Reproductive Ecology of Prochilodus brevis an Endemic Fish from the Semiarid Region of Brazil

The commercially important migratory fish Prochilodus brevis is from the Neotropical region, and understanding the reproductive ecology of this potamodromous fish is essential for its conservation and management. This study investigated the length-mass relationship, sex ratio, length at first gonadal maturity, gonadal development stages, gonadosomatic index, condition factor, and reproductive period of P. brevis. Temporal distribution of rainfall, temperature, dissolved oxygen concentration, pH, and electrical conductivity of the water were related to the reproductive period of this fish. Rainfall seems to be the main environmental factor which modulates changes in limnological parameters and the timing of the spawning period of this fish. P. brevis migrates into lower reaches of the river to feed during the dry season and returns to the upper reaches during the rainy season to spawn. Inadequate facilities for migration create obstacles for spawning success of this ecologically important fish

Macroinvertebrates responses based on chemical and physical variables in urban streams

The Land uses and occupations around small watersheds generate negative impacts such as deterioration of water quality, environmental simplification, reduced availability of habitats for species, and loss of biodiversity. Benthic macroinvertebrates are an important aquatic community and are widely used in environmental monitoring actions in aquatic ecosystems, including urban streams, which are still little studied in Brazil. In our study, an urban headwater basin (Monjolinho River Basin) was studied on the benthic community structure, together with the physical and chemical variables of the water, as an environmental monitoring tool calculated by RHDEP, TSI, BMWP indexes and abundance-biomass curves. The results showed a gradient of environmental quality, where the best environments are a consequence of preserving the vegetation cover. These environments (Espraiado and Canchim) present groups sensitive to environmental degradation (Ephemeroptera, Plecoptera and Trichoptera), greater diversity and a better structure in the respective benthic macroinvertebrate assemblages. Among the streams sampled, one is very clean, four are moderately polluted, and one is severely polluted. Thus, considering that these streams’ waters are essential for public supply, actions to clean up and recover degraded environments are urgent and a priority

Desenvolvimento Gonadal de machos e fêmeas de Pseudotothyris obtusa (Ribeiro,1911) (Loricariidae, Hypoptopomatinae)

Escalas de desenvolvimento gonadal de peixes são fundamentais para compreensão da biologia reprodutiva das espécies. No entanto, pouco foi estudado para as espécies de pequeno porte. Assim, elaboramos escalas de desenvolvimento gonadal para machos e fêmeas do cascudinho Pseudotothyris obtusa, baseadas em características macroscópicas e microscópicas. Foram registrados 7 estádios de desenvolvimento nos testículos e nos ovários. Os testículos de P. obtusa são alongados, em forma de fita, com as bordas irregulares e ondulados em vista lateral; variaram de incolores a brancos, e de 5% a 30% de ocupação na cavidade abdominal. Os ovários são saciformes, incolores nos estádios iniciais e amarelos nos estádios finais e a ocupação variou de 5% a 90% da cavidade abdominal. Os ovócitos maduros de P. obtusa são de grande tamanho, atingindo 2068,2 mm. O padrão geral de desenvolvimento das gônadas é semelhante ao de outros loricarídeos. A ocorrência dos estádios semi-desovado e semi-esgotado, e o tipo de desenvolvimento ovocitário sugerem que ocorra desova parcelada para a espécie estudada. ABSTRACT The study of gonadal development in fishes is important to understand the reproductive biology of species, however there just a few works with small fish. Then, males and females gonadal development scales were described for P. obtusa, based on macroscopic and microscopic features. Seven stages of development were registered in each sex. The testes of P. obtusa are elongated, ribbonlike, with irregular borders and wavy shape in a lateral view. They vary from colourless to white, and between 5% to 30% of body cavity occupation. The ovaries are sac-like and vary from colourless in the early stages to yellow in the last ones. The occupation varies between 5% to 90% of abdominal cavity. The ripe oocytes of P. obtusa have big size. The general pattern of gonadal development is similar to other loricariids. The occurrence of partial spent stages and the oocyte development type, suggest that P. obtusa presents partial spawn. RÉSUMÉ Les échelles de maturation gonadique des poissons sont fondamentales pour la compréhension de la biologie reproductive des espèces. Cependant, on en connait peu concernant les espèces de petite taille. Des échelles de maturation gonadique des duex sexes du cascudinho Pseudotothyris obtusa ont été établies. Elles sont fondées sur des observations et des caractéristiques macro et microscopiques. On a reconnu sept stades de maturation dans les deux glandes sexuelles. Les testicules de P. obtusa sont allongés; la couleur varie du translucide au blanc, et le volume relatif occupe 5% à 90% de la cavité abdominale. Les ovocytes mûrs de P. obtusa sont de grande taille. Le développement des gonades ressemble à celui dautres Loricariidae. La fréquence des stades mi-ponte et mi-mûrs, ainsi que le mode de développement ovocytaire, suggèrent que la ponte est fractionée

Induced reproduction and reproductive characteristics of Rhinelepis aspera Agassiz, 1829 (osteichthyes: Siluriformes, Loricariidae)

