Mapping the environmental strontium isotopic ratio in South America to reveal the life history of freshwater fishes

ESTEBAN AVIGLIANO; MING-TSUNG CHUNG; POUILLY, MARC; KUO-FANG HUANG; CASALINUOVO, MIGUEL; JAEL DOMININO; NATALIA SILVA; SEBASTIAN SANCHEZ; JUAN F. FACETTI; ALEJANDRA V. VOLPEDO

Viña del Mar

Simposio; 7th International Otolith Symposium; 2023

International Otolith Symposium Commite

Salminus brasiliensis is one of the largest and most important commercial and sporting fish species in South America, of which little is known about its habitat use, especially in semi-fragmented rivers. The aims of this study were to expand the water 87Sr/86Sr baseline of the La Plata Basin, and to study the migratory patterns of S. brasiliensis from Paran´a dam-free stretch and a representative tributary semi-fragmented using otolith isotopicchemistry. Water samples were collected at 10 sites on the upper Paran´a River and two sites on the middle and lower Carcara˜n´a Basin (tributary of the lower Paran´a River). Fourteen fish were caught in the upper Paran´a River and 13 in two sites of the middle and lower Carcara˜n´a Basin. 87Sr/86Sr was measured in water and otolith coreto-edge transect by MC-ICPMS and LA-MC-ICPMS, respectively. Water results were incorporated into a dataset with 53 other sampling points from the La Plata Basin and subjected to a cluster analysis, which resulted in ninedifferentiable chemical signatures. Discriminant analysis confirmed the presence of at least eight contrasting isotopic signals. Based on the otolith core 87Sr/86Sr, four individuals from the upper Paran´a River were classified as originating from Paraguay sub-basin, while the rest were assigned to Paran´a River. All fish from the Carcara˜n´asub-basin were classified as originating from the Paran´a River, except two individuals which were assigned to the Carcara˜n´a sub-basin. Results indicated that the fish run up the Carcara˜n´a sub-basin overcoming up to three open spillways, and could live there for years and even reproduce. However, the Paran´a River had the largest contribution to the fish caught in both the upper Paran´a River and the Carcara˜n´a sub-basin