SIZE-REACTIVITY OF DISSOLVED ORGANIC MATTER IN THE CAPE VERDE FRONTAL ZONE

Oral communicationDissolved organic matter (DOM) plays a major role in the recycling, export and sequestration of biogenic organic carbon, being a key component of ocean biogeochemical cycles and of the biological and microbial carbon pumps. Microbial degradation of DOM not only produces CO 2 but also generates dissolved molecules of decreasing bioavailability that can accumulate in the oceans for hundreds to thousands of years. The size-reactivity continuum (SRC) model is the conceptual framework to explain the DOM reactivity on a size basis, although field tests are still scarce and some of the pieces of this puzzle remain unclear. Taking advantage of the FLUXES-I cruise in the Cape Verde Frontal Zone (CVFZ), we have studied the size fractionated reactivity of the high (HMW; >1 KDa) and low (LMW; <1 KDa) molecular weight fractions of the DOM from surface down to 4000 m, using a high-efficiency and low-concentration-factor ultrafiltration cell. The wide ageing range covered by the water masses of the CVFZ makes it an excellent site to test the SRC model. Regarding the bulk C and N pools, the water masses with higher oxygen utilization were more depleted in HMW molecules, with a significant preference for the degradation of large N-containing compounds. Accordingly, preferential degradation of HMW fluorescent protein-like compounds was observed. In parallel, fluorescent humic-like compounds of both HMW and LMW were generated as by-product of the degradation of HMW organic compounds, and the remineralization of the DOM increases the aromaticy of both fractions, but especially the LMW one.ASL

DISSOLVED ORGANIC MATTER MOLECULAR FINGERPRINT OF THE WATER MASSES IN THE CAPE VERT FRONTAL ZONE

Oral communicationOcean water masses have been traditionally characterized by the thermohaline and conservative chemical properties (e.g. preformed nutrients) at their respective source regions. However, water masses also can exhibit characteristic levels of other individual compounds or emerging properties associated to compound classes. In this regard, the objective of this contribution is to characterize the dissolved organic matter (DOM) molecular fingerprint of the water masses present in the Cape Vert Frontal Zone (CVFZ). For this purpose, a set of 133 samples was collected from the surface to 4000 m depth in the CVFZ during the FLUXES I cruise (12 July - 11 August 2017) and isolated by solid-phase extraction (SPE), using styrene divinyl benzene polymer cartridges (PPL). The molecular analysis of these SPE-PPL extracts was performed using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), a method capable of identifying thousands of molecular formulae in DOM. These analyses have been combined with an optimum multiparameter (OMP) water mass analysis to obtain characteristic molecular indices for the eleven water masses present in the CVFZ, stemming from the subtropical and subpolar North and South Atlantic as well as from the Arctic and Antarctic Oceans. In particular, emerging properties such as the molecular diversity (D), mean molecular mass (MW), mean C:N ratio, aromaticity index (AI), double bond equivalent (DBE), and main molecular groups, as well as different compounds (e.g. Lignin) and individual heteroatoms were quantified.ASL

Estudio de la inclusión de aditivos en piensos con altas sustituciones de harina de pescado para trucha. Efecto en la salud intestinal

[EN] Based on projected population growth over the next few decades, the aquaculture sector has become necessary in order to provide for the population's protein requirements, since most of the fishing grounds are currently overexploited. The optimization of food management and the formulation of feeds in the aquaculture sector are one of the most important solutions in order to reduce the production cost in this sector. Originally, aquaculture feed was formulated based on fishmeal and fish oils obtained from commercial fishing, which is actually a limited and unsustainable resource, from an environment as well as from an economical point of view. The objective of this study is to evaluate the growth and nutritional parameters of the rainbow trout, supplied with different feed, with a high substitution of fishmeal, for a mixture of vegetable meals, made up mainly of soybean press cake and wheat gluten. Animals in groups of 40 and with an average starting weight of 14g were used. Every feed was tested three times. The experiment lasted 78 days. The average survival rate was slightly higher than 50% due to the high temperature. The results show significantly (p <0.05) that the higher the substitution levels, the worse the results in final weight, the instantaneous growth rate, the feed conversión index and the coefficient of growth efficiency.The higher sustitution levels increase significantly the results of the viscerosomatic index and the hepatosomatic index. The results of the efficiencies retentions were lower tan the least amount of fishmeal in the feed.La acuicultura es una de las industrias de producción animal con mayor tasa de crecimiento en todo el mundo y su sostenibilidad depende en gran medida de la reducción de los costos de los piensos, por lo que es necesario buscar nuevos ingredientes para los piensos capaces de provocar un crecimiento efectivo de los peces a costos reducidos, sin afectar a la salud de los mismos. Las sustituciones de harina de pescado por fuentes proteicas alternativas de origen vegetal y animal, se han estudiado ampliamente en los últimos años dado a que suelen ser más económicas y cuentan con una mayor disponibilidad. Las fuentes de proteína de origen vegetal han recibido la mayor atención debido a su bajo costo, alta calidad y altos rendimientos anuales, pero altas sustituciones con estas fuentes proteicas afectan el crecimiento de los peces y reducen la utilización de los nutrientes, especialmente en las especies carnívoras, además de contener compuestos antinutritivos que empeoran el aprovechamiento de los nutrientes y la salud intestinal. Esto hace que sea necesario suplementar los piensos con aditivos con el fin de aumentar la ingesta, mejorar la digestibilidad y la utilización del alimento, incrementar la ganancia en peso y evitar problemas con el sistema inmuitario.Jerusalén Lleó, E. (2017). Estudio de la inclusión de aditivos en piensos con altas sustituciones de harina de pescado para trucha. Efecto en la salud intestinal. http://hdl.handle.net/10251/89845TFG