Subterranean Fishes of the World

7051

2025

19th International Congress of Speleology and 38o Congresso Brasileiro de Espeleologia - Belo Horizonte 2025 - Vol. VII

The population ecology of Rhamdia enfurnada, moderately specialized troglobitic catfish endemic to Gruna do Enfurnado, Serra do Ramalho karst area, was studied using mark-recapture techniques, along three annual cycles. Individual marks were achieved with subcutaneous tags. Population size in the studied area was estimated in ca. 2,500 individuals ≥ 50 mm SL, and average population density in 0.27 ind.m-2. R. enfurnada is moderately philopatric, similarly to Trichomycterus itacarambiesis and less than Pimelodella kronei. Monthly individual growth rates were highly variable, in average much lower during dry seasons, with several instances of negative values. Higher growth rates were observed between years, including at least one rainy season, when large amounts of nutrients are introduced in the cave by floods. Therefore, growth in pulses, as suggested for other troglobitic species based on data from dry seasons, is confirmed by this long-term study. Larger individuals tend to grow less than the smaller ones during dry seasons, but grow faster in rainy seasons. This indicates that large fish are more sensitive to food shortage, but perform better when food is abundant. R. enfurnada reaches the highest sizes among the studied troglobitic catfishes (standard length up to 240 mm). Based on average growth rates, longevities may reach 15-20 years. Population dynamics of R. enfurnada is greatly influenced by the high seasonality in Serra do Ramalho karst area.

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