Diatoms as a paleoproductivity proxy in the NW Iberian coastal upwelling system (NE Atlantic)

The objective of the current work is to improve our understanding of how water column diatom's abundance and assemblage composition is seasonally transferred from the photic zone to seafloor sediments. To address this, we used a dataset derived from water column, sediment trap and surface sediment samples recovered in the NW Iberian coastal upwelling system. Diatom fluxes (2.2 (+/- 5.6) 10(6) valves m(-2) d(-1)) represented the majority of the siliceous microorganisms sinking out from the photic zone during all studied years and showed seasonal variability. Contrasting results between water column and sediment trap diatom abundances were found during downwelling periods, as shown by the unexpectedly high diatom export signals when diatom- derived primary production achieved their minimum levels. They were principally related to surface sediment remobilization and intense Minho and Douro river discharge that constitute an additional source of particulate matter to the inner continental shelf. In fact, contributions of allochthonous particles to the sinking material were confirmed by the significant increase of both benthic and freshwater diatoms in the sediment trap assemblage. In contrast, we found that most of the living diatom species blooming during highly productive upwelling periods were dissolved during sinking, and only those resistant to dissolution and the Chaetoceros and Leptocylindrus spp. resting spores were susceptible to being exported and buried. Fur-thermore, Chaetoceros spp. dominate during spring-early summer, when persistent northerly winds lead to the upwelling of nutrient-rich waters on the shelf, while Leptocylindrus spp. appear associated with late-summer upwelling relaxation, characterized by water column stratification and nutrient depletion. These findings evidence that the contributions of these diatom genera to the sediment's total marine diatom assemblage should allow for the reconstruction of different past upwelling regimes.CAIBEX [CTM2007-66408-C02-01/MAR]; REIMAGE [CTM2011-30155-C03-03]; Spanish Government, EXCAPA project [10MDS402013PR]; Xunta de Galicia; EU FEDER [INTERREG 2009/2011-0313/RAIA/E]; RAIA. co [INTERREG2011/2013-052/RAIA.co/1E]; CALIBERIA project [PTDC/MAR/102045/2008]; Fundacao para a Ciencia e a Tecnologia (FCT-Portugal) [COMPETE/FEDER-FCOMP01-0124-FEDER-010599]; Xunta de Galicia (Spain) [SFRH/BPD/111433/2015]; FCT (Portugal) [SFRH/BPD/111433/2015]; [SFRH/BD/88439/2012

Seasonal contribution of living phytoplankton carbon to vertical fluxes in a coastal upwelling system (Ría de Vigo, NW Spain)

The aim of this study is to explore the contribution of living phytoplankton carbon to vertical fluxes in a coastal upwelling system as a key piece to understand the coupling between primary production in the photic layer and the transfer mechanisms of the organic material from the photic zone. Between April 2004 and January 2005, five campaigns were carried out in the Ría de Vigo (NW Iberian Peninsula) covering the most representative oceanographic conditions for this region. Measurements of particulate organic carbon (POC), chlorophyll-a (chl a), phaeopigments (phaeo), and identification of phytoplankton species were performed on the water column samples and on the organic material collected in sediment traps.The POC fluxes measured by the sediment traps presented no seasonal variation along the studied period ranging around a mean annual value of 1085±365mgm-2d-1, in the upper range of the previously reported values for other coastal systems. The fact that higher POC fluxes were registered during autumn and winter, when primary production rates were at their minimum levels points to a dominant contribution of organic carbon from resuspended sediments on the trap collected material. On the contrary, fluxes of living phytoplankton carbon (Cphyto) and chl a clearly presented a seasonal trend with maximum values during summer upwelling (546mgm-2d-1 and 22mgchl am-2d-1, respectively) and minimum values during winter (22mgm-2d-1 and 0.1mgchl am-2d-1, respectively). The contribution of Cphyto to the vertical flux of POC ranged between 2% and 49% in response to the pelagic phytoplankton community structure. Higher values of Cphyto fluxes were registered under upwelling conditions which favour the dominance of large chain-forming diatoms (Asterionellopsis glacialis and Detonula pumila) that were rapidly transferred to the sediments. By contrast, Cphyto fluxes decreased during the summer stratification associated with a pelagic phytoplankton community dominated by single-cell diatoms and flagellates. Minimal Cphyto fluxes were observed during the winter mixing conditions, when the presence of the benthic specie Paralia sulcata in the water column also points toward strong sediment resuspension.Financial support came from CICYT projectREN 2003-04458 and EU projectEVK3-19 CT-2002-00071. D.Z. is funded by a postdoctoral fellowship (Jae-Doc) from the CSIC.Peer reviewe

