Estrutura populacional e biologia reprodutiva de Parastacus defossus (Crustacea: Decapoda: Parastacidae)

Este trabalho descreve a estrutura populacional e aspectos da biologia reprodutiva de Parastacus defossus Faxon, 1898, uma espécie com hábito fossorial que passa sua vida no interior de galerias subterrâneas. Aproximadamente 30 exemplares foram coletados mensalmente, de janeiro de 2003 a agosto de 2005 na região do Lami, Município de Porto Alegre, Rio Grande do Sul, Brasil. Registrou-se o comprimento mínimo, máximo e médio da carapaça de machos, fêmeas, juvenis e animais com ootestículo. Analisou-se a distribuição de freqüência por classes de tamanho, a proporção sexual, o recrutamento e o período reprodutivo. Foram amostrados um total de 766 exemplares, 315 machos (41,12%), 278 fêmeas (36,30%), 166 juvenis (21,67%) e sete animais com ootestículo (0,91%). Machos e fêmeas estiveram presentes durante todos os meses de amostragem e em todas as classes de tamanho, sendo que a maior freqüência de indivíduos foi registrada nas classes de tamanho ente 24 a 30 mm. A maior freqüência de juvenis foi observada na primavera/2003 e verão/2005. Diferenças significativas no tamanho de machos e fêmeas foram registradas apenas nas classes de tamanho entre 26-30 mm. A proporção sexual no período amostral foi de 1:0,88 (x² = 2,3; p > 0,05) e entre as classes de tamanho foram constatadas diferenças significativas nas classes de tamanho 26-28 mm (x² = 5,43; p < 0,05) e 28-30 mm (x² = 4,77; p < 0,05) de comprimento de carapaça, nas quais os machos foram mais freqüentes. Das 278 fêmeas coletadas, apenas 17 estavam ovígeras (6,11%), sendo a estação reprodutiva bem definida na primavera.<br>This study investigates the population structure and the reproductive biology of Parastacus defossus Faxon, 1898, a fossorial species that spends its life inside subterranean tunnels. Around 30 specimens were collected each month in the region of Lami, municipality of Porto Alegre, state of Rio Grande do Sul, Brazil, from January, 2003 to August, 2005. The minimum, the maximum, and the mean carapace length of males, females, juveniles and individuals with ootestis were recorded. The frequency distribution by size classes, the sexual proportion, the recruitment, and the reproductive period were analyzed. A total of 766 specimens were collected, from which 315 were males (41.12%), 278 were females (36.30%), 166 were juveniles (21.67%), and seven individuals had ootestis (0.91%). Males and females were present in all months and in all size classes. The highest frequency of individuals matched the size classes from 24 to 30 mm. The highest frequency of juveniles was recorded during the spring of 2003 and the summer 2005. Significant differences in the size of males and females were recorded in the size classes between 26 and 30 mm. The sex ratio between all males and females was 1:0.88 (x² = 2.3, p > 0.05). The proportion between males and females showed significant differences between the size classes 26-28 mm (x² = 5.43, p < 0.05) and 28-30 mm (x² = 4.77, p < 0.05) carapace length, were the number of males was highest. Of the 278 females, only 17 were ovigerous (6.11%) and the reproductive period was clearly restricted to the spring

Biologia reprodutiva de Oligosarcus jenynsii (Günther) (Characiformes, Characidae) da Lagoa das Custódias, Tramandaí, Rio Grande do Sul, Brasil Reproductive biology of Oligosarcus jenynsii (Güntiier) (Characiformes, Characidae) from Custódias Lagoon, Tramandaí, Rio Grande do Sul, Brazil

<abstract language="eng">The Custódias lagoon has a great importance in the Tramandaí system, because it works as reproduction area, feeding and nursery grounds to several fish species. The aim of this work is the study of aspects related to the reproduction of Oligosarcus jenynsii (Günther, 1864) as such as reproductive period, sexual ratio, fecundity and size of the first gonadal maturation. The specimens were sampled monthly from October/1994 to October/1995. For each sex, maturation curves were established, based on the monthly variation of the gonadossomatic index mean values, as well as, the relative frequencies of the sexual maturity stages. Breeding seasons took place during the winter and spring. The sex ratio was significanthly different from 1:1, with more females than male in almost all month. The species had a average fecundity of 9.694 ovocytes. The estimated size of first sexual maturation was 114 mm for male and 131 mm for females

Growth curve of Atlantoscia floridana (van Name) (Crustacea, Isopoda, Philosciidae) from a Brazilian Restinga Forest

The terrestrial isopod Atlantoscia floridana (van Name, 1940) occurs from the U.S.A. (Florida) to Brazil and Argentina. In the southernmost Brazilian State, Rio Grande do Sul, the species is recorded in many localities, in urban and in non-urban areas. The growth curve of Atlantoscia floridana based on field data is presented. The specimens were sampled from April, 2000 to October, 2001 at the Reserva Biológica do Lami (RBL), Rio Grande do Sul. Captured individuals were sexed and had their cephalothorax width measured, with the data analyzed with von Bertalanffy's model. The growth curves for males and females are described, respectively, by the equations: Wt = 1.303 [1 - e-0.00941 (t + 50.37)] and Wt = 1.682 [1 - e-0.00575 (t + 59.13)]. The curves showed differential growth between sexes, where females reach a higher Wµ with a slower growth rate. Based on the growth curves it was also possible to estimate life expectancy for males and females.<br>O isópodo terrestre Atlantoscia floridana (van Name, 1940) ocorre desde os Estados Unidos (Flórida) até o Brasil e Argentina. No Rio Grande do Sul a espécie é registrada em muitas localidades, em áreas urbanas e não-urbanas. Este trabalho apresenta a curva de crescimento de Atlantoscia floridana, baseada em dados de campo. Os espécimes foram amostrados desde abril, 2000 a outubro, 2001 na Reserva Biológica do Lami (RBL), Rio Grande do Sul. Os indivíduos capturados foram sexados e tiveram o cefalotórax medido. Os dados foram analisados utilizando-se o modelo de von Bertalanffy. A curva de crescimento para machos e fêmeas são descritas, respectivamente, pelas equações Wt = 1.303 [1 - e-0.00941 (t + 50.37)] e Wt = 1.682 [1 - e -0.00575 (t + 59.13)]. As curvas mostraram crescimento diferencial entre os sexos, onde as fêmeas atingem o maior Wµ com uma taxa de crescimento menor. Com base nas curvas de crescimento também foi possível estimar a expectativa de vida para machos e fêmeas