Ricardo Vieira Rodrigues

Deleterious effects of water-soluble fraction of petroleum, diesel and gasoline on marine pejerrey Odontesthes argentinensis larvae.

Accidental discharges and oil spills are frequent around the world. Petroleum-derived hydrocarbons are considered one of the main pollutants of aquatic ecosystem. The importance of petroleum and refined fuels is notorious because todays society depends on them. Researches related to the toxic water-soluble fraction (WSF) of petroleum and derivatives to aquatic biota are scarce. For this reason, deleterious effects of WSF of Brazilian petroleum, automotive diesel and unleaded gasoline to marine pejerrey Odontesthes argentinensis larvae were studied employing toxicity tests and histopathological examination. Each WSF was generated in a laboratory by mixing four parts of seawater with one part of pollutant by approximately 22 h. Larvae were exposed during 96 h to different concentrations of WSF of petroleum, diesel, and gasoline, plus a control. After 96 h of exposure to the different WSFs, three larvae were sampled for histopathological studies. The median lethal concentration after 96 h (LC50) of exposure for WSF of petroleum was equal to 70.68%, it was significantly higher (P<0.05) than the values for WSF of diesel and gasoline, which were 13.46% and 5.48%, respectively. The histological examination of pejerrey larvae exposed to WSF of petroleum, diesel and gasoline after 96 h revealed a variety of lesions in the larvae. The gills, pseudobranchs and esophagus presented epithelial hyperplasia, and the liver presented dilatation of hepatic sinusoids, hepatocitomegaly, bi-nucleated and nuclear degeneration of hepatocytes, such as pyknotic nuclei. The acute toxicity of diesel and gasoline is at least fivefold higher than Brazilian petroleum. However, all toxicants induced histopathological abnormalities in pejerrey larvae. The results are of importance since much attention has been paid to large visible surfaces of petroleum spills instead of potential toxic effects of dissolved aromatic hydrocarbons, which are more available to marine biota.

Taxa e frequência alimentar no crescimento de juvenis de pampo

The objective of this work was to evaluate the ideal feeding rate and frequency for juvenile pompano (Trachinotus marginatus). Two experiments were carried out in a completely randomized design, with three replicates each. In experiment I, 25 fish (4.8±0.6 g and 6.48±0.01 cm) were stocked in 15 tanks (50 L) during 21 days and fed 4, 8, 12, 16, and 20% body weight per day. In experiment II, 20 fish (4.1±0.1 g and 6.6±0.1 cm) were stocked in 15 tanks (40 L) during 28 days and fed 2, 6, 8, and 10 times a day. The tested feeding rates and frequencies did not influence survival. Final weight and length in experiment I were significantly lower in fish fed 4% body weight per day, whereas in experiment II only weight was significantly lower in fish fed 2 and 6 times a day. At the end of both experiments, apparent feed conversion showed significant difference, with the worst value observed for fish fed 20% body weight per day in experiment I and 2 times a day in experiment II. Juvenile pompano show better growth performance when fed 8% body weight per day and 8 times a day.

Ontogenic development of kidney, thymus and spleen and phenotypic expression of CD3 and CD4 receptors on the lymphocytes of cobia (Rachycentroncanadum )

In the present study was evaluated the ontogenic of immunocompetent organs of cobia up to 53 days after hatching (dah) through histology and immunohistochemistry techniques. The kidney was the first lymphohematopoietic organ to appear, at 1 dah, followed by the spleen at 5 dah and the thymus at 7 dah. The first CD3 receptors on the lymphocytes were observed in 27% of the thymic tissue at 7 dah and in 99% at 53 dah. The phenotypic expression of CD3 receptors was registered in 10% of the kidney at 8 dah and in 32% at 53 dah. CD4 receptors were observed in 5% and 63% of the thymic area at 7 and 53 dah, respectively. In the kidney, T4 lymphocytes were first observed at 13 dah in 9% of the organ and in 28% at 53 dah, defining the functional development of the specific system associated with immunological memory capacity.