Influence of mussel culture on the vertical export of phytoplankton carbon in a coastal upwelling embayment (Ría de Vigo, NW Iberia)

14 páginas, 2 tablas, 8 figurasThe goal of this paper is to find out whether suspended mussel culture affects the vertical fluxes of biogenic particles in the Ría de Vigo on a seasonal scale. With this aim, vertical fluxes of particulate organic carbon (POC) and the magnitude and composition of vertical export of phytoplankton carbon (Cphyto) collected in sediment traps were examined by comparing data obtained inside a mussel farming area (RaS) with those found at a reference station (ReS) not affected by mussels. Our results indicate that mussel farming has a strong impact on sedimentation fluxes under the rafts, not only increasing POC flux but also altering the magnitude and composition of Cphyto fluxes. Average POC flux at RaS (2564 ± 1936 mg m−2 day−1) was four times higher than at ReS (731 ± 276 mg m−2 day−1), and much of this increase was due to biodeposit fluxes (Cbiodep) which accounted for large proportion of POC flux (35–60 %). Indeed, because of this high Cbiodep flux, only a small proportion of the POC flux was due to Cphyto flux (3–12 %). At the same time, we observed an increased sedimentation of phytoplankton cells at RaS that could be explained by a combination of mechanisms: less energetic hydrodynamic conditions under mussel rafts, ballast effect by sinking mussel feces, and diatom aggregates. Moreover, mussel farming also altered the quality of the Cphyto flux by removing part of the predatory pressure of zooplankton and thus matching diatom composition in water column and sediment trapsFinancial support came from MICINN RAFTING project (CTM2007-61983/MAR, CTM2007-30624-E/MAR). D. Z. was funded by a postdoctoral fellowship (Plan I2C) from Xunta de GaliciaPeer reviewe

Coupling between the Iberian basin–scale circulation and the Portugal boundary current system. A chemical study

15 páginas, 7 figurasThe role played by the Portugal Current System in the ventilation of the different modes of Eastern North Atlantic Central Water (ENACW) is evaluated with data from a series of cruises carried out along the western coast of the Iberian Peninsula. Results show the Portugal Current, located west of 10.3°W, conveying fresh modes of recently ventilated ENACW of subpolar origin to the south. Within 70 km of the slope, the Portugal Coastal Countercurrent transports northwards low oxygen/high nutrient ENACW of subtropical origin. Downstream ventilation of ENACW of subtropical origin occurs by mixing or entrainment with offshore ventilated ENACW. We point to mesoscale eddies as the main mechanism for this downstream indirect ventilation, which reconciles opposing views from direct current measurements and hydrographic studies.Financial support for this work came from the EU, contract No. MAS2-CT93-65, and the Spanish CICYT, Contract No. AMB93-1415-CE.Peer reviewe

