Feeding habits of Guiana dolphins, Sotalia guianensis, from south-eastern Brazil: New items and a knowledge review

This study presents new information on feeding habits of Guiana dolphins, Sotalia guianensis, in south-eastern Brazil, together with new regression equations to evaluate the weight and length of fish from otoliths, showing an overview on the knowledge about this species-diet in this area. Eighteen stomach contents had been analysed and compared to 180 samples collected in another eight feeding studies. The analysed specimens were either incidentally caught in gillnets used in coastal waters by the fleet based in the Cananéia main harbour (25°00âS 47°55âW), south of São Paulo State, or found dead in inner waters of the Cananéia estuary between 2003 and 2009. Based on the index of relative importance analysis, the most important fish species were the banded croaker, Paralonchurus brasiliensis. Doryteuthis plei was the most representative cephalopod species. Stellifer rastrifer was the most important fish species observed in dolphins in inner estuarine waters and P. brasiliensis in recovered dolphins from coastal waters. Loliguncula brevis is the only cephalopod species reported from dolphins found in inner estuarine waters up to date. Doryteuthis plei was the most important cephalopod species observed in coastal dolphins. When considering other feeding studies, the most representative fish family in the diet of S. guianensis was Sciaenidae, which is mainly represented by demersal fishes. The main preys of S. guianensis are abundant in the studied areas, which may indicate an opportunistic feeding habit. The majority of them are not the most important target species by the commercial fishery in south-eastern Brazil. © 2012 Marine Biological Association of the United Kingdom.

Applying spatial analysis of genetic and environmental data to predict connection corridors to the New World screwworm populations in South America

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Feeding habits of Guiana dolphins, Sotalia guianensis, from south-eastern Brazil: new items and a knowledge review

This study presents new information on feeding habits of Guiana dolphins, Sotalia guianensis, in south-eastern Brazil, together with new regression equations to evaluate the weight and length of fish from otoliths, showing an overview on the knowledge about this species' diet in this area. Eighteen stomach contents had been analysed and compared to 180 samples collected in another eight feeding studies. The analysed specimens were either incidentally caught in gillnets used in coastal waters by the fleet based in the Cananeia main harbour (25 degrees 00'S 47 degrees 55'W), south of Sao Paulo State, or found dead in inner waters of the Cananeia estuary between 2003 and 2009. Based on the index of relative importance analysis, the most important fish species were the banded croaker, Paralonchurus brasiliensis. Doryteuthis plei was the most representative cephalopod species. Stellifer rastrifer was the most important fish species observed in dolphins in inner estuarine waters and P. brasiliensis in recovered dolphins from coastal waters. Loliguncula brevis is the only cephalopod species reported from dolphins found in inner estuarine waters up to date. Doryteuthis plei was the most important cephalopod species observed in coastal dolphins. When considering other feeding studies, the most representative fish family in the diet of S. guianensis was Sciaenidae, which is mainly represented by demersal fishes. The main preys of S. guianensis are abundant in the studied areas, which may indicate an opportunistic feeding habit. The majority of them are not the most important target species by the commercial fishery in south-eastern Brazil.

Ar-40/Ar-39 Evidence for Middle Proterozoic (1300-1500 Ma) Slow Cooling of the Southern Black Hills, South Dakota, Midcontinent, North America: Implications for Early Proterozoic P-T Evolution and Posttectonic Magmatism

Ar-40/Ar-39 total gas and plateau dates from muscovite and biotite in the southern Black Hills, South Dakota, provide evidence for a period of Middle Proterozoic slow cooling. Early Proterozoic (1600-1650 Ma) mica dates were obtained from metasedimentary rocks located in a synformal structure between the Harney Peak and Bear Mountain domes and also south of Bear Mountain. Metamorphic rocks from the dome areas and undeformed samples of the similar to 1710 Ma Harney Peak Granite (HPG) yield Middle Proterozoic mica dates (similar to 1270-1500 Ma). Two samples collected between the synform and Bear Mountain dome yield intermediate total gas mica dates of similar to 1550 Ma. We suggest two end-member interpretations to explain the map pattern of cooling ages: (1) subhorizontal slow cooling of an area which exhibits variation in mica Ar retention intervals or (2) mild folding of a Middle Proterozoic (similar to 1500 Ma) similar to 300 degrees C isotherm. According to the second interpretation, the preservation of older dates between the domes may reflect reactivation of a preexisting synformal structure (and downwarping of relatively cold rocks) during a period of approximately east-west contraction and slow uplift during the Middle Proterozoic. The mica data, together with hornblende data from the Black Hills published elsewhere, indicate that the ambient country-rock temperature at the 3-4 kbar depth of emplacement of the HPG was between 350 degrees C and 500 degrees C, suggesting that the average upper crustal geothermal gradient was 25 degrees-40 degrees C/km prior to intrusion. The thermochronologic data suggest HPG emplacement was followed by a similar to 200 m.y. period of stability and tectonic quiescence with little uplift. We propose that crust thickened during the Early Proterozoic was uplifted and erosionally(?) thinned prior to similar to 1710 Ma and that the HPG magma was emplaced into isostatically stable crust of relatively normal thickness. We speculate that uplift and crustal thinning prior to HPG intrusion was the result of differential thinning of the subcrustal lithosphere beneath the Black Hills. If so, this process would have also caused an increase in mantle heat flux across the Moho and triggered vapor-absent melting of biotite to produce the HPG magma. This scenario for posttectonic granite generation is supported, in part, by the fact that in the whole of the Black Hills, the HPG is spatially associated with the deepest exposed Early Proterozoic country rock.

