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Climate variability is one of the main challenges faced by mankind, and understanding its relationship with water quality will generate knowledge that will enable the development of early adaptation strategies and the integral management of water resources. This study assessed the impact of the different intensities of the "El Niño-Southern Oscillation" (ENSO) climate phenomenon on Dissolved Oxygen (DO) from 1985 to 2015, at two monitoring stations on Cauca River. Spatial-temporal variation analysis of DO was performed using descriptive and inferential statistical techniques under different ENSO phases. The correlation between DO and the intensities of the ENSO phases was assessed using the Spearman correlation coefficient. No statistical differences were found in DO concentration at the two studied stations (p = 0.1164). Statical differences of DO were found depending on the ENSO phases at the Mediacanoa station (p = 0.002556); it was also found that the highest median concentrations of DO took place when La Niña was present. No correlation was found at the studied stations between the intensities of the ENSO phases and DO. The water quality of the Cauca River, at the Yotoco and Mediacanoa stations, showed very poor conditions, which has produced negative social, economic and environmental effects. [ABSTRACT FROM AUTHOR]

Ecosystem approach involves the understanding of the relationships among structures, processes and ecosystem services. Therefore, the article designs and applies a procedure to assess spatial-temporal variability, which may be present, in a support process to ecosystem services. Specific sites of assimilable phosphorus are used in a soil under sugarcane cultivation, to quantify a cost for excess phosphoric fertilizer. Differences in economic values between categories of this element in the soil are provided. This emphasizes the management and adaptation to the spatial-temporal variability of the nutrient availability process, for the sustainability of the sugar agribusiness. [ABSTRACT FROM AUTHOR]

La corriente de Yucatán fluye en dirección norte, sobre el lado occidental del canal que se denomina con el mismo nombre, el cual es la única conexión entre el golfo de México y el mar Caribe. En este trabajo se caracterizó la corriente de Yucatán y se estimó su variabilidad espacio-temporal en un periodo de seis años (2012-2018), para esto se utilizaron los datos de los anclajes oceanográficos YUC5, ubicados en este canal sobre la trayectoria de la corriente de Yucatán. Las series de datos fueron filtradas para conservar las frecuencias subinerciales, se efectuó un análisis estadístico y se obtuvieron rosas de corriente de 16 rumbos. Los resultados hallados complementan investigaciones anteriores sobre la variabilidad de la corriente de Yucatán y las aguas oceánicas regionales. Además, se hallaron anomalías de la magnitud de la corriente de Yucatán con una periodicidad de aproximadamente dos años. Las anomalías mensuales de la rapidez de la corriente de Yucatán y las de temperatura superficial del mar (TSM), que son indicadores del ONI (Oceanic Niño Index), fueron comparadas durante el evento de ENOS, que presentó categoría fuerte (+2.6oC) entre 2015-2016. A pesar de que estas variables no mostraron una relación directa, se encontró una correlación alta por encima de 0,7 y estadísticamente significativa, que presenta una relación inversa entre ambas series, con un desfase de 5 a 6 meses. El estudio de esta área aportó información acerca de la circulación y la conectividad dinámica existente entre las aguas adyacentes, así como la interrelación océano-atmosfera.

La variabilidad espacio-temporal del Material Particulado en Suspensión (MPS) en el Río de la Plata (RdlP) fue analizada para el periodo 2002-2014 a partir de datos Aqua-MODIS (Moderate Resolution Imaging Spectroradiometer), y posteriormente se explicó su variabilidad en términos de sus principales tributarios. La media mensual de la concentración del MPS mostró, un máximo a partir de fines del verano hasta mediados de otoño, y un mínimo, a partir de mediados del invierno hasta comienzos del verano. El río Bermejo (RBe), es el tributario que más sedimentos en suspensión transporta, situación que se reflejó en la relación significativa hallada entre la concentración media mensual del MPS y la descarga mensual promedio del RBe. La variación estacional del MPS, tuvo valores máximos durante el otoño y el verano, y valores mínimos en el invierno y la primavera, reflejando así el patrón mensual de descarga del RBe con uno y dos meses de retraso. La variación espacial evidenció tres regiones: interior, central y exterior. Por su parte, la variabilidad anual denotó una marcada estacionalidad en el patrón de cobertura espacial de las aguas con mayor concentración de MPS. La distribución de las anomalías estuvo relacionada con la influencia de la descarga de los ríos, lo que puso de manifiesto que el patrón temporal no está vinculado con el ciclo ENSO (El Niño – Sourthen Oscillation). Estos resultados nos permitieron denotar la importancia del RBe (no ENSO dependiente) para explicar el patrón de anomalías del MPS observado en el RdlP.