Temporal variability of downward fluxes of organic carbon off Monterey Bay

17 USC 105 interim-entered record; under review.Sediment traps were deployed at two depths (300 m and 1200 m) off Monterey Bay (36°40′N and 122°25′W, Central California) for 7.3 years (1998–2005). The sediment trap data provided information about the quantity and quality of settling material, and allowed exploration of the relationship of the sinking material with the environmental conditions in this coastal upwelling region. The magnitude and composition of the settling material were highly variable over time. Organic carbon (Corg) fluxes ranged between 4–296 mg C m−2 day−1 and 0.1–142 mg C m−2 day−1 for shallow and deep sediment traps, respectively. The time series of Corg vertical flux was characterized by pulses of intense fluxes that were associated with peaks of primary production, generally during upwelling periods. Despite considerable variability, fluxes varied seasonally with highest values during the upwelling season and the lowest in winter. Attenuation of Corg vertical fluxes with depth (300 m vs. 1200 m) varied between 31% and 24% except for the late upwelling period, when there was an increase with depth likely due to resuspension of material from Monterey Canyon. Calculation of a seasonal vertical budget of organic carbon off Monterey Bay resulted in a transfer between 4.0% and 4.9% of the primary production to the deep ocean, suggesting that coastal upwelling efficiently sequestered CO2.The principal source of support for these measurements was the David and Lucile Packard Foundation. CGC was partially supported by a National Research Council Fellowship at the Naval Postgraduate School.

Factores que inciden en el habito de fumar de escolares de educación basica y media del Chile

