Citral as food additive for common snook - zootechnical parameters and digestive enzymes / Citral como aditivo na ração para robalo flecha - parâmetros zootécnicos e enzimas digestivas

ABSTRACT: Essential oils of plants whose main compound is citral showed beneficial effects when added to fish feed. The objective of the present study was to evaluate the dietary effect of the addition of citral on zootechnical parameters and digestive enzyme activities of Centropomus undecimalis. Juveniles were fed for 45 days with diets containing different amounts of citral (0.0 - control, 0.5, 1.0, and 2.0 mL per kg of diet). The water quality parameters were kept stable during the experiment and no mortality was observed. At the end of the experimental period, the treatment 0.5 mL citral per kg of diet had the lowest weight gain and specific growth rate, and the highest feed conversion, while the same parameters did not differ between the other treatments. Pepsin activity was higher in the stomach of fish fed with 0.5 mL citral per kg of diet and amylase activity was higher in the intestine of fish fed with 0.5 and 2.0 mL citral per kg of diet compared to the control group. Intestinal lipase activity was higher in all groups that were fed with citral compared to the control group. Chymotrypsin and trypsin activities showed no difference between groups. Consequently, dietary addition of citral at any of the levels tested is not recommended for common snook.

RESUMO: Óleos essenciais de plantas, cujo composto majoritário é o citral, mostraram efeitos benéficos quando adicionados à ração para peixes. O objetivo do presente estudo foi avaliar o efeito da adição de citral sobre os parâmetros zootécnicos e atividades das enzimas digestivas de Centropomus undecimalis. Os juvenis foram alimentados por 45 dias com dietas contendo diferentes quantidades de citral (0,0 - controle, 0,5, 1,0 e 2,0 mL por kg de ração). Os parâmetros de qualidade da água foram mantidos estáveis ​​durante o experimento e nenhuma mortalidade foi observada. Ao final do período experimental, o tratamento 0,5 mL citral por kg de ração teve o menor ganho de peso e taxa de crescimento específico e a maior conversão alimentar, enquanto os mesmos parâmetros não diferiram entre os demais tratamentos. A atividade da pepsina foi maior no estômago de peixes alimentados com 0,5 mL de citral por kg de ração e a atividade de amilase foi maior no intestino de peixes alimentados com 0,5 e 2,0 mL citral por kg de ração comparado ao grupo controle. A atividade da lipase intestinal foi maior em todos os grupos que foram alimentados com citral, em comparação ao grupo controle. As atividades de quimotripsina e tripsina não mostraram diferença entre os grupos. Consequentemente, a adição de citral na ração em qualquer um dos níveis testados não é recomendada para robalo flecha.

Reproducción de los róbalos Centropomus undecimalis y C. Ensiferus (Perciformes: Centropomidae) en una laguna costera tropical / Reproduction of Centropomus undecimalis and C. ensiferus (Perciformes: Centropomidae) in a tropical coastal lagoon

ResumenLos róbalos (C. undecimalis y C. ensiferus) son recursos pesqueros de importancia en toda su área de distribución. En Venezuela son capturados por pesquerías artesanales a lo largo de toda la costa, sin embargo, los estudios sobre su biología que permitan orientar regulaciones de su pesca son escasos. Para analizar aspectos de la reproducción de ambas especies se analizaron 1 325 individuos de C. undecimalis y 2 025 de C. ensiferus, provenientes de la pesca artesanal en la Laguna de Tacarigua, en el norte de Venezuela, desde julio 2009 a septiembre 2010. Se midió la longitud total, peso total, sexo y madurez sexual de cada individuo. La proporción sexual varió a lo largo del año, se observó una diferencia significativa en favor de los machos para C. undecimalis (1:1.5) y de las hembras para C. ensiferus (1:3.3). Se evidenciaron diferencias en la proporción sexual de la talla para ambas especies: los machos dominan las tallas inferiores, mientras que las hembras dominan las superiores. Lo cual señala un patrón típico de hermafroditismo secuencial (protándrico) en ambas. Se estimaron las tallas de madurez sexual (Lm50) para C. undecimalis (♀= 73.6 y ♂= 59.3 cm) y C. ensiferus (♀= 26 y ♂= 21.5 cm). C. ensiferus se reproduce durante todo el año con dos periodos de mayor intensidad (agosto a septiembre y febrero a abril), mientras para C. undecimalis fueron escasos los individuos maduros, mostrando febrero el pico de reproducción más importante. Se encontró diferencia en el crecimiento entre machos y hembras de C. undecimalis: alométrico positivo para hembras (P= 0.0022*L3.353) y negativo para machos (P= 0.0108*L2.945), mientras no se encontraron diferencias para C. ensiferus, que presentó alometría positiva (P= 0.0049*L3.235) para ambos sexos. La falta de regulación y controles de pesca, la evidencia de importantes volúmenes de individuos inmaduros en las capturas, así como el carácter particular de la biología reproductiva de estas especies, sugiere la necesidad de establecer regulaciones para garantizar su aprovechamiento responsable, como un periodo de veda durante el primer trimestre de año y tallas mínimas de captura para ambas especies.

