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Chaparro D.,Polytechnic University of Catalonia | Chaparro D.,Institute Destudis Espacials Of Catalonia | Chaparro D.,Barcelona Expert Center | Vall-Llossera M.,Polytechnic University of Catalonia | And 9 more authors.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2016

Recent climate trends evidence a rise of temperatures and an increase in the duration and intensity of droughts which is in turn leading to the occurrence of larger wildfires, which threaten the environment as well as human lives and beings. In this context, improved wildfires prediction tools are urgently needed. In this paper, the use of remotely sensed soil moisture data as a key variable in the climate-wildfires relationship is explored. The study is centered in the fires registered in the Iberian Peninsula during the period 2010-2014. Their prior-to-occurrence surface moistureerature conditions were analyzed using SMOS-derived soil moisture data and ERA-Interim land surface temperature reanalysis. Results showed that moisture and temperature conditions limited the extent of wildfires, and a potential maximum burned area per moistureerature paired values was obtained (R2 = 0.43). The model relating fire extent with moistureerature preconditions was improved by including information on land cover, regions, and the month of the fire outbreak (R2 = 0.68). Model predictions had an accuracy of 83.3% with a maximum error of 40.5 ha. Results were majorly coherent with wildfires behavior in the Iberian Peninsula and reflected the duality between Euro-Siberian and Mediterranean regions in terms of expected burned area. The proposed model has a promising potential for the enhancement of fire prevention services. © 2016 IEEE. Source

Ortega-Retuerta E.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Ortega-Retuerta E.,CNRS Microbial Oceanography Laboratory | Fichot C.G.,University of South Carolina | Fichot C.G.,Jet Propulsion Laboratory | And 3 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2014

The activity of heterotrophic bacterioplankton and their response to changes in primary production in the Arctic Ocean is essential to understand biogenic carbon flows in the area. In this study, we explored the patterns of bacterial abundance (BA) and bacterial production (BP) in waters coinciding with a massive under-ice phytoplankton bloom in the Chukchi Sea in summer 2011, where chlorophyll a (chl a) concentrations were up to 38.9mgm-3. Contrary to our expectations, BA and BP did not show their highest values coinciding with the bloom. In fact, bacterial biomass was only 3.5% of phytoplankton biomass. Similarly, average DOC values were similar inside (average 57.2±3.1μM) and outside (average 64.3±4.8μM) the bloom patch. Regression analyses showed relatively weak couplings, in terms of slope values, between chl a or primary production and BA or BP. Multiple regression analyses indicated that both temperature and chl a explained BA and BP variability in the Chukchi Sea. This temperature dependence was confirmed experimentally, as higher incubation temperatures (6.6°C vs. 2.2°C) enhanced BA and BP, with Q10 values of BP up to 20.0. Together, these results indicate that low temperatures in conjunction with low dissolved organic matter release can preclude bacteria to efficiently process a higher proportion of carbon fixed by phytoplankton, with further consequences on the carbon cycling in the area. © 2014 Elsevier Ltd. Source

Alacid E.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Park M.G.,Chonnam National University | Turon M.,CSIC - Center for Advanced Studies of Blanes | Petrou K.,University of Technology, Sydney | Garces E.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas
Frontiers in Microbiology | Year: 2016

Marine microbial interactions involving eukaryotes and their parasites play an important role in shaping the structure of phytoplankton communities. These interactions may alter population densities of the main host, which in turn may have consequences for the other concurrent species. The effect generalist parasitoids exert on a community is strongly dependent on the degree of host specificity. Parvilucifera sinerae is a generalist parasitoid able to infect a wide range of dinoflagellates, including toxic-bloom-forming species. A density-dependent chemical cue has been identified as the trigger for the activation of the infective stage. Together these traits make Parvilucifera-dinoflagellate hosts a good model to investigate the degree of specificity of a generalist parasitoid, and the potential effects that it could have at the community level. Here, we present for the first time, the strategy by which a generalist dinoflagellate parasitoid seeks out its host and determine whether it exhibits host preferences, highlighting key factors in determining infection. Our results demonstrate that in its infective stage, P. sinerae is able to sense potential hosts, but does not actively select among them. Instead, the parasitoids contact the host at random, governed by the encounter probability rate and once encountered, the chance to penetrate inside the host cell and develop the infection strongly depends on the degree of host susceptibility. As such, their strategy for persistence is more of a game of Russian roulette, where the chance of survival is dependent on the susceptibility of the host. Our study identifies P. sinerae as a potential key player in community ecology, where in mixed dinoflagellate communities consisting of hosts that are highly susceptible to infection, parasitoid preferences may mediate coexistence between host species, reducing the dominance of the superior competitor. Alternatively, it may increase competition, leading to species exclusion. If, however, highly susceptible hosts are absent from the community, the parasitoid population could suffer a dilution effect maintaining a lower parasitoid density. Therefore, both host community structure and host susceptibility will determine infectivity in the field. © 2016 Alacid, Park, Turon, Petrou and Garcés. Source