INTRODUÇÃO: Considerando a indiscutível evidência dos efeitos adversos do fumo para a saúde, milhões de pessoas continuam fumando. A situação é de maior gravidade, já que muitos dos fumantes e a maioria dos novos fumantes, tanto no Chile, como em outros países, são adolescentes. Dicidiu-se realizar estudo com o objetivo de determinar a prevalência do tabagismo em escolares chilenos e quantificar o impacto de fatores socioeconômicos, socioculturais, familiares, de exposição aos meios de comunicaçao de massa, demográficos, educacionais e psicosociais. MATERIAL E MÉTODO: Foi selecionada uma amostra aleatória representativa e proporcional de 2.967 escolares de educação básica e média, na Região Metropolitana do Chile, de acordo com o grau do curso (IV, VI e VIII básico de I e IV medio), sexo, tipo de escola e área geográfica. A prevalência de tabagismo foi determinada por meio de questionário auto administrado. O nível socioeconômico (NSE) foi avaliado pelo método de Graffar modificado determinando-se além das condições familiares, a exposicião aos meios de comunicação de massa e aos fatores psicosociais. O rendimento escolar foi determinado por um teste de idiomas e de matemáticas, além de outras variáveis educacionais. A análise estatística inclui análise de variância, teste "t" de Student e teste de Scheffe para comparar os médias, correlação, regressao múltipla, teste do qui-quadrado e o método de OPS/OMS para o cálculo de risco relativo(RR). RESULTADOS: A prevalência de tabagismo (10,6%) aumentou significativamente com a idade de 1,3% nos escolares menores de 13 anos, a 15,4 a 36,9% nos adolescentes entre 13-15 anos e ³ 16 anos, respectivamente (p < 0,001), e foi maior nos escolares de sexo feminino. Os níveis de plazer (r = 0,499 p < 0,001), rebeldía (r = 0,124 p < 0,001), recreação familiar (r = -0,131 pUNTRODUCTION: Despite the harmful effects of tobacco millions of people continue to smoke. Many of these smokers, including most news smokers, are adolescents - both in Chile and in other countries. This study sought to determine the prevalence of smoking among Chilean elementary and high school children and to quantify the relative impact of socioeconomic, socio-cultural, familial, mass media exposure, demographic, educational and psychosocial factors on smoking. MATERIAL AND METHOD: A representative sample of 2,967 elementary and high school children from Chile's Metropolitan Region were chosen at random, by grade (IV, VI, and VIII elementary school grades and I and IV high school grades), sex, type of school and geographical area. Prevalence of smoking was determined through an anonymous self-administered questionnaire. Socioeconomic status (SES) was measured by means of Graffar's modified method and family conditions, mass media exposure and psychosocial factors were registered. Scholastic achievement was measured by a language and mathematics test and other educational variables were considered. Statistical procedures included analysis of variance, Student's test and Scheffe's test for comparison of means, correlation, stepwise multiple regression, chi-squared and PAHO/WHO risk approach methodology. RESULTS: Prevalence of smoking (10.6%) increased significantly with age, from 1.3% in school children aged < 13 years to 15.4% and 36.9%, in adolescent students aged 13-15 years and ;³; 16 years, respectively (p< 0.001) and was higher in females than in males. Pleasure level (r= 0.499 p < 0.001), level of rebelliousness (r= 0.124 p < 0.0001), family recreation level (r=-0.131 p < 0.0001) and the percentage of school attendance (r=-0.118 p < 0.0001) were the independent variables with the greatest explanatory power in smoking variance (r²= 0.2860), but pleasure level was the variable with the greatest explanatory power in the explained variance (89.2%) and with the greatest RR (34.3). The relative impact of the independent variables on smoking varied according to age, sex and SES. CONCLUSIONS: The result demonstrate that pleasure level, level of rebelliousness, family recreation lvel and the percentage of school attendance were the independent variables with the greatest explanatory power in smoking. These findings may be useful in the implementation of education and health policies with a view to the reduction of this serious public health risk factor.INTRODUCCIÓN: Considerando la indiscutible evidencia de los efectos adversos del tabaco, para la salud, millones de personas continúan fumando. La situación es de mayor gravedad, ya que muchos de estos fumadores y la mayoría de los nuevos fumadores, tanto en Chile, como en otros países, son adolescentes. Los objetivos de este estudio fueron determinar la prevalencia de tabaquismo en escolares chilenos y cuantificar el impacto relativo que ejercen factores socioeconómicos, socioculturales, familiares, de exposición a medios de comunicación de masas, demográficos, educacionales y psicosociales, sobre la prevalencia de tabaquismo. MATERIAL E MÉTODO: Se seleccionó una muestra aleatoria, representativa de 2.967 escolares de educación básica y media de la Región Metropolitana de Chile, proporcional de acuerdo al curso(IV, VI, y VIII año básico y I y IV año medio), sexo, tipo de colegio y área geográfica. La prevalencia de tabaquismo se determinó mediante un cuestionario autoadministrado. El nivel socioeconómico(NSE) se midió por medio del método de Graffar modificado, midiéndose además, las condiciones familiares, la exposición a medios de comunicación de masas y factores psicosociales. El rendimiento escolar se determinó mediante un test de castellano y matemáticas, al mismo tiempo que se registraron otras variables educacionales. El análisis estadístico incluyó análisis de varianza, test de la t de Student y test de Scheffe para comparación de medias, correlación, regresión múltiple stepwise, chi-cuadrado y la metodología del enfoque de riesgo de OPS/OMS, para el cálculo del riesgo relativo simple (RR). RESULTADOS: La prevalencia de tabaquismo (10,6%) aumentó significativamente con la edad, de 1,3% en los escolares menores de 13 años, a 15,4% y 36,9%, en los adolescentes entre 13-15 años y ;³; 16 años, respectivamente (p< 0,001), a la vez que fue mayor en los escolares de sexo femenino. El grado de placer(r=0,499

Oxygen declines and the shoaling of the hypoxic boundary in the California Current

6 páginas, 4 figuras, 1 tabla.We use hydrographic data from the California Cooperative Oceanic Fisheries Investigations program to explore the spatial and temporal variability of dissolved oxygen (DO) in the southern California Current System (CCS) over the period 1984–2006. Large declines in DO (up to 2.1 μmol/kg/y) have been observed throughout the domain, with the largest relative DO declines occurring below the thermocline (mean decrease of 21% at 300 m). Linear trends were significant (p < 0.05) at the majority of stations down to 500 m. The hypoxic boundary (∼60 μmol/kg) has shoaled by up to 90 m within portions of the southern CCS. The observed trends are consistent with advection of low-DO waters into the region, as well as decreased vertical oxygen transport following near-surface warming and increased stratification. Expansion of the oxygen minimum layer could lead to cascading effects on benthic and pelagic ecosystems, including habitat compression and community reorganization.We acknowledge the California Current Ecosystem Long-Term Ecosystem Research (CCE-LTER) project, supported by a grant from NSF (OCE-0417616), and grants from the NSF (OCE-0526640), the David and Lucile Packard Foundation and the NOAA Fisheries and the Environment (FATE) program.Peer reviewe