Radiocarbon ages on mollusk shells, which account for about half of the more than 8,000 dates from cultural deposits on the west coast of North America, need to be corrected for the local marine reservoir effect (ΔR) to yield true ages. Assays on "pre-bomb" shells show that ΔR increases poleward, echoing the age gradient in offshore waters. The meridional gradient in ΔRis not appreciably affected by the transition either from an upwelling regime to a downwelling regime north of 40°N--45°N or from a winter maximum-high alkalinity river discharge pattern to a summer maximum-low alkalinity pattern at the same latitude, probably because these changes are offset by increasing storminess and tidal energy in coastal areas. Mesoscale variations in ΔR along this gradient are attributable to contrasts in shore morphology and exposure. Data from123 shell-wood pairs reveal similar patterns of temporal variation in ΔR in the late Holocene in the coastal ecoregions. The characteristic temporal pattern echoes phases of variable El Niño-Southern Oscillation (ENSO) activity. The high degree of variability in ΔR argues against the indiscriminate application of regionally uniform or trans-Holocene ΔR values and demands improvements in spatiotemporal resolution if shell is used to date cultural deposits. [ABSTRACT FROM AUTHOR]

The spatial-temporal dynamic of physical-chemical variables of the water was characterized and monitored in the Ranchería River in the Colombian Guajira. Five sampling stations were chosen, three in the arm The Riíto: Desembocadura (DB), El Mirador (EM) and Villa Fatima (VF), and two stations in the arm Calancalá: Cangrejito (CG) and Valle de los Cangrejos (VC), monthly measurements for one year were made of temperature, dissolved oxygen, salinity, turbidity, alkalinity, total hardness, ammonium, nitrite, nitrate, phosphorus and N/P relationship. The results indicate that the arms have a different dynamics between them. The salinity increased during the study period; it was higher in the stations of the Calancalá; the highest average was recorded in CG with 46.72±13.56 ups., the dissolved oxygen showed a different pattern in both arms, decreased from the rainy season (3.19-4.40 mg./L.) to dry (2.04-3.01 mg./L.) in the Riíto, while the opposite occurred in the arm Calancalá. The pH tended to be higher in the Calancalá with respect to Riito, being significantly different in both arms in the two seasons studied; alkalinity was statistically different in the dry season for both arms. The waters of the Riíto were more turbid (61.39 -81.71 ntu.) with regard to the Calancalá (30.02-30.17 ntu.) in the rainy season. The nutrients nitrogen and phosphorus showed little variability, becoming more notorious during the dry season. A great spatio-temporal variability of the physicochemical variables was evidenced, which distinguishes the two arms of the Ranchería River Delta, as a result of climatic factors and specific features of each arm, which generates an environmental heterogeneity, mainly during the dry season. [ABSTRACT FROM AUTHOR]

The coastal spaces are fragile and complex areas that receive strong pressure because of the many uses and activities that are developed in them. The tourism of sun and beaches is one of the main economic practices present in these spaces that value the physical-natural conditions and their environmental variables. Of all of them, the sea surface temperature (SST) has been the least studied variable, especially associated to tourist destinations. The coastal zone of the province of Buenos Aires, Argentina, concentrates numerous tourist centers like the Partido de la Costa, Pinamar and Villa Gesell that attract in the summer time, a great flow of population. The objective of the present paper was to perform a descriptive and comparative analysis of SST in these parties through the use of monthly satellite images obtained by the Aqua-MODIS satellite-sensor during the period 2003-2013. The results showed a spatial and seasonal behavior of the SST differentiated for the entire study area. The SST for the warm period (January-March) ranged between 21.5 - 24.5°C and for the cold (July-September) between 9.4 - 11.5°C. This difference was lower in the cold period, allowing distinguishing 3 thermal zones with variations smaller than 0.5°C between them: Costa Norte, Costa Centro- Costa Sur, and Pinamar-Villa Gesell. The warm period presented more intense spatial thermal variations between the studied tourist destinations. Four thermal zones with 0.5°C differences were identified: Costa Norte, Costa Centro, Costa Sur, and Pinamar-Villa Gesell.

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A detailed study of the mechanisms generated through the turbidity plume and its variability at the Guadalquivir estuary has been carried out with remote sensing and in situ data. Several sensors with different characteristics have been required (spatial, temporal and spectral resolution), thereby providing information for a multi-sensor analysis. The main objective was to determine the water quality parameters (suspended solids and chlorophyll) and implement the methodology to define the empirical and semi-analytical algorithms from satellite data (MODIS, METIS, Deimos-1). The processes occurred in the estuary and adjacent region have been examined identifying those involved in the different variability scales. The forcings associated with rainfall and discharge from Alcalá del Río dam in addition to the climatic NAO index control seasonal and inter-annual fluctuations, while tide effects (semi-daily and fortnightly cycles) modulate the plume at the mouth throughout the year with significant variability. Special emphasis is focused on diagnosing the role of these mechanisms on the continental shelf ecosystems, constituting a powerful tool for the water quality management and coastal resources.

