Pogonias courbina sperm characteristcs in its first reproductive season.

Southern black drum (Pogonias courbina) is a species distributed along the western Atlantic Ocean, and it is the largest Sciaenidae observed in the coast of Rio Grande do Sul state, Brazil. However, it is listed as a vulnerable species at The IUCN Red List of Threatened Species™, and their fishing is prohibited. The objective of this study was to determine the sperm characteristics of P. courbina. Sperm samples of five young males (two-year-old fish) were collected through abdominal pressure. The sperm kinetics parameters were sperm motility (MOT) 10.7 ± 5.6%, curvilinear velocity (VCL) 120.07 ± 16.16 mm s ± 1, average path velocity (VAP) 75.64 ± 23.78 mm s ± 1, straight-line velocity (VSL) 62.49 ± 15.83 mm s ± 1, straightness (STR) 83.9 ± 5.3%, wobble (WOB) 61.9 ± 12.7%, beat cross frequency (BCF) 42.981 ± 4.627 Hz and progression (PRG) 1,805.4 ± 564.5 µm. The proportion of normal spermatozoa was 35.6 ± 6.1%. About the abnormalities observed, 22.7% occurred in the tail (short tail = 0.6 ± 0.5%, distally curled tail = 2.4 ± 1.6%, strongly curled tail = 1.9 ± 1.3%, broken tail = 7.9 ± 5.1%, folded tail = 5.5 ± 0.8%, loose tail = 4.4 ± 1.9%); 14.2% occurred in the head (degenerate head = 4.2 ± 1.6%, microcephaly = 1.8 ± 2.5%, loose head = 8.2 ± 2.1%) and 27.5% of the spermatozoa showed cytoplasmatic gouts (proximal gout = 20.0 ± 8.4%, distal gout = 7.5 ± 2.8%). Besides that, a correlation analysis was performed between sperm morphology and kinetics parameters, and the spermatozoa were measured for the morphometric parameters. There was a positive correlation between BCF and normal spermatozoa (r =  0.9269). A negative correlation occurred between BCF and loose head (r =  -0.9047); WOB and strongly curled tail (r =  -0.8911); and PROG and strongly curled tail (r =  -0.9191). The morphometric measures found for the head were length of 2.50 ± 0.21 µm and width of 2.12 ± 0.22 µm, and for the tail it was length of 37.97 ± 2.01 µm. It was possible to verify that the animals have sperm characteristics that indicate reproductive aptitude, but an abnormal behavior on sperm activation and high presence of the cytoplasmic gout abnormality indicates that the animals are not fully mature in their first reproductive season. This work contributes to a better understanding of the P. courbina spermatic parameters, what can be allies to recovery this species population in nature and promote its production in fish farms.

Electroencephalographic Response in Juvenile Tambaqui, Colossoma macropomum, Exposed to Short-Term Anaesthetic Baths with Geraniol and Citronellol.

The aim of this study was to evaluate the level of neuronal depression in juvenile tambaqui, Colossoma macropomum, exposed to geraniol (GRL) and citronellol (CTL) in immersion baths. A total of 36 juveniles weighing 35.2 ± 9.4 g were used, organised into six experimental groups: I-control (clean water); II-ethanol (water containing the highest volume of ethanol used in the anaesthetic pre-dilution); III-GRL induction (70 µL·L-1); IV-CTL induction (90 µL·L-1); V-GRL recovery; VI-CTL recovery. Electroencephalographic (EEG) recordings were performed for 300 s in each group. EEG tracings of the control and ethanol groups showed regular and similar activity. Upon exposure to the anaesthetics, irregularities were observed in the tracings showing neuronal excitability and increased amplitudes, mainly in the case of CTL. Overall, GRL-exposed fish showed depression of the central nervous system with low and regular tracings throughout induction, presenting a gradual recovery and stable tracings, which were consistent with an adequate general anaesthetic effect. On the other hand, fish exposed to CTL showed altered EEG activity during induction, that could be considered incompatible with an appropriate anaesthetic effect and smooth recovery, presenting high and irregular EEG tracing amplitudes.

Does acidification lead to impairments on oxidative status and survival of orange clownfish Amphiprion percula juveniles?

The nitrification process in recirculating aquaculture systems can reduce water pH. Fish can also be exposed to water acidification during transport, an important feature in the aquarium industry, as live fish can be kept in a closed environment for more than 24 h during overseas aerial transportation. Therefore, it is important to study the responses of fish to acidic environments. We investigated the impacts of acute exposure to decreasing pH levels in orange clownfish Amphiprion percula juveniles on their survival and oxidative stress status. Fish were exposed to pH 5, 6, 7, and 8 for 96 h. We observed a significant reduction in survival (85%) and protein damage as measured by P-SH (protein thiol) for fish maintained at pH 5. Despite no effects on survival or oxidative damage, fish exposed to pH 6 showed an increase in their antioxidant defense systems, demonstrating this pH level could not be suitable for them as well. Furthermore, there were no negative effects for fish kept at pH 7, compared to those maintained at pH 8 during this short-term evaluation.