Evidencias do cambio climático na hidrografía e a dinámica das rías e da plataforma galega

16 páginas, 9 figuras, 3 tablas[EN] This study is focused on multidecadal-scale variations of the hydrographic and hydrodynamic features of Rías and shelf waters off Galicia. Water masses take, through their thermohaline characteristics, a footprint of the climatic variability, mainly caused by changes either in the hydrological budget (precipitation, evaporation, runoff), in heat exchange and wind stress. In this study we focus in the evidences of change in the surface and sub-surface water mass characteristics. Regarding surface water masses, a significant warming during the last 45 years has been noticed, at a rate of 0.17 ºC/ decade. This warming was especially intense from the 1970’s, 0.27 ºC/decade. The tendency is opposite in subsurface waters, but it only takes into account data from the last 15 years. Regarding hydrodynamics, because of its strong influence in the renewal time of the Rías and consequently in their living resources, a study of decadal changes in the estuarine circulation of the Rías de Vigo and Arousa has been made. Results showed a progressive decay in the estuarine circulation, which causes an increase of renewal times. On the other hand, indirect evidence of a possible deceleration of the winter Iberian Poleward Current (IPC) are reported. This slow down is partially caused by a decrease in the meridional (N-S) temperature gradient off the Iberian coast. Nevertheless, the fall of the meridional gradient is not clear because it has been inferred from surface waters. On the contrary, IPC seems to be intensified by the increasing southerly autumn winds, although it appears weakened by the decreasing southerly winter winds. Thus, the overall effect of the CIP is still uncertain. Finally, a study of sea level and wave changes on the Galician coast has been made. An increase of (2-2.5 cm/ decade) in the sea level as well as a decrease in the wave height (3 cm/decade) has been reported, but in this last topic results are not significant[GA] Este estudo centrarase en determinar as variacións que ocorren a escalas multidecadais nas características hidrográficas e hidrodinámicas das augas das rías e da plataforma fronte a Galicia. As masas de auga reciben a través das súas características termohalinas unha pegada das alteracións climáticas, principalmente a causa de cambios no balance hidrolóxico (precipitación, evaporación, achegas continentais), do intercambio de calor e da acción do vento. Neste estudo analizaremos as evidencias de cambio nas características das masas de auga superficiais e subsuperficiais. Nas primeiras detectouse quentamento de xeito significativo nos últimos 45 anos a unha taxa media de 0,17 ºC por década, especialmente intenso desde hai 30 anos, 0,27 ºC por década. Nas augas subsuperficiais a tendencia é a inversa, aínda que só se conta con datos dos últimos 15 anos. En canto á hidrodinámica, e pola súa forte implicación nos tempos de renovación da ría e, polo tanto, nos recursos mariños que viven nela, fíxose un estudo sobre os cambios na circulación estuárica das rías de Vigo e Arousa nas últimas décadas. Os resultados amosan un descenso paulatino a longa escala temporal da circulación que causa un aumento dos tempos de renovación. Por outra banda, achéganse evidencias indirectas dunha posible ralentización da corrente invernal cara ao Polo (CIP) causada por un descenso no gradiente meridional (N-S) de temperatura fronte ás costas ibéricas. Non obstante, o descenso do gradiente meridional non está claro, pois induciuse só a partir de datos superficiais. Ademais, a propia CIP amosa estar intensificada pola maior intensidade dos ventos sur no outono e debilitada polo descenso dos ventos do sur no inverno, polo que o efecto global na CIP é aínda incerto. Por último, faise un estudo dos cambios do nivel do mar e da ondada nas costas galegas que amosa un aumento daquel (2-2,5 cm/década) e un descenso desta (3 cm/década), aínda que no caso da ondada os resultados non son concluíntesPeer reviewe

