Institute Investigaciones Oceanologicas

Ensenada, Mexico

Institute Investigaciones Oceanologicas

Ensenada, Mexico
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Rueda-Lopez S.,Autonomous University of Baja California | Reyes G.C.,Institute Investigaciones Oceanologicas | Viana M.T.,Institute Investigaciones Oceanologicas
Aquaculture | Year: 2011

The protein to energy ratio (P:E) to maximize growth was evaluated for the totoaba (Totoaba macdonaldi) an endemic fish of the Gulf of California with a high potential for aquaculture. A complete factorial design was used to formulate six experimental diets at three protein levels (43, 48 and 52% Crude protein; CP) and two lipid levels (8.5 and 18% Crude lipids; CL). Two hundred and seventy juvenile totoaba (mean initial weight 12.12±0.09g) were randomly distributed in 18 (375L) tanks (6 treatments in triplicate groups) and fed the experimental diets for 10weeks. At the end of the experiment, fish fed the high protein and low lipid diet (P:E of 25.7mg protein:kJ01) resulted in significantly higher weight gain (489%) compared to the other treatments. Dietary protein levels significantly affected weight gain but within a protein level, higher lipid levels resulted in reduced growth. No significant differences in survival were observed at the end of the experiment. The fish fed diets containing 18% lipid resulted in reduced feed intake and explained the reduced growth rates observed in fish fed the high lipid diets. However the protein efficiency ratio (PER) was unaffected. The high lipid with low and medium protein content diets significantly reduced growth due to a reduction of feed intake from the unbalanced P:E ratio. No differences in body fat accumulation were observed, both in muscle or viscera, due to a high quality protein and lipid sources ingredients used in the present work. Further research is warranted evaluating lipid digestion in totoaba to optimize lipid utilization. © 2011 Elsevier B.V.

Martinez-Montano E.,Autonomous University of Baja California | Pena E.,Autonomous University of Baja California | Focken U.,University of Hohenheim | Viana M.T.,Institute Investigaciones Oceanologicas
Aquaculture | Year: 2010

The absorption rates of different amino acids (AAs) were compared using the everted intestine technique with fresh proximal intestinal sections from the Pacific bluefin tuna (Thunnus orientalis). Sardine muscle was hydrolyzed in two steps; first with porcine pepsin, followed by an alkaline pancreatic bluefin tuna extract. The hydrolyzed extract was tested in triplicate samples at three concentrations (0.14, 0.09, and 0.06 mg of soluble protein mL- 1). In general, the non-essential amino acids (NEAAs; mainly Ala, Glu, and Gly) were assimilated in preference to the essential amino acids (EAAs). It was observed that certain AAs, such as Arg and Lys, had more affinity with the cationic transporters than did His. The glucogenic AA Glu always displayed double the absorption rate observed for Asp, probably to satisfy an energy requirement of the cells. The neutral AAs, Ala and Gly, showed the highest absorption rates at all concentrations. Other AA relations are also discussed. This is the first study that evaluates the use of this gastrointestinal system to estimate AA absorption and kinetics from a natural pool of AAs obtained from sardine muscle hydrolyzed with bluefin tuna digestive enzymes. © 2010 Elsevier B.V. All rights reserved.

Mejia-Pina K.G.,Autonomous University of Baja California | Huerta-Diaz M.A.,Institute Investigaciones Oceanologicas | Gonzalez-Yajimovich O.,Autonomous University of Baja California
Talanta | Year: 2016

Handheld X-ray fluorescence spectrometers (XRFs) represent a more practical, efficient and economic tool to determine the elemental composition of solid inorganic and organic samples than conventional analytical techniques. The objective of this work was to demonstrate that handheld XRFs could be a precise, accurate and reliable tool to analyze up to 27 different elements. This objective was accomplished through the optimization of an empirical calibration curve that, in addition to include certified reference materials (CRM), it also introduced new approaches, such as the use of solid CRM mixtures and combinations of organic and inorganic matrices. These approaches significantly increased the number of calibration points and eliminated hiatuses in the calibration curve. Several factors were evaluated before construction of the calibration curve: incidence time of the X-ray beam, type of film through which the X-ray beams reach the samples, container type, minimum sample volume and sample moisture content. Results show that single elements can be analyzed with variable exposure times or, alternatively, multielemental analyses can be carried out with a constant exposure time (180 s). Costs can be reduced by using Ziploc® bags as sample containers, but the number of measurable elements drops from 27 to 21, while the possibility of contamination increases. © 2016

Linacre L.P.,Autonomous University of Baja California | Landry M.R.,University of California at San Diego | Lara-Lara J.R.,Research Center Cientifica Educacion Superior Of Ensenada | Hernandez-Ayon J.M.,Institute Investigaciones Oceanologicas | Bazan-Guzman C.,Research Center Cientifica Educacion Superior Of Ensenada
Journal of Plankton Research | Year: 2010