The aim of this study is to characterize the space and time variability of rainfall in the Santa Catarina state, searching for trends and cycles in time series. We analyzed 127 rainfall time series, distributing them spatially and identified six regions with homogeneous behavior. From these, representing rainfall time series were selected, which were submitted to Mann Kendall's and Sen's tests (trends analyze) and Wavelet Analysis to identify cycles. We found a east-west space division, with rainfall distributions different both in intensity and in relation to the rainy season. The time series analyzed, in general, no significant trend were identified. As for the temporal behavior, it was possible to verify cycles with temporal multiscale coincident with climatic events such as El Niño and Pacific Decadal Oscillation (PDO). [ABSTRACT FROM AUTHOR]

Copyright of Innotec is the property of Laboratorio Tecnologico del Uruguay and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Innotec is the property of Laboratorio Tecnologico del Uruguay and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Species resource use can vary throughout ontogeny, potentially affecting community dynamics. This can be particularly important for species facing high variability in environmental conditions and going through several orders of magnitude in size, as intertidal fishes. However, the influence of the resulting ontogenetic changes in guild membership on the spatio-temporal structure of fish assemblages remains virtually unknown. Here we assessed the spatial and temporal variability in the ontogenetic feeding guild (OFG) structure of the fish assemblage inhabiting the temperate rocky intertidal zone along central Chilean coast. This was done applying principal component analysis (PCA) and randomization tests (R-test) on the relative OFG composition of fish assemblages, obtained from seasonal samples from ten pools located at two heights in the intertidal zone in three localities between 33° and 34° S. Overall, the PCA and R-tests suggest that spatial variability dominated over temporal variability in OFG structure, mainly due to a higher representation of omnivore species at high intertidal pools in two of the three sampled localities. However, phenology-related changes in the representation of fish size-classes (i.e. carnivore recruitment in spring-summer) along with ontogenetic differences in habitat selection (e.g., selection for low intertidal pools by bigger-sized carnivore OFG) contributed to both spatial and temporal differentiation in OFG structure. Finally, the relative representation of each OFG correlated with that of their dominant species, without evidence for density compensation. This suggests low levels of functional redundancy among species in each OFG, highlighting the vulnerability of assemblage functioning to size-biased disturbances as fishing.El uso de los recursos puede variar a través de la ontogenia, afectando potencialmente las dinámicas comunitarias. Esto puede ser de particular importancia en especies que enfrentan alta variabilidad en las condiciones ambientales, especialmente en peces intermareales, los que alcanzan varios órdenes de magnitud en tamaño corporal. Sin embargo, la influencia de los cambios ontogenéticos en la membresía gremial sobre la estructura espacio-temporal de los ensambles de peces permanece virtualmente desconocida. En este trabajo estudiamos la variabilidad espacio-temporal en la estructura de los gremios alimenticios ontogenéticos (OFG) de los ensambles de peces intermareales que ocurren en el intermareal rocoso de la costa de Chile central. Para esto realizamos an��lisis de componentes principales (PCA) y pruebas de aleatorización (pruebas R) de la composición relativa de las OFG de estos ensambles, obtenidos de muestreos estacionales en diez pozas intermareales ubicadas en dos alturas de mareas en la zona intermareal en tres localidades entre los 33° y 34° S. En general, los PCA y pruebas R sugieren que la variabilidad espacial domina sobre la variabilidad temporal en la estructura de las OFG, debido principalmente a la alta representatividad de las especies omnívoras en las pozas altas del intermareal en dos de las tres localidades muestreadas. Sin embargo, cambios relacionados a la fenología en la representación de las clases de tamaño de los peces (i.e. reclutamiento de carnívoros en primavera-verano) junto con diferencias ontogenéticas en la selección de hábitat (e.g., selección por pozas del intermareal bajo por la OFG de carnívoros de gran tamaño) contribuyeron a una diferenciación espacial y temporal de la estructura de la OFG. Finalmente, la representación relativa de cada OFG se correlacionó con la de sus especies dominantes, sin evidencia de una compensación por densidad. Esto sugiere bajos niveles de redundancia funcional entre las especies en cada OFG, lo cual denota la vulnerabilidad del funcionamiento de estos ensambles a perturbaciones sesgadas en tamaño corporal tales como la pesca.