RESUMO

During January 2013, a mining spill occurred in the Santa Maria mining region, releasing around 300,000 m3 of tailings on Los Remedios river, which was transported through the San Lorenzo river and finally to El Comedero (EC) dam. Twenty months later, we examined the concentrations of Hg and Se in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) captured in the EC dam to assess the performance of the cleaning operations. A high Se concentration in the liver of all species (carp, 1.2 ± 0.4; tilapia, 3.9 ± 2.1; bass, 3.5 ± 1.1 µg g-1 ww) was consistently observed, while this behavior was only found in the blue tilapia for Hg (0.15 ± 0.11 µg g-1 ww). Tilapia (benthic-detritivorous) exhibited the highest Se concentrations compared to the carp (omnivore) and the largemouth bass (piscivore). In contrast, the largemouth bass had the highest Hg levels in the muscle compared with the other fishes. Such differences could be related to the different metabolism and feeding habits among species. Compared to a tilapia study carried out three months after the mine spill during a mortality event, a decrease was evident in the liver for Se and Hg by 7.2 and 4.7 times, respectively. This reveals that cleaning operations were more efficient for Se and less for Hg, and that a prolonged period was required for the partial recovery of the element levels in fish from sites impacted by mining. Considering the Mexican consumption scenarios for each fish species, it could be concluded that there will be no non-cancer risk by exposure to Hg or Se.

Assuntos

RESUMO

The failure of a tailings dam occurred in January 2013 at the Santa María de Otáez mining region (Mexico) released a spill (~ 300,000 m3) on Los Remedios River, which was transported through the San Lorenzo River, and finally to El Comedero (EC) dam. The concentrations of metal(loid)s in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) collected from EC dam were examined twenty months later to assess the performance of the cleaning operations. The bioaccumulation patterns of the metal(loid)s in the tissues were different in the three fish species. Tilapia had the highest Cd (11.23 ± 8.53 µg g-1) and Cu (871 ± 1261 µg g-1) concentrations in the liver, as well as As concentration (83.6 ± 61.7 µg g-1) in the gut, while the highest Zn concentration (745 ± 356 µg g-1) was measured in the gills of the carp. Such variability can be caused by the variant bioavailability of the metal(loid)s and by the feeding habits of each species; and also by the fact that some metals are essential and better regulated by organisms than other non-essential. Compared to a study of tilapia carried out 90 days after mine spill, a decrease was evident in the liver for As, Cd, Cu, and Zn by 129, 5, 10, and 1.7 times, respectively. This revealed that cleaning operations were more efficient for As. The target hazard quotient and the hazard index were < 1, which indicates there will be no risk of consuming muscle in moderated rations of the three fish species.

Assuntos

RESUMO

Aquatic ecosystems have been suffering deleterious effects due to the development of different economic activities. Metal(loid)s are one of the most persistent chemicals in environmental reservoirs, and may produce adverse effects on different organisms. Since fishes have been largely used in studies of metal(loid)s exposure, tilapia and largemouth bass were collected in three ecosystems from the Yaqui River Basin to measure the concentrations of metal(loid)s (chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn) arsenic (As), mercury (Hg), and selenium (Se)) and some biomarkers (somatic indices, metallothionein expression and histopathological analysis) in tissues of both species. Metal(loid) concentrations varied seasonally among ecosystems in tissues of both species. The elements varied seasonally and spatially in tissues of both species, with a general distribution of liver > gills > gonads. Also, biomarkers showed variations indicative that the fish species were exposed to different environmental stressor conditions. The highest values of some biomarkers were in largemouth bass, possibly due to differences in their biological characteristics, mainly feeding habits. The multivariate analysis showed positive associations between metal(loid)s and biomarkers, which are usually associated to the use of these elements in metabolic and/or regulatory physiological processes. Both fish species presented histological damage at different levels, from SI types (changes that are reversible for organ structure) to SII types (changes that are more severe but may be repairable). Taken together, the results from this study suggest that the Yaqui River Basin is moderately impacted by metals and metalloids.

