Habitat and population data of troglobitic armored cave catfish, Ancistrus cryptophthalmus Reis, 1987, from central Brazil (Siluriformes : Loricariidae)

摘要

Population ecology of the troglobitic armored catfish, A. cryptophthalmus, from caves in Sao Domingos karst area of central Brazil, was studied in a two-census capture-mark-recapture study carried out during the dry season of 1999. Like many loricariids, including epigean Ancistrus catfishes from that area, A. cryptophthalmus is a typical bottom-dweller with a strong preference for rocky substrates in fast-flowing stream sectors. Relatively high population densities, when compared to other cavefishes, were recorded in the studied cave sections: 0.9 individuals m(-2) in Angelica Cave and 0.5 individuals m(-2) in Passa Tres Cave. Passa Tres Stream is a small tributary of the Sao Vicente Cave system, and the estimated population for Passa Tres Cave (ca. 2000 m long) is around 1000 individuals. On the other hand, the large Angelica Cave Stream (similar to8 km long) harbors a very large population, conservatively estimated at 20 000 individuals. No fish movements of distances longer than 100 m were recorded in the 40-day period. In Passa Tres Cave, a few movements of distances up to 60 m were detected. Proportion of mature females in Angelica Cave was higher than in Passa Tres Cave, possibly reflecting a greater food availability in the first cave. Mean individual growth rates in Angelica Cave (1.35 mm month(-1) for size class <41 mm SL, 0.17 mm month(-1) for size class >41 mm SL) point to relatively high longevities, possibly attaining 15 years.