Oxidative stress and antioxidant responses in juvenile Brazilian flounder Paralichthys orbignyanus exposed to sublethal levels of nitrite.

This study evaluated the effects of short-term exposure to sublethal levels of nitrite on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus. An assessment of fish recovery was also performed. Fish were exposed to 0.08 (control), 5.72, 10.43, and 15.27 NO2-N mg L-1 for 10 days followed by the same recovery time. Gill, liver, and muscle samples were collected after 1, 5, and 10 days of exposure and after recovery for the measurement of antioxidant capacity against peroxyl radicals (ACAP), glutathione-S-transferase (GST) activity, content of non-protein (NPSH) and protein thiols (PSH), and lipid peroxidation levels by thiobarbituric acid-reactive substances (TBARS) content. Nitrite exposure induced alterations which compromised the overall antioxidant system (reduced ACAP and GST activity) and enhanced oxidative damage in lipids and proteins. Increases in GST activity and NPSH and PSH contents were also demonstrated. The recovery period allowed for resumption of basal levels for all (treatment 5.72 NO2-N mg L-1) or some of the evaluated parameters (other treatments). In conclusion, exposure to nitrite concentrations from 5.72 to 15.27 NO2-N mg L-1 induced oxidative stress and antioxidant responses in juvenile Brazilian flounder. The 10-day recovery period was sufficient for a complete resumption of basal physiological condition of fish exposed to concentrations of up to 5.72 NO2-N mg L-1.

Ammonia exposure and subsequent recovery trigger oxidative stress responses in juveniles of Brazilian flounder Paralichthys orbignyanus.

The effects of ammonia exposure and recovery on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus were evaluated. The fish were exposed to 0.12, 0.28 and 0.57 mg NH3-N L-1, plus a control, for 10 days followed by the same recovery time in ammonia-free water. Gill, liver and muscle samples (n = 9) were collected after 1, 5 and 10 days of exposure and after recovery for oxidative stress analysis (antioxidant capacity against peroxyl radicals (ACAP); glutathione S-transferase (GST) activity; lipoperoxidation levels measured through thiobarbituric acid reactive substances (TBARS) content). For histological assessment, gill, liver and brain samples were collected. Exposure to all NH3-N concentrations induced different time- and dose-dependent changes in oxidative stress parameters. Reduced antioxidant capacity of the liver and muscle and enhanced TBARS levels in the gills and liver were demonstrated. Differently, a high ammonia concentration elicited lower hepatic TBARS levels. Enhanced GST activity in all organs and increased antioxidant capacity of the gills were also observed. No ammonia-induced histopathological effects were demonstrated. After recovery, most parameters (liver ACAP, GST activity in the muscle and liver and TBARS in the gills) returned to baseline levels. However, liver TBARS and gill GST activity remained altered 0.57 mg NH3-N L-1 treatment. The recovery period also led to a decrease in gill antioxidant capacity and an increase in muscle antioxidant capacity. In conclusion, a concentration of 0.12 mg NH3-N L-1 induces oxidative stress and antioxidant responses in juvenile Brazilian flounder. Moreover, a 10-day recovery period is not sufficient to restore fish homeostasis.

Oxidative stress parameters in juvenile brazilian flounder Paralichthys orbignyanus (Valenciennes, 1839) (Pleuronectiformes: Paralichthyidae) exposed to cold and heat shocks

The aim of this study was to determine oxidative stress parameters in the liver and gill of Brazilian flounder juveniles (307.0 ± 16.0 g and 30.0 ± 4.0 cm) submitted to different water temperature (17.1, 23.0 and 28.8ºC) for 72 h and maintained at salinity 25‰. After the acclimation of 7 days, in 23ºC, fish were transferred to 200 L tanks containing seawater (salinity 25‰) at 28.8ºC (heat shock), 17.1ºC (cold shock) or 23.0ºC (control), five replicates (five fish tank-1). The sampled collection occurred in 0 (pre-challenge), 3, 24, 48 and 72 h after temperature shock. Flounder exposed to 17.1ºC and 28.8ºC showed significantly higher TBARS levels and GST activity in the liver post-exposition (PE) in relation to the control (23ºC). CAT activity in liver present a significantly increase at 17.1ºC, in first 48 h, and subsequently decrease in 72 h PE in relation to 28.8ºC. The gills of flounder showed significantly higher TBARS levels, GST and CAT activity when submitted at 17.1 and 28.8ºC in relation to 23.0ºC. There were observed changes in lipid peroxidation levels (LPO), CAT and GST activities in the liver and gill of Brazilian flounder in response to reactive oxygen species (ROS) produced by thermal shocks.