Pablos M.,Polytechnic University of Catalonia | Pablos M.,Barcelona Expert Center | Piles M.,Polytechnic University of Catalonia | Piles M.,Barcelona Expert Center | And 6 more authors.
Journal of Geophysical Research C: Oceans | Year: 2015

The Dome-C region, in the East Antarctic Plateau, is regarded as an ideal natural laboratory for calibration/validation of space-borne microwave radiometers. At L-band, the thermal stability of this region has been confirmed by several experimental campaigns. However, its use as an independent external calibration target has recently been questioned due to some spatial inhomogeneities and seasonal effects revealed in the brightness temperatures (TB) acquired in this area. This paper shows the observed relationship, from exploratory research, between the Antarctic ice thickness spatial variations and the measured Aquarius TB changes. A 3-months no-daylight period during the Austral winter has been analyzed. Four transects have been defined over East Antarctica covering areas with different ice thickness variations and ranges. The theoretical L-band penetration depth has been estimated to understand the possible contributions to the measured signal. A good agreement has been observed between Aquarius TB and ice thickness variations over the whole Antarctica, with correlations of ∼0.6-0.7. The two variables show a linear trend with slopes of ∼8.3-9.5 K/km. No correlation has been observed with the subglacial bedrock. The maximum L-band penetration depth has been estimated to be ∼1-1.5 km. Results are therefore consistent: the spatial variations found on Aquarius TB are not related to the emissivity of the bedrock, which lies deeper. This study provides evidence that new L-band satellite observations could contribute to further our understanding of Antarctic geophysical processes. Key Points: Relationship between Antarctic ice thickness and observed Aquarius TB Maximum L-band penetration depth over Antarctic ice Possible influence of subglacial lakes on Aquarius TB © 2015. American Geophysical Union. All Rights Reserved. Source

Fajar N.M.,CSIC - Institute of Marine Research | Guallart E.F.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Steinfeldt R.,University of Bremen | Rios A.F.,CSIC - Institute of Marine Research | And 5 more authors.
Progress in Oceanography | Year: 2015

Methods based on CO2 and chlorofluorocarbon (CFC) data are used to describe and evaluate the anthropogenic CO2 (Cant) concentrations, Cant specific inventories, and Cant storage rates in the Equatorial Atlantic Ocean. The Cant variability in the water masses is evaluated from the comparison of two hydrographic sections along 7.5°N carried out in 1993 and 2010. During both cruises, high Cant concentrations are detected in the upper layers, with values decreasing progressively towards the deep layers. Overall, the Cant concentrations increase from 1993 to 2010, with a large increment in the upper North Atlantic Deep Water layer of about 0.18±0.03μmolkg-1y-1. In 2010, the Cant inventory along the whole section amounts to 58.9±2.2 and 45.1±2.0molm-2 using CO2 and CFC based methods, respectively, with most Cant accumulating in the western basin. Considering the time elapsed between the two cruises, Cant storage rates of 1.01±0.18 and 0.75±0.17molm-2y-1 (CO2 and CFC based methods, respectively) are obtained. Below ~1000m, these rates follow the pace expected from a progressive increase of Cant at steady state; above ~1000m, Cant increases faster, mainly due to the retreat of the Antarctic Intermediate Waters. © 2015 Elsevier Ltd. Source

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