

@mastersthesis {6437,
	title = {Suspension-feeding behaviour of black fly larvae ({Diptera}: {Simuliidae}): {Hydrodynamical} perspectives},
	year = {1990},
	note = {NN60326},
	school = {University of Alberta (Canada)},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {Hydrodynamics of suspension feeding and concurrent microenvironment selection by aquatic larvae of the black fly Simulium vittatum Zett. are investigated under laboratory conditions, and a compact and versatile flume for studying influence of hydrodynamical factors on benthic invertebrate behaviour is described. Detailed study of the suspension-feeding stance and examination of water flow through filtering appendages (i.e., labral fans) demonstrate that change in body deflection with increasing water velocity is most likely passive. However, overall feeding stance is the outcome of active feedback between flow forces and behavioural reactions to maintain the fans at optimal filtering position. Unexpectedly, labral-fans react to velocity increases with structural reconfiguration resulting in aperture expansion. An increasing fraction of the water directly approaching the fan aperture flows around its perimeter as velocity decreases; no flow through the fans is observed below 2.5 cm/s, and fluid transmissivity never exceeds 30-35\%, even at flows up to 50 cm/s. Calculations of suspension-feeding efficiency are reformulated to reflect labral fan transmissivity and behavioural components of the feeding process. Accordingly, S. vittatum larvae are shown to be ca. 4 to 26 times more efficient at suspension feeding than previously assessed. Larvae did not assume stances nor select positions along the flat substrate demonstrating any significant response to changing boundary layer thickness, leading me to reject the hypothesis that simuliid larvae hide entirely in the boundary layer to reduce direct influence of the mainstream current. Contrary to general belief, larvae do not necessarily seek maximum velocity in a longitudinal velocity gradient. Larvae preferably gather along the separation zone where the thin boundary layer detaches from the curved substrate{\textquoteright}s surface. Larvae always avoid zones of maximum surface shear stress. Larval reaction to changes in flow conditions is immediate, and it is suggested that larvae scan the velocity profile at the substrate to cue on a sharp difference experienced between the abdomen and labral fan level, hence maximizing particle-flux through the fans while minimizing drag forces on the bulbous portion of the body. Scaling microdistribution studies to the organismal level enables isolation of the proximal factors affecting formation of local assemblages.},
	keywords = {0353:Entomology, 0793:Freshwater ecology, Biological sciences, Entomology, Freshwater ecology, Simulium vittatum},
	url = {http://search.proquest.com/docview/219868224?accountid=14270},
	author = {Lacoursiere, Jean O}
}
