Author(s): Wojciech Prekurat; Piotr Parasiewicz

Linked Author(s):

Keywords: Ichthyoplankton; Fish larvae; Drift dynamics; Power plant impact; Fish mortality; Vistula River; Once-through cooling system

Abstract: This study analyzed the drift of early developmental stages of fish (ichthyoplankton) in the vicinity of the Połaniec Power Plant, one of the largest installations of this type in Poland, using an open cooling system. Samples were collected at night in bi-weekly cycles from May to July 2024 using conical plankton nets in cross-sections located upstream and downstream of the power plant's infrastructure, as well as in the cooling water intake channel and the heated water discharge channel. A total of 4,026 larvae were collected from 18,990 m³ of filtered water. Drift exhibited strong seasonal growth, peaking in early July, and showed a pronounced nocturnal pattern with maximum activity around midnight. Spatial variability was high, with the highest concentrations along the riverbanks and downstream of the power plant. Entrainment losses were estimated at 7.6 million larvae, representing 6.75% of the parallel drifting population. The results indicate that while entrainment is measurable, local larval production in the downstream reach may partially compensate for the losses.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.287

Year: 2026