Resource use by the facultative lepidophage Roeboides affinis (Günther, 1868): a comparison of size classes, seasons and environment types related to impoundment

We report the consumption of scales and other food resources by the facultative lepidophage Roeboides affinis in the upper Tocantins River where it was impounded by the Serra da Mesa Hydroelectric Dam. We compared the diet among size classes, between dry and wet seasons, and between sites with distinct water flow characteristics (lotic vs. lentic) related to the distance from the dam and phase of reservoir development. As transparency and fish abundance increased after impoundment, we expected a higher consumption of scales in lentic sites. Likewise, habitat contraction, higher transparency and decrease in terrestrial resources availability, would promote a higher consumption of scales. Scales were consumed by 92% of individuals and represented 26% of the total volume of resources ingested by R. affinis. Diet composition varied significantly among size classes, with larger individuals consuming more scales and larger items, especially odonatans and ephemeropterans. Scale consumption was not significantly different between dry and wet seasons. Roeboides affinis incorporated some food items into the diet as a response to the impoundment, like other species. Scale consumption was higher in lotic sites, refuting our initial hypothesis, what suggests that the lepidophagous habit is related the rheophilic nature of R. affinis. .(AU)

Caracterizamos o consumo de escamas e outros recursos alimentares por Roeboides affinis, um lepidófago facultativo, no alto rio Tocantins, na região represada pela Usina Hidrelétrica de Serra da Mesa. A dieta foi avaliada em relação a classes de tamanho, estações chuvosa e seca, e entre locais com características distintas de fluxo d'água (lótico vs. lêntico) relacionadas com a distância da barragem e fase de desenvolvimento do reservatório. Com o aumento da abundância de peixes e da transparência da água após o represamento, esperamos um maior consumo de escamas nos locais lênticos. Da mesma forma, na época seca, o habitat menor e mais transparente, além da redução da disponibilidade de itens terrestres, levaria a um maior consumo de escamas. Escamas foram consumidas por 92% dos indivíduos e representaram 26% do volume total de itens ingeridos por R. affinis. A composição da dieta variou significativamente entre classes de tamanho, com indivíduos maiores consumindo mais escamas e itens de maior porte, especialmente odonatas e efemerópteros. Não houve diferença no consumo de escamas entre as estações seca e chuvosa. Roeboides affinis incorporou itens à sua dieta como resposta ao represamento, a exemplo de outras espécies na bacia do alto rio Tocantins. O consumo de escamas foi maior nas localidades lóticas, contrariando a hipótese inicial e sugerindo que o hábito lepidofágico está ligado à natureza reofílica de R. affinis.(AU)

Feeding habits, microhabitat use, and daily activity of Cycloramphus brasiliensis (Anura: Cycloramphidae) from the Atlantic Rainforest, Brazil

We analyzed the feeding habits, microhabitat use, and daily activity period of the anuran species Cycloramphus brasiliensis (Steindachner, 1864), endemic to the Atlantic Rainforest biome. The only previous studies on this species focused on the systematics and new altitudinal records. This study was conducted in a large forest remnant located in the municipalities of Guapimirim and Cachoeiras de Macacu. We captured frogs through visual encounter surveys and recorded the frequency of microhabitat types used by them, and the time of capture. Diet was analyzed in terms of number, volume and frequency of occurrence of items. Individuals of C. brasiliensis occurred in association with fast-moving rocky portions of clear freshwater rivers, indicating a rheophilic habit, and were active mainly at night. Such as most anuran species, the diet of Cycloramphus brasiliensis was mainly based on arthropods, and included Blattodea, Formicidae, and Coleoptera as most important prey items.

Feeding habits, microhabitat use, and daily activity of Cycloramphus brasiliensis (Anura: Cycloramphidae) from the Atlantic Rainforest, Brazil

We analyzed the feeding habits, microhabitat use, and daily activity period of the anuran species Cycloramphus brasiliensis (Steindachner, 1864), endemic to the Atlantic Rainforest biome. The only previous studies on this species focused on the systematics and new altitudinal records. This study was conducted in a large forest remnant located in the municipalities of Guapimirim and Cachoeiras de Macacu. We captured frogs through visual encounter surveys and recorded the frequency of microhabitat types used by them, and the time of capture. Diet was analyzed in terms of number, volume and frequency of occurrence of items. Individuals of C. brasiliensis occurred in association with fast-moving rocky portions of clear freshwater rivers, indicating a rheophilic habit, and were active mainly at night. Such as most anuran species, the diet of Cycloramphus brasiliensis was mainly based on arthropods, and included Blattodea, Formicidae, and Coleoptera as most important prey items.

Feeding habits, microhabitat use, and daily activity of Cycloramphus brasiliensis (Anura: Cycloramphidae) from the Atlantic Rainforest, Brazil

We analyzed the feeding habits, microhabitat use, and daily activity period of the anuran species Cycloramphus brasiliensis (Steindachner, 1864), endemic to the Atlantic Rainforest biome. The only previous studies on this species focused on the systematics and new altitudinal records. This study was conducted in a large forest remnant located in the municipalities of Guapimirim and Cachoeiras de Macacu. We captured frogs through visual encounter surveys and recorded the frequency of microhabitat types used by them, and the time of capture. Diet was analyzed in terms of number, volume and frequency of occurrence of items. Individuals of C. brasiliensis occurred in association with fast-moving rocky portions of clear freshwater rivers, indicating a rheophilic habit, and were active mainly at night. Such as most anuran species, the diet of Cycloramphus brasiliensis was mainly based on arthropods, and included Blattodea, Formicidae, and Coleoptera as most important prey items.