Estrutura e persistência temporal da comunidade de peixes de três riachos do Alto Rio Tocantins, GO

Miranda, Jean Carlos; Mazzoni, Rosana

doi:10.1590/s1676-06032009000400008

Cited by 2 publications

(3 citation statements)

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“…We confirmed its numerical rarity because only 81 individuals were captured over a decade of field sampling. Other studies have also reported low abundance of M. paucisquamatus within fish assemblages (Marques et al, 2009;Miranda & Mazzoni, 2009;Claro-Garcia & Shibatta, 2013). Moreover, we also observed spatial rarity considering that the species occurred in 13 out of 35 sites, and most captures occurred in some specific sites, probably linked to the distribution of preferential habitats.…”

Section: Discussionmentioning

confidence: 89%

“…This variation is probably associated with seasonal movements between the main channel (Tocantins and Paranã rivers) and smaller tributaries. The rainfall regime has well-defined wet and dry seasons in this watershed (Ribeiro et al, 1995;Miranda & Mazzoni, 2009;Mérona et al, 2010). During dry months, water flow is significantly reduced in some tributaries and fish may find refuge at lower reaches, e.g., the main channel and river confluences.…”

Section: Discussionmentioning

confidence: 95%

“…One such species is Mylesinus paucisquamatus Jégu & Santos, 1988, a small endemic fish from the rio Tocantins basin, usually found in riverine habitats such as rapids, waterfalls and streams (Jégu & Santos, 1988;Santos et al, 2004). Some studies suggest that it is rare in terms of abundance and spatial occurrence (e.g., Marques et al, 2009;Miranda & Mazzoni, 2009;Claro-Garcia & Shibatta, 2013), currently listed as endangered (category "vulnerable") in the Brazilian official list of endangered species (Ministério do Meio Ambiente, Portaria n° 445, 2014). Although not evaluated by IUCN, the conservation status of this species is matter of great concern, because the construction of dams along the Tocantins caused extensive habitat losses and degradation (Araújo et al, 2013;Medeiros et al, 2014); populations may have been extirpated from some river sections.…”

Section: Introductionmentioning

confidence: 99%

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Ecology of Mylesinus paucisquamatus Jégu & Santos, 1988, an endangered fish species from the rio Tocantins basin

2016

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Mylesinus paucisquamatus is a threatened fish endemic to the rio Tocantins basin, with little information about its natural history. Using monitoring data obtained between 1998 and 2009, we investigated the spatial distribution, feeding and reproduction of this species in a long stretch of the middle-upper rio Tocantins. Eighty-one individuals were captured over a decade of intensive sampling. In addition, we recorded the species in only 13 out of 35 sites, particularly in the Tocantins and Paranã rivers. Most individuals were captured alone, while the remaining formed small groups. These results indicate that this fish is rheophilic and rare. We recorded seasonal variation in fish abundance, with higher values during the dry season, indicating seasonal movements. The species is herbivorous and specialized in the consumption of plants attached to substrates, particularly bryophytes. We also observed seasonality in reproduction, since reproductive activity increased during the early dry season. These ecological traits, e.g., rarity, rheophilic and specialized feeding habits, indicates that M. paucisquamatus is vulnerable to environmental changes, particularly river damming. Considering that three large dams currently regulate and fragment this section of the rio Tocantins, the persistence of this species is jeopardized, demanding effective conservation actions.Mylesinus paucisquamatus é um peixe endêmico da bacia do rio Tocantins, ameaçado de extinção mas com escassa informação sobre sua história natural. Usando dados de monitamentos obtidos entre 1998 e 2009, investigamos a distribuição espacial, ecologia alimentar e reprodução desta espécie em um longo trecho do médio-alto rio Tocantins. Um total de 81 indivíduos foi capturado em mais de uma década de monitoramento. Além disso, a espécie ocorreu em apenas 13 dos 35 locais monitorados, principalmente nos canais dos rios Tocantins e Paranã. A maior parte dos indivíduos foi capturado sozinho, enquanto que os demais foram capturados em pequenos grupos (dois a cinco indivíduos). Tais resultados indicam que a espécie é reofílica e rara. Registramos variação sazonal de abundância, com valores mais elevados durante a estiagem, o que indica deslocamentos sazonais. A espécie é herbívora e especializada no consumo de plantas ancoradas em substratos, particularmente briófitas. A reprodução foi também sazonal, com aumento da atividade durante o início da estação de estiagem. Essas características ecológicas, e.g., raridade, hábito reofílico e hábito alimentar especializado, indica que M. paucisquamatus é vulnerável a mudanças ambientais, particularmente o barramento de rios. Considerando que atualmente três grandes barragens regulam e fragmentam esse trecho do rio Tocantins, a persistência da espécie encontra-se severamente ameaçada, demandando ações de conservação efetivas.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 95%