Abstract:Snooks C. undecimalis and C. ensiferus are important fishery resources in their distribution area. In Venezuela they are caught by artisanal fisheries along the entire coast. However, studies on their biology that would help establish fishing regulations are scarce. To study reproduction aspects of these species, we analyzed 1 325 individuals of C. undecimalis and 2 025 of C. ensiferus caught by artisanal fishing in the Laguna de Tacarigua in Northern Venezuela, from July 2009 to September 2010. Total length, total weight, sex and stage of gonadal development were recorded. The sex ratio varied throughout the year: there was a significant difference in favor of C. undecimalis males (1.5:1), and C. ensiferus females (1:3.3). Differences were also evident in the sexual proportion at each size group. For both species, males dominated in the lower size ranges while females dominated in the larger size ranges. These results suggested sequential hermaphroditism (protrandry) in both species. Size at sexual maturity (Lm50) for C. undecimalis was ♀= 73.6 and ♂= 59.3 cm, and ♀= 26 and ♂= 21.5 cm for C. ensiferus. C. ensiferus reproduced throughout the year with two periods of higher intensity (August to September and February to April). Although we found very few mature individuals for C. undecimalis, February showed an important reproduction peak. Growth differences were found between males and females of C. undecimalis: positive allometry for females (P= 0.0022*L3.353) and negative allometry for males (P= 0.0108*L2.945). Both males and females of C. ensiferus showed a positive allometric relationship (P= 0.0049*L3.235). Lack of fishing regulations and controls, evidenced in this study by significant volumes of immature individuals in the catches, and the particular reproductive biology of these species, strongly indicates the need to establish regulations to ensure their responsible use. We recommend establishing a closed season during the first quarter of the year and minimum catch sizes for both species. Rev. Biol. Trop. 65 (1): 181-194. Epub 2017 March 01.

Hábitos alimentarios de los jóvenes de Centropomus robalito (Centropomidae: Actinopterygii) en la laguna de Barra de Navidad, Jalisco, México

n América, las especies del género Centropomus (róbalos) son un componente clave de la ictiofauna estuarina tropical. Estas especies usan los cuerpos de agua salobre como áreas de crianza principalmente, aunque especímenes adultos están presentes también en estos hábitats. El robalito de aletas amarillas Centropomus robalito (Jordan & Gilbert, 1882) es una de las especies más abundantes en humedales costeros del Pacífico central mexicano pero hay pocos datos sobre su biología. El objetivo de este trabajo, fue el análisis de la composición de la dieta de los jóvenes de C. robalito y los cambios ontogénicos que sufre la misma dentro de la laguna costera de Barra de Navidad, ubicada en el Pacífico central mexicano. Los especímenes fueron capturados entre marzo 2011 y enero 2012 utilizando varios artes de pesca (atarraya, redes de enmalle y chinchorro playero experimental). Un total de 681 peces jóvenes fueron obtenidos y clasificados en tres clases de longitud (pequeños < 69 mm LT; intermedios 70-139 mm LT; grandes ≥ 140 mm LT) para el análisis del contenido estomacal. Los estómagos con contenido fueron 292 y la composición general de la dieta incluyó 14 entidades alimentarias dominadas por crustáceos (Alpheidae, Penaeidae y Brachyura) y peces (Gobiidae, Engraulidae y Mullidae), con una representación menor de copépodos e insectos. Se encontraron cambios significativos en la composición de la dieta entre clases de longitud. La dieta de los peces pequeños (< 69 mm LT) y medianos (70-139 mm LT) estuvo dominada por camarones peneidos jóvenes y peces (principalmente Gobiidae); mientras que en los peces mayores (≥ 140 mm LT) los camarones Alpheidae y en segundo lugar peces de las familias Engraulidae y Mullidae fueron dominantes en la dieta. Se concluye que C. robalito es una especie generalista con cambios ontogénicos en su dieta.

n America, the species of genus Centropomus (Snooks) are a key component of the tropical estuarine ichthyofauna. These species use brackish water bodies mainly as nursery areas, although adult specimens are also present. The Yellow-fin snook Centropomus robalito (Jordan & Gilbert, 1882) is one of the most abundant species in the coastal wetlands of the Mexican Central Pacific but there is very few data on its biology. The goal of this research was to analyze the diet composition of juvenile specimens of C. robalito and to study its ontogenic changes in Barra de Navidad coastal lagoon located in the Mexican Central Pacific. Specimens were collected between January 2011 and March 2012 using several fishing gears (cast net, gillnets and beach purse seine). A total of 681 juvenile fish were obtained and classified in three sizeclasses (small < 69 mm TL; intermediate 70-139 mm TL; large ≥ 140 mm TL) to analyze stomach contents. The number of stomachs with some content was 292, and the general diet composition included 14 food items dominated by crustaceans (Alpheidae, Penaeidae, Brachyura) and fishes (Gobiidae, Engraulidae, Mullidae), with minor representation of copepods and insects. Significant changes in the diet composition between size-classes were found. Diet of small and intermediate fish was dominated by juvenile peneid shrimps, and fishes (mainly Gobiidae); while for larger fish, Alpheidae shrimps, and in second place, fish from Engraulidae and Mullidae were dominant in the diet. It is concluded that C. robalito is a generalist species with ontogenic changes in its diet. Rev. Biol. Trop. 63 (4): 1071-1081. Epub 2015 December 01.

