Testing the applicability of a Marine Biotic Index (AMBI) to assessing the ecological quality of soft-bottom benthic communities, in the South America Atlantic region   总被引：2，自引：0，他引：2  

Muniz P  Venturini N  Pires-Vanin AM  Tommasi LR  Borja A 《Marine pollution bulletin》2005,50(6):624-637

Recently, several monitoring programmes have been undertaken to evaluate the impact of different anthropogenic activities, upon a range of coastal ecosystems located in the South-western Atlantic. In the present contribution, the applicability of the AZTI's Marine Biotic Index (AMBI) is tested, to establish the benthic health of the ecosystem using these data sets. As the AMBI was created previously for use in European estuarine and coastal environments, its general applicability to new geographical locations is discussed. In general, the results are in agreement with those obtained using traditional univariate and multivariate methods. Some inconsistent results are observed, when low abundances and/or number of taxa are recorded in the samples. Moreover, when the macrofauna samples are dominated by large nematodes, the classification of the benthic ecosystem health using AMBI is not consistent with previous results achieved applying other statistical techniques. Thus, parallel to the application of this index to a wider extend, the complementary use of different indices and/or methods is recommended to assess confidently the environmental quality of a coastal area.  相似文献   

The historical (218 ± 14 aBP) explosive eruption of Tutupaca volcano (Southern Peru)     

Pablo Samaniego  Patricio Valderrama  Jersy Mariño  Benjamín van Wyk de Vries  Olivier Roche  Nélida Manrique  Corentin Chédeville  Céline Liorzou  Lionel Fidel  Judicaëlle Malnati 《Bulletin of Volcanology》2015,77(6):1-18

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High-frequency multi-solute calibration using an in situ UV–visible sensor     

Juan Pesántez  Christian Birkel  Giovanny M. Mosquera  Pablo Peña  Viviana Arízaga-Idrovo  Emma Mora  William H. McDowell  Patricio Crespo 《水文研究》2021,35(9):e14357

Monitoring the temporal variation of solute concentrations in streams at high temporal frequency can play an important role in understanding the hydrological and biogeochemical behaviour of catchments. UV–visible spectrometry is a relatively inexpensive and easily used tool to infer those concentrations in streams at high temporal resolution. However, it is not yet clear which solutes can be modelled with such an in-situ sensor. Here, we installed a UV–visible spectrometer probe (200–750 nm) in a high-altitude tropical Páramo stream to record the wavelength absorbance at a 5-min temporal resolution. For calibration, we simultaneously sampled stream water at a 4-h frequency from February 2018 to March 2019 for subsequent laboratory analysis. Absorbance spectra and laboratory-determined solute concentrations were used to identify the best calibration method and to determine which solute concentrations can be effectively inferred using in situ spectrometry through the evaluation of six calibration methods of different mathematical complexity. Based on the Nash – Sutcliffe efficiency (NSE) and Akaike information criterion metrics, our results suggest that multivariate methods always outperformed simpler strategies to infer solute concentrations. Eleven out of 21 studied solutes (Al, DOC, Ca, Cu, K, Mg, N, Na, Rb, Si and Sr) were successfully calibrated (NSE >0.50) and could be inferred using UV–visible spectrometry even with a reduced daily sampling frequency. It is worth noting that most calibrated solutes were correlated with wavelengths (WLs) in the low range of the spectra (i.e., UV range) and showed relatively good correlation with DOC. The latter suggests that estimation of metal concentrations could be possible in other streams with a high organic load (e.g., peat dominated catchments). In situ operation of spectrometers to monitor water quality parameters at high temporal frequency (sub-hourly) can enhance the protection of human water supplies and aquatic ecosystems as well as providing information for assessing catchment hydrological functioning.  相似文献   

Improving the accuracy of daily MODIS OWL flood inundation mapping using hydrodynamic modelling     

Catherine Ticehurst  Dushmanta Dutta  Fazlul Karim  Cuan Petheram  Juan Pablo Guerschman 《Natural Hazards》2015,78(2):803-820

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Effects of afforestation on groundwater recharge and water budgets in the western region of Uruguay          下载免费PDF全文

Luis Silveira  Pablo Gamazo  Jimena Alonso  Leticia Martínez 《水文研究》2016,30(20):3596-3608

Uruguay has stimulated the development of its forest sector since the promulgation of Forest Law N° 15 939 in December of 1987. Nevertheless, the substitution of natural grasslands with forest plantations for industrial use has raised concerns regarding hydrological processes of groundwater recharge and water consumption involving evapotranspiration. The purpose of this study is to assess the effects of this substitution approach on water resources. Input data were collected from two small experimental watersheds of roughly 100–200 hectares located in western Uruguay. The watersheds are characterized by Eucalyptus Globulus ssp. Maidenni and natural grasslands for cattle use. Total rainfall, stream discharge, rainfall redistribution, soil water content and groundwater level data were collected. Groundwater recharge was estimated from water table fluctuations and from groundwater contributions to base flows. Seasonal and annual water budgets were computed from October of 2006 to September of 2014 to evaluate changes in the hydrological processes. The data show a decrease in annual specific discharge of roughly 17% for mean hydrological years and no conclusive effects on annual groundwater recharge in the forested watershed relative to the reference pasture watershed. Reduced annual specific discharge is equivalent to the mean annual interception. The computed actual annual evapotranspiration is consistent with international catchment measurements. Reduction rates vary seasonally and according to accumulated rainfall and its temporary distribution. The degree of specific discharge decline is particularly high for drier autumns and winters (32 to 28%) when the corresponding rainfall varies from 275 to 400 mm. These results are of relevance for water resources management efforts, as water uses downstream can be affected. These findings, based on a study period dominated by anomalous wet springs and summers and by dry autumns and winters, oppose earlier results based on 34 years of rainfall and discharge data drawn from Uruguayan large basins. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Methodology for applying the Limits of Acceptable Change process to the management of recreational boating in the Balearic Islands, Spain (Western Mediterranean)     

