected in wells at depths ranging from the surface down to the water table. This loess, which has a high proportion of volcanic components, mainly rhyolitic glass, exhibits a chemical composition corresponding to that of a dacite.The loess and the volcanic glass show anomalous contents of all contaminant trace elements, mainly arsenic and selenium. For this reason loess is considered the most important contamination source in the groundwater under study.  相似文献   

Post glacial lacustrine event sedimentation in an ancient mountain setting: Carboniferous Lake Malanzán (Western Argentina)     

Luis Alberto Buatois  Maria Gabriela Mángano 《Journal of Paleolimnology》1995,14(1):1-22

Lacustrine deposits of the Malanzán Formation record sedimentation in a small and narrow mountain paleovalley. Lake Malanzán was one of several water bodies formed in the Paganzo Basin during the Late Carboniferous deglaciation. Five sedimentary facies have been recognized. Facies A (Dropstones-bearing laminated mudstones) records deposition from suspension fall-out and probably underflow currents coupled with ice-rafting processes in a basin lake setting. Facies B (Ripple cross-laminated sandstones and siltstones) was deposited from low density turbidity currents in a lobe fringe environment. Facies C (Massive or graded sandstones) is thought to represent sedimentation from high and low density turbidity currents in sand lobes. Facies D (Folded sandstones and siltstones) was formed from slumping in proximal lobe environments. Facies E (Wave-rippled sandstones) records wave reworking of sands supplied by turbidity currents above wave base level.The Lake Malanzán succession is formed by stacked turbidite sand lobe deposits. These lobes were probably formed in proximal lacustrine settings, most likely relatively high gradient slopes. Paleocurrents indicate a dominant direction from cratonic areas to the WSW. Although the overall sequence shows a regressive trend from basin fine-grained deposits to deltaic and braided fluvial facies, individual lobe packages lack of definite vertical trends in bed thickness and grain size. This fact suggests aggradation from multiple-point sources, rather than progradation from single-point sources. Sedimentologic and paleoecologic evidence indicate high depositional rate and sediment supply. Deposition within the lake was largely dominated by event sedimentation. Low diversity trace fossil assemblages of opportunistic invertebrates indicate recolonization of event beds under stressed conditions.Three stages of lake evolutionary history have been distinguished. The vertical replacement of braided fluvial deposits by basinal facies indicates high subsidence and a lacustrine transgressive episode. This flooding event was probably linked to a notable base level rise during postglacial times. The second evolutionary stage was typified by the formation of sand turbidite lobes from downslope mass-movements. Lake history culminates with the progradation of deltaic and braided fluvial systems  相似文献   

On the use of the checker-board test to assess the resolution of tomographic inversions   总被引：4，自引：1，他引：4  

Jean-Jacques Lév&#;que  Luis Rivera  Gérard Wittlinger 《Geophysical Journal International》1993,115(1):313-318

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