Genetic variability of the Common Snook Centropomus undecimalis (Perciformes: Centropomidae) in connected marine and riverine environments / Variabilidad genética del robalo común Centropomus undecimalis (Perciformes: Centropomidae) en ambiente marino y ribereño interconectados

The Common Snook, Centropomus undecimalis, inhabits riverine and marine areas of Southern Gulf of Mexico, where it is subject to intense use and exploitation. It has been reported that the genetic identification of fish stocks constitutes a valuable tool for wild population management; nevertheless, there is no available information on the genetic identification on fish stocks of this species in the region. The aim of this study was to determine the genetic relationship between C. undecimalis captured in marine and freshwater environments of the Gulf of Mexico and the San Pedro River. For this, muscle tissue samples of 79 specimens were obtained from areas located more than 300km apart. The genotype of each individual was determined using seven microsatellite primer pairs. Five primers amplified efficiently presenting between six and 28 alleles per locus. High levels of heterozygosis were observed in samples from both environments. Deviation from HWE due to an excess of heterozygotes was observed. The values of genetic difference indicate an absence of population structure (F ST=0.0075 and R ST=0.016, p=0.051) and similarity in the allele frequencies, defined by Nei’s index (0.805). Data showed the existence of a high gene flow due to the number of migrants (Nm=18.7). Our results suggest that individuals living in these environments belong to the same genetic population. We suggest the development of management and protection plans for this fish species population in the wild. Rev. Biol. Trop. 62 (2): 627-636. Epub 2014 June 01.

El robalo común Centropomus undecimalis habita en áreas ribereñas y marinas del sur del Golfo de México donde es sujeto a explotación intensiva. Aunque la identificación de las poblaciones de peces representa una valiosa herramienta para el manejo de las poblaciones silvestres, no hay información disponible para identificar genéticamente las poblaciones de peces de esta especie en la región. El objetivo de este estudio fue determinar la relación genética entre C. undecimalis capturado en ambiente marino y dulceacuícola del Golfo de México y río San Pedro. Muestras de tejido muscular de 79 individuos fueron obtenidas en áreas separadas por más de 300km. El genotipo de cada individuo fue determinado usando siete pares de cebadores microsatélites. Cinco cebadores amplificaron eficientemente presentando entre seis y 28 alelos por locus. Altos niveles de heterocigosidad se observaron en las muestras de ambos ambientes. Se observó desviación del equilibrio HW debido a exceso de heterocigotos. Los valores de diferenciación genética indican ausencia de estructuración poblacional F ST (0.0075) y R ST (0.016, p=0.051) y similitud en las frecuencias alélicas definidas por el índice de Nei (0.805). Los datos mostraron elevado flujo genético debido al número de migrantes (Nm=18.7). Estos resultados sugieren que los individuos en estos ambientes provienen de la misma población genética. La información obtenida en este estudio, por lo tanto contribuirá con elementos que pueden ser considerados en el desarrollo de programas de manejo y protección de las poblaciones de peces silvestres.

Uso de biomarcador histopatológico em brânquias de Centropomus undecimalis (Bloch, 1972) na avaliação da qualidade da água do Parque Ecológico Laguna da Jansen, São Luís - MA / Using histopathological biomarker in gills of Centropomus undecimalis (Bloch, 1972) in assessing the water quality at Ecological Park Laguna da Jansen, São Luís -MA

Com o objetivo de analisar a intensidade das alterações histológicas em brânquias de Centropomus undecimalis para avaliar a qualidade da água do Parque Ecológico Laguna da Jansen, em São Luís, Estado do Maranhão, coletaram-se exemplares de peixes no período chuvoso de 2012 e amostras de água nos períodos seco de 2011 e chuvoso de 2012 para análises físico-química e bacteriológica. Os resultados mostraram que a maioria dos parâmetros físico-químicos e bacteriológicos estava de acordo com os valores estabelecidos pela Resolução do CONAMA nº 357 de 2005. As alterações histológicas observadas foram: elevação do epitélio lamelar; proliferação excessiva de células dos epitélios filamentar e lamelar causando fusão total ou parcial das lamelas; alteração da estrutura das lamelas; hiperplasia das células mucosas; ruptura do epitélio lamelar; espessamento descontrolado do tecido proliferativo filamentar e lamelar e aneurismas de vários tamanhos. Também foi observada a presença de parasito em alguns exemplares. O Índice de Alteração Histológica (IAH) por indivíduo variou de 2 a 114. O valor médio do IAH obtido foi de 40,3, demonstrando que as brânquias dos indivíduos amostrados da espécie C. undecimalis apresentaram alterações de moderadas para severas no tecido. As alterações histológicas encontradas indicam que esses indivíduos desenvolveram mecanismos de defesa contra a ação de estressores presentes na água da laguna e a um provável desequilíbrio parasito-hospedeiro-ambiente associado à baixa qualidade do ambiente...