O objetivo deste estudo foi determinar os parâmetros de estresse oxidativo no fígado e brânquias de juvenis de linguado (307,0 ± 16,0 g e 30,0 ± 4,0 cm) submetidos a diferentes temperaturas da água (17,1, 23,0 e 28,8ºC) por 72 h e mantidos na salinidade de 25‰. Após uma aclimatação de sete dias, em 23ºC, os peixes foram transferidos para tanques de 200 L contendo água do mar (salinidade 25‰) em 28,8ºC (choque quente), 17,1ºC (choque frio) ou 23,0ºC (controle), cinco repetições (cinco peixes/tanque). A coleta de amostras ocorreu em 0 (pré-exposição), 3, 24, 48 e 72 h após o choque térmico. O linguado exposto a 17,1ºC e 28,8ºC apresentaram um significante aumento dos níveis de TBARS e atividade da GST no fígado pós-exposição (PE) em relação ao controle (23ºC). A atividade da CAT no fígado apresentou um aumento significativo em 17,1ºC, nas primeiras 48 h, e subsequente diminuição em 72 h PE em relação a 28,8ºC. As brânquias do linguado apresentaram significante aumento dos níveis de TBARS e atividade da GST e CAT quando submetidos a 17,1ºC e 28,8ºC em relação a 23,0ºC. Foram observadas alterações nos níveis de peroxidação lipídica (LPO) e atividade de GST e CAT no fígado e brânquias de linguado em resposta as espécies reativas de oxigênio (ROS) produzidas pelo choque térmico.

Effect of salinity on survival, growth and biochemical parameters in juvenile Lebranch mullet Mugil liza (Perciformes: Mugilidae)

Teleost fish growth may be improved under isosmotic condition. Growth and metabolic performance of juvenile Mugil liza (isosmotic point: 12‰) were evaluated after 40 days in different salinities (0, 6, 12 and 24‰). Tests were performed in quadruplicate (30 fish/tank; 0.48 ± 0.1 g body weight; 3.27 ± 0.1 cm total length) under controlled water temperature (28.2 ± 0.1ºC) and oxygen content (>90% saturation). Fish were fed on artificial diet (50% crude protein) four times a day until apparent satiation. Results showed that salinity influenced juvenile mullet growth. Fish reared at salinity 24‰ grew better than those maintained in freshwater (salinity 0‰). Gill Na+,K+-ATPase activity and whole body oxygen consumption showed an U-shape-type response over the range of salinities tested, with the lower values being observed at the intermediate salinities. Although no significant difference was observed in liver glycogen content at different salinities, it tended to augment with increasing salinity. These findings indicate that energy demand for osmorregulation in juvenile M. liza can be minimized under isosmotic condition. However, the amount of energy spared is not enough to improve fish growth. Results also suggest that M. liza is able to alternate between different energy-rich substrates during acclimation to environmental salinity.

O crescimento de peixes teleósteos pode ser melhorado em condição isosmótica. O crescimento e o desempenho metabólico de juvenis da tainha Mugil liza (ponto isosmótico: salinidade de 12‰) foram avaliados após 40 dias de cultivo em diferentes salinidades (0, 6, 12 e 24‰). Os testes foram realizados em 4 réplicas (30 peixes/tanque; 0,48 ± 0,1 g de peso corporal; 3,27 ± 0,1 cm de comprimento total) em condições controladas de temperatura (28,2 ± 0,1ºC) e conteúdo de oxigênio (>90% saturação). Os peixes foram alimentados quatro vezes ao dia com dieta artificial (50% de proteína bruta) até a saciedade aparente. Os resultados mostraram que a salinidade influenciou o crescimento dos juvenis da tainha. Os peixes cultivados na salinidade 24‰ cresceram melhor que aqueles mantidos na água doce (salinidade 0‰). A atividade da Na+,K+-ATPase branquial e o consumo corporal de oxigênio mostraram uma resposta do tipo em forma de U, na faixa de salinidade testada, com os menores valores sendo observados nas salinidades intermediárias. Apesar de não ter sido observada diferença significativa no conteúdo de glicogênio entre os peixes mantidos nas diferentes salinidades, este parâmetro tendeu a aumentar com o incremento da salinidade. Estes achados indicam que a demanda energética para osmorregulação em juvenis de M. liza podem ser minimizados em condição isosmótica. Entretanto, a quantidade de energia poupada não é suficiente para melhorar o crescimento. Os resultados também sugerem que M. liza é capaz de alternar entre diferentes substratos ricos em energia durante a aclimatação à salinidade da água.

