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The official homepage of FWF Project P 31258-B29 "Intricate bodies in the boundary layer –
bridging fluid mechanics, morphology and ecology in larval Drusinae (Insecta: Trichoptera)" |
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The Project Team (from left): Carina Zittra (University of Vienna, Dept. of Limnology &
Bio-Oceanography) Johann
Waringer
(University of Vienna, Dept. of Limnology & Bio-Oceanography; PI) Hendrik Kuhlmann (Vienna University of Technology;
Inst. of Fluid Mechanics & Heat Transfer; PI) Simon
Vitecek (Wassercluster
Lunz, Aquatic Entomology Lab) Ariane Neale Ramos Vieira (Vienna University of Technology,
Inst. of Fluid Mechanics & Heat Transfer) |
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Mission statement |
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Drusinae are restricted to high-gradient,
turbulent running waters in hard-substrate channels covering the Eurasian
mountain ranges from Spain to Iran. Larval heads are frequently fitted with
frontal concavities, dimples, setal and lanuginose
hair covers, and pronota show steep dorsal humps or
high, sharp ridges. A molecular phylogeny of the subfamily yielded three
well-supported clades which completely correlated the strange head and pronotum morphology with the feeding ecology of larvae:
omnivorous shredders (one morphological type), epilithic
grazers (three morphotypes), and carnivorous filter
feeders (three morphotypes). Data available
suggest that these seven morphotypes inhabit distinct stream sections differing in hydrodynamic stress. We
hypothesize that shredders are restricted to hydrodynamic low stress patches
within their habitat, because their food items are concentrated near the
banks. Carnivorous filter feeders are expected to be most abundant within
medium to high stress patches because current velocity is required to
efficiently operate their filtering apparatus. Grazer types should be
generally restricted to hydrodynamic high stress patches because autotrophic
biofilms and epilithic algae are most abundant near
midstream. In work package 1 we
will critically test this hypothesis by measuring hydraulic stress acting at
the larval locations based on acoustic Doppler velocimetry;
this information will be combined with video documentations of body postures
and flow exposition using a waterproof endoscope camera both at the sediment
surface and within substrate interstices. In the second work package we propose that
the diversification of external head capsule shapes of the seven morphotypes will impact internal head capsule structures.
We hypothesize a shift in the origins of the main muscle bundles as well as
innervation patterns in response to the development of frontoclypeal
rims, concavities, steep frons sections and dorsal depressions. X-ray microtomography will be used to create virtual 3D models
of the seven larval morphotypes to identify
anatomic key innovations promoted by feeding type evolution and exploitation
of hydrological niches in Drusinae. AutoCad-based virtual 3D
models provided by X-ray microtomography will be
used for the numerical flow simulations intended in work package 3. This fluid-mechanical approach will allow 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 the range of head
morphologies of Drusinae larvae can be explained by
the flow conditions to which the larvae are exposed. Hydraulic niche
utilization combined with species-specific shear stress conditions triggered
evolutionary differentiations of head and pronotum
morphology, thereby optimizing lift force reduction required for the larvae
to stay attached to the riverbed. |
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