Assessing tropical freshwater fish diversity: altitudinal, seasonal, and circadian insights from the Sarapiquí River, Costa Rica
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| Auteurs: | , , |
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| Formaat: | artículo original |
| Status: | Versión publicada |
| Publicatiedatum: | 2026 |
| Omschrijving: | Introduction: The Sarapiquí River basin in Costa Rica, characterized by significant environmental diversity and increasing human impact, serves as a valuable location to examine the dynamics of tropical freshwater fish communities, including variations by altitude, season, and day-night cycles, with the latter being an important factor when assessing nocturnal species. Objectives: To describe the richness, abundance, and size structure of freshwater fish in the Sarapiquí River sub-basin. Methods: Ichthyofaunal surveys were conducted monthly at sites along an altitudinal gradient from 48 to 409 m a.s.l. Two capture methods were used: cast netting and electrofishing. At each site, both daytime and nighttime sampling sessions took place. Additionally, the physicochemical parameters of the water were recorded to characterize the environmental conditions at each site. Results: A total of 1,042 individuals from 16 species and 12 families were recorded. Electrofishing captured most individuals (15 species; n = 765), while cast nets yielded 12 species (n = 277). Dominant taxa were Dajaus monticola (28%), Rhamdia laticauda (26%), Tomocichla tuba (14%), and Astyanax orstedii (12%). Richness peaked in Chilamate (13 species) and was lowest in San Miguel and Cariblanco, following an altitudinal trend. Abundance was higher at night (602 vs. 440 individuals), and some species were exclusively observed during the night. CCA explained 60.3% of the species variance, highlighting temperature, conductivity, and dissolved solids as key predictors. Conclusions: This study characterized the ichthyofauna of the Sarapiquí River sub-basin between April 2013 and March 2014, assessing variations in altitude, season, and time of day. Abundant species (D. monticola, R. laticauda, T. tuba, A. orstedii) and vulnerable taxa (Hypostomus aspidolepis, Gobiomorus dormitor, Joturus pichardi) were identified, with the distribution range of G. dormitor extended up to 189 m a.s.l. Species richness and abundance decreased with altitude, although local factors such as habitat and riparian cover influenced patterns. Circadian sampling revealed nocturnal species underestimated in diurnal surveys. Temperature and conductivity were the main environmental variables associated with fish diversity. |
| Land: | Portal de Revistas UCR |
| Instelling: | Universidad de Costa Rica |
| Repositorio: | Portal de Revistas UCR |
| Taal: | Español |
| OAI Identifier: | oai:portal.revistas.ucr.ac.cr:article/11268 |
| Online toegang: | https://revistas.ucr.ac.cr/index.php/rrbt/article/view/11268 |
| Keyword: | Sarapiquí River sub-basin; freshwater fishes; seasonality; altitudinal gradient; circadian distribution. Subcuenca del río Sarapiquí; peces dulceacuícolas; estacionalidad; gradiente altitudinal; actividad circadiana. |