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Pereira P.,University of Aveiro | Raimundo J.,IPMA Portuguese Institute for the Sea and Atmosphere | Barata M.,IPMA Aquaculture Research Station | Araujo O.,IPMA Portuguese Institute for the Sea and Atmosphere | And 5 more authors.

There are several aspects of inorganic mercury (iHg) toxicokinetics in fish that remain undeveloped despite its environmental ubiquity, bioaccumulation capacity and toxicity. Thus, this study presents new information on the uptake, distribution and accumulation of iHg following water contamination by adopting a novel set of body compartments (gills, eye wall, lens, blood, liver, brain and bile) of the white sea bream (Diplodus sargus) over 14 days of exposure. Realistic levels of iHg in water (2 μg L-1) were adopted in order to engender reliable conclusions in the assessment of fish health. A depuration phase of 28 days was also considered with the purpose of clarifying iHg elimination. It was found that iHg was accumulated faster in the gills (within 1 day), which also had the highest accumulated levels among all the target tissues/organs. Moreover, iHg increased gradually with exposure time in all the tissues/organs, except for the lens that showed relatively unaltered levels throughout the experiment. After 14 days of exposure, lower values of Hg were recorded in the brain/eye wall compared to the liver, which is probably related with the presence of blood-organ protection barriers, which limit iHg influx. iHg reached the brain earlier than the eye wall (3 and 7 days, respectively) and, hence, higher accumulated levels were recorded in the former. A depuration period of 28 days did not allow the total elimination of iHg in any of the tissues/organs. Despite this, iHg was substantially eliminated in the gills, blood and liver, whereas the brain and eye wall were not able to eliminate iHg within this timeframe. The brain and eye wall are more "refractory" structures with regard to iHg elimination, and this could represent a risk for wild fish populations. © 2015 The Royal Society of Chemistry. Source

Pereira P.,University of Aveiro | Puga S.,University of Minho | Puga S.,ICVS 3Bs PT Government Associate Laboratory | Cardoso V.,University of Minho | And 9 more authors.
Aquatic Toxicology

The current study contributes to fill the knowledge gap on the neurotoxicity of inorganic mercury (iHg) in fish through the implementation of a combined evaluation of brain morphometric alterations (volume and total number of neurons plus glial cells in specific regions of the brain) and swimming behavior (endpoints related with the motor activity and mood/anxiety-like status). White seabream (Diplodus sargus) was exposed to realistic levels of iHg in water (2μgL-1) during 7 (E7) and 14 days (E14). After that, fish were allowed to recover for 28 days (PE28) in order to evaluate brain regeneration and reversibility of behavioral syndromes. A significant reduction in the number of cells in hypothalamus, optic tectum and cerebellum was found at E7, accompanied by relevant changes on swimming behavior. Moreover, the decrease in the number of neurons and glia in the molecular layer of the cerebellum was followed by a contraction of its volume. This is the first time that a deficit on the number of cells is reported in fish brain after iHg exposure. Interestingly, a recovery of hypothalamus and cerebellum occurred at E14, as evidenced by the identical number of cells found in exposed and control fish, and volume of cerebellum, which might be associated with an adaptive phenomenon. After 28 days post-exposure, the optic tectum continued to show a decrease in the number of cells, pointing out a higher vulnerability of this region. These morphometric alterations coincided with numerous changes on swimming behavior, related both with fish motor function and mood/anxiety-like status. Overall, current data pointed out the iHg potential to induce brain morphometric alterations, emphasizing a long-lasting neurobehavioral hazard. © 2015 Elsevier B.V. Source

Saavedra M.,Portuguese Institute for the Ocean and Atmosphere IPMA | Pereira T.G.,Portuguese Institute for the Ocean and Atmosphere IPMA | Grade A.,Portuguese Institute for the Ocean and Atmosphere IPMA | Barbeiro M.,Portuguese Institute for the Ocean and Atmosphere IPMA | And 5 more authors.
International Journal of Food Science and Technology

Larger meagre are more common in the market but, recently, smaller fish have started to be commercialised as well. This study aims to evaluate flesh quality and muscle cellularity of meagre of three different sizes: 800, 1500 and 2500 g. Results showed a higher fat content in larger fish (2.9% compared to 1.3% in small fish), and that texture was not affected by fish size. In terms of muscle cellularity, a higher frequency of smaller fibres was observed in 800 and 1500 g (33% compared to 18% in 2500 g) meagre, whereas in 2500 g meagre, there was a higher frequency of larger fibres. Muscle fibre density was reduced with fish weight (431 and 297 fibres mm-2 for 800 and 2500 g meagre, respectively). In conclusion, this study shows that meagre of different weights are different in terms of fat content and muscle cellularity and that 800 g meagre seems to have a good potential for being commercialised. © 2015 Institute of Food Science and Technology. Source

Saavedra M.,Portuguese Institute for the Ocean and Atmosphere IPMA | Candeias-Mendes A.,IPMA Aquaculture Research Station | Castanho S.,IPMA Aquaculture Research Station | Teixeira B.,Portuguese Institute for the Ocean and Atmosphere IPMA | And 2 more authors.

The indispensable amino acid (AA) profile of fish carcass has been commonly used to estimate the AA requirements of fish. In this study the AA composition of whole body tissue of meagre, Argyrosomus regius, was determined at 0, 3, 6, 8, 12, 17, 20, 24, 30 and 39days after hatching (DAH). Several differences were observed during meagre larval ontogeny with the AA profile at 0DAH being different from the remaining larval ages and with a change occurring around 12 and 17DAH which was reflected in some AA such as arginine, valine and tyrosine. Meagre and diet AA profiles were compared and several AAs were found to be in apparent deficiency in the diets. In rotifers a lower number of AA were apparently in deficiency but the correlation between larval and diet AA profiles was low (R2 lower than 0.7). Although a higher number of AA were apparently in deficiency in Artemia and dry feed, the correlations obtained were high (R2 above 0.75). Histidine appeared to be the limiting AA in all diets. These results suggest that the higher nutritional imbalances in meagre larval ontogeny occur during the first 10days of feeding when larvae are fed on rotifers. To solve these apparent nutritional imbalances, an alternative to rotifers should be found or at least a reduction of the period when larvae are fed on rotifers alone. Given the potential of meagre to aquaculture, the use of suitable diets for this species should be formulated. The results obtained in this study can be used to formulate AA balanced diets which are expected to increase growth and decrease larval mortality. © 2015 Elsevier B.V. Source

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