Aiming to analyze the intensity of the histological changes in the gills of Centropomus undecimalis to assess the water quality at Ecological Park of the Laguna da Jansen, in São Luís, State of Maranhão, specimens of fish were collected during the rainy season of 2012 and water samples during the dry season in 2011 and rainy season in 2012 for physical-chemical and bacteriological analyses. The results showed that most of the physical-chemical and bacteriological parameters analyzed agreed with the values established by CONAMA Resolution nº 357 of 2005. The histological changes were elevation of the lamellar epithelium, excessive cell proliferation of the filamentum and lamellar epithelium causing total or partial melting of the lamellar; changing the structure of the lamellar, hyperplasia of mucous cells, disruption of the lamellar epithelium, uncontrolled proliferative tissue filamentum thickening and lamellar and aneurysms in various sizes. We noted the presence of parasites in some samples. The Index Histological Amendment (IAH) per individual ranged from 2 to 114. The mean IAH obtained was 40.3, demonstrating that the gills of the individuals of the C. undecimalis species showed moderate to severe changes in the tissue. The histological findings indicate that these individuals have developed defense mechanisms against the action of stressors present in the water of the Laguna da Jansen and a probable parasite-host-environment imbalance associated with the environment's low quality...

Morphological and anatomical characterization of the digestive tract of Centropomus parallelus and Centropomus undecimalis - doi: 10.4025/actascibiolsci.v35i4.14352

Centropomus parallelus and Centropomus undecimalis are the most common species of Centropomidae in Brazil. Some authors attribute their failure to grow under in artificial conditions due to limited knowledge on the morphological and functional development of their digestive system and on nutrition requirements of both species. Current research characterizes histologically and histochemically the digestive tract of Centropomus parallelus and Centropomus undecimalis to provide a histophysiological assessment for studies related to their nutritional needs. In the esophagus, the mucous cells in the epithelium stained positively for PAS and AB. In the stomach, positive reactions to PAS and negative to AB respectively occurred on surface and mucous cells in the epithelium and in the lamina propria. In the intestine, goblet cells showed ratio similarity, with mucus being positive in AB and PAS. A greater concentration of these cells existed in the middle and distal intestine, with a greater increase of secretions when compared to those in the proximal intestine. Results show that Centropomus parallelus and Centropomus undecimalis display the main features of the digestive tract of carnivorous fish, a well-developed stomach and a relatively short intestine. In fact, they give insights for future studies on the mechanisms related to the species´s digestive and absorptive physiology.

Morphological and anatomical characterization of the digestive tract of Centropomus parallelus and C. undecimalis / Caracterização Morfológica e Anatômica do Tubo Digestório de Centropomus parallelus e C. undecimalis

Centropomus parallelus and C. undecimalis are the most common species of Centropomidae in Brazil. Some authors attribute their failure to grow under in artificial conditions due to limited knowledge on the morphological and functional development of their digestive system and on nutrition requirements of both species. Current research characterizes histologically and histochemically the digestive tract of C. parallelus and C. undecimalis to provide a histophysiological assessment for studies related to their nutritional needs. In the esophagus, the mucous cells in the epithelium stained positively for PAS and AB. In the stomach, positive reactions to PAS and negative to AB respectively occurred on surface and mucous cells in the epithelium and in the lamina propria. In the intestine, goblet cells showed ratio similarity, with mucus being positive in AB and PAS. A greater concentration of these cells existed in the middle and distal intestine, with a greater increase of secretions when compared to those in the proximal intestine. Results show that C. parallelus and C.undecimalis display the main features of the digestive tract of carnivorous fish, a well-developed stomach and a relatively short intestine. In fact, they give insights for future studies on the mechanisms related to the species's digestive and absorptive physiology.

Centropomus parallelus e C. undecimalis são as espécies mais comuns de Centropomidae no Brasil. Alguns autores atribuem o insucesso no seu cultivo devido ao escasso conhecimento sobre o desenvolvimento morfológico e funcional do sistema digestório, assim como o desconhecimento das exigências nutricionais das espécies. Dessa forma realizou-se o presente trabalho, com o objetivo de caracterizar histológica e histoquimicamente o tubo digestório de C. parallelus e C. undecimalis, para estudos histofisiológicos relacionados às necessidades nutricionais deste peixe. No esôfago, as células mucosas, presentes no epitélio coraram-se positivamente tanto em PAS como em AB. No estômago, as células superficiais e mucosas presentes no epitélio e na lâmina própria respectivamente, apresentaram reações positivas em PAS e negativa em AB. No intestino as células caliciformes apresentaram similaridade na proporção entre os mucos sendo positivos tanto em PAS como em AB; nos intestinos médio e distal observou-se uma maior concentração destas células, resultando em uma quantidade maior de secreções em comparação ao intestino proximal. Através dos resultados observados, conclui-se que o C. parallelus e C. undecimalis exibem as principais características do trato digestório de peixes carnívoros, como um estômago bem desenvolvido e um intestino relativamente curto. Estes resultados darão subsídios para futuros estudos sobre mecanismos da fisiologia digestiva e absortiva desta espécie.

