Experimental Evaluation of the Response of Coastal Mediterranean Planktonic and Benthic Metabolism to Warming     

Raquel Vaquer-Sunyer  Carlos M. Duarte 《Estuaries and Coasts》2013,36(4):697-707

The Mediterranean Sea has been identified as one of the hotspots for climate change. Intense warming in the Mediterranean Sea may have strong implications for biological activity and ecosystem functioning. To elucidate the effects of warming on planktonic and benthic metabolism, we performed experiments under different increasing temperature regimes, ranging from three to six different temperatures. The lowest range of temperatures assessed was of 2.6 °C and the maximum was 7.5 °C. Our results suggest that a 6 °C warming of the Mediterranean waters may yield a mean increment in planktonic respiration rates of coastal communities of 24 %, higher than the mean increase expected for planktonic gross primary production (9 %). These results confirm earlier theories, and agree with previous experiments, of a higher increase in respiration rates than in primary production with warming, with the subsequent consequences for the carbon cycle, resulting in a negative feedback to climate warming, as ocean communities will capture less CO₂.  相似文献   

Low-pH Freshwater Discharges Drive Spatial and Temporal Variations in Life History Traits of Neritic Copepod Acartia tonsa     

Victor M. Aguilera  Cristian A. Vargas  Patricio H. Manríquez  Jorge M. Navarro  Cristian Duarte 《Estuaries and Coasts》2013,36(5):1084-1092

  相似文献   

Radiological and geochemical characteristics of an ultramafic massif (NE Portugal) regarding the site aptness to host a near surface repository for low and intermediate level radwaste     

Pedro Duarte  Lídia Silva  António Mateus  M. Fátima Araújo  Mário Reis  Romão Trindade  Isabel Paiva 《Environmental Earth Sciences》2013,68(2):547-557

The search for suitable sites to install near-surface repositories for low to intermediate level radioactive wastes has increased in the recent years, reflecting both the continuous rise in radioactive materials applications by the society and the increasing awareness of public perception regarding radwaste management. International recommendations towards the application of higher safety standards to low and intermediate level waste disposal sites being developed by the International Atomic Energy Agency (IAEA), and the European Commission decision that each Member State must safely dispose its own radwaste in its territory, according to national radwaste management plans, has leading to new soundly scientific studies. In Portugal, possible locations for that purpose are under study since 2006, following the pre-requisites indicated by IAEA. One of these sites overlaps a significant portion of an ultramafic massif, corresponding to an allochthonous and metamorphosed ophiolite complex. In the surveyed area of this massif, the prevailing rock type consists of (serpentinised) peridotites, occasionally containing irregular bodies of (amphibolitised) gabbros, over which an irregular/ill-developed regolith exists. The activities of ⁴⁰K, ¹³⁷Cs, ²¹⁰Pb, ²²⁶Ra and ²³²Th measured in samples representing three consecutive levels of the regolith upper portion in 13 stations confirm the heterogeneity put in evidence through in situ γ-ray surveys previously performed. The available dataset also demonstrates that radionuclide contents decrease prominently with depth, becoming closer to the bedrock values (up to ca. 41 Bq kg^?1 for ⁴⁰K in flaser-gabbros and near zero for all the remaining cases) but never reaching them. Therefore, the low/moderate radionuclide activity in the regolith upper portion reflect the contribution of sources that are independent of the lithological background; i.e. they indicate external and miscellaneous contributions to the “soil”-forming components, most of them coming from (dry or wet) atmospheric deposition. The chemical composition of the (serpentinised) peridotites and (amphibolitised) gabbros in the surveyed area, as well as their alteration products included in regolith, is homogeneous enough to be used as a faithful reference in monitoring studies of any kind. In addition, the significant ¹³⁷Cs activities measured in some top “soil” samples (up to 92 Bq kg^?1) strongly suggest that there are mineralogical specificities of the peridotite-derived regolith able to fix that radionuclide. This particular feature reinforces the existing criteria that favour the peridotites of Morais as a suitable host for a near surface repository of low to intermediate level radwaste.  相似文献   

