Environmental influence on the reproductive strategy of Helogenes marmoratus (Siluriformes: Cetopsidae) in the Amazonian streams
ABSTRACT The reproductive strategy of a species must be adjusted to variations in environmental conditions to guarantee population balance. Hydrological fluctuations in Amazonian streams of terra firme (non-flooded) are controlled primarily by local rainfall. Fish assemblages are composed predominan...
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| Published in: | Neotropical Ichthyology Vol. 19; no. 4 |
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| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Sociedade Brasileira de Ictiologia
01-01-2021
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | ABSTRACT The reproductive strategy of a species must be adjusted to variations in environmental conditions to guarantee population balance. Hydrological fluctuations in Amazonian streams of terra firme (non-flooded) are controlled primarily by local rainfall. Fish assemblages are composed predominantly of species of small size. We investigated the reproductive strategy of the cryptic catfish Helogenes marmoratus and assessed the influence of environmental variables (e.g., rainfall, conductivity, habitat descriptors) on its reproductive activity in a catchment of the Guamá River in the eastern Brazilian Amazon. Through monthly collections between March 2019 and March 2020, we identified an extended reproductive period between July 2019 and March 2020. Males mature at smaller sizes than females (♂ = 27.41 mm; ♀ = 31.36 mm). We confirmed batch spawning, low fecundity (59.55 ± 22.76 stage IV oocytes), and large oocytes (1.24 ± 0.15 mm). Our results indicated that H. marmoratus strategy occupies an intermediate place between opportunistic and equilibrium gradient. Multiple regressions showed that thalweg depth, electrical conductivity, leaf litter, and rainfall are important drivers of reproductive activity of females of H. marmoratus, explaining 32% of the variation of the GSI. Our study provides evidence of differentiated reproductive response between the sexes to environmental variables.
RESUMEN La estrategia reproductiva de una especie debe ajustarse a las variaciones de las condiciones ambientales para garantizar el equilibrio poblacional. En los riachos amazónicos de tierra firme las fluctuaciones hidrológicas están controladas principalmente por las lluvias locales, predominando especies de peces de pequeño porte. Investigamos la estrategia reproductiva de Helogenes marmoratus y la influencia de variables ambientales (e.g., lluvia, conductividad, descriptores del hábitat) en su actividad reproductiva. Colectamos mensualmente entre marzo de 2019 y marzo de 2020 en una microcuenca del río Guamá, en la Amazonia oriental brasileña. Identificamos un período reproductivo prolongado entre julio de 2019 y marzo de 2020. Los machos comienzan a reproducirse con un menor tamaño (♂ = 27.41; ♀ = 31.36 mm). Confirmamos desove parcial, baja fecundidad (59.55 ± 22.76 ovócitos) y ovócitos grandes (1.24 ± 0.15 mm). La estrategia reproductiva de H. marmoratus ocupa un lugar intermedio entre el gradiente oportunista y de equilibrio. Regresiones múltiples destacan la importancia de la profundidad, la conductividad eléctrica, los bancos de hojas y la lluvia como reguladores de la actividad reproductiva de las hembras, explicando 32% de la variación del IGS. Nuestro estudio proporciona evidencia de una respuesta reproductiva diferenciada entre los sexos a las variables ambientales. |
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| ISSN: | 1679-6225 1982-0224 |
| DOI: | 10.1590/1982-0224-2021-0092 |