The effect of salinity on osmoregulation and development of the juvenile fat snook, Centropomus parallelus (POEY) / O efeito da salinidade sobre a osmoregulacao e o desenvolvimento do juvenil de robalo-peva, Centropomus parallelus (POEY)

Eurihaline fish support waters with different salt concentration. However, numerous studies have shown that salinity can affect fish development. Thus, the effect of salinity change from 20 to 5 and 35 on survival, weight, length, gill chloride cell ultrastructure and gill Na+, K+ ATPase activity was evaluated in Centropomus parallelus following short-term (6, 24 and 96 hours) and long-term exposure (30 and 60 days). Salinity did not affect C. parallelus survival, final weight and length. The quantity of chloride cells increased visibly at salinities of 5 and 35, with the cells exhibiting the typical features of uptake and secretory cells, respectively. Na+, K+ ATPase activity in the gill of the C. parallelus was significantly greater at a salinity of 5 than at a salinity of 20 or 35 after 96 hours, but not after 30 or 60 days. These results indicate that salinity change from high to low salt water induces gill chloride cell and Na+, K+ ATPase activity adaptations after short-term exposure. However, after long-term exposure at salinity 5, gill Na+, K+ ATPase activity is no more necessary at high levels. The increase in salinity to 35 does not induce significant change in gills. Juveniles of C. parallelus may thus be capable of acclimating to salinities of 5 to 35 for 60 days without significant effects on development.

Peixes eurihalinos suportam águas com diferentes concentrações de sal. Contudo, muitos estudos têm mostrado que a salinidade pode afetar o desenvolvimento do peixe. Portanto, o efeito da mudança de salinidade de 20 para 5 e 35 na taxa de sobrevivência, peso, comprimento, morfologia das células de cloreto branquiais e atividade da Na+, K+ ATPase foram avaliadas no Centropomus parallelus após curto (6, 24 e 96 horas) e longo tempo de exposição (30 e 60 dias). A salinidade não afetou a sobrevivência, o peso e comprimento final do robalo-peva. A quantidade de células de cloreto aumentou visivelmente nas salinidades 5 e 35, exibindo morfologias típicas de células que absorvem e secretam sal, respectivamente. A atividade da Na+, K+ ATPase nas brânquias do C. parallelus foi significativamente maior na salinidade 5 do que nas salinidades 20 ou 35 após 96 horas, mas não após 30 e 60 dias. Esses resultados indicam que a mudança de alta para baixa salinidade provoca adaptações nas células de cloreto e na atividade da Na+, K+ ATPase branquial em curto prazo. Contudo, após longa exposição na salinidade 5, a alta atividade da Na+, K+ ATPase branquial não é mais necessária. O aumento de salinidade para 35 não induz mudanças significativas nas brânquias. Portanto, juvenis de C. parallelus possuem a capacidade de aclimatação nas salinidades de 5 a 35 semefeitos significativos no desenvolvimento após 60 dias.

Comparative age and growth of common snook Centropomus undecimalis (Pisces: Centropomidae) from coastal and riverine areas in Southern Mexico

Common snook Centropomus unidecimalis is an important commercial and fishery species in Southern Mexico, however the high exploitation rates have resulted in a strong reduction of its abundances. Since, the information about its population structure is scarce, the objective of the present research was to determine and compare the age structure in four important fishery sites. For this, age and growth of common snook were determined from specimens collected monthly, from July 2006 to March 2008, from two coastal (Barra Bosque and Barra San Pedro) and two riverine (San Pedro and Tres Brazos) commercial fishery sites in Tabasco, Mexico. Age was determined using sectioned saggitae otoliths and data analyzed by von Bertalanffy and Levenberg-Marquardt among others. Estimated ages ranged from 2 to 17 years. Monthly patterns of marginal increment formation and the percentage of otoliths with opaque rings on the outer edge demonstrated that a single annulus was formed each year. The von Bertalanffy parameters were calculated for males and females using linear adjustment and the non-linear method of Levenberg-Marquardt. The von Bertalanffy growth equations were FLt=109.21(1-e-0.21(t+0.57)) for Barra Bosque, FLt=94.56(1-e-0.27(t+0.48)) for Barra San Pedro, FLt=97.15(1-e-0.17(t+1.32)) for San Pedro and FLt=83.77(1-e-0.26(t+0.49)) for Tres Brazos. According to (Hotelling’s T², p<0.05) test growth was significantly greater for females than for males. Based on the Chen test, von Bertalanffy growth curves were different among the study sites (RSS, p<0.05). Based on the observed differences in growth parameters among sampling sites (coastal and riverine environments) future research need to be conducted on migration and population genetics, in order to delineate the stock structure of this population and support management programs.

El robalo blanco Centropomus undecimalis representa un ingreso monetario significativo y un recurso alimentario para todas las comunidades rurales cercanas a su distribución. Se determinó la edad y crecimiento de esta especie. Los organismos se recolectaron mensualmente en los desembarcos de la pesca artesanal de las cooperativas de mayor contribución en la zona costera (Barra Bosque y San Pedro) y ribereña (San Pedro y Tres Brazos) entre julio 2006 y marzo 2008. La edad se determinó mediante otolitos seccionados. La edad estimada fue de 2 a 17 años. Mensualmente se estableció la formación anillos opacos y traslúcidos. Para ambas zonas de estudio agrupadas, se validó el retrocálculo por comparación de tres métodos (Fraser-Lee, Dahl-Lea y Whitney-Carlander), se encontraron diferencias significativas (ANCOVA, p<0.05) entre el promedio de la longitud observada y la longitud retrocalculada. Las constantes de la ecuación de von Bertalanffy fueron calculadas para cada sexo y combinados, se empleó el método no lineal de Levenberg-Marquardt’s. La edad estimada para el robalo blanco fue de 2 a 17 años. Se encontraron diferencias significativas en el crecimiento entre sexos (T² Hotelling, p<0.05). Los parámetros de crecimiento para ambos sexos fueron, zona costera: Barra Bosque Lf t=109.21(1-e-0.21(t+0.57)), Barra San Pedro Lf t=94.56(1-e-0.27(t+0.48)), y para la zona ribereña: San Pedro Lf t=97.15(1-e-0.17(t+1.32)) y Tres Brazos Lf t=83.77(1- e-0.26(t+0.49)). Se encontraron diferencias significativas en las curvas de crecimiento de von Bertalanffy entre las poblaciones comparadas (RSS, p<0.05).

