Responses of cyprinid (Ancherythroculter nigrocauda) to flow with a semi‐circular cylinder patch

• DOI: 10.1111/jfb.15020
• Publication Date: 2022-02-24T06:56:30Z
• Authors: Fan Yang; Yuhong Zeng; Wenxin Huai; Wei Zha; Yunjiao Wan
• Keywords: Flume; Patch dynamics

Flows in river habitats are characterized by unsteady turbulence due to the existence of woody debris, boulders and vegetation. As a representative aquatic species, fish is important for riverine ecosystems, with its complex behavioural responses turbulent flows. Previous studies investigated fish-vortices interaction vortex streets placing objects simplified geometries centred at flow. Nonetheless, morphology natural rivers results much more spatially heterogeneous flows randomly distributed obstructions. Thus, semi-circular cylinder patch located on one side flume used mimic vegetation riverbank. The varies diameter (D0 = 16, 20 24 cm) density (φ 0.04 0.1), whereas flow velocity fixed 25 cm s-1 . Fish observed swim three typical patterns, which "swim around" (pattern 1), "spill" 2) through" 3). For dense patch, all patterns recorded, but only 1 2 sparse patches. It noticed that 2, prefer hold place zones low turbulence. Moreover, variations have little influence pattern selection. Results showed tail beat amplitude (TBA*) each zone displayed compared frequency (TBF). In addition, Spearman's rank tests revealed TBA* affected none four hydrodynamic variables ( U,ustd,τxy,Ωz ), imposes most TBF. Both no significant