913 resultados para Angela Santa Clara
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EXTRACT (SEE PDF FOR FULL ABSTRACT): The 1983 El Nino resulted in a decrease in the flux of diatoms and planktonic foraminiferans into the Santa Barbara basin. These may both be related to the decrease in productivity and therefore standing crops of these two groups.
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Los peces constituyen uno de los atractivos principales en los arrecifes coralinos para el buceo turístico, por lo cual resulta necesario monitorear su abundancia y valores estéticos. El objetivo de esta investigación fue evaluar el estado de conservación de las asociaciones de peces arrecifales en cuatro de los principales polos turísticos del Archipiélago Sabana-Camagüey, Cuba en el año 2010. Se muestrearon 23 sitios de buceo turísticos en áreas adyacentes a las regiones de Varadero (5 sitios), cayos de Villa Clara (6 sitios), Cayo Coco (6 sitios) y Santa Lucia (6 sitios). En cada uno de ellos se realizaron seis réplicas de censos visuales de todas las especies de peces en recorridos lineales de 50 m de largo por 2 m de ancho, ocupando un área total de 600 m2. El puntaje más alto de conservación lo presentó los cayos de Villa Clara (37), siguiéndole en orden decreciente Cayo Coco (35), y con valores más bajos Varadero (24) y Santa Lucia (22). Los puntajes de las cuatro regiones fueron inferiores a los encontrados en otros arrecifes de Cuba y el Caribe. Los valores de Varadero y Santa Lucia se correspondieron con los de arrecifes de hábitats degradados y sometidos a explotación pesquera. En general, en la mayoría de las regiones predominaron peces de talla pequeña (<20 cm) pertenecientes a las familias Pomacentridae y Labridae y hubo poca abundancia de peces carnívoros y herbívoros de mediana (20-40 cm) y gran talla (>40 cm). ABSTRACT Fish are one of the main attractions on coral reefs for diving tourism; therefore, it is necessary to monitor their condition and aesthetic values. The objective of this research was to evaluate the status of reef fish assemblages in four tourist areas of Sabana-Camaguey Archipelago, Cuba in 2010. Twentythree tourist diving sites were sampled in adjacent areas to regions of Varadero (five sites), Villa Clara keys (6 sites), Coco key (6 sites) and Santa Lucia (6 sites). In each region, six replicated visual census of all fish species were conducted along belt transects of 50 m length and 2 m width, occupying a total area of 600 m2. The highest conservation score was obtained by Villa Clara keys (37), followed in decreasing order by Coco key (35), and with lower values Varadero (24) and St. Lucia (22). The scores of the four regions were lower than the values of other Cuban and Caribbean reefs. The values of Varadero and Santa Lucia corresponded to reefs with degraded habitats and subject to overfishing. In general, small fish (< 20 cm) from families Pomacentridae and Labridae, and low abundance of carnivore and herbivore fish of middle (20-40 cm) and large size (> 40 cm) predominated in most regions.
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Dating of annually varved sediments of Santa Barbara Basin down to AD 1650 in absence of precise radiometric methods was achieved by (1) counting varves and determining mean annual sedimentation rates from x-radiographs, and (2) correlation with historical rainfall and tree-ring records.
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A 1844-1987 time-series of carbon stable isotope ratios from dated sedimentary total organic carbon from the center of the Santa Barbara basin is compared with historical climate and oceanographic records. Carbon derived from carbon-13-depleted phytoplankton and carbon-13-enriched kelp appear responsible for a large part of the isotopic variance in sedimentary total organic carbon. El Niño/Southern Oscillation events are recorded by the isotopic response of marine organic carbon in sediments.
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Sediments in Santa Barbara Basin contain microfossil and sedimentological information that allows reconstruction of major features of the California Current such as water temperature, strength of upwelling, and productivity. ... Until now, investigations of Santa Barbara Basin sediments have utilized analytical techniques that could not resolve seasonal laminae, permitting annual resolution of variations in sediment composition and structure only. ... Based on a successful technique for preparation of epoxy-embedded and highly polished thin-sections that permit economical optical and electron microscope evaluation of laminated sequences, it is our long-term goal to reconstruct, with unprecedented detail, the history of sedimentation processes in the Santa Barbara Basin by developing ultra-high-resolution time series of biotic and detrital proxies.
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Like pages of a "natural coastal diary", successive layers of anoxic varved sediment in the central Santa Barbara Basin have been used by paleoceanographers to reconstruct aspects of past coastal climate. This report focuses on the end of the "Little Ice Age" (15th to 19th century) and on the beginning of this century, a period known to encompass extreme climate excursions and weather events in the Santa Barbara Basin and other parts of Southern California. El Niño events are known to disrupt Southern California's coastal ecosystems and to cause anomalous weather conditions, but El Niño events in Southern California before 1990 have been largely undocumented.
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Annual radiolarian flux (1954-1986) extrapolated from varved Santa Barbara Basin sediments was compared to instrumental data to examine the effect of interannual climate variability. Paleo-reconstructions over large geographic areas or 10^3 years and longer typically rely on changes in species composition to signal environment or climate shifts. In the relatively short period studied, climate fluctuations were insufficient to significantly alter the assemblage, but there was considerable variability in the total flux of radiolarians. This variability, greatest on 5- to 25-year time scales, appears to be linked to regional climate variability. Total flux correlates to regional California sea surface temperature and the composite of sea level pressure over the Northern Hemisphere for years of high radiolarian flux resembles positive PNA circulation.
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2009
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2010
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2010
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2010