Variación estacional de la composición proximal en tres especies de importancia comercial del Golfo de Nicoya, Puntarenas, Costa Rica / Seasonal variation of proximate composition in three commercially important species in the Gulf of Nicoya, Puntarenas, Costa Rica

Nutritional value of seafood for human consumption is worldwide recognized. Some information have been generated in other countries, nevertheless, there is limited information describing the chemical composition of some fishery important species caught in the Gulf of Nicoya. For this reason, we studied the levels of proximal components of the edible parts (fresh) of three commercially important species. The meat samples of snook Centropomus unionesis, the shrimp Trachypenaeus byrdi and the bivalve Polymesoda radiata, were collected from the Puntarenas local fish market during the fishing season of February 2009 to January 2010. Proximate composition analysis was determined according to AOAC methodology, and evaluated the moisture content, and protein and lipid composition of shellfish meats. The results indicated that the moisture content ranged from 74.6-80.6g/100g for snook 76.9-80.0g/100g for shrimp and 77.9-89.5g/100g for green mussel. After the moisture, the protein was the most abundant chemical fraction (6.8 to 21g/100g) showing the highest values in February for the shrimp and green mussel, and December for snook. The largest fluctuations in the lipid content were found in the snook, ranging from 0.7g/100g to 5.6g/100g; the highest values in this fraction were found in shrimp, green mussel and snook, for July, February and April samples respectively. Considering these results, we concluded that fish and shrimp species studied are a good alternative for human consumption as a source of protein and low lipid content.

La información disponible sobre la composición química de algunos recursos pesqueros que se capturan en el Golfo de Nicoya es muy limitada. Por tal razón se determinaron los niveles de los componentes proximales de las partes comestibles (fresco) de tres especies de importancia comercial. Las muestras fueron adquiridas en el Mercado de Puntarenas entre febrero 2009 y enero 2001 durante la temporada de pesca. Los análisis de la composición proximal se determinaron según la metodología de AOAC. Los resultados indicaron que el contenido de humedad varió entre 74.6-80.6g/100g en robalo (Centropomus unionesis), 76.9-80.0g/100g en camarón (Trachypenaeus byrdi) y 77.9-89.5g/100g en almeja verde (Poymesoda radiata). Después de la humedad la fracción química más abundante fue la proteína presentando los valores más altos en diciembre para el robalo y febrero para el camarón y la almeja verde. Las mayores fluctuaciones en el contenido de lípidos se presentaron en el robalo, variando desde 0.7g/100g hasta 5.6g/100g. Los valores más altos en esta fracción fueron encontrados en julio, febrero y abril en camarones, almeja y robalo respectivamente. Se concluye que la especie de pescado y camarón estudiados son una buena alternativa para el consumo humano por ser una fuente importante de proteínas y por su bajo contenido en lípidos.

Three new species of Monogenea (Platyhelminthes) parasites of fish in the Guandu river, southeastern Brazil / Três novas espécies de Monogenea (Platyhelminthes) parasitos de peixes do rio Guandu, Sudeste do Brasil

Current essay describes three new Monogenean species, namely, Cosmetocleithrum striatuli sp. nov., Jainus leporini sp. nov. and Rhabdosynochus guanduensis sp. nov., parasites on the gills of Trachelyopterus striatulus (Steindachner, 1877), Leporinus copelandii Steindachner, 1875 and Centropomus undecimalis (Bloch, 1792), respectively. Fish were collected from the Guandu river, State of Rio de Janeiro, Brazil between August 2005 and November 2008. Cosmetocleithrum striatuli sp. nov. differs from all other congeneric species by the shape of an accessory piece (more robust and resembling a crustacean claw or chela) and by the shape of its ventral and dorsal bars (not V -shaped and with expanded lateral ends directed to the rear). Jainus leporini sp. nov. differs from all other Jainus species by the male copulation organ (MCO), with a 2-ring coil, by the absence of medial projection on ventral bar and by a plate-like sclerotized structure associated to the vagina. Rhabdosynochus guanduensis sp. nov. differs from all other congeneric species by the morphology of the copulation complex and by a shell-shaped vagina.