Assuntos

RESUMO

Non-native predators are known to cause ecological impacts through heightened consumption of resources and decimation of native species. One such species is Micropterus salmoides. Often introduced for sport fishing worldwide; it has been listed by International Union for Conservation of Nature and Natural Resources as one of the 100 of the world's worst invasive species. Whilst impacts conferred towards native prey are well known, its relationship with other non-native species has received much less attention. Therefore, the aim of this study was to experimentally investigate the feeding preference of M. salmoides towards native prey (Geophagus iporangensis) compared to non-native prey (Oreochromis niloticus and Coptodon rendalli) using comparative consumption and the Manly-Chesson selectivity index. We found a higher consumption by M. salmoides towards the non-native prey and a tendency for this non-native preference to increase when prey availability increased. Our results are in line with the hypothesis that the invasion of the non-native predator can be facilitated by the high abundance and reproductive rate of the non-native prey. This is relevant considering the interaction of multiple invaders in an ecosystem, in particular environments modified by humans. Interspecific relationships are complex and their understanding is necessary for environmental management decision-making.(AU)

Predadores não-nativos são conhecidos por causar impactos ecológicos com o aumento do consumo de recursos e do declínio das espécies nativas. Uma dessas espécies é Micropterus salmoides. Frequentemente introduzida ao redor do mundo para pesca esportiva; essa espécie foi listada pela União Internacional para a Conservação da Natureza como uma das 100 piores espécies invasoras do mundo. Embora os impactos nas presas nativas sejam bem conhecidos, sua relação com outras espécies não-nativas tem recebido muito menos atenção. Portanto, o objetivo deste estudo foi pesquisar experimentalmente a preferência alimentar de M. salmoides por presas nativas (Geophagus iporangensis) em comparação com presas não-nativas (Oreochromis niloticus e Coptodon rendalli) comparando o consumo e o índice de seletividade de Manly-Chesson. Encontramos que M. salmoides tem um maior consumo de presas não-nativas e uma tendência de aumento de preferência pela presa não-nativa com o aumento da disponibilidade de presas. Nossos resultados são consistentes com a hipótese de que a invasão do predador não-nativo pode ser facilitada pela grande abundância e capacidade reprodutiva de presas não-nativas. Isso é relevante considerando a interação de múltiplos invasores em um ecossistema, particularmente em ambientes modificados pelo homem. Relações interespecíficas são complexas e seu entendimento é necessário para a tomada de decisões de gestão ambiental.(AU)

Assuntos

RESUMO

Micropterus salmoides is an important fish species for sport fishing activities, condition that has promoted its introduction to different reservoirs in Mexico and worldwide. With the aim to improve its fisheries management, this research dealt with some reproductive aspects of this species in the Gustavo Díaz Ordaz reservoir, where it was studied from August 2008 through March 2011. To this end, we obtained 938 specimens, with gillnets of different sizes, to determine their total length (Lt, in cm), weight (Pt, in g), sex, gonadosomatic index, condition factor, fecundity and size at first maturity. Lt and Pt ranged from 15.9 to 63cm (37.4±78.0) and 57 to 4 431g (731.7±619.0), respectively. The Pt-Lt relationship showed a positive allometric growth, with no significant difference between males and females (F=0.9955, p=0.3187). The male: female ratio obtained was 1:0.83. Mass spawning lasted from December to April. Size at first maturity was 33.7cm and average fecundity was 32 294±12 878.7 oocytes/female. The gonadosomatic index was low from May through November, and increased between January and March. The condition factor was high before the spawning season and decreased after the reproductive period. We recommend a fishing ban from January to March, and to allow the capture size between 33 and 40cm.

Micropterus salmoides es un pez de importancia para la pesca deportiva en la mayoría de los embalses de México y del mundo, por lo que en el embalse Gustavo Díaz Ordaz se realizó un estudio sobre aspectos reproductivos entre agosto 2008 y marzo 2011. Se recolectaron 938 organismos, a los cuales se les midió la longitud (Lt cm), peso (Pt g), se determinó el sexo, índice gonadosomático, factor de condición, fecundidad y talla de primera madurez. La longitud y peso de los ejemplares recolectados varió de 15.9 a 63 cm (37.4±78.0) y de 57 a 4 431g (731.7±619.0), respectivamente. La relación peso total-longitud total se ajustó a un modelo tipo potencial, el crecimiento fue alométrico positivo, no se obtuvieron diferencias significativas entre machos y hembras (F=0.9955, p=0.3187). La proporción macho-hembra fue 1:0.83. Los desoves masivos inician en diciembre y finalizan en abril. La talla de primera reproducción fue de 33.7cm y la fecundidad promedio de 32 294±12 878.7 ovocitos/hembra. El índice gonadosomático se mantuvo bajo desde mayo hasta noviembre y alto entre enero y marzo. El factor de condición registró valores altos previos al desove y disminuyó al final del periodo reproductivo.