Genotoxicity and histological alterations in grey mullet Mugil liza exposed to petroleum water-soluble fraction (PWSF).

Petroleum hydrocarbons are considered one of the main organic chemicals found in water bodies. In the present study, the median lethal concentration (LC50) was estimated for mullet Mugil liza after acute exposure to petroleum water-soluble fraction (PWSF). Furthermore, histopathological studies and micronuclei frequency were also performed in order to observe deleterious effects of medium-term exposition to PWSF. Mullets (25 ± 2.3 g) were exposed to chronic concentrations (1.7, 3.5 and 7 % of PWSF), plus the control group, for 14 and 7 days of clearance time. Throughout the experimental period (1, 4, 14 and 21 days), blood samples were collected for analysis of micronucleus (MN) and liver and gills for histopathological study. For these procedures, seven fish were sampled per concentration tested. The LC50-96 h was estimated at 37.5 % of the PWSF. The time required for MN induction was 96 h of exposure. The time of clearance was sufficient to achieve a MN frequency similar to that of the control group. Histopathological studies showed severe changes in the gill and liver tissues. The most relevant histopathology in the gills was telangiectasia. Hepatic histopathology such as cholestasis, dilated sinusoids and inflammatory infiltrates were commonly described. The MN test and histological study effectively detected damages caused by medium-term exposition to the PWSF, and despite the toxicity, a few days without exposure can minimize PWSF genotoxicity in juveniles of M. liza.

Growth of Critically Endangered annual fish Austrolebias wolterstorffi (Cyprinodontiformes: Rivulidae) at different temperatures

Given the importance of knowledge of the biology of endangered species for the planning of conservation and management efforts, the aim of this study was to investigate the influence of temperature on the growth of Austrolebias wolterstorffi (Ahl, 1924). To clarify the thermal influence on the growth of the species, temperatures of 16, 20, 24 , and 28°C were tested in triplicate. The present study showed that a water temperature of 28°C is detrimental to the growth of the species. Among the other tested temperatures, it was found that the optimum temperature for growth decreases as an individual ages and is slightly lower for females. It was demonstrated here that males reach a higher weight and length, and grow faster than females, reaching sexual maturity earlier. To optimize the growth of this species in captivity, the ideal temperature of the water during the initial life period is 24°C, until after puberty when the temperature should decrease to about 21°C.

Devido à importância do conhecimento da biologia das espécies ameaçadas de extinção para o planejamento de ações de conservação e manejo, o objetivo deste estudo foi investigar a influência da temperatura sobre o crescimento de Austrolebias wolterstorffi (Ahl, 1924). Para verificar a influência da temperatura no crescimento da espécie, as temperaturas de 16, 20, 24 e 28° C foram testadas em triplicata. O presente estudo mostrou que a temperatura da água de 28° C é prejudicial para o crescimento da espécie. Entre as outras temperaturas testadas, verificou-se que a temperatura ótima para o crescimento diminui ao longo da vida e é ligeiramente menor para as fêmeas. Foi demonstrado aqui que os machos alcançam um maior peso e comprimento e crescem mais rápido do que as fêmeas, atingindo a maturidade sexual anteriormente. Para otimizar o crescimento da espécie em cativeiro, a temperatura ideal da água durante o período inicial de vida é de 24° C, já após a puberdade, a temperatura deverá diminuir para cerca de 21°C.

Effect of temperature on growth of the threatened annual fish Austrolebias nigrofasciatus Costa & Cheffe 2001 / Efeito da temperatura no crescimento do peixe anual ameaçado Austrolebias nigrofasciatus Costa & Cheffe 2001

This study evaluated the effect of temperature on growth of Austrolebias nigrofasciatus, an endemic and threatened annual killifish species of the Patos-Mirim lagoon system in Southern Brazil. In order to verify the effect of temperature on initial growth of A. nigrofasciatus, eggs stored in the laboratory were hatched and juveniles reared for eight weeks at 16 and 22 ºC. The standard length of newly hatched fishes was 4.67 ± 0.25 mm and after eight weeks they reached 23.68 ± 3.73 and 22.68 ± 5.36 mm, respectively at 16 and 22 ºC. However, initial growth of fish reared at 22 ºC was faster and they reached sexual dimorphism at an earlier age compared to those reared at 16 ºC. Final length of females reared at 22 ºC was 23.00 ± 2.83 mm, they were significantly larger than those reared at 16 ºC (17.91 ± 2.47 mm). Males were significantly larger than the females at 16 ºC, but there was no difference for growth between sexes of fish reared at 22 ºC. The sex ratios were 1:0.6 and 1:1.1 (M:F) at 16 ºC and 22 ºC, respectively, suggesting temperature determination of phenotypic sex. Considering the results, it appears that juveniles to be developed in captivity should be kept at 22 ºC during the first six weeks of life, thus ensuring a higher growth rate until puberty.

