Rising and Spreading: First record and ecological aspects of Platanichthys platana (Regan, 1917) in a major tributary of the Upper Paraná River, Brazil

Abstract

This study presents the first record of the sardine Platanichthys platana (Regan, 1917) in the Paranapanema River basin and provides insights into the species' ecological traits. A total of 164 juveniles and adults were sampled in 2019 and 2020 in the Lower Paranapanema River. Morphological analyses confirmed species identification, while reproductive analyses revealed different age classes among individuals, with higher sex ratio of females and mature gonads. Additionally, stomach analyses indicated a diet primarily composed of insects, followed by microcrustaceans. This species has been dispersing rapidly in the Upper Paraná River, where its reproductive characteristics may help its establishment, especially in reservoirs. Also, its feeding ecology favors its survival. However, interactions with large-sized invasive predators and influx of heavy metals in the food chain can occur, in addition to competition with small-sized native species.