Reduction in Northward Incursions of the South Asian Monsoon Since ~1400 AD Inferred from a Mt. Everest Ice Core

A highly resolved Mt. Everest ice core reveals a decrease in marine and increase in continental air masses related to relatively high summer surface pressure over Mongolia, and reduction in northward incursions of the summer South Asian monsoon since similar to 1400 AD. Previously published proxy records from lower sites south of the Himalayas indicate strengthening of the monsoon since this time. These regional differences are consistent with a south north seesaw in convective activity in the Asian monsoon region, and reflect a southward shift in the mean summer position of the monsoon trough since similar to 1400 AD. The change in monsoonal circulation at 1400 AD is synchronous with a reduction in solar irradiance and the onset of the LIA. This demonstrates a hemispheric scale circulation reorganization at this time, and the potential for future large shifts in monsoonal circulation.

Desarrollo y validación de una escala para evaluación de daño por orugas defoliadoras en soja (Glycine max L.), para el sur de la provincia de Córdoba

Para desarrollar y validar una escala logarítmica diagramática de evaluación de daño por orugas defoliadoras al cultivo de soja, para el centro-sur de Córdoba, se colectaron folíolos dañados a fin de obtener la máxima defoliación presente. Se calculó el porcentaje de defoliación escaneando cada folíolo, utilizando el software WinFolia. Se planteó una escala de siete clases obteniendo el valor medio de cada una con el programa DOSLOG. Posteriormente 140 folíolos, cuya defoliación real se determinó con WinFolia, fueron evaluados por seis evaluadores con y sin experiencia previa en estimaciones de defoliación, con y sin escala. La validación por precisión y exactitud se realizó por regresión lineal simple entre la defoliación real y la estimada, y la reproducibilidad por regresión entre las 140 estimaciones de los evaluadores combinados de a pares. Sin la escala la mayoría de los evaluadores sobreestimaron la defoliación, indicando desvíos positivos constantes para todos los niveles, y en 9 de 12 evaluadores ocurrieron desvíos sistemáticos. Con la escala mejoró la exactitud (-1,74 a 1,39), precisión (0,77 a 0,90) y reproducibilidad, por lo que se la considera adecuada para evaluaciones de daños causados por orugas defoliadoras al cultivo de soja, en la región centro-sur de Córdoba.

Temperaturas óptimas para resembrar especies mesotérmicas sobre céspedes de Cynodon dactylon en el centro-sur de la provincia de Córdoba, Argentina

Los objetivos fueron determinar temperaturas medias de suelo (TMS) y mínimas de aire (TMA) adecuadas para realizar resiembras otoñales; evaluar la tasa de crecimiento (TCC) de Cynodon dactylon (Bermuda) que minimice la competencia con la especie resembrada y el comportamiento de distintas especies mesotérmicas en el centro-sur de la provincia de Córdoba. Se resembró durante 2010 y 2011, en un diseño de parcelas divididas con cinco fechas de siembra (FS) quincenalmente desde principios de marzo, con tres genotipos: Lolium multiflorum cv Axcella, L. perenne y L. perenne cv Excel I. Las temperaturas se midieron entre principios de marzo y hasta que la bermuda entró en dormición, calculando TMA y TMS. En las subparcelas resembradas se registraron calidad visual y cobertura total; además, en la bermuda se calculó la TCC. Las resiembras que lograron valores más altos de calidad visual, cobertura y bajas TCC de la Bermuda, se dieron con TMS entre 18 - 21°C y TMA entre 11,5 - 15,5°C. De acuerdo con los valores medios normales de la región centro-sur de Córdoba, las temperaturas óptimas se observan entre la segunda década de marzo y primera de abril. Los tres genotipos tuvieron comportamientos similares independientemente de la FS utilizada.

