Dataset of field and experimental studies on the stygobiont shrimp Troglocaris planinensis from the Classical Karst

From June 2020 to January 2025, we conducted repeated diurnal and nocturnal surveys of Troglocaris planinensis at 64 springs in the Classic Karst (NE Italy). Each site was characterized for abiotic and biotic parameters. In laboratory assays, specimens from cave and spring populations were tested for behavioral responses to light stimuli and predator cues as potential adaptations to contrasting habitat conditions.In springs, T. planinensis density reached up to 116 shrimps/m², with significantly higher abundances at night and lower densities at sites with pike (top-predator fish in the investigated springs) presence. Laboratory tests showed that predator cues, but not light exposure, influenced shrimp behavior regardless of their cave or spring origin.A key unresolved question is whether stygobionts like T. planinensis can detect and discriminate the contrasting physical and biotic attributes of subterranean versus surface habitats. In particular, responses to predator cues, Landscape of Fear (LOF), Hunters' Horizon (HuHo) and hydrodynamic variation warrant investigation, since drift away from the spring mouth can expose shrimps to markedly unsuitable conditions with low survival probability. Similarly, thermal gradients between springs and adjacent epigean habitats at the ecotonal boundary may drive differentiation among individuals or subpopulations that intermittently exploit this interface.