Rhinelepis aspera is the largest Loricariidae species found in the São Francisco river basin where it is now rarely caught. Brooders kept in tanks were hypophysed with crude carp pituitary extract (CCPE). Approximately 82% of the females responded positive to the treatment. The egg was opaque, demersal, round, yellow and adhesive. Egg stripping was done at 212 hour-degrees (= 8.2 h) after application of the second dose of CCPE (water temperature = 25-26 ºC). Hatching of the larvae occurred at 1022 hour-degrees (= 42.2 h), after fertilization of the eggs (water temperature =24-25 ºC). Fertilization rate of the eggs was 72%. Absolute fecundity (AF), initial fertility (IF) and final fertility (FF) in relation to the females' body weight are expressed, respectively, by the equations: AF = - 33993 + 122308 Wt (r² = 0.88), IF = - 14823 + 58619 Wt (r² = 0.71) and FF = - 6553 + 29741 (r² = 0.61

Seasonal Variation in the Abundance of Seabirds in Areas of Mariculture

Mariculture has emerged as a complementary income for small fishermen along the coast of the state of Santa Catarina, Brazil, causing significant alterations in the coastal landscape and creating a new substratum seabirds. From March 1998 to February 1999, 48 censuses were carried out at four sample times, registering an average annual occurrence of 4448.7 birds, distributed among five seabird species. Laridae dominated in diversity and abundance, contributing with 98.1% of the birds recorded. The number of birds per float varied depending on the time of day and season of the year, showing an average of 2.09/1. Seabirds use the mariculture area as a place to rest, to clean their feathers and to overnight

Seasonal Variation in the Abundance of Seabirds in Areas of Mariculture

Mariculture has emerged as a complementary income for small fishermen along the coast of the state of Santa Catarina, Brazil, causing significant alterations in the coastal landscape and creating a new substratum seabirds. From March 1998 to February 1999, 48 censuses were carried out at four sample times, registering an average annual occurrence of 4448.7 birds, distributed among five seabird species. Laridae dominated in diversity and abundance, contributing with 98.1% of the birds recorded. The number of birds per float varied depending on the time of day and season of the year, showing an average of 2.09/1. Seabirds use the mariculture area as a place to rest, to clean their feathers and to overnight

Desenvolvimento Gonadal de machos e fêmeas de Pseudotothyris obtusa (Ribeiro,1911) (Loricariidae, Hypoptopomatinae)

Escalas de desenvolvimento gonadal de peixes são fundamentais para compreensão da biologia reprodutiva das espécies. No entanto, pouco foi estudado para as espécies de pequeno porte. Assim, elaboramos escalas de desenvolvimento gonadal para machos e fêmeas do cascudinho Pseudotothyris obtusa, baseadas em características macroscópicas e microscópicas. Foram registrados 7 estádios de desenvolvimento nos testículos e nos ovários. Os testículos de P. obtusa são alongados, em forma de fita, com as bordas irregulares e ondulados em vista lateral; variaram de incolores a brancos, e de 5% a 30% de ocupação na cavidade abdominal. Os ovários são saciformes, incolores nos estádios iniciais e amarelos nos estádios finais e a ocupação variou de 5% a 90% da cavidade abdominal. Os ovócitos maduros de P. obtusa são de grande tamanho, atingindo 2068,2 mm. O padrão geral de desenvolvimento das gônadas é semelhante ao de outros loricarídeos. A ocorrência dos estádios semi-desovado e semi-esgotado, e o tipo de desenvolvimento ovocitário sugerem que ocorra desova parcelada para a espécie estudada. ABSTRACT The study of gonadal development in fishes is important to understand the reproductive biology of species, however there just a few works with small fish. Then, males and females gonadal development scales were described for P. obtusa, based on macroscopic and microscopic features. Seven stages of development were registered in each sex. The testes of P. obtusa are elongated, ribbonlike, with irregular borders and wavy shape in a lateral view. They vary from colourless to white, and between 5% to 30% of body cavity occupation. The ovaries are sac-like and vary from colourless in the early stages to yellow in the last ones. The occupation varies between 5% to 90% of abdominal cavity. The ripe oocytes of P. obtusa have big size. The general pattern of gonadal development is similar to other loricariids. The occurrence of partial spent stages and the oocyte development type, suggest that P. obtusa presents partial spawn. RÉSUMÉ Les échelles de maturation gonadique des poissons sont fondamentales pour la compréhension de la biologie reproductive des espèces. Cependant, on en connait peu concernant les espèces de petite taille. Des échelles de maturation gonadique des duex sexes du cascudinho Pseudotothyris obtusa ont été établies. Elles sont fondées sur des observations et des caractéristiques macro et microscopiques. On a reconnu sept stades de maturation dans les deux glandes sexuelles. Les testicules de P. obtusa sont allongés; la couleur varie du translucide au blanc, et le volume relatif occupe 5% à 90% de la cavité abdominale. Les ovocytes mûrs de P. obtusa sont de grande taille. Le développement des gonades ressemble à celui dautres Loricariidae. La fréquence des stades mi-ponte et mi-mûrs, ainsi que le mode de développement ovocytaire, suggèrent que la ponte est fractionée