Potential Effects of Dams in the Geographic Range Expansion of Hylid Frogs Associated with Aquatic Macrophytes

PABLO J. TORRES; JUAN M. BOERIS; JUAN A. INSAURRALDE; DIEGO BALDO; ANDRÉS E. BRUNET

Herpetological Conservation and Biology

Herpetological Conservation and Biology

Año: 2021 vol. 16 p. 259 - 270

1931-7603

The Fluorescent Frog (Boana punctata) and the Uruguay Harlequin Frog (Lysapsus limellum) are twohylid species found in seasonal swamps and along large rivers in South America. Despite their wide distribution inthe Amazon and Paraná River basins, they had never been recorded along the margins of the more than 340 km ofthe Paraná River in the provinces of Misiones, Itapúa, and Alto Paraná in Argentina and Paraguay. Comparisonsof historical and recent satellite images and analyses of the Paraná River structure indicate that the lake formedafter the construction of the Yacyretá Dam (140,000-160,000 ha), which has made novel lentic and semi-lenticenvironments in the tributary streams identified as large inlets, bays, and lagoons. These transformations favoredpermanent settlement of aquatic macrophytes, mainly Water Hyacinth (Eichhornia crassipes) and floating ferns(Salvinia sp.), which are the characteristic habitat of L. limellum and B. punctata. Because of these changes, weconducted surveys by boat and from shore to determine whether these frog species colonized the novel environments.We found L. limellum and B. punctata at several localities on the margins of Paraná River within the boundariesof the Yacyretá Lake. Because all observations of both species were at sites with abundant macrophytes, andbecause neither of them were found in field surveys we conducted before 2011 (i.e., when the Yacyretá Lake filledto maximum capacity), our results support the hypothesis that the new records are related to the artificial wetlandscreated after the construction of the Yacyretá Dam.