Time filter

Source Type

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.


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.


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.


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.


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.


Alexander B.E.,University of Amsterdam | Alexander B.E.,Porifarma B.V. Poelbos | Liebrand K.,University of Amsterdam | Osinga R.,Porifarma B.V. Poelbos | And 9 more authors.
PLoS ONE | Year: 2014

This study describes in vivo cell turnover (the balance between cell proliferation and cell loss) in eight marine sponge species from tropical coral reef, mangrove and temperate Mediterranean reef ecosystems. Cell proliferation was determined through the incorporation of 5-bromo-29-deoxyuridine (BrdU) and measuring the percentage of BrdU-positive cells after 6 h of continuous labeling (10 h for Chondrosia reniformis). Apoptosis was identified using an antibody against active caspase-3. Cell loss through shedding was studied quantitatively by collecting and weighing sponge-expelled detritus and qualitatively by light microscopy of sponge tissue and detritus. All species investigated displayed substantial cell proliferation, predominantly in the choanoderm, but also in the mesohyl. The majority of coral reef species (five) showed between 16.1615.9% and 19.062.0% choanocyte proliferation (mean6SD) after 6 h and the Mediterranean species, C. reniformis, showed 16.663.2% after 10 h BrdU-labeling. Monanchora arbuscula showed lower choanocyte proliferation (8.163.7%), whereas the mangrove species Mycale microsigmatosa showed relatively higher levels of choanocyte proliferation (70.566.6%). Choanocyte proliferation in Haliclona vansoesti was variable (2.8-73.1%). Apoptosis was negligible and not the primary mechanism of cell loss involved in cell turnover. All species investigated produced significant amounts of detritus (2.5-18% detritus bodyweight21?d21) and cell shedding was observed in seven out of eight species. The amount of shed cells observed in histological sections may be related to differences in residence time of detritus within canals. Detritus production could not be directly linked to cell shedding due to the degraded nature of expelled cellular debris. We have demonstrated that under steady-state conditions, cell turnover through cell proliferation and cell shedding are common processes to maintain tissue homeostasis in a variety of sponge species from different ecosystems. Cell turnover is hypothesized to be the main underlying mechanism producing sponge-derived detritus, a major trophic resource transferred through sponges in benthic ecosystems, such as coral reefs. © 2014 Alexander et al.


Isari S.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Anto M.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Saiz E.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas
PLoS ONE | Year: 2013

Copepods have been considered capable of selective feeding based on several factors (i.e., prey size, toxicity, and motility). However, their selective feeding behaviour as a function of food quality remains poorly understood, despite the potential impact of such a process on copepod fitness and trophodynamics. In this study, we aimed to evaluate the ability of copepods to feed selectively according to the nutritional value of the prey. We investigated the feeding performance of the calanoid copepod Acartia grani under nutritionally distinct diets of the dinoflagellate Heterocapsa sp. (nutrient-replete, N-depleted and P-depleted) using unialgal suspensions and mixtures of prey (nutrient-replete vs. nutrient-depleted). Despite the distinct cell elemental composition among algal treatments (e.g., C:N:P molar ratios) and the clear dietary impact on egg production rates (generally higher number of eggs under a nutrient-replete diet), no impact on copepod feeding rates was observed. All unialgal suspensions were cleared at similar rates, and this pattern was independent of food concentration. When the prey were offered as mixtures, we did not detect selective behaviour in either the N-limitation (nutrient-replete vs. N-depleted Heterocapsa cells) or P-limitation (nutrient-replete vs. P-depleted Heterocapsa cells) experiments. The lack of selectivity observed in the current study contrasts with previous observations, in which stronger nutritional differences were tested. Under normal natural circumstances, nutritional differences in natural prey assemblages might not be sufficiently strong to trigger a selective response in copepods based on that factor alone. In addition, our results suggest that nutritional quality might depend not only on the growing conditions but also on the inherent taxonomical properties of the prey. © 2013 Isari et al.


Acevedo M.J.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Acevedo M.J.,University of Alicante | Fuentes V.L.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | Olariaga A.,Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas | And 6 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2013

The box jellyfish Carybdea marsupialis has proliferated in some areas of the north-western Mediterranean Sea since July 2008. As for many species, controlled experimentation in the laboratory is needed to improve our knowledge about C. marsupialis, with the ultimate goal of extrapolating the knowledge gained to the marine environment. The aims of this study were to identify the optimal conditions (i.e. aquarium design, environmental parameters and prey type) for the growth and maintenance of this cubomedusa in the laboratory and, additionally, to quantify the feeding rates of the juveniles of this species. We were able to maintain healthy medusae for 140. days. During this time they reached the subadult condition (fact corroborated by observing the gonadal tissue), growing from 2 to 15. mm in diagonal bell width from June to November 2010, respectively. We observed a progressive shift in their preferred dietary composition as the individuals grew. The medusae fed on Artemia salina nauplii along the entire development. Other, larger, prey types (e.g. Mysis sp., Acartia granii copepods and adult Artemia salina) were progressively ingested at the same time as they increased their umbrella size. We also describe the clearance rates, ingestion rates, prey selectivity and digestion times of juvenile C. marsupialis on natural zooplankton and on the copepod Acartia grani. Growth and mortality rates were also calculated. © 2012 Elsevier B.V.


PubMed | Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas
Type: Journal Article | Journal: PloS one | Year: 2014

Copepods have been considered capable of selective feeding based on several factors (i.e., prey size, toxicity, and motility). However, their selective feeding behaviour as a function of food quality remains poorly understood, despite the potential impact of such a process on copepod fitness and trophodynamics. In this study, we aimed to evaluate the ability of copepods to feed selectively according to the nutritional value of the prey. We investigated the feeding performance of the calanoid copepod Acartia grani under nutritionally distinct diets of the dinoflagellate Heterocapsa sp. (nutrient-replete, N-depleted and P-depleted) using unialgal suspensions and mixtures of prey (nutrient-replete vs. nutrient-depleted). Despite the distinct cell elemental composition among algal treatments (e.g., C:N:P molar ratios) and the clear dietary impact on egg production rates (generally higher number of eggs under a nutrient-replete diet), no impact on copepod feeding rates was observed. All unialgal suspensions were cleared at similar rates, and this pattern was independent of food concentration. When the prey were offered as mixtures, we did not detect selective behaviour in either the N-limitation (nutrient-replete vs. N-depleted Heterocapsa cells) or P-limitation (nutrient-replete vs. P-depleted Heterocapsa cells) experiments. The lack of selectivity observed in the current study contrasts with previous observations, in which stronger nutritional differences were tested. Under normal natural circumstances, nutritional differences in natural prey assemblages might not be sufficiently strong to trigger a selective response in copepods based on that factor alone. In addition, our results suggest that nutritional quality might depend not only on the growing conditions but also on the inherent taxonomical properties of the prey.

Loading Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas collaborators
Loading Institute Of Ciencies Del Mar Consejo Superior Of Investigaciones Cientificas collaborators