New FWF project

The caddisfly subfamily Drusinae is restricted to high-gradient, turbulent running waters in hard-substrate channels. Their heads are frequently fitted with frontal concavities, dimples, setal and lanuginose hair covers, and their pronota show steep dorsal humps or high, sharp ridges.

Preliminary data suggest that the seven Drusinae morphotypes identified so far inhabit distinct stream sections differing in hydrodynamic stress. In addition to obtaining hydraulic stress data acting at the larval locations using acoustic Doppler velocimetry in the field we will create AutoCad-based virtual 3D models provided by X-ray microtomography of the seven larval morphotypes (upper left). These models are used for numerical flow simulations (upper right) for analyzing the effects of roughness elements on morphotype-specific hydrodynamic drag and lift forces over a wide range of Reynolds numbers and for interpreting hydrodynamic profiles obtained in the field. We hypothesize that hydraulic niche utilization, combined with species-specific shear stress conditions, triggered the evolutionary differentiations of head and pronotum morphology that we observe today (PI: Johann Waringer; national research partner:  Univ.Prof. Dr. Hendrik Kuhlmann, Institute of Fluid Mechanics and Heat Transfer, Technical University, Vienna).