Assuntos

RESUMO

The black bass, Micropterus salmoides, was introduced to Brazil from North America in 1922. Since then the species has been reared in aquaculture facilities intended to stock reservoirs as additions to native stocks available for angling. At present no scientific information on the biology of black bass in Brazilian waters is available. Since black bass dispersion may cause severe impacts on native Brazilian fish fauna, information on the basic biological parameters of this species is necessary. The objective of the present study is to provide information on the growth, age structure, and mortality of the species in a small reservoir in southern Brazil, where the species reproduces regularly. Based on scale readings, the von Bertalanffy growth curve was calculated and compared to the length-frequency distribution of the population. Both methods showed similar results. Maximum length was about 44 cm. The mean length at the end of the first year was 23.1 cm (s.d. = 13.88); at that of the second, 37.3 cm (s.d. = 12.52); and 41.4 cm (s.d. = 9.92) at the third. Oldest fish were three years old. The growth performance index ø' was 3.28 cm year-1. Mortality increased from 0.16 year-1 between the first and the second cohort, to 0.8 year-1 between the second and third. The results show that black bass in Brazil grows faster than in its area of origin, but longevity is shorter and body shape, stouter. The cause of high mortality at a relatively early age may be connected with the loss of genetic diversity due to inbreeding of the Brazilian stocks, which originated from few introduced individuals a long time ago. The fact that black bass reproduces in reservoirs and grows rapidly may be considered a threat to conserving fish diversity in Brazilian ecosystems.

O black bass, Micropterus salmoides, proveniente da América do Norte, foi introduzido no Brasil em 1922. A partir dessa data, a espécie foi criada na piscicultura brasileira para fins de soltura em açudes e reservatórios com o objetivo de sustentar a pesca amadora. Atualmente não há informações sobre a biologia da espécie em águas brasileiras. Como a dispersão da espécie em águas naturais pode causar impactos imprevisíveis, é necessário levantar dados sobre parâmetros básicos de sua biologia. O objetivo do presente trabalho é investigar o crescimento, a estrutura etária e a mortalidade da espécie num pequeno reservatório no sul do Brasil, onde ela se reproduz todos os anos. Por meio da leitura de escamas foi calculada a curva de crescimento von Bertalanffy e comparada à distribuição do comprimento. Ambos os métodos chegaram a resultados similares. O comprimento máximo foi de aproximadamente 44 cm. No primeiro ano de vida, o comprimento médio foi de 26,1 cm (d.p. = 13,88); no segundo, 37,3 cm (d.p. = 12,52); e no terceiro, 41,5 cm (d.p. = 9,92). O índice de performance de crescimento foi ø' = 3,28 cm ano-1. A mortalidade Z aumentou aproximadamente quatro vezes, de 0,16 anos-1 entre a primeira e a segunda coorte para 0,8 anos-1 entre a segunda e a terceira coorte. Os resultados mostram que o black bass cresce mais rapidamente no Brasil e tende a ser mais enxuto que em sua área de origem, mas não atinge a longevidade dos espécimes nos Estados Unidos. A causa dessa mortalidade elevada é vista na provável diminuição da diversidade genética dos estoques brasileiros, originados de poucos indivíduos introduzidos muito tempo atrás. O fato de a espécie se reproduzir e crescer rapidamente em sistemas seminaturais pode ser considerado uma ameaça para a conservação dos ecossistemas brasileiros.

RESUMO

To determine dietary protein and energy retention of juvenile largemouth bass one thousand, three hundred and fifty feed-conditioned fish (average weight 14.46 ± 0.81 g) were stocked in 60-L cages set up in 1,000 L containers, and fed for 64 days with a dry, extruded feed containing varying levels of crude protein - CP (34, 38, 42, 46, 50 and 54%) and energy (3,600 to 4,100 kcal kg-1 feed, with increases of 125 kcal kg-1). The trial was set up in a totally randomized 6 x 5 factorial design (n=3). Data on weight gain, daily feed consumption, hepatosomatic index, viscerosomatic index, nutrient protein, energy retention, liver glycogen and visceral fat were evaluated. There were no interaction effects (P > 0.05) between feed energy and protein levels in respect to all evaluated parameters. Best performance was attained with levels of 42% CP and 3,850 kcal kg-1 in the diets, a condition which resulted in higher levels of liver glycogen (P 0.0442) and higher hepatosomatic indexes (P 0.0001) usually when diets presented less than 30% starch. Higher levels of dietary lipid induced significant increases in whole body lipids considering dietary energy (P 0.0001), and this also induced higher deposition of visceral fat for pooled means of dietary protein (P 0.0001) and energy (P 0.0021) contents. These results will help understanding the nutritional energetics of carnivorous fish, increasing the feasibility of their intensive production.

