Reproductive Schedules in Southern Bluefin Tuna: Are Current Assumptions Appropriate?

Southern bluefin tuna (SBT) appear to comprise a single stock that is assumed to be both mixed across its distribution and having reproductive adults that are obligate, annual spawners. The putative annual migration cycle of mature SBT consists of dispersed foraging at temperate latitudes with migration to a single spawning ground in the tropical eastern Indian Ocean. Spawning migrations have been assumed to target two peaks in spawning activity; one in September-October and a second in February-March. SBT of sizes comparable to that of individuals observed on the spawning ground were satellite tagged in the Tasman Sea region (2003–2008) and demonstrated both migrations to the spawning grounds and residency in the Tasman Sea region throughout the whole year. All individuals undertaking apparent spawning migrations timed their movements to coincide with the second recognised spawning peak or even later. These observations suggest that SBT may demonstrate substantial flexibility in the scheduling of reproductive events and may even not spawn annually as currently assumed. Further, the population on the spawning grounds may be temporally structured in association with foraging regions. These findings provide new perspectives on bluefin population and spatial dynamics and warrant further investigation and consideration of reproductive schedules in this species

DEVELOPMENT OF A PrFeB CRYOGENIC UNDULATOR AT NSLS-II

Abstract Recent cryogenic undulators use Praseodymium-IronBoron (PrFeB) magnets cooled down to 80K. The main drawback of the PrFeB magnet grades developed so far are their relatively low coercive field at ambient temperature, below 2 T which prevents PrFeB based cryogenic undulator from baking. Some precautions are required during the undulator assembling and shimming to ensure Ultra High Vacuum (UHV) compatibility. However Hitachi Metal Industry (HMI) recently developed two different grades of PrFeB magnet with large coercive field but at the expense of the remanent field. The magnetization curves have been measured from 40 K up to 400 K to determine the field increase and to investigate the magnet withstanding to baking. An In Vacuum Undulator (IVU) prototype has also been baked. Magnetic measurements before and after baking are also presented

Estudio de las variaciones hidroquímicas en profundidad en un embalse afectado por procesos de drenaje acido de mina

En climas semiáridos, la construcción de embalses es una alternativa común para cubrir las necesidades de agua de la población y la industria. La vulnerabilidad de estas aguas frente a la contaminación es mucho mayor que la de las aguas subterráneas. EI embalse de El Sancho (Faja Pirítica Ibérica, SW España) fue construido en 1962 y' se nutre de las aguas del río Meca, el cual recibe aguas contaminadas procedentes de diferentes tributarios subsidiarios, sobre todo de la mina abandonada de Tharsis. El presente trabajo se focaliza en el estudio de las variaciones hidroquímicas en las aguas del embalse de El Sancho, con el fin de definir potenciales procesos de estratificación en la carga metálica y de sulfatos. Para ello, se llevó a cabo, en octubre de 2011, un muestreo estratificado desde la superficie, con intervalos de 1 metro, hasta el fondo del embalse. De los gráficos de evolución en profundida, resulta una clara estratificación de los valores de temperatura, pH conductividad y oxígeno disuelto, así como de las correspondientes cargas metálicas y de sulfatos asociados a esta. Los datos obtenidos ponen en evidencia el incremento de la carga metálica en el fondo del embalse, que estudios previos tan solo detectaban para el hierro. El incremento de concentraciones es más evidente en el hypolimnion para Cu, Pb, Fe, Al y Mn