Três novas espécies, Cosmetocleithrum striatuli sp. nov., Jainus leporini sp. nov. e Rhabdosynochus guanduensis sp. nov., parasitando as brânquias de Trachelyopterus striatulus (Steindachner, 1877), Leporinus copelandii Steindachner, 1875 e Centropomus undecimalis (Bloch, 1792), respectivamente, são descritas no presente trabalho. Os peixes foram coletados do rio Guandu, Estado do Rio de Janeiro, Brasil, no período de agosto de 2005 a novembro de 2008. Cosmetocleithrum striatuli sp. nov. difere de todas as outras espécies congenéricas pelo formato da pesca acessória (muito robusta e semelhante a uma quela de crustáceo) e pelo formato das barras ventral e dorsal (sem o formato de V e com as extremidades laterais expandidas e direcionadas posteriormente). Jainus leporini sp. nov. difere de todas as outras espécies do gênero pelo órgão copulatório masculino (OCM) ter duas voltas de diâmetro do anel, pela ausência de projeção medial na barra ventral e por possuir uma vagina associada a uma estrutura esclerotizada em forma de placa. Rhabdosynochus guanduensis sp. nov. difere de todas as outras espécies congenéricas pela morfologia do complexo copulatório e pela vagina em forma de concha.

Reproductive biology of common snook Centropomus undecimalis (Perciformes: Centropomidae) in two tropical habitats

In Southeastern Mexico, Centropomus undecimalis is an important fish species of sport and commercial fisheries for coastal and riverine communities. Fisheries along rivers and coasts depend on migratory habits of this species, and these movements are probably related to reproduction. In spite of its economic importance, few studies have been conducted focusing on its reproductive biology, and this research aims to analyze these habits. Samples (fork length, somatic and gonads weight, and macroscopic maturity stages) were obtained from organisms collected by fishermen from the largest fishing cooperatives along the coastal and riverine areas of Tabasco, from July 2006 to March 2008. Fish size ranged from 34 to 112cm fork length, with an average age of 6.42 years for males and 9.12 years for females. In riverine areas, fish sizes ranged from 30 to 85cm and the average age was 5.5 years for males and 6.6 years for females. Significant differences were recorded between lengths of males and females from the two areas (Kruskal-Wallis, p<0.05). The male:female ratio was 1:0.68 in the coast, and 1:0.16 in riverine areas. The length-weight relationship did not vary between both sexes among areas (ANCOVA, p>0.05). A curve for eviscerated weight was calculated for both sexes, for coastal fishes SW=0.0059(FL) 3.07, and the riverine ones SW=0.0086(FL) 2.98, with an isometric growth (b=3). The period of maximum reproduction was from July to August, with temperatures of 28 to 30°C. A significant correlation between the gonadosomatic index (GSI) and rainfall was recorded for samples of both males and females from coastal areas (r=0.63, r=0.70) whereas only one positive correlation was recorded for riverine females (r=0.57). The size at first maturity (L50) was estimated at 60cm and 80cm (FL), corresponding to 5.5 and 8.5 years of age, for males and females, respectively. An important proportion of mature females of eight years and older, suggests that these ages contribute significantly to the reproductive biomass. The results indicate that due to changes in the exploitation period, we recommend to protect populations of the common snook. Rev. Biol. Trop. 59 (2): 669-681. Epub 2011 June 01.

En este estudio, se analizó la biología reproductiva y poblacional del robalo blanco (Centropomus undecimalis). El material biológico se obtuvo en los desembarcos de la pesca artesanal de las cooperativas de mayor contribución en la zona costera y ribereña durante julio de 2006 a marzo de 2008. En la zona costera las tallas oscilaron entre 34 a 112cm (LF) y en la zona ribereña entre 30 a 85cm. Se encontraron diferencias significativas entre las longitudes de machos y hembras en ambas zonas de estudio (Kruskal-Wallis, p<0.05). La proporción machos:hembras fue 1:0.68 en la costa y 1:0.16 para la zona ribereña. La relación longitud-peso no difirió entre sexos en las dos zonas de estudio (ANCOVA, p>0.05). El periodo máximo reproductivo fue de julio a agosto. En la zona costera, se encontró una correlación significativa entre el iGS y precipitación pluvial para machos y hembras (r=0.63, r=0.70), en la zona ribereña solo se encontró un correlación positiva en las hembras (r=0.57). La talla de primera madurez (L50) se estimó a los 60cm para hembras y 80cm (LF) para machos correspondiendo a 5.5 y 8.5 años de edad respectivamente. Los resultados sugieren un cambio en el periodo de explotación para la conservación de las poblaciones del robalo blanco y su producción.

Caracterización cariotípica en mitosis y meiosis del robalo blanco Centropomus undecimalis (Pisces: Centropomidae)

Karyotypic characterization in mitosis and meiosis of the common snook Centropomus undecimalis (Pisces: Centropomidae). The common snook Centropomus undecimalis inhabits marine, brackish and freshwater habitats in the Western Central Atlantic Ocean, including the Gulf of Mexico. Common snook is an economically important fish in many localities, nevertheless the number of studies on its biology and genetics are still few. The present study attempts to establish the cytogenetic profiles of the specimens collected in Paraiso Municipality Tabasco, Mexico. Tissue of five females and eight male organisms were processed by conventional cytological techniques to obtain chromosome slides of high quality in order to assemble the karyotype. The results from the kidney tissue analysis showed that 85.1% of 288 mitosis had a 2n=48 chromosomes, and 52.8% of 104 meiosis exhibited the haploid number 1n=24. The diploid karyotype showed 48 monoarmed chromosomes of the telocentric (T) type. There was no chromosome heteromorphism between females and males. The diploid karyotype was very similar to that observed in the majority of marine fishes. Rev. Biol. Trop. 59 (2): 683-692. Epub 2011 June 01.