Este estudo avaliou o efeito da temperatura no crescimento de Austrolebias nigrofasciatus, uma espécie de peixe anual endêmica e ameaçada do sistema lagunar Patos-Mirim no extremo sul do Brasil. Para avaliar o efeito da temperatura no crescimento inicial e na diferenciação sexual de A. nigrofasciatus, ovos mantidos em laboratório foram eclodidos e os peixes foram mantidos por oito semanas a temperaturas de 16 e 22 ºC. O comprimento padrão dos peixes recém eclodidos foi de 4,67 ± 0,25 mm e ao final de oito semanas atingiram 23,68 ± 3,73 e 22,68 ± 5,36 mm, respectivamente para 16 e 22 ºC. O crescimento inicial foi maior a 22 ºC e os peixes apresentaram precocidade na maturação sexual quando comparados a 16 ºC. As fêmeas criadas a 22 ºC atingiram maior comprimento (23,00 ± 2,83 mm) em relação aquelas mantidas em 16 ºC (17,91 ± 2,47 mm). Machos foram significativamente maiores que as fêmeas a 16 ºC, mas não foi constatada diferença de comprimento entre os sexos dos peixes mantidos a 22 ºC. A relação sexual foi de 1:0.6 e 1:1.1 (M:F) a 16 ºC e 22 ºC, respectivamente, sugerindo uma possível influência da temperatura na diferenciação sexual fenotípica. Considerado os resultados obtidos concluímos que juvenis de A. nigrofasciatus devem ser criados a 22 ºC durante os primeiros meses de idade, garantindo assim uma maior taxa de crescimento até a puberdade.

Growth and histopathological effects of chronic exposition of marine pejerrey Odontesthes argentinensis larvae to petroleum water-soluble fraction (WSF).

The water-soluble fraction (WSF) of petroleum contains a mixture of polycyclic aromatic hydrocarbons, volatile hydrocarbons, phenols, and heterocyclic compounds, considered deleterious to aquatic biota. Marine "pejerrey" Odontesthes argentinensis (Teleostei: Atherinopsidae) has a great commercial importance in local fisheries and a high potential for aquaculture. The aim of this study was to evaluate the histopathological effects in "pejerrey" larvae exposed to different concentrations of petroleum WSF. The chronic toxicity test was conducted with newly hatched larvae exposed for 21 days to sublethal concentrations of WSF (2.5, 5, 10, and 20 % of WSF), plus one control. Survival and growth were significantly lower in the highest concentration. Several histopathological changes were found in the gills (e.g., hyperplasia, aneurisms, edema, and necrosis), kidney (e.g., nuclear alterations, decrease in the hematopoietic cells), and liver (e.g., hypertrophy, karyorrhexis, and karyopyknosis). An index of branchial lesion was proposed to standardize gill lesions to different pollutants.

NPY and sbGnRH gene expression in juvenile and adult male Brazilian flounder Paralichthys orbignyanus / Expressão gênica do NPY e do sbGnRH em machos juvenis e adultos de linguado Paralichthys orbignyanus

The objective of this study was to evaluate neuropeptide Y (NPY) and sea bream gonadotropin-release hormone (sbGnRH) gene expression in juvenile and adult males of Brazilian flounder. Hypothalamuses from fish were sampled for total RNA extraction. After cDNA synthesis, real-time PCR was used to measure gene expression. NPY showed approximately 2-fold increases in their mRNA levels while sbGnRH showed 3-fold increases in adult fish. These results suggest that these peptides could be involved on hypothalamic regulation of Brazilian flounder sexual maturation.

O objetivo deste estudo foi avaliar a expressão gênica do neuropeptídeo Y (NPY) e da variante sea bream do hormônio liberador de gonadotrofinas (sbGnRH) em linguados machos juvenis e adultos. O hipotálamo foi isolado para a extração de RNA total. Após a síntese de cDNA, a PCR em tempo real foi usada para avaliar a expressão gênica. Foi observado um aumento de aproximadamente duas vezes nos níveis de NPY e de aproximadamente três vezes nos níveis de sbGnRH nos peixes adultos. Esses resultados demonstram que estes peptídeos podem estar envolvidos na regulação, via hipotálamo, da maturação sexual no linguado.

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 today's 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.

