Resumo
The biology of Branchiura sowerbyi Beddard, 1892 has been the focus of many studies in temperate regions, where the species is exotic, according to literature data. Due to its high productivity and easy cultivation, B. sowerbyi is of great interest as a food source for fish farming. The present study reports information on the reproductive biology and growth of B. sowerbyi under laboratory conditions at 25 ± 1ºC. Weekly observations during 52 weeks indicated that the time between cocoon laying and young hatching was 14 to 16 days, the specific daily growth rate was 0.91 ± 0.04% (mean ± SD) and the time to reach sexual maturity was 40.83 ± 6.88 days. As reported by other authors, the hatching rate observed was low (33.08%), but the survival rate of young was high, approximately 96%. Laboratory observations showed that B. sowerbyi has two annual reproductive cycles, the first (between the 5th and 24th week) being more pronounced than the second (between the 31st and 51st week) concerning the number of cocoons.
Resumo
The biology of Branchiura sowerbyi Beddard, 1892 has been the focus of many studies in temperate regions, where the species is exotic, according to literature data. Due to its high productivity and easy cultivation, B. sowerbyi is of great interest as a food source for fish farming. The present study reports information on the reproductive biology and growth of B. sowerbyi under laboratory conditions at 25 ± 1ºC. Weekly observations during 52 weeks indicated that the time between cocoon laying and young hatching was 14 to 16 days, the specific daily growth rate was 0.91 ± 0.04% (mean ± SD) and the time to reach sexual maturity was 40.83 ± 6.88 days. As reported by other authors, the hatching rate observed was low (33.08%), but the survival rate of young was high, approximately 96%. Laboratory observations showed that B. sowerbyi has two annual reproductive cycles, the first (between the 5th and 24th week) being more pronounced than the second (between the 31st and 51st week) concerning the number of cocoons.
Resumo
The biology of Branchiura sowerbyi Beddard, 1892 has been the focus of many studies in temperate regions, where the species is exotic, according to literature data. Due to its high productivity and easy cultivation, B. sowerbyi is of great interest as a food source for fish farming. The present study reports information on the reproductive biology and growth of B. sowerbyi under laboratory conditions at 25 ± 1ºC. Weekly observations during 52 weeks indicated that the time between cocoon laying and young hatching was 14 to 16 days, the specific daily growth rate was 0.91 ± 0.04% (mean ± SD) and the time to reach sexual maturity was 40.83 ± 6.88 days. As reported by other authors, the hatching rate observed was low (33.08%), but the survival rate of young was high, approximately 96%. Laboratory observations showed that B. sowerbyi has two annual reproductive cycles, the first (between the 5th and 24th week) being more pronounced than the second (between the 31st and 51st week) concerning the number of cocoons.
Resumo
The tubificid worm Limnodrilus hoffmeisteri Claparede, 1862 is widely used as an indicator of organic pollution in aquatic environments. Nevertheless, little is known about its biology. The present work aimed to compare the reproductive rate of L. hoffmeisteri raised at three different temperatures (15, 20 and 25°C). Seventy-five adult individuals were kept in fifteen 250 ml beakers (five individuals per beaker) containing sand and dechlorinated tap-water each. Beakers were arranged so as to form three groups of five. Each group was kept in a given temperature for 21 days. Results show that worms raised at 25°C produced a significantly larger number of eggs compared to those raised either at 15 or 20°C, as observed in the tropical tubificid Branchiura sowerbyi Beddard, 1892.
Resumo
The tubificid worm Limnodrilus hoffmeisteri Claparede, 1862 is widely used as an indicator of organic pollution in aquatic environments. Nevertheless, little is known about its biology. The present work aimed to compare the reproductive rate of L. hoffmeisteri raised at three different temperatures (15, 20 and 25°C). Seventy-five adult individuals were kept in fifteen 250 ml beakers (five individuals per beaker) containing sand and dechlorinated tap-water each. Beakers were arranged so as to form three groups of five. Each group was kept in a given temperature for 21 days. Results show that worms raised at 25°C produced a significantly larger number of eggs compared to those raised either at 15 or 20°C, as observed in the tropical tubificid Branchiura sowerbyi Beddard, 1892.
Resumo
The tubificid worm Limnodrilus hoffmeisteri Claparede, 1862 is widely used as an indicator of organic pollution in aquatic environments. Nevertheless, little is known about its biology. The present work aimed to compare the reproductive rate of L. hoffmeisteri raised at three different temperatures (15, 20 and 25°C). Seventy-five adult individuals were kept in fifteen 250 ml beakers (five individuals per beaker) containing sand and dechlorinated tap-water each. Beakers were arranged so as to form three groups of five. Each group was kept in a given temperature for 21 days. Results show that worms raised at 25°C produced a significantly larger number of eggs compared to those raised either at 15 or 20°C, as observed in the tropical tubificid Branchiura sowerbyi Beddard, 1892.