Browsing by Autor "Jacques Panfili"

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Environment‐related life‐history trait variations of the red‐bellied piranha <i>Pygocentrus nattereri</i> in two river basins of the Bolivian Amazon
(Wiley, 2007) Fabrice Duponchelle; Faviany Lino; Nicolas Hubert; Jacques Panfili; Jean‐François Renno; Etienne Baras; J.P. Torrico; Remi Dugué; J. N. Rodrìguez
Life‐history traits of Pygocentrus nattereri were compared in two populations inhabiting connected tributaries of the upper Madera River: the white water Mamoré River and the clear water Iténez River. As white waters provide better trophic conditions than clear waters, the size at maturity, fecundity, reproductive effort, condition and growth of P. nattereri should be greater in the more productive white water river (Mamoré) than in the less‐productive clear water river (Iténez). Breeding periods were highly seasonal and similar in both rivers and under strong influence of photoperiod. Oocyte size‐frequency distributions, together with the frequent occurrence of recovering females indicated that an individual female spawns at least twice during the breeding season. As predicted, fish of the Mamoré were significantly larger at maturity and had higher fecundity and condition factor values than those of the Iténez. Fish from both rivers matured as yearlings. The higher growth potential of females was better expressed in the Mamoré than in the Iténez, where growth differences between sexes were weak. Females had a significantly better growth in the Mamoré than in the Iténez. The observed life‐history traits associations were consistent with the hypothesis of better trophic conditions in the Mamoré. In addition, previous genetic analyses evidenced that the colonization of the two basins is recent and that extant populations have very similar genetic backgrounds. This suggests that the observed variations in life‐history traits of P. nattereri are not related to historical factors (genetic drift) between two phylogeographically distinct lineages, but rather due to the contrasting environmental conditions in the white and clear waters.
Trans‐Amazonian natal homing in giant catfish
(Wiley, 2016) Fabrice Duponchelle; Marc Pouilly; Christophe Pécheyran; Marília Hauser; Jean‐François Renno; Jacques Panfili; Audrey M. Darnaude; Aurea Rosa GARCÍA-VÁSQUEZ; Fernando M. Carvajal‐Vallejos; Carmen Rosa GARCÍA-DÁVILA
Summary Knowledge of fish migration is a prerequisite to sustainable fisheries management and preservation, especially in large international river basins. In particular, understanding whether a migratory lifestyle is compulsory or facultative, and whether adults home to their natal geographic area is paramount to fully appraise disruptions of longitudinal connectivity resulting from damming. In the Amazon, the large migratory catfishes of the Brachyplatystoma genus are apex predators of considerable interest for fisheries. They are believed to use the entire length of the basin to perform their life cycle, with hypothesized homing behaviours. Here, we tested these hypotheses, using the emblematic B. rousseauxii as a model species. We sampled adults close to major breeding areas in the Amazon basin (upper Madeira and upper Amazonas) and assessed their lifetime movements by measuring variations in 87 Sr/ 86 Sr along transverse sections of their otoliths (ear stones) using laser ablation multicollector mass spectrometry ( LA ‐ MC ‐ ICPMS ). We demonstrate that larvae migrate downstream from the Andean piedmont to the lower Amazon, where they grow over a protracted period before migrating upstream as adults. Contrary to prevailing inferences, not all fish spend their nursery stages in the Amazon estuary. By contrast, the passage in the lower or central Amazon seems an obligate part of the life cycle. We further evidence that most adults home to their natal geographic area within the Madeira sub‐basin. Such long‐distance natal homing is exceptional in purely freshwater fishes. Synthesis and applications . By using otolith microchemistry, we were able to demonstrate a seemingly compulsory basin‐wide migratory life cycle of large Amazonian catfishes. This makes them the organisms performing the longest migrations (>8000 km) in fresh waters. This exceptional life history is already jeopardized by two dams recently built in the Madeira River, which block a major migration route and access to a substantial part of their spawning grounds. Major impacts can be anticipated from the current and forthcoming hydroelectric development in the Amazon basin, not only on the populations and fisheries of this apex predator, but also on Amazonian food webs through trophic cascades.