Consumo de oxigênio pós-prandial de juvenis do pampo Trachinotus marginatus / Postprandial oxygen consumption of juvenile pompano Trachinotus marginatus

Para determinar a viabilidade do cultivo de uma espécie, é importante o conhecimento dos fatores limitantespara sua produção. Conhecer a taxa de consumo de oxigênio pós-prandial pode auxiliar na determinação da freqüênciaalimentar ideal para as espécies cultivadas. O objetivo deste trabalho foi estudar a taxa de consumo de oxigênio pós-prandial para juvenis do pampo Trachinotus marginatus. A avaliaçãodo consumo de oxigênio foi feita a 24°C e 33‰, com pampos (9,64±0,2g) alimentados com 12% da biomassa por dia com dieta NRD INVE (59% proteína). Foi observado um pico de consumo de oxigênio 30min após a alimentação (1,06mgO2 g-1 h-1) e seu retorno ao nível de jejum (0,79mgO2 g-1 h-1) depois de decorridos mais 120min. A alimentação de juvenis de pampo pode ser realizada com uma freqüência de aproximadamente oito vezes por dia, pois a cada 2,5h a taxa de consumo de oxigênio já não mostra a elevação característica da fase pósprandial, sugerindo que os processos de digestão e assimilação dos nutrientes estejam finalizados.

In order to determine the viability of new species for aquaculture, it is important to know the limiting factors forits production. The knowledge about postprandial oxygen consumption of fish is useful to estimate the time for returning to appetite and allows to estimate the proper feeding frequency.The objective of this research was to study the postprandial oxygen consumption of juvenile pompano Trachinotus marginatus. Oxygen consumption rate was determined at 24°C and 33‰ and fish (9.64±0.2g) were fed daily with 12% total of biomass NRD INVE diet (59% protein). Postprandialincrease in oxygen consumption was observed 30min after feeding (1.06mgO2 g-1 h-1), and it returned to the routine metabolic rate (0.79mgO2 g-1 h-1) within the next 120min. According to these results, it seems appropriated to feed juvenile pompano 8 times per day, because every 2.5h the oxygen consumption rate declines to the unfed level, suggesting that the process of digestion and assimilation have already finished.

Benzocaína e eugenol como anestésicos para juvenis do pampo Trachinotus marginatus / Benzocaine and eugenol as anaesthetics for pompano juvenile Trachinotus marginatus

O objetivo deste trabalho foi avaliar a eficácia da benzocaína e do eugenol como anestésicos para juvenis de Trachinotus marginatus. Foram testadas concentrações de 25, 50, 75, 100 e 150ppm de benzocaína e de 25, 37,5, 50, 62,5 e 75ppm de eugenol. Os testes foram realizados em aquários de vidro contendo 30l de água (salinidade 30‰ e temperatura 19°C). Os peixes (51,4±13,5g) foram expostos individualmente às diferentes concentrações de cada anestésico (n=5 para cada concentração). Enquanto ainda anestesiados, eles foram medidos e pesados para posteriormente serem colocados em um aquário sem anestésico para recuperação. Posteriormente, os peixes foram colocados em um aquário sem anestésico para observação da recuperação. O tratamento estatístico dos resultados foi feito pela Análise de Variância (One-Way - ANOVA) com 95 por cento de significância e, quando encontradas diferenças significativas, o teste de Duncan foi aplicado. Os períodos para atingir a latência para os juvenis de pampos variaram entre 11min para a concentração de 25ppm e 2min na concentração de 150ppm para a benzocaína e de 10min (25ppm) a 2min (75ppm) para o eugenol. Os tempos de recuperação foram entre 3min para 25ppm e 14min para a concentração de 150ppm para a benzocaína e de 2min (25ppm) a 8min (75ppm) para o eugenol. A dose de 50ppm de benzocaína e eugenol proporcionou um período de latência e recuperação dentro da faixa considerada adequada (3mim para a latência e 5mim para a recuperação). Entretanto, é importante salientar que o custo da benzocaína para anestesiar juvenis de pampo é 1/3 inferior ao custo do eugenol.

