Abstract
A study on population structure of Aegla schmitti Hobbs III, 1979 was carried out at Mananciais da Serra, in the municipality of Piraquara, state of Parana, Brazil (25o29'S, 48o58'W). The following aspects were treated: temporal fluctuation in abundance, sex ratio, reproductive period and size composition based on carapace length. The animals were colleted with traps, nets, measured and returned to the reservoirs. This population was sampled monthly, in two reservoirs (Carvalho and Carvalhinho) constructed in the headwater streams with swift current and steep gradient, located on west side of Serra do Mar mountains, from November, 2004 to January, 2006. The water temperature varied from 11.0 (July, 2005) to 18.2oC (March, 2007), dissolved oxygen from 7.0 to 9.5 mg/l and pH from 4.8 to 6.7, during collection period. A total of 1230 individuals were collected, among which, 819 were males and 411 females (30 ovigerous). The abundance varied from 23 (December, 2004) to 122 (June, 2005) crabs and the sex ratio of the whole population was 1:0.5 (M:F). Male carapace length varied from 4.38 to 36.46 mm and female, from 4.28 to 32.56 mm. Ovigerous females occurred from April, 2005 to November, 2005. Higher crab abundance was recorded in the Carvalho Reservoir, which explained by the presence of numerous breaches on the old tank walls that acted as shelters for these animals. Aegla schmitti females incubate egg mass during colder months and its juveniles hatch mainly in spring, as most Aegla Leach, 1820 species occurring in southeastern and southern Brazil.
Highlights
2004) to 122 (June, 2005) crabs and the sex ratio of the whole population was 1:0.5 (M:F)
Higher crab abundance was recorded in the Carvalho Reservoir, which explained by the presence of numerous breaches on the old tank walls that acted as shelters for these animals
Aegla spp. são habitantes de arroios, riachos, rios, lagos e cavernas e são encontrados em profundidades variadas, desde águas rasas de riachos até 320 m de profundidade em lagos chilenos e, em altitudes de até 4500 m acima do nível do mar, em rios da Cordilheira dos Andes (BOND-BUCKUP 2003)
Summary
O trabalho foi desenvolvido nos Mananciais da Serra (25°29’S, 48°58’W) que estão localizados no município de Piraquara, região metropolitana de Curitiba, distando cerca de km da capital. A temperatura média mensal do ar variou de 13,3oC (julho/2005) a 21,3oC (janeiro/2006), e a precipitação de 46,2 mm (dezembro/2005) a 210,0 mm (setembro/2005) na região dos Manancias da Serra (SIMEPAR 2006). O Reservatório Carvalhinho possui apenas uma barragem de concreto como forma de retenção de água, com profundidade de dois metros e capacidade de aproximadamente 200 m3. Espécimens de A. schmitti foram coletados mensalmente, nos dois reservatórios descritos acima, no período de novembro/2004 a janeiro/2006, totalizando 15 coletas. Redes do tipo “hand net” com 2 mm de abertura de malha foram utilizadas para capturar os poucos animais que escalavam as paredes dos tanques. As coletas dos meses de novembro, dezembro/2004 e janeiro/2005 não foram incluídas nessa análise para que o período compreendesse um ano. Estrutura populacional de Aegla schmitti nos reservatórios dos Mananciais da Serra
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