El robalo blanco Centropomus undecimalis, vive en hábitats marinos, salobres y dulceacuícolas en el océano Atlántico occidental, incluyendo el golfo de México. La especie, es económicamente importante en varias localidades, no obstante los estudios sobre su biología y genética son hasta el momento pocos. El presente estudio tiene como propósito, la caracterización citogenética de especímenes recolectados en el municipio de Paraíso, Tabasco, México. Cinco hembras y ocho machos fueron procesados por técnicas citológicas convencionales para la obtención de preparaciones cromosómicas de buena calidad para elaborar el cariotipo. Los resultados del análisis del tejido del riñón, mostraron que 85.1% de 288 mitosis tienen 2n=48 cromosomas y 52.8% de 104 meiosis exhiben el número haploide de 1n=24. El cariotipo diploide mostro 48 cromosomas monorrámeos de tipo telocéntrico (T). No se observó heteromorfismo cromosómico entre hembras y machos. El cariotipo diploide fue similar a los observados en la mayoría de peces marinos.

Cytogenotoxicity biomarkers in fat snook Centropomus parallelus from Cananéia and São Vicente estuaries, SP, Brazil

The aquatic environment receives many contaminants that can induce damages at the molecular, biochemical, cellular and physiological levels. Centropomus parallelus, an important food resource for local populations, is a predator fish that feeds on small fishes and benthic invertebrates, thus being vulnerable to the bioconcentration and biomagnification processes. This study aimed to evaluate cytogenotoxic responses in erythrocytes from C. parallelus juveniles collected in the Cananéia and São Vicente estuaries, both in winter and in summer. After anesthesia, blood samples were collected by caudal puncture. Blood smears were prepared on glass slides and stained with May-Grünwald-Giemsa dye. Two thousand cells were analyzed per slide (1000x), and nuclear abnormalities (NA) and micronuclei (MN) were scored. The São Vicente sample showed MN and NA frequencies (%/1000 cells) of 0.325 and 3.575, in winter, and of 0.125 and 2.935 in summer respectively; the Cananéia sample showed frequencies of 0.0325 and 0.03, in winter, and of 0.065 and 0.355 in summer, respectively. The rates found in São Vicente were significantly higher than those found in Cananéia, evidencing that the levels of pollution in that estuary were high enough to induce genetic damages.

Community ecology of metazoan parasites of the later juvenile common snook Centropomus undecimalis (Osteichthyes: Centropomidae) from the coastal zone of the state of Rio de Janeiro, Brazil

Between April and December 2000, seventy-nine specimens of Centropomus undecimalis from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23º01'S, 44º19'W), Brazil, were necropsied to study their infracommunities of metazoan parasites. Nine species of metazoan parasites were collected: 1 digenean, 1 monogenean, 1 acantocephalan, 1 nematode, 4 copepods, and 1 isopod, and 96.2% of the fishes were parasitized by one or more metazoan, with mean of 85.3 ± 122.9 parasite/fish. The digenean Acanthocollaritrema umbilicatum Travassos, Freitas & Bührnheim represented the majority of the parasites specimens collected, totaling, 94.7%. This species was the most abundant, prevalent, and dominant, showing positive correlation with the host's total body length and parasite abundance. The copepod species Acantholochus unisagittatus Tavares & Luque presented differences in abundance in relation to sex of host. The mean diversity in the infracommunities of C. undecimalis was H = 0.095 ± 0.116, with no correlation with the host's total body length but correlated with the host's sex. No pair of parasite species showed positive or negative association or covariation. The dominance of digenean A. umbilicatum in the later juvenile common snook parasite community could be related with the predatory food habits of common snook and an apparent feeding transition period which might occasion great exposure to infective forms.

Entre abril e dezembro de 2000, 79 espécimes de C. undecimalis, provenientes de Angra dos Reis, litoral do Estado do Rio de Janeiro (23º01'S, 44º19'W), Brasil, foram necropsiados para o estudo de suas infracomunidades de metazoários parasitos. Foram coletadas nove espécies de metazoários parasitos: 1 digenético, 1 monogenético, 1 acantocéfalo, 1 nematóide, 4 copépodes e 1 isópode; e 96,2% dos peixes estavam parasitados por um ou mais metazoários parasitos, com média de 85,3 ± 122,9 parasitos/peixe. O digenético Acanthocollaritrema umbilicatum Travassos, Freitas & Bührnheim foi o táxon maioritário, representando 94,7% do total de parasitos coletados. Esta espécie foi a mais abundante, prevalente e dominante, apresentando correlação positiva entre o comprimento total dos hospedeiros e a abundância parasitária. O copépode Acantholochus unisagittatus Tavares & Luque apresentou diferenças em sua abundância em relação ao sexo dos hospedeiros. A diversidade média das infracomunidades de C. undecimalis foi de H = 0,095 ± 0,116 sem correlação com o comprimento total dos hospedeiros e com diferenças em relação ao sexo dos hospedeiros. Nenhum par de espécies demonstrou associação e covariação positiva ou negativa. A dominância do digenético A. umbilicatum na comunidade parasitária dos robalos jovens pode estar relacionada ao hábito predador e ao aparente período de transição alimentar, que pode levar a uma grande exposição às formas infectantes.