O objetivo deste trabalho foi avaliar alterações nas formas de reserva de energia na carcaça de juvenis de "black bass" (14,46 ± 0,81 g de peso vivo). Peixes condicionados a aceitar alimento artificial foram estocados em 90 gaiolas de volume 60 L alojadas em caixas de 1.000 L em laboratório com condições ambientais controladas, e alimentados por 64 dias com rações extrusadas com níveis de proteína variando entre 34 e 54% (incrementos de 4%) e teores de energia digestível variando de 3.600 a 4.100 kcal kg-1 de alimento (incrementos de 125 kcal kg-1). Foram analisados as variáveis de ganho de peso, consumo alimentar diário, relação hepato-somática, relação víscero-somática, deposição protéica e energética, glicogênio tecidual hepático e lipídio visceral. Não houve interação (P > 0,05) entre níveis de proteína e energia para os parâmetros avaliados. Os níveis de proteína e energia digestível dietética que garantiram melhor desempenho foram 42% e 3.850 kcal kg-1, respectivamente. Dietas com teores médios de 42% de proteína bruta, induziram um alto acúmulo de glicogênio hepático (P 0,0442), assim como aumento da relação hepato-somática (P 0,0001), mostrando alta eficiência no acúmulo de energia prontamente utilizável bem como melhor capacidade de retenção dos nutrientes, quando os níveis de carboidratos foram inferiores a 30% na ração. O aumento dos níveis de energia das dietas, através da inclusão de óleo nas rações, induziu aumentos significativos no acúmulo total de lipídios na carcaça quando as médias eram agrupadas por níveis de energia, e induziu acúmulo de lipídios nas vísceras para os agrupamentos de médias tanto por teor de proteína (P 0,0001) como de energia dietética (P 0,0021).

RESUMO

To determine dietary protein and energy retention of juvenile largemouth bass one thousand, three hundred and fifty feed-conditioned fish (average weight 14.46 ± 0.81 g) were stocked in 60-L cages set up in 1,000 L containers, and fed for 64 days with a dry, extruded feed containing varying levels of crude protein - CP (34, 38, 42, 46, 50 and 54%) and energy (3,600 to 4,100 kcal kg-1 feed, with increases of 125 kcal kg-1). The trial was set up in a totally randomized 6 x 5 factorial design (n=3). Data on weight gain, daily feed consumption, hepatosomatic index, viscerosomatic index, nutrient protein, energy retention, liver glycogen and visceral fat were evaluated. There were no interaction effects (P > 0.05) between feed energy and protein levels in respect to all evaluated parameters. Best performance was attained with levels of 42% CP and 3,850 kcal kg-1 in the diets, a condition which resulted in higher levels of liver glycogen (P 0.0442) and higher hepatosomatic indexes (P 0.0001) usually when diets presented less than 30% starch. Higher levels of dietary lipid induced significant increases in whole body lipids considering dietary energy (P 0.0001), and this also induced higher deposition of visceral fat for pooled means of dietary protein (P 0.0001) and energy (P 0.0021) contents. These results will help understanding the nutritional energetics of carnivorous fish, increasing the feasibility of their intensive production.

O objetivo deste trabalho foi avaliar alterações nas formas de reserva de energia na carcaça de juvenis de "black bass" (14,46 ± 0,81 g de peso vivo). Peixes condicionados a aceitar alimento artificial foram estocados em 90 gaiolas de volume 60 L alojadas em caixas de 1.000 L em laboratório com condições ambientais controladas, e alimentados por 64 dias com rações extrusadas com níveis de proteína variando entre 34 e 54% (incrementos de 4%) e teores de energia digestível variando de 3.600 a 4.100 kcal kg-1 de alimento (incrementos de 125 kcal kg-1). Foram analisados as variáveis de ganho de peso, consumo alimentar diário, relação hepato-somática, relação víscero-somática, deposição protéica e energética, glicogênio tecidual hepático e lipídio visceral. Não houve interação (P > 0,05) entre níveis de proteína e energia para os parâmetros avaliados. Os níveis de proteína e energia digestível dietética que garantiram melhor desempenho foram 42% e 3.850 kcal kg-1, respectivamente. Dietas com teores médios de 42% de proteína bruta, induziram um alto acúmulo de glicogênio hepático (P 0,0442), assim como aumento da relação hepato-somática (P 0,0001), mostrando alta eficiência no acúmulo de energia prontamente utilizável bem como melhor capacidade de retenção dos nutrientes, quando os níveis de carboidratos foram inferiores a 30% na ração. O aumento dos níveis de energia das dietas, através da inclusão de óleo nas rações, induziu aumentos significativos no acúmulo total de lipídios na carcaça quando as médias eram agrupadas por níveis de energia, e induziu acúmulo de lipídios nas vísceras para os agrupamentos de médias tanto por teor de proteína (P 0,0001) como de energia dietética (P 0,0021).