Efeito da intensidade luminosa sobre a capacidade de predação de larvas do peixe-rei marinho Odontesthes argentinensis

This study evaluated the effect of light intensity on predation capacity of marine pejerrey Odontesthes argentinensis larvae. Fertilized eggs were collected at Cassino Beach (Rio Grande-RS). At two and 14 days after hatching, 15 groups of 10 larvae were transferred for 800mL beakers and maintained without food during under light intensities of 0, 75, 150, 1,500 and 3,000lux (each treatment was replicated three times) during 12h. Immediately after that, Artemia sp. (8 nauplii mL-1) were offered during 15 min and larvae were sampled, anaesthetized and fixed in formol 10% to count the number of nauplii in the digestive tract of each larvae. The number of prey consumed 2 days after hatching did not differ (P>0.05) among larvae kept under 75, 150, 1,500 and 3,000lux, but there is a trend towards a smaller prey consumption as light intensity increases. Larvae kept in the dark consumed significantly less Artemia (P 0.05) to those under 3,000lux, suggesting that high light intensity and darkness are not appropriate for newly hatched larvae. Considering 14 days old larvae, Artemia nauplii consumption increased proportionally to the light intensity until 1,500lux, when it was stabilized. Therefore, it is suggested that O. argentinensis larvae should be maintained under light intensity equal or higher than 75lux for the first feeding, and light intensity should be increased to 1,500lux 14 days after hatching.

Toxicidade aguda da amônia em juvenis de sardinha-verdadeira Sardinella brasiliensis

A sardinha-verdadeira (Sardinella brasiliensis) é o principal recurso pesqueiro do Brasil que sustenta diretamente a indústria de enlatados, como matéria prima, e indiretamente a pesca dos tunídeos, pois juvenis são utilizados como isca-viva. A UFSC através do Projeto Isca-Viva vem desenvolvendo técnicas de produção de sardinha-verdadeira em cativeiro com vistas ao uso sustentável do recurso, entretanto não existem informações sobre a toxicidade dos compostos nitrogenados no cultivo desta espécie. O objetivo deste estudo foi de estimar a toxicidade aguda de amônia (NH3-N) em juvenis de sardinha-verdadeira. Grupo de cinco peixes (1,04 ± 0,20 g) foram expostos a cinco concentrações de NH3-N (0,60 a 1,47 mg L-1) durante 96 h mais um grupo controle em triplicata. Os testes foram conduzidos em um sistema semi-estático com renovação diária total dos meios experimentais. Os resultados foram apresentados como dados de mortalidade, registrados nas diferentes concentrações testadas, utilizando o software Trimmed Spearman Karber Method. A concentração letal (LC50) após 96 h de exposição a NH3-N foi estimada em 0,74 (0,61-0,90) mg L-1. Os resultados indicam que juvenis de sardinha-verdadeira são relativamente sensíveis à amônia em relação a outros peixes marinhos e atenção especial deve ser dada a este composto em sistemas de cultivo. Palavras-chave: amônia; LC50; toxicidade; peixes marinhos; sardinha-verdadeira Doi: 10.20950/1678-2305.2017v43n1p135

Thyroid gland development in Rachycentron canadum during early life stages

The aim of this study was to describe the ontogeny of thyroid follicles in cobia Rachycentron canadum. Larvae were sampled daily (n=15 - 20) from hatching until 15 dah (days after hatching). Following, larvae were sampled every two days by 28 dah; a new sample was taken at 53 dah. The samples were dehydrated, embedded in Paraplast, and sections of 3 µm were dewaxed, rehydrated and stained with HE and PAS. A single follicle was already present 1 dah and three follicles were found 8 dah. The number of follicles increased up to 19 on 53 dah. The diameter of follicles and follicular cell height were lower 1 dah (6.83 ± 1.00 and 4.6 ± 0.01 µm), but increased from 8 dah (24.03 ± 0.46 µm e 6.43 ± 0.46 µm). From 8 dah, the presence of reabsorption vesicles was observed in the colloid and from the 19 dah some follicles did not present colloid. The early thyroid follicle appearance in cobia larvae as well as the high quantity of follicles without colloid and/or with vesicles even after the metamorphosis, might be the explanation of the fast growth of the cobia.