Particulate and phytoplankton absorption during POLARSTERN cruises ANT-XXVI/3 and ANT-XXVIII/3

The euphotic depth (Zeu) is a key parameter in modelling primary production (PP) using satellite ocean colour. However, evaluations of satellite Zeu products are scarce. The objective of this paper is to investigate existing approaches and sensors to estimate Zeu from satellite and to evaluate how different Zeu products might affect the estimation of PP in the Southern Ocean (SO). Euphotic depth was derived from MODIS and SeaWiFS products of (i) surface chlorophyll-a (Zeu-Chla) and (ii) inherent optical properties (Zeu-IOP). They were compared with in situ measurements of Zeu from different regions of the SO. Both approaches and sensors are robust to retrieve Zeu, although the best results were obtained using the IOP approach and SeaWiFS data, with an average percentage of error (E) of 25.43% and mean absolute error (MAE) of 0.10 m (log scale). Nevertheless, differences in the spatial distribution of Zeu-Chla and Zeu-IOP for both sensors were found as large as 30% over specific regions. These differences were also observed in PP. On average, PP based on Zeu-Chla was 8% higher than PP based on Zeu-IOP, but it was up to 30% higher south of 60°S. Satellite phytoplankton absorption coefficients (aph) derived by the Quasi-Analytical Algorithm at different wavelengths were also validated and the results showed that MODIS aph are generally more robust than SeaWiFS. Thus, MODIS aph should be preferred in PP models based on aph in the SO. Further, we reinforce the importance of investigating the spatial differences between satellite products, which might not be detected by the validation with in situ measurements due to the insufficient amount and uneven distribution of the data.

Microbiota and Microsatellite genotypes of Pacific oysters stemming from three oyster bed in the Northern Wadden Sea

Background: Studies of oyster microbiomes have revealed that a limited number of microbes, including pathogens, can dominate microbial communities in host tissues such as gills and gut. Much of the bacterial diversity however remains underexplored and unexplained, although environmental conditions and host genetics have been implicated. We used 454 next generation 16S rRNA amplicon sequencing of individually tagged PCR reactions to explore the diversity of bacterial communities in gill tissue of the invasive Pacific oyster Crassostrea gigas stemming from genetically differentiated beds under ambient outdoor conditions and after a multifaceted disturbance treatment imposing stress on the host. Results: While the gill associated microbial communities in oysters were dominated by few abundant taxa (i.e. Sphingomonas, Mycoplasma) the distribution of rare bacterial groups correlated to relatedness between the hosts under ambient conditions. Exposing the host to disturbance broke apart this relationship by removing rare phylotypes thereby reducing overall microbial diversity. Shifts in the microbiome composition in response to stress did not result in a net increase in genera known to contain potentially pathogenic strains. Conclusion: The decrease in microbial diversity and the disassociation between population genetic structure of the hosts and their associated microbiome suggest that disturbance (i.e. stress) may play a significant role for the assembly of the natural microbiome. Such community shifts may in turn also feed back on the course of disease and the occurrence of mass mortality events in oyster populations.

Colonización, inmigración y etnicidad en la provincia de Misiones, Argentina. Etapa II. Cartografia etnografica de la plurietnicidad en Misiones. Argentina. 16H237

La provincia de Misiones constituye un área particularmente relevante para el estudio de los procesos migratorios. En un espacio que abarca 30.719 km2, cuyos límites de frontera alcanzan un 90% entre los países de Paraguay y Brasil, se asentaron pobladores de más de veinte nacionalidades diferentes, fenómeno que se constituye en un paisaje étnico particular y diverso para el estudio del poblamiento de la provincia. Poblamiento que se ha constituido desde fines del siglo XIX con población de la zona -paraguayos, correntinos, aborígenes- a los que se suman las colonizaciones que se dividen en oficiales y privadas, así como por el poblamiento espontáneo. A partir del análisis de lo antedicho, observamos que la influencia de las migraciones y asentamiento de población extranjera en Misiones prefigura particularidades vinculadas a: la organización del espacio geográfico, la gestación de la historia regional, los procesos de interculturización, la constitución de identidades culturales y las relaciones interétnicas e intraétnicas. Tan es así que entre las caracterizaciones de la Provincia, la mayoría de las publicaciones existentes, destacan esta particularidad desde la denominación de “Misiones crisol de razas” u otros como “provincia pluriétnica”. Frente a esta caracterización de Misiones, la elaboración de una “cartografía etnográfica” de los habitantes y de las colectividades ubicadas en la provincia será de gran utilidad para el conocimiento de: lugares de procedencia, periodización de los movimientos migratorios, lugares de asentamiento, relaciones (de trabajo, de parentesco, religiosas, etc.) establecidas entre los diferentes grupos étnicos, la población de origen y de fronteras de la zona. De la misma manera, conociendo la inserción en el medio de “los que llegaron” y la “descendencia” filial de los mismos, podremos reconstruir un mapa poblacional en cuanto a sus ascendencias y descendencias, hecho que sin dudas se convierte en un diacrítico interesante al momento de su caracterización. 7

Practice advisory: interim guidance for care of obstetric patients during a zika virus outbreak

Zika during pregnancy has been associated with birth defects, specifically significant microcephaly. Transmission of Zika to the fetus has been documented in all trimesters; Zika virus RNA has been detected in fetal tissue from early missed abortions, amniotic fluid, term neonates and the placenta. However, much is not yet known about Zika virus in pregnancy. Uncertainties include the incidence of Zika virus infection among pregnant women in areas of Zika virus transmission, the rate of vertical transmission and the rate with which infected fetuses manifest complications such as microcephaly or demise. The absence of this important information makes management and decision making in the setting of potential Zika virus exposure (i.e. travel to endemic areas) or maternal infection, difficult. Currently, there is no vaccine or treatment for this infection.