Population structure of Aegla schmitti (Crustacea: Anomura: Aeglidae) in the reservoirs of Mananciais da Serra, Piraquara city, state of Parana, Brazil

A study on population structure of Aegla schmitti Hobbs 111, 1979 was carried out at Mananciais da Serra, in the municipality of Piraquara, state of Parana, Brazil (25 degrees 29'S, 48 degrees 58'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 head-water 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 18.2 degrees C (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.