The ecological dynamics of picoplankton were investigated at a coastal upwelling system of northern Baja California during six cruises (September 2007-November 2008). Populations of Prochlorococcus, Synechococcus, PicoEukaryotes and heterotrophic bacteria were assessed by flow cytometry (FCM). On each sampling date, we used an abbreviated three-treatment dilution technique and 14C-uptake experiments to determine population (FCM) and community (TChl a) rates of growth, grazing and production from 24-h in situ incubations at three to four euphotic depths. Overall, picoplankton comprised an active and important component of the community, with biomass values (2.3-69.8 μg C L-1) and production rates (0.8-68.4μg C L -1 day-1) that varied positively with Chl a and community 14C-production. The exception was an intense algal bloom (>25 μg Chl a L-1) during La Niña-intensified upwelling conditions in April 2008, during which biomass and production estimates of picophytoplankton were at their lowest levels, suggesting that the smallest primary producers were being replaced by larger cells. Thus, for most of the environmental circumstances encountered during our study, our results supported the recent "rising tide" hypothesis that improved growth (nutrient) conditions benefit all size classes, including picophytoplankton. Under extreme conditions of upwelling, however, the picophytoplankton declined abruptly, despite seemingly strong (average) growth rates. Future studies need to provide a better mechanistic understanding of the physical (advection), physiological (nutrient uptake and temperature) and ecological (food web) factors that result in this dramatic nonlinearity in picophytoplankton response to system forcing and richness.

Martinez-Montantildo E.,Autonomous University of Baja California | Pentilda E.,Autonomous University of Baja California | Viana M.T.,Institute Investigaciones Oceanologicas
Aquaculture Nutrition | Year: 2011

The amino acid (AA) absorption along the intestinal tract of the Pacific bluefin tuna (Thunnus orientalis) was evaluated using two hydrolysed protein sources (fresh sardine muscle and soybean meal) with the everted intestine technique. Pork pepsin and pancreatic enzyme extract from the bluefin tuna were used to hydrolyse the protein from fresh sardine (FSH) and soybean meal (SMH) under optimal bluefin tuna fish physiological conditions. Both of the hydrolysate solutions were tested within three intestinal sections from the bluefin tuna. The everted intestinal fractions immersed in the hydrolysate solutions were sampled at different times to analyse for AA and absorption rate calculations. Fresh sardine and SMH contained greater amounts of essential amino acids (EAA) than those of non-essential amino acids (NEAA); however, the profiles of AA absorbed showed higher absorption of NEAA in both cases. Using a similar concentration solution, the absorption rates within the intestinal fractions showed a preferential absorption in the proximal and distal regions for Arg and His when FSH was used. However, the absorption rates for Lys resulted in a decreasing proximal-to-distal gradient between the different intestinal regions for FSH and SMH. The possibility of a catabolic role of certain AAs in the enterocytes being able to explain the differences in absorption is discussed. © 2011 Blackwell Publishing Ltd.

Badillo D.,Autonomous University of Baja California | Herzka S.Z.,Research Center Cientifica Educacion Superior Of Ensenada | Viana M.T.,Institute Investigaciones Oceanologicas
PLoS ONE | Year: 2014

This is second part from an experiment where the nitrogen retention of poultry by-product meal (PBM) compared to fishmeal (FM) was evaluated using traditional indices. Here a quantitative method using stable isotope ratios of nitrogen (δ15N values) as natural tracers of nitrogen incorporation into fish biomass is assessed. Juvenile rainbow trout (Oncorhynchus mykiss) were fed for 80 days on isotopically distinct diets in which 0, 33, 66 and 100% of FM as main protein source was replaced by PBM. The diets were isonitrogenous, isolipidic and similar in gross energy content. Fish in all treatments reached isotopic equilibrium by the end of the experiment. Two-source isotope mixing models that incorporated the isotopic composition of FM and PBM as well as that of formulated feeds, empirically derived trophic discrimination factors and the isotopic composition of fish that had reached isotopic equilibrium to the diets were used to obtain a quantitative estimate of the retention of each source of nitrogen. Fish fed the diets with 33 and 66% replacement of FM by PBM retained poultry by-product meal roughly in proportion to its level of inclusion in the diets, whereas no differences were detected in the protein efficiency ratio. Coupled with the similar biomass gain of fishes fed the different diets, our results support the inclusion of PBM as replacement for fishmeal in aquaculture feeds. A re-feeding experiment in which all fish were fed a diet of 100% FM for 28 days indicated isotopic turnover occurred very fast, providing further support for the potential of isotopic ratios as tracers of the retention of specific protein sources into fish tissues. Stable isotope analysis is a useful tool for studies that seek to obtain quantitative estimates of the retention of different protein sources. © 2014 Badillo et al.