El sur de Córdoba en peligro : Acerca de la articulación entre ranqueles y refugiados unitarios (1841)

La Frontera Sur de Córdoba formó parte de la larga extensión conocida como Frontera Sur argentina, con la cual comparte un conjunto de relaciones estructurales definidas no sólo por la desgarradora experiencia de la guerra sino también por el cruce, las conexiones y el diálogo inter-cultural. El trabajo se ocupa de la vinculación de los ranqueles con los unitarios que se refugiaron en las tolderías después de la derrota de las fuerzas de Gregorio Aráoz de Lamadrid que ocupó Córdoba en 1840. Procura establecer cómo la articulación de estas dos fuerzas sociales afectó el ejercicio de la soberanía por parte del gobierno provincial. Se sostiene que los ataques ranqueles integrados por refugiados unitarios habrían puesto en cuestionamiento el ejercicio del poder territorial por parte del Estado provincial

Clay mineraology and grain size composition of surface sediments from South Pacific Ocean

The reconstruction of low-latitude ocean-atmosphere interactions is one of the major issues of (paleo-)environmental studies. The trade winds, extending over 20° to 30° of latitude in both hemispheres, between the subtropical highs and the intertropical convergence zone, are major components of the atmospheric circulation and little is known about their long-term variability on geological time-scales, in particular in the Pacific sector. We present the modern spatial pattern of eolian-derived marine sediments in the eastern equatorial and subtropical Pacific (10°N to 25°S) as a reference data set for the interpretation of SE Pacific paleo-dust records. The terrigenous silt and clay fractions of 75 surface sediment samples have been investigated for their grain-size distribution and clay-mineral compositions, respectively, to identify their provenances and transport agents. Dust delivered to the southeast Pacific from the semi- to hyper-arid areas of Peru and Chile is rather fine-grained (4-8 µm) due to low-level transport within the southeast trade winds. Nevertheless, wind is the dominant transport agent and eolian material is the dominant terrigenous component west of the Peru-Chile Trench south of ~ 5°S. Grain-size distributions alone are insufficient to identify the eolian signal in marine sediments due to authigenic particle formation on the sub-oceanic ridges and abundant volcanic glass around the Galapagos Islands. Together with the clay-mineral compositions of the clay fraction, we have identified the dust lobe extending from the coasts of Peru and Chile onto Galapagos Rise as well as across the equator into the doldrums. Illite is a very useful parameter to identify source areas of dust in this smectite-dominated study area.

El sur de Córdoba en peligro : Acerca de la articulación entre ranqueles y refugiados unitarios (1841)

La Frontera Sur de Córdoba formó parte de la larga extensión conocida como Frontera Sur argentina, con la cual comparte un conjunto de relaciones estructurales definidas no sólo por la desgarradora experiencia de la guerra sino también por el cruce, las conexiones y el diálogo inter-cultural. El trabajo se ocupa de la vinculación de los ranqueles con los unitarios que se refugiaron en las tolderías después de la derrota de las fuerzas de Gregorio Aráoz de Lamadrid que ocupó Córdoba en 1840. Procura establecer cómo la articulación de estas dos fuerzas sociales afectó el ejercicio de la soberanía por parte del gobierno provincial. Se sostiene que los ataques ranqueles integrados por refugiados unitarios habrían puesto en cuestionamiento el ejercicio del poder territorial por parte del Estado provincial

Sea surface temperature estimation of the South Tasman Rise

The Subtropical Front (STF) marking the northern boundary of the Southern Ocean has a steep gradient in sea surface temperature (SST) of approximately 4°C over 0.5° of latitude. Presently, in the region south of Tasmania, the STF lies nominally at 47°S in the summer and 45°S in the winter. We present here SST reconstructions in a latitudinal transect of cores across the South Tasman Rise, southeast of Australia, during the late Quaternary. SST reconstructions are based on two paleotemperature proxies, alkenones and faunal assemblages, which are used to assess past changes in SST in spring and summer. The north-south alignment in core locations allows reconstruction of movement of the STF over the last 100 ka. Surface water temperatures during the last glaciation in this region were ~4°C colder than today. Additional temperature changes greater in magnitude than 4°C seen in individual cores can be attributed to changes in the water mass overlying the core site caused by the movement of the front across that location. During the penultimate interglacial, SST was ~2°C warmer and the STF was largely positioned south of 47°S. Movement of the STF to the north occurred during cool climate periods such as the last marine isotope stages 3 and 4. In the last glaciation, the front was at its farthest north position, becoming pinned against the Tasmanian landmass. It moved south by 4° latitude to 47°S in summer during the deglaciation but remained north of 45°S in spring throughout the early deglaciation. After 11 ka B.P. inferred invigoration of the East Australia Current appears to have pushed the STF seasonally south of the East Tasman Plateau, until after 6 ka B.P. when it achieved its present configuration.

