The distribution of species of caddisfly larvae within the study stretch of the Whiteadder Water was attributed to three main environmental factors, near bed velocity, depth and amount of Coarse Particulate Organic Matter and was consistent with previous research. Species of caddisfly that occurred within riffles generally had unsynchronised lifecycles, compared to a more synchronised lifecycle to species that occurred in pools, and this was the most pronounced in the case-less caddisfly larvae. The incidence of stranding in cased caddisfly larvae n bank side quadrats increased with discharge once a threshold had been exceeded. The incidence of stranding was dependent on the adjacent bank side microhabitat, topography and larval case type. Stranding was not homogeneous, with more individuals stranded adjacent to riffles than pools on gravel substrates than turf substrates. Cased caddisfly larvae with fine mineral cases mineral cases were the most abundant type found stranded, while species with vegetative cases were rarely found, though present in the benthos. Flume experiments indicated that cased caddisfly larvae were passively deposited on the inundated bank sides and they did not actively seek this refuge. The ability of some cased caddisfly larvae to regain the water once stranded varied with case type, and the topography (substrate and slope) of the bank in experimental arenas. Time taken to regain the water was species/case specific with vegetative cased larvae regaining the water fastest and fine mineral cased larvae the slowest. Time taken to regain the water increased with increasing substrate complexity and distance from the water, but decreased with increasing slope. The incidence of stranding of cased caddisfly larvae by hydraulic disturbance within the Whiteadder Water, while it may be important did not have a significant negative impact on the assemblage of cased caddisfly larvae. Only an estimated 12% of the vulnerable population of cased caddisfly larvae are lost from the benthic population by stranding over a year with a typical discharge regime.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651960 |
| Date | January 2002 |
| Creators | Hall, Kevin Andrew |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13978 |
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