Changes of the Macrobenthos Community with Non-native Mangrove Rehabilitation (Kandelia obovata) and Salt Marsh Invasion (Spartina alterniflora) in Ximen Island,Zhejiang, China     

Wang  Qiuxuan  Song  Li  Agusti  Susana  Duarte  Carlos  Christakos  George  Wu  Jiaping 《Ocean Science Journal》2021,56(4):395-405

Ocean Science Journal - Macrobenthos organisms are vital ecological components of intertidal wetlands. This work studied effects of non-native mangrove rehabilitation (Kandelia obovata) and salt...  相似文献   

Population ecology of Sinelobus stanfordi (Crustacea: Tanaidacea) in a temperate southern microtidal estuary     

AC Ferreira  ES Ambrosio  A Rodrigues Capítulo 《新西兰海洋与淡水研究杂志》2013,47(4):462-471

Sinelobus stanfordi is a tanaidacean of worldwide distribution of considerable significance within coastal ecosystems. The aim of this research was to provide essential information on the poorly-known population biology of this species. Benthic samples were taken seasonally from winter 2005 through summer 2007 along 155?km of shoreline within the Río de la Plata Estuary, Argentina. The density of this tanaidacean was higher in vegetated than in bare sediments. The smaller individuals flourished in spring and summer, whereas the larger mature members prevailed in the cooler seasons. Females were always twice as abundant as males. Copulatory females, with 18?±?8 eggs each, were collected during all the seasons. Five cohorts were distinguished by the von Bertalanffy growth function. This research represents a baseline investigation for future studies on the population dynamics of S. stanfordi both in this estuary and in other places where this species is found.  相似文献   

On Frontal Zone Analysis in the Tropical Region of the Northeast Brazil     

Natalia Fedorova  Vladimir Levit  Cezar Duarte da Cruz 《Pure and Applied Geophysics》2016,173(4):1403-1421

  相似文献   

Stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry: An effective tool for determining persistent organic pollutants and nonylphenol in coastal waters in compliance with existing Directives   总被引：1，自引：0，他引：1  

Juan Sánchez-Avila  Francesc Ventura  Carlos M. Duarte 《Marine pollution bulletin》2010,60(1):103-160

A multi-residual method based on stir bar sorptive extraction coupled with thermal desorption-gas chromatography-mass spectrometry (SBSE-TD-GC-MS) has been developed to measure 49 organic pollutants (organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers and nonylphenol) in seawater. Using 100 ml of water, the method exhibited good linearity, with recoveries between 86% and 118% and relative standard deviation between 2% and 24% for almost all compounds. The method was applied to determine target contaminants in Catalonian seawater, including coastal areas, ports and desalination plant feed water. Overall individual compound levels oscillated between 0.16 and 597 ng l⁻¹; PAHs and nonylpenol were the compounds found at the highest concentrations. The method provided LODs between 0.011 and 2.5 ng l⁻¹, lower than the Environmental Quality Standards (EQS) fixed by Directive 2008/105/EC. In compliance with the directive, this method can be used as a tool to survey target compounds and is aimed at protecting coastal ecosystems from chemical pollution.  相似文献   

Evolution of fluid geochemistry at the Turrialba volcano (Costa Rica) from 1998 to 2008   总被引：3，自引：1，他引：2  

O. Vaselli  Franco Tassi  E. Duarte  E. Fernandez  R. J. Poreda  A. Delgado Huertas 《Bulletin of Volcanology》2010,72(4):397-410