Compilation of 231Protactinium/230 Thorium excess ratios in various surface sediment samples from the South Atlantic

In large areas of the world's oceans, there is a relationship between the mass flux of particulate matter and the unsupported 231Pa/230Th (xs231Pa/xs230Th) activity ratio of recent sediments. This observation forms the basis for using the xs231Pa/xs230Th ratio as a proxy for past changes in export productivity. However, a simple relationship between xs231Pa/xs 230Th ratio and particle flux requires that the water residence time in an ocean basin is far in excess of the scavenging residence time of 231Pa, and that the composition of sinking particles maintains a strong preference for the adsorption of 230Th over 231Pa with a constant 230Th/231Pa fractionation factor (F). The best correlation between xs231Pa/xs230Th ratio and mass flux is found in the Pacific Ocean. In the Atlantic, the contrast in the xs231Pa/xs230Th ratios between open ocean (low flux regions) and ocean margins (high flux regions) is much less pronounced due to the shorter residence time of deep water, resulting in less effective boundary scavenging of 231Pa. In the Southern Ocean, south of the Polar Front, there is no more a simple relationship between xs231Pa/xs230Th and particle flux. This is a result of a southward decrease in F, probably reflecting the increased opal content of sinking particles. Opal does not fractionate 231Pa and 230Th significantly. This lack of fractionation results in high xs231Pa/xs230Th ratios in opal-dominated regions, even in areas of very low particle fluxes such as the Weddell Sea. The xs231Pa/xs230Th ratio can therefore only be used as a paleoproductivity proxy if, in the time interval of interest, changes in the basin ventilation rate and differential scavenging of both radionuclides due to changes in the chemical composition of particulate matter can be excluded.

Millenial variability of dust in South Atlantic sediment records

Fluxes of lithogenicmaterial and fluxes of three palaeo productivity proxies (organic carbon, biogenic opal and alkenones) over the past 100,000 years were determined using the 230Th-normalization method in three sediment cores from the Subantarctic South Atlantic Ocean. Features in the lithogenic flux record of each core correspond to similar features in the record of dust deposition in the EPICA Dome C ice core. Biogenic fluxes correlate with lithogenic fluxes in each sediment core. Our preferred interpretation is that South American dust, most probably from Patagonia, constitutes a major source of lithogenic material in Subantarctic South Atlantic sediments, and that past biological productivity in this region responded to variability in the supply of dust, probably due to biologically available iron carried by the dust. Greater nutrient supply as well as greater nutrient utilization (stimulated by dust) contributed to Subantarctic productivity during cold periods, in contrast to the region south of the Antarctic Polar Front (APF), where reduced nutrient supply during cold periods was the principal factor limiting productivity. The anti-phased patterns of productivity on opposite sides of the APF point to shifts in the physical supply of nutrients and to dust as cofactors regulating productivity in the Southern Ocean.

Middle Eocene-Early Pliocene Subantarctic planktic foraminiferal biostratigraphy of ODP Site 1090 on the Agulhas Ridge, South Atlantic

The analysis of planktic foraminiferal assemblages from Site 1090 (ODP Leg 177), located in the central part of the Subantarctic Zone south of South Africa, provided a geochronology of a 330-m-thick sequence spanning the Middle Eocene to Early Pliocene. A sequence of discrete bioevents enables the calibration of the Antarctic Paleogene (AP) Zonation with lower latitude biozonal schemes for the Middle-Late Eocene interval. In spite of the poor recovery of planktic foraminiferal assemblages, a correlation with the lower latitude standard planktic foraminiferal zonations has been attempted for the whole surveyed interval. Identified bioevents have been tentatively calibrated to the geomagnetic polarity time scale following the biochronology of Berggren et al. (1995). Besides planktic foraminiferal bioevents, the disappearance of the benthic foraminifera Nuttallides truempyi has been used to approximate the Middle/Late Eocene boundary. A hiatus of at least 11.7 Myr occurs between V78 and V71 m composite depth extending from the Early Miocene to the latest Miocene-Early Pliocene. Middle Eocene assemblages exhibit a temperate affinity, while the loss of several planktic foraminiferal species by late Middle to early Late Eocene time reflects cooling. During the Late Eocene-Oligocene intense dissolution caused impoverishment of planktic foraminiferal assemblages possibly following the emplacement of cold, corrosive bottom waters. Two warming peaks are, however, observed: the late Middle Eocene is marked by the invasion of the warmer water Acarinina spinuloinflata and Hantkenina alabamensis at 40.5 Ma, while the middle Late Eocene experienced the immigration of some globigerinathekids including Globigerinatheka luterbacheri and Globigerinatheka cf. semiinvoluta at 34.3 Ma. A more continuous record is observed for the Early Miocene and the Late Miocene-Early Pliocene where planktic foraminiferal assemblages show a distinct affinity with southern mid- to high-latitude faunas.