Andmebaasi logo

Sirvi Autor "Tambets, Meelis" järgi

Nüüd näidatakse 1 - 2 2
  • Pisipilt
    Kirje
    Migrating silver eels return from the sea to the river of origin after a false start
    (The Royal Society, 2021) Tambets, Meelis; Kärgenberg, Einar; Järvalt, Ain; Økland, Finn; Kristensen, Martin Lykke; Koed, Anders; Bernotas, Priit; Chair of Hydrobiology and Fishery
    The European eel’s singular spawning migration from European waters towards the Sargasso Sea remains elusive, including the early phase of migration at sea. During spawning migration, the movement of freshwater resident eels from river to sea has been thought to be irreversible. We report the first recorded incidents of eels returning to the river of origin after spending up to a year in the marine environment. After migrating to the Baltic Sea, 21% of the silver eels, tagged with acoustic transmitters, returned to the Narva River. Half returned 11–12 months after moving to the sea, with 15 km being the long- est upstream movement. The returned eels spent up to 33 days in the river and migrated to the sea again. The fastest specimen migrated to the outlet of the Baltic Sea in 68 days after the second start—roughly 1300 km. The surprising occurrence of returning migrants has implications for sustainable management and protection of this critically endangered species.
  • Pisipilt
    Kirje
    Niche partitioning of invasive Amur sleeper (Perccottus glenii) amongst native fish communities in three different freshwater ecosystems
    (Pensoft Publishers, 2024) Ercoli, Fabio; Kiljunen, Mikko; Teesalu, Paul; Tuvikene, Arvo; Tambets, Meelis; Kärgenberg, Einar; Nõges, Tiina
    The invasive fish, Amur sleeper, poses a significant and growing threat to Central European freshwater ecosystems. Despite its rapid spread, the ecological implications of its invasion have been poorly explored. Recent findings confirm its presence in various Estonian freshwater systems, raising concerns about its imminent expansion into larger lakes. To better understand its potential ecological impacts, we explored the isotopic niche of the Amur sleeper in comparison with native fish species co-existing in three Estonian freshwater ecosystems. We employed carbon and nitrogen stable isotope analyses alongside gut content analyses. Our findings show that the Amur sleeper’s diet in newly-invaded Estonian water bodies predominantly comprises benthic macroinvertebrates, although it may also include fish, confirming its role as a predator in the local food web. Notably, Amur sleeper populations exhibited clear isotopic niche partitioning in three invaded ecosystems. A logistic regression model, based on stomach content analyses, revealed an ontogenetic diet shift from benthivorous to piscivorous feeding habits from small to large specimens. Amur sleeper exhibits voracious, non-selective feeding habits, which can negatively impact native freshwater communities. The ability to occupy a distinct isotopic niche, with minimal overlap with native fish populations, may reduce interspecific competition, facilitating the spread and establishment of Amur sleeper in newly-invaded habitats. Managing the spread of this invasive species thus becomes even more critical to safeguard the integrity of native aquatic ecosystems.