Turrialba (10°02′N, 83°45′W) is a 3,349-m high stratovolcano belonging to the Holocene “Cordillera Central” volcanic belt of Costa Rica. The summit consists of three EW-oriented craters (East, Central, and West). Since its last eruptive phase (1864–1866), the Central and West craters have displayed modest fumarolic activity, with outlet temperatures clustering around 90°C. In 2001, seismic swarms, ground deformation, and increasing fumarolic activity occurred. From 2005 to 2008, new fumarolic vents opened between and within the Central and West craters, and along the western and southwestern outer flanks of the volcanic edifice. These physical changes were accompanied by a drastic modification in the gas chemistry that can be divided in three stages: (1) hydrothermal (from 1998 to autumn 2001), characterized by the presence of H₂O, CO₂, H₂S, and, to a very minor extent, HCl and HF; (2) hydrothermal/magmatic (autumn 2001–2007), with the appearance of SO₂ and a significant increase of HCl and HF; and (3) magmatic-dominated (2007–2008), characterized by increased SO₂ content, SO₂/H₂S > 100, and temperatures up to 282°C. Accordingly, gas equilibrium in the CO₂-CH₄-H₂ system suggests a progressive evolution of the deep fluid reservoir toward higher temperatures and more oxidizing conditions. The chemical–physical modifications of Turrialba in the last decade can be interpreted as part of a cyclic mechanism controlling the balance between the hydrothermal and the magmatic systems. Nevertheless, the risk of rejuvenation of the volcanic activity cannot be excluded, and an appropriate seismic, ground deformation, and geochemical monitoring program is highly recommended. Turrialba lies at a distance of 35 and 15 km from San José and Cartago, respectively, the two largest cities in Costa Rica.  相似文献   

Controlling factors and environmental implications of mercury contamination in urban and agricultural soils under a long-term influence of a chlor-alkali plant in the North–West Portugal     

A. Cachada  S. M. Rodrigues  C. Mieiro  E. Ferreira da Silva  E. Pereira  A. C. Duarte 《Environmental Geology》2009,57(1):91-98

This study aims at assessing the extent of total mercury (Hg) contamination in urban and agricultural soils under long-term influence of a chlor-alkali plant, located at about 1 km away from a town centre. Moreover, it aims at identifying the main factors controlling Hg contents’ distribution and associated potential hazards to environment and human health. The median value of total Hg for soil surface layer (0–10 cm) was 0.20 mg/kg (data ranging from 0.050 to 4.5 mg/kg) and for subsurface layer (10–20 cm) 0.18 mg/kg (data ranging from 0.046 to 3.0 mg/kg). The agricultural area showed higher Hg concentrations (ranging from 0.86 to 4.5 mg/kg) than urban area (ranging from 0.05 to 0.61 mg/kg), with some results exceeding target values set by the Dutch guidelines. Mercury concentrations observed in the studied area are more likely to be associated with the influence of the chlor-alkali plant and with the use of historically contaminated sludges and water from a nearby lagoon in agriculture, than to the impacts of urban development. The statistical correlations between Hg concentrations and soil properties suggest that anthropogenic metal sources should influence the spatial distribution more than the geological properties. Although the Hg emissions were drastically reduced 10 years ago, the area under influence of the chlor-alkali plant is still facing potential health and environmental threats arising from soil contamination.  相似文献   

Bacterial Community Dynamics in a Seagrass (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) Meadow Sediment     

Micaela García-Martínez  Arantxa López-López  María Ll. Calleja  Núria Marbà  Carlos M. Duarte 《Estuaries and Coasts》2009,32(2):276-286

Some traits of the bacterial community dynamics associated to the rhizosphere of the Mediterranean seagrass Posidonia oceanica, growing in carbonate sediments, were analyzed during a 2-year period in an enclosed bay of the Balearic Islands. The diversity of the bacterial community was studied by the construction of 16S rDNA clone library. For testing temporal and vertical differences in the abundance of total cells and active Bacteria, we used 4′,6-diamidino-2-phenylindole (DAPI) staining and fluorescence in situ hybridization (FISH). Moreover, some relevant groups of sulfate-reducing bacteria (SRB) were occasionally assessed by FISH. Despite the observed decrease in the total DAPI-stained cells, bacterial counts, and sulfate reduction rates throughout the sampling time, we found an increase in both the pore-water sulfide concentration and the proportion of SRB. Overall, the results revealed a very high bacterial diversity and indicated shifts in bacterial dynamics that could not be related to temperature-dependent factors, suggesting a link between the documented regression of the seagrass meadow and the decline of the microbial community, likely due to large organic matter inputs to the bay.  相似文献