Aquafeed quality for striped bass (Morone saxatilis) was evaluated under commercial conditions in sea cages using stable isotopes as tracers for nitrogen. Using a crossover experimental design, fish that were fed during 270 days with aquafeed "A" was switched to aquafeed "B" during the following 160 days. Samples of aquafeeds and of muscle, and liver tissues were analyzed before and during feeding with aquafeed "B". The isotopic value from diet "A" and muscle and liver tissues after being fed during 270 days were 10.3, 14.6 and 13.1% resulting in a discrimination factor of 4.3 and 2.7 for muscle and liver. At day 90 and 160 the discrimination factor reach the equilibrium both for muscle and liver tissues (2.3 and 0.0). It was concluded that diet "B" hadbetter quality as a result of a lower discrimination factor than that observed with diet "A". The nitrogen stable isotope is a reliable tool to evaluate aquafeeds quality under commercial conditions where the other estimations like feed intake and apparent digestibility are difficult to obtain.

A feed trial conducted with juvenile yellowtail kingfish (Seriola lalandi) was designed to address the effect of dietary cholesterol content on growth performance and the cholesterol concentration in liver and muscle. For 60 days fish were fed four diets based on defatted fish meal, soy protein concentrate, cholesterol-free fish oil, canola oil, and olive oil, with four different concentrations of cholesterol (treatments Ch0.0, Ch0.05, Ch0.12, and Ch0.19 containing 530, 2880, 4120, and 6170 mg kg-1 of crude fat, respectively). After 60 days, maximum weight gain was obtained with diet Ch0.05, and it was significantly higher than that obtained with diets Ch0.0 and Ch0.19, but not different from that obtained with Ch0.12. Cholesterol concentration in liver and muscle tissues was not affected by the diet, showing no significant differences among dietary treatments with levels reported as normal. Though cholesterol biosynthesis could not be measured in the present work, we discuss the possibility that fish are able to synthesize cholesterol when fed diets containing no or less cholesterol than required, but at the expense of energy consumption, limiting fish growth. We conclude that cholesterol content in aquafeeds affects fish growth when diets are formulated with vegetable ingredients, and the optimal content should be between 2880 and 4120 mg kg-1 of crude fat to avoid consequent cholesterol accumulation in liver or muscle tissues. © 2015, Universidad Autonoma de Baja California. All rights reserved.

Valdes J.,Institute Investigaciones Oceanologicas
Environmental Monitoring and Assessment | Year: 2012

Concentrations of Ni, Cd, Pb, Cu, and Zn were measured in the surface sediments of Mejillones Bay at 32 sites ranging in depth from 10 to 95 m. A similarity dendrogram analysis separated the study area into two large sedimentary facies: a coastal zone with low metal concentrations and a deep zone with high metal concentrations. The abundances of Zn, Ni, and Pb increased between two sampling periods (5 years apart) in association with greater anthropogenic activity along the coastline of the bay at the present. The results were analyzed with the index of geoaccumulation and by applying the sediment quality guideline. Although similar to preindustrial levels, current Cu and Ni concentrations pose a likely threat to communities of benthic organisms. Concentrations of Zn and Pb are enriched, probably in connection with the industrial development of the zone, but do not reach dangerous levels for the benthic communities. Cd concentrations are toxic to benthic life, even though those measured herein are similar to preindustrial levels. Thus, these Cd levels are a result of the bay's natural characteristics (e.g., high biological productivity, the microxic watersediment interface). The results of the Chilean aquatic sediment quality standards and the international standard (sediment quality guideline) were similar but differed from those found using the index of geoaccumulation, which suggests that the proposed reference values for Chilean aquatic sediment should be reviewed. © Springer Science+Business Media B.V. 2011.

Lares M.L.,CICESE | Huerta-Diaz M.A.,Institute Investigaciones Oceanologicas | Marinone S.G.,CICESE | Valdez-Marquez M.,CICESE
Journal of Food Protection | Year: 2012

Three regions (cephalic, central, and caudal) of the dorsal and ventral muscle tissue (R1 through R6) and the caudal peduncle muscle tissue (CPMT) of 20 farmed bluefin tuna (Thunnus orientalis) were analyzed for mercury (Hg) and cadmium (Cd) concentrations. Region 1 (cephalic-ventral) had significantly lower concentrations of Hg but significantly higher concentrations of Cd than did the other regions. However, average metal concentrations of all regions (R1 through R6) were only 6% lower for Hg and were not significantly different for Cd from those in the CPMT. Therefore, the CPMT was used to monitor the concentrations of these two metals in more than 100 farmed tuna collected from July 2004 to January 2009 under the assumption that the Cd concentrations in the CPMT would be representative of the Cd concentration in the whole body and that the Hg concentrations would be, in the worst case, overestimated by approximately 6%. The Hg and Cd concentrations in these tuna were inversely related to the condition index, i.e., the tuna in better condition had the lowest concentrations of these metals. The mean concentrations in the CPMT of all fish analyzed were 0.31 ± 0.17 μg/g wet weight for Hg and 0.007 ±; 0.006 μg/g wet weight for Cd. These concentrations were below the limits established by Mexican regulations for seafood (1.0 and 0.5 μg/g for Hg and Cd, respectively) and Japan (0.4 μg/g for Hg). © International Association for Food Protection.

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