The aim of this experiment was to evaluate the efficacy of benzocaine and eugenol as anesthetics for Trachinotus marginatus juveniles. Five concentrations of benzocaine (25, 50, 75, 100, and 150ppm) and eugenol (25, 37.5, 50, 62.5, and 75ppm) were tested. The trials were conducted in glass aquariums filled with 30l seawater (salinity 30‰ and temperature 19°C). The fish (51.4±13.5g) were individually exposed to different concentrations of each anesthetic (n=5 for each concentration). They were measured and weighed under anesthesia, and then returned to another aquarium without anesthetic for recovery. The results were evaluated using Analyses of Variance (One-Way - ANOVA) followed by the test of Duncan (95 percent confidence level) when necessary. Anesthesia time varied from approximately 11min (25ppm) to 2min (150ppm) for benzocaine, and from 10min (25ppm) to 2min (75ppm) for eugenol. Recovery time ranged from 3min (25ppm) to 14min (150ppm) for benzocaine and from 2min (25ppm) to 8min (75ppm) for eugenol. Benzocaine and eugenol, both at 50ppm, induce quick anesthesia and recovery (3mim for anesthesia and 5mim for recovery) for juvenile Trachinotus marginatus, and therefore are considered efficient anesthetics for this species. However, it is important to emphasize that the cost of benzocaine is 1/3 lower than eugenol to anesthetize juvenile pompano.

Efeito da intensidade luminosa sobre a capacidade de predação de larvas do peixe-rei marinho Odontesthes argentinensis / Effect of light intensity on prey consumption of marine pejerrey Odontesthes argentinensis larvae

Este estudo teve como objetivo determinar o efeito da intensidade luminosa sobre a capacidade de predação de larvas do peixe-rei marinho Odontesthes argentinensis. Ovos fertilizados foram coletados na Praia do Cassino,Rio Grande, Rio Grande do Sul (RS). Ao completarem dois dias e posteriormente, 14 dias de vida, 15 grupos com 10 larvas foram transferidos para béqueres de 800mL. As larvas foram mantidas em jejum durante 12 horas nas intensidades luminosas de 0, 75, 150, 1500 e 3000lux (três repetições para cada tratamento). Logo em seguida foram oferecidos náuplios de Artemia sp. na densidade de oito náuplios mL-1 durante 15 minutos. As larvas foram imediatamente anestesiadas e fixadas em formol 10 por cento. Posteriormente foi contado o número de náuplios presentes no trato digestório de cada larva. O número de presas ingeridas na primeira alimentação não diferiu significativamente (P>0,05) entre as larvas mantidas sob 75, 150, 1500 e 3000lux, mas foi observada uma tendência de redução na ingestão de náuplios à medida que a intensidade luminosa aumenta. Na intensidade de zero lux, o consumo foi significativamente inferior (P<0,05) em relação a 75, 150 e 1500lux, mas semelhante (P>0,05) ao consumo das larvas mantidas a 3000lux, sugerindo que as intensidades luminosas elevadas e o escuro não são apropriados para larvas de peixe-rei recém-eclodidas. O aumento no consumo de Artemia pelas larvas de 14 dias foi proporcional ao aumento da intensidade luminosa até 1500lux, quando foi estabilizado. Considerando a capacidade de predação, este estudo indica a utilização da intensidade luminosa igual ou superior a 75lux para a alimentação inicial das larvas de O. argentinensis, entretanto a intensidade luminosa deve ser ao menos de 1500lux a partir do 14o dia de vida.

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 percent 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) than those maintained at 75, 150 and 1,500lux, but similar (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.

Produção de juvenis do linguado Paralichthys orbignyanus: efeito da duração do período de co-alimentação durante o desmame / Production of Brazilian flounder Paralichthys orbignyanus juveniles: the effect of co-feeding period during the weaning

O desmame, ou seja, a substituição do alimento vivo por alimento inerte é uma etapa crítica para a produção de alevinos de peixes marinhos. Este trabalho teve por objetivo avaliar o efeito do período de co-alimentação (alimento vivo e inerte) sobre a sobrevivência, o crescimento e os custos de produção de juvenis do linguado Paralichthys orbignyanus. Durante o período de co-alimentação, os juvenis (idade inicial 32 dias) receberam Artemia enriquecida juntamente com ração. Foram testados três períodos de co-alimentação: 15, 20 e 25 dias, mais um grupo controle alimentado com Artemia enriquecida. Ao final do experimento (76 dias), os juvenis alimentados exclusivamente com Artemia enriquecida apresentaram sobrevivência (82 por cento), peso (480±157mg) e comprimento (35,5±5,0mm) significativamente maiores (P<0,05) que os juvenis alimentados com ração. Não houve diferença significativa (P>0,05) no crescimento entre os juvenis alimentados com ração nos diferentes períodos, entretanto, um período maior de co-alimentação favoreceu a sobrevivência. Os resultados obtidos demonstram que os linguados alimentados exclusivamente com Artemia apresentam melhor performance do que aqueles alimentados com ração. Entretanto, o custo de produção quando a Artemia é substituída por ração aos 58 dias de vida é menor do que quando o desmame é realizado mais cedo ou quando os alevinos são alimentados apenas com Artemia.

