A technique for assessing the composition and density of the macroinvertebrate fauna of large stones in streams

Abstract

Keywords : sampling device for macroinvertebrates of large stones in streams, surface area of stones Abstract A device for quantitatively sampling the macroinvertebrates of large stones in streams is described . In comparison to the usual method for sampling the fauna of large stones, (the lifting of stones upstream of a hand net), the present method accurately samples stonedwelling animals that are good swimmers . Details are given of a reliable method to measure the surface area of stream stones using thin plastic sheeting .

Diel changes in the benthos of stones and of drift in a southern Australian upland stream

“…The stones were collected by lifting them into a handnet . However, this method, as shown by Doeg and Lake (1981), underestimates the density of mobile species such as baetid and leptophlebiid ephemeropterans . In a later study, Kovalak (1979) reduced the variability in his samples by using implanted bricks rather than natural stones .…”

“…The fauna of ten stones was collected every four hours using the rock fauna sampler described by Doeg & Lake (1981) . Each stone sampled was free on the bottom of the stream, not embedded .…”

“…The surface of the stone was scrubbed with a brush to remove all attached animals, periphyton and epilithic detritus and all of this material was washed into collecting bottles . The surface area of each stone sampled was estimated using thin plastic film (Doeg & Lake, 1981) . The depth of each stone below the surface was recorded and the current speed immediately alongside the stone was measured with a SLAP current meter .…”

The Effect of Riffle-Scale Environmental Variability on Macroinvertebrate Assemblages in a Tropical Stream

“…Stone surface area was measured fohowing Doeg & Lake (1981). Some environmental factors were recorded at 10 uniformly distributed positions within each rilfle: current velocity (in m/s); water depth (in cm); surface area of the nearest stone (in cm^); sphericity ofthat stone: {bc/a^y^^ (a being the first axis, b the second axis and c the third axis of the stone; Gordon et al, 1992); water direction (categorized as 0: 0-10°, 1: 10-20°, 2: 20^5°); water turbulence (categorized as 0: no turbulence, 1: low degree of turbulence, 2: high degree of turbulence); canopy cover (categorized as 0: no cover, 1: cover); degree of burial of that stone (categorized as 0: no burial, 1 : less than 20% of the stone buried, 2: more than 20% of the stone buried); and dominant substrate type (stones, gravel, sand, mud, bedrock, or leaf litter).…”

The effect of substrate texture on colonization by stream macroinvertebrates

“…At each substrate patch, the following environmental factors were recorded: current velocity, measured with an Owens River Hydroprop (Great Atlantic, UK) flowmeter at 5 cm above the streambed (at each of the two sampling times); water depth, measured with a meter ruler; and total cobble surface area, calculated as the sum of the surface area of the two cobbles in the patch, which was estimated by foil wrapping (following Doeg & Lake 1981).…”