Benthic oxygen fluxes in a coastal upwelling system (Ria de Vigo, NW Iberia) measured by aquatic eddy covariance

Organic carbon mineralization and nutrient cycling in benthic environments are critically important for their biogeochemical functioning, but are poorly understood in coastal up - welling systems. The main objective of this study was to determine benthic oxygen fluxes in a muddy sediment in the Ria de Vigo (NW Iberian coastal upwelling), by applying the aquatic eddy covariance (AEC) technique during 2 campaigns in different seasons (June and October 2017). The main drivers of benthic fluxes were studied and compared among days in each season and between seasons. The 2 campaigns were characterized by an upwelling-relaxation period followed by a downwelling event, the last of which was due to the extratropical cyclone Ophelia in October. The mean (±SD) seasonal benthic oxygen fluxes were not significantly different for the 2 campaigns despite differences in hydrodynamic and biogeochemical conditions (June: -20.9 ± 7.1 mmol m-2d-1vs. October: -26.5 ± 3.1 mmol m-2d-1). Benthic fluxes were controlled by different drivers depending on the season. June was characterized by sinking labile organic material, which enhanced benthic fluxes in the downwelling event, whereas October had a significantly higher bottom velocity that stimulated the benthic fluxes. Finally, a comparison with a large benthic chamber (0.50 m2) was made during October. Despite methodological differences between AEC and chamber measurements, concurrent fluxes agreed within an acceptable margin (AEC:benthic chamber ratio = 0.78 ± 0.13; mean ± SD). Bottle incubations of water sampled from the chamber interior indicated that mineralization could explain this difference. These results show the importance of using non-invasive techniques such as AEC to resolve benthic flux dynamicsPostprin

La competencia aprender a aprender desde una perspectiva cultural innovadora

The deep and constant changes in today's world commit educational institutions to adapt their training systems according to current knowledge trends, which implies the unavoidable commitment in order to guarantee quality education, contributing to the training of responsible citizens and professionals, capable of meeting the needs of their environment, at the height of the complexity of current times. In this sense, the purpose of this research is aimed at promoting the debate around the implementation of the learning to learn competence from an educational and intercultural perspective, for the achievement of autonomous and permanent learning. For this reason, it is pertinent to resize the teacher's practice and, thus, consolidate the integral or holistic formation of the human being, hence, education must direct its efforts towards the development of skills and competences in the individual, as demanded by actual society, due to the achieving effective learning, associated with innovative strategies that promote Learning to Learn (AaA), in favor of his quality of life and his environment.Los profundos y constantes cambios en el mundo de hoy, comprometen a las instituciones educativas, a adecuar sus sistemas de formación de acuerdo a las actuales, tendencias del conocimiento, lo que implica, el compromiso ineludible en aras de garantizar una educación de calidad, contribuyendo en la formación de ciudadanos y profesionales responsables, capaces de atender las necesidades de su entorno, a la altura de la complejidad de los tiempos actuales. En tal sentido, el propósito de la presente investigación está dirigido a propiciar el debate en torno a la implementación de la &nbsp;competencia aprender a aprender desde una perspectiva educativa e intercultural, para el logro de un&nbsp; aprendizaje autónomo y permanente. &nbsp;Por ello, es pertinente redimensionar la práctica del docente y, así, consolidar la formación integral u holística del ser humano, de allí que, la educación debe dirigir sus esfuerzos hacia el desarrollo de habilidades y competencias en el individuo, tal como demanda la sociedad de hoy, producto de alcanzar un aprendizaje efectivo, asociado a &nbsp;estrategias innovadoras que promuevan el Aprender a Aprender (AaA), en pro de su calidad de vida y su entorno