Weaning is a critical period for production of marine fish juveniles. The objective of this research was to evaluate the effect of co-feeding on survival, growth, and cost of production after the weaning of juveniles of Brazilian flounder Paralichthys orbignyanus. Juvenile flounder (32 days after hatching) were fed on HUFA enriched Artemia and subsequently three periods of co-feeding with dry diets (15, 20, and 25 days) were tested, a control group, where flounder were fed exclusively on Artemia was also followed until the end of the experiment. Juveniles fed on Artemia showed significantly higher (P<0.05) survival (82 percent), weight (480±157mg) and total length (35.5±5.0mm) than flounder weaned into dry diets, independent of the co-feeding period. Growth was similar (P>0.05) for juveniles fed on dry diets, but a higher survival rate was registered when the co-feeding period was longer. The results obtained demonstrate that flounder fed exclusively on Artemia have a better performance than those weaned into dry diets. However, unitary cost of production is reduced when juveniles are weaned 58 days after hatching.

Criação de juvenis de peixe-rei (Odontesthes argentinensis) em diferentes taxas de arraçoamento / Rearing of pejerrey (Odontesthes argentinensis) juveniles at different feeding rates

Este estudo teve como objetivos avaliar os efeitos de diferentes taxas de arraçoamento sobre a sobrevivência e o crescimento de juvenis do peixe-rei (Odontesthes argentinensis). Juvenis de peixe-rei (100mg) foram estocados na densidade 10 peixes L-1, em tanques circulares de 50L. Foram testadas cinco taxas de alimentação (4, 8 12, 16 e 20 por cento do peso vivo diário) em duplicata durante 30 dias, mais um controle negativo no qual os peixes não foram alimentados. Durante o experimento, a temperatura foi de 23°C, a salinidade 26ë e a água foi constantemente aerada. A mortalidade total dos peixes mantidos em jejum foi observada após 20 dias de criação; entretanto, não foi verificada diferença significativa de sobrevivência entre os peixes submetidos aos demais tratamentos até o final do experimento, pois a mortalidade foi inferior a 10 por cento, independentemente da taxa de arraçoamento testada. Pelos resultados da regressão polinomial quadrática dos dados de ganho em peso e eficiência alimentar, sugere-se que a taxa de arraçoamento ótima para juvenis de peixe-rei entre 100 e 500mg é igual a 9,0 por cento do peso vivo ao dia.

Toxicidade aguda do nitrito em larvas do peixe-rei marinho Odontesthes argentinensis (Teleostei, Atherinopsidae) / Acute toxicity of nitrite on larvae of the marine pejerrey Odontesthes argentinensis (Teleostei, Atherinopsidae)

Este trabalho visou a determinar o efeito tóxico do nitrito sobre larvas do peixe-rei marinho Odontesthes argentinensis através de testes agudos com 96h de duração. As larvas utilizadas neste experimento foram cultivadas no Laboratório de Maricultura da FURG (Rio Grande - RS). Foi utilizada água do mar filtrada na salinidade 35ë, na temperatura de 23°C, com fotoperíodo de 14 horas de luz e aeração constante. Diariamente, as larvas mortas foram retiradas e, em seguida, 100 por cento do meio experimental foi renovado. Não foi fornecido alimento durante a exposição ao nitrito. As larvas foram expostas a cinco concentrações de nitrito: 50, 150, 250, 350 e 450mg L-1 N-NO2-, mais um controle onde o nitrito não foi adicionado. A CL50-96h (concentração letal para 50 por cento dos organismos após 96 horas) e seu intervalo de confiança (95 por cento) foram de 199,3 (142,0-279,6)mg L-1 N-NO2-. Os resultados deste trabalho sugerem que, assim como outras espécies de peixes marinhos, o O. argentinensis é uma espécie tolerante a altas concentrações de nitrito e é pouco provável que este último seja um problema para o cultivo intensivo desta espécie.

This work evaluated the toxicity of nitrite on larvae of the marine pejerrey Odontesthes argentinensis through acute exposure during 96h. Larvae used in this experiment were cultivated in the Laboratory of Mariculture of the University of Rio Grande. During the tests temperature was 23°C, salinity 35ë, and 14 hours of light were provided. Every day dead larvae were removed and the experimental media were completely renewed. Larvae were deprived of food during the test. Concentrations for the acute tests were 50, 150, 250, 350 and 450mg L-1 N-NO2-, plus a control with no nitrite added. Lethal concentration for 50 percent of the organisms (LC50-96h), and its confidence interval, was 199.3 (142.0-279.6)mg L-1 N-NO2-. The results of the acute tests suggest that, as other species of marine fish larvae, O. argentinensis is tolerant to high concentrations of nitrite, and it is unlikely that it would be a problem for the intensive culture of this species.