Amy Diedrich  Pablo Balaguer Huguet  Joaquín Tintoré Subirana 《Ocean & Coastal Management》2011,54(4):341-351

The objective of this study is to propose a simple methodological approach, based on the Limits of Acceptable Change process, to support the formulation of management measures for recreational boating in bays. Management measures have been determined using statistical and geospatial analyses of data of biophysical characteristics, use, and user perceptions in a bay on the island of Mallorca. The results suggest that the optimal use level of the study site is being surpassed and a range of potential management options is provided. This methodology is applicable to additional management scenarios where balancing social and environmental needs is necessary and should be implemented as part of a broader Integrated Coastal Zone Management framework.  相似文献   

Production and respiration control the marine microbial metabolic balance in the eastern North Atlantic subtropical gyre     

María Aranguren-Gassis  Pablo SerretEmilio Fernández  Juan L. HerreraJose F. Domínguez  Valesca PérezJose Escanez 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(7):768-775

Two main contrasted hypotheses have arisen during the last decades about the factors controlling the planktonic net metabolic balance in oligotrophic waters: gross primary production controls net community production vs. variability of net community production is also influenced by changes in microbial respiration. This work discusses both hypotheses analyzing the variability of metabolic rates along a gradient from the margin to the centre of the North Atlantic oligotrophic gyre, i.e. from relatively productive to more oligotrophic conditions. Net community production (NCP) was close to zero (between −3.34 and −11.77 mmol O₂ m⁻² d⁻¹) at the margin of the gyre and tended towards net heterotrophy (−44.03 mmol O₂ m⁻² d⁻¹) to the centre of the gyre as both gross primary production (GPP) and community respiration (CR) decreased. The strong relationships found between nutrient availability and both NCP and GPP suggest that factors controlling GPP are prevalent in determining NCP variability in this biogeographic region. However implementation of existing models to predict NCP from the measured GPP indicates that the precise estimation of NCP in different oligotrophic systems requires consideration of the magnitude and variability of microbial respiration rates.  相似文献   

Age,growth and mortality in the giant snail Adelomelon beckii (Broderip 1836) on the Argentinean shelf     

Florencia Arrighetti  Thomas Brey  Andreas Mackensen  Pablo E. Penchaszadeh 《Journal of Sea Research》2011,65(2):219-223

The marine subtidal volutid snail Adelomelon beckii was studied in order to obtain their population dynamics, particularly on growth, age, mortality and production. Stable oxygen isotope ratios confirmed semiannual formation of internal growth marks. A von Bertalanffy growth model fitted 308 size-at-age data pairs. A. beckii potential lifespan in Mar del Plata (Argentina) region is 29 years, being rather long lived compared to other large gastropods. Total mortality Z and natural mortality M were calculated to be 0.210 y^?1 and 0.081 y^?1 respectively. Fishing mortality F amounts to 0.129 y^?1 corresponding to an exploitation rate E of 0.614, a value much beyond the optimum rate of 0.427. The current exploitation regime will be unsustainable in the long run unless a proper management approach establishes.  相似文献   

The impact of soil moisture–atmosphere coupling on daily maximum surface temperatures in Southeastern South America     

Coronato  Tanea  Carril  Andrea F.  Zaninelli  Pablo G.  Giles  Julián  Ruscica  Romina  Falco  Magdalena  Sörensson  Anna A.  Fita  Lluis  Li  Laurent Z. X.  Menéndez  Claudio G. 《Climate Dynamics》2020,55(9-10):2543-2556

Based on a series of experiments conducted by two regional climate models (RCA4 and LMDZ) with and without soil moisture-atmosphere coupling, we investigate the role of soil moisture on the occurrence of surface air temperature extremes and its persistence in Southeastern South America. Our analysis reveals that both factors, soil moisture-atmosphere coupling and relatively drier soil conditions, enhance the temperature extremes. In addition, the existence of soil-atmosphere coupling and the associated soil moisture variability is crucial for the development of the extremes in SESA. The key role of soil-atmosphere coupling is also reflected in the intrinsic persistence of hot days, which is greater in simulations with interactive soil moisture than in those with prescribed soil conditions. In the absence of soil-atmosphere coupling, the imprint of the anomalous dry (and also wet) soil conditions on the intensity and persistence of hot days is weaker.

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Episodic flood inundations of the northern plains of Mars     

Alberto G. Fairén  James M. Dohm  Miguel A. de Pablo  Javier Ruiz  Robert C. Anderson 《Icarus》2003,165(1):53-67

Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems, and the extremely flat northern plains topography at the distal reaches of these outflow channel systems. Paleotopographic reconstructions of the Tharsis magmatic complex reveal the existence of an Europe-sized Noachian drainage basin and subsequent aquifer system in eastern Tharsis. This basin is proposed to have sourced outburst floodwaters that sculpted the outflow channels, and ponded to form various hypothesized oceans, seas, and lakes episodically through time. These floodwaters decreased in volume with time due to inadequate groundwater recharge of the Tharsis aquifer system. Martian topography, as observed from the Mars Orbiter Laser Altimeter, corresponds well to these ancient flood inundations, including the approximated shorelines that have been proposed for the northern plains. Stratigraphy, geomorphology, and topography record at least one great Noachian-Early Hesperian northern plains ocean, a Late Hesperian sea inset within the margin of the high water marks of the previous ocean, and a number of widely distributed minor lakes that may represent a reduced Late Hesperian sea, or ponded waters in the deepest reaches of the northern plains related to minor Tharsis- and Elysium-induced Amazonian flooding.  相似文献