Oceanografía biológica de Cabo Polonio: apuntes sobre investigaciones recientes

Los resultados presentados en esta publicación se enmarcan dentro del proyecto financiado por ANII, código: ANII_FCE_2017_136372.Oceanografía biológica de Cabo Polonio: apuntes sobre investigaciones recientes ofrece una muy rápida recorrida por los orígenes de la oceanografía como área del conocimiento científico y las actividades que investigadores de la Facultad de Ciencias y del Centro Universitario Regional Este, ambos de la Universidad de la República, desarrollan en la zona marina costera de Cabo Polonio. Cabo Polonio es interesante desde diversos puntos de vista: histórico, arqueológico, sociológico, paisajístico, ecológico. Durante el siglo XX fue epicentro de la explotación de la mayor población de lobos marinos del Atlántico Sur. Rastros de ese pasado se conservan en la infraestructura de la Base que alojaba a los trabajadores: comedor-cocina, galpones y dormitorios, caldera industrial y un gran bote a remo; implementos para la faena: garrotes, cuchillas, estaqueaderos de cueros... Aún es posible encontrar en ciertos boliches o almacenes del Cabo a veteranos de aquellas lides y - con un poco de suerte - aprender sus historias. El valor paisajístico de Cabo Polonio ha impulsado el crecimiento del centro poblado gracias al influjo del turismo estival y de no pocos que llegaron de visita y decidieron quedarse. Esto plantea enormes desafíos para la conservación de un sitio que no dispone de facilidades como agua potable y saneamiento, electricidad, caminería y cuya biodiversidad - uno de sus grandes atractivos - es muy sensible a cambios en el paisaje. La biodiversidad es uno de los elementos que llevó a incluir a Cabo Polonio en el Sistema Nacional de Areas Protegidas. Sin embargo, el conocimiento de la fauna y flora marinas, así como de los procesos bio-físicos que sustentan esa biodiversidad son muy poco conocidos. El trabajo que aquí se presenta busca contribuir a dicho conocimiento e - indirectamente- al buen uso y manejo del sitio

Replacement of Marine Fish Oil with de novo Omega-3 Oils from Transgenic Camelina sativa in Feeds for Gilthead Sea Bream (Sparus aurata L.)

Omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) are essential components of the diet of all vertebrates and. The major dietary source of n-3 LC-PUFA for humans has been fish and seafood but, paradoxically, farmed fish are also reliant on marine fisheries for fish meal and fish oil (FO), traditionally major ingredients of aquafeeds. Currently, the only sustainable alternatives to FO are vegetable oils, which are rich in C18 PUFA, but devoid of the eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) abundant in FO. Two new n-3 LC-PUFA sources obtained from genetically modified (GM) Camelina sativa containing either EPA alone (ECO) or EPA and DHA (DCO) were compared to FO and wild-type camelina oil (WCO) in juvenile sea bream. Neither ECO nor DCO had any detrimental effects on fish performance, although final weight of ECO-fed fish (117 g) was slightly lower than that of FO- and DCO-fed fish (130 and 127 g, respectively). Inclusion of the GM-derived oils enhanced the n-3 LC-PUFA content in fish tissues compared to WCO, although limited biosynthesis was observed indicating accumulation of dietary fatty acids. The expression of genes involved in several lipid metabolic processes, as well as fish health and immune response, in both liver and anterior intestine were altered in fish fed the GM-derived oils. This showed a similar pattern to that observed in WCO-fed fish reflecting the hybrid fatty acid profile of the new oils. Overall the data indicated that the GM-derived oils could be suitable alternatives to dietary FO in sea bream

Modulation of the expression of components of the stress response by dietary arachidonic acid in European sea bass (Dicentrarchus labrax) larvae

This study reports for the first time in European sea bass, Dicentrarchus labrax (L.), larvae, the effect of different levels of dietary arachidonic acid (ARA; 20:4n-6) on the expression of genes related to the fish stress response. Copies of mRNA from genes related to steroidogenesis (StAR (steroidogenic acute regulatory protein), c-Fos, and CYP11β (11β- hydroxylase gene)), glucocorticoid receptor complex (GR (glucorticoid receptor) and HSP (heat shock proteins) 70 and 90) and antioxidative stress (catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX)) were quantified. Eighteen day-old larvae were fed for 14 days with three experimental diets with increasing levels of ARA (0.3, 0.6 and 1.2% d.w.) and similar levels of docosahexaenoic (DHA; 22:6n-3) and eicosapentaenoic (EPA; 20:5n-3) acids (5 and 3%, respectively). The quantification of stress-related genes transcripts was conducted by One-Step TaqMan real time RT-PCR with the standard curve method (absolute quantification). Increase dietary levels of ARA induced a significantly (p<0.05) down-regulation of genes related to cortisol synthesis, such as StAR and CYP11β and up-regulated genes related to glucocorticoid receptor complex, such as HSP70 and GR. No effects were observed on antioxidant enzymes gene expression. These results revealed the regulatory role of dietary ARA on the expression of stress-related genes in European sea bass larvae

Life history traits influence in gonad composition of two sympatric species of flatfish

AbstractParalichthys orbignyanus and Paralichthys patagonicus are flatfish with different life history traits, having in common the condition of breeding in seawater. Paralichthys patagonicus remain their whole life in open seawater and Paralichthys orbignyanus are sometimes found in brackish water bodies. As marine and estuarine food webs have different fatty acid (FA) compositions, the aim of this study was to characterize the gonadal maturation of P. orbignyanus and P. patagonicus females through the analysis of lipid content and FA profile in order to understand to what extent life history traits are reflected in the ovarian composition. During gonadal maturation lipid content increased and FA profiles changed in both species, but the lipid increase was greater in P. orbignyanus. The N-3FA and n-3HUFA proportions increased in both species but were higher in P. orbignyanus. The differences between the lifestyles of these species were reflected in the ovarian FA profile mainly as a result of differences in their FA metabolism, causing a greater accumulation of n-3FA and n-3HUFA in P. orbignyanus than in P. patagonicus. The higher lipid accumulation in P. orbignyanus’ ovaries could indicate that this species, feeding in brackish water bodies, has the possibility of storing more energy than P. patagonicus

Effect of different dietary polar lipid levels and different n - 3 HUFA content in polar lipids on gut and liver histological structure of gilthead seabream (Sparus aurata) larvae

In a previous study feeding larval gilthead seabream on microdiets, an improved growth rate was observed when dietary n−3 HUFA (n−3 highly unsaturated fatty acids) were contained in the polar lipid fraction. A beneficial effect of dietary lecithin on n−3 HUFA incorporation to the larval polar lipids was also observed. To confirm those results and in order to obtain additional information on larval gut and liver histological structure, 11-day-old larvae were fed 4 microdiets differing in lipid composition. In diets N′ and NL′, the main sources of n−3 HUFA were neutral lipids, and polar lipids in diets P′ and PL′. Three lecithin levels were tested, being the highest in diet NL′ and the lowest in diet P′. The total n−3 HUFA level in diets N′ and NL′ was enough to meet the essential fatty acid requirement of larval gilthead seabream obtained in a previous study with a triacylglyceride based diet, while diets P′ and PL′ had a total n−3 HUFA level lower than the minimum determined. A reduction in the larval essential fatty acid requirement to 1.5% d.w. was obtained by feeding dietary n−3 HUFA present in the polar lipid fraction. Feeding larvae with microdiets with low polar lipid levels produced an accumulation of lipid droplets in the enterocytes and a high number of lipid vacuoles in the hepatocytes producing nuclear migration and suggesting a need of dietary polar lipid for lipid transport.2632531,137Q2SCI