Source of Error in Water Velocity Measurement for Aquatic Studies

Morantz, D. L.; Barbour, S. E.; Sweeney, Rachel

doi:10.1139/f86-111

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…A number of factors were considered before choosing the best size for the hemispheres. Although the smaller the size the hetter the indication of flow close to the substrate at a scale appropriate to that of small benthic organisms, the use of very small hemispheres poses some practical problems: (i) very small hemispheres can easily get lost in the field; further, incorporating an attachment onto these very small hemispheres would change their shape characteristics considerably; (ii) it is more difficult to produce very small hemispheres in replicable sizes and densities; (iii) the moment a hemisphere is released on the horizontal plane the flow in its vicinity is disturbed (see Morantz, Barbour & Sweeney. 1986); this disturbance may cause initial movement of a hemisphere that would not have moved in undisturbed tlow; small hemispheres would be disturbed more in this moment than larger ones; (iv) if hemispheres are exposed for longer periods in the flow, aufwuchs growth on the surface of the hemispheres and around them on the horizontal plane, as well as deposition of sediments around the hemispheres will change the flow extreme indicated by a certain hemisphere; small hemispheres are more sensitive to these effects than larger ones.…”

Section: Methodsmentioning

confidence: 99%

Standard hemispheres as indicators of flow characteristics in lotic benthos research

Statzner¹,

Müller²

1989

Freshwater Biology

130

117

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SUMMARY. 1. Standard hemispheres of identical size and surface but different densities were exposed on a horizontal plane at the bottom of streams. The heaviest hemisphere moved was used as an indicator of flow conditions close to the substrate. 2. Techniques of manufacture, maintenance, and use of the equipment were considered in detail. 3. The method was an easily applicable and integrated indicator of key hydraulic characteristics (turbulence or force of flow prevailing at the stream bottom) previously measured in lotic benthos research, and can replace these more laborious techniques. 4. The hemispheres enabled a rapid flow characterization in stream reaches, in smaller areas where the benthos was being quantitatively sampled, and in en/exclosure cages used in experimental studies. 5. The method also has the potential to characterize and compare physics of flow in individual running water segments with regard to frequencies and intensities of disturbances caused by long‐term variations in discharge. 6. The hemispheres could be used as a standard in benthic research. since they offer a well defined scale that is directly comparable not only between studies in running waters but also in wave‐exposed shores of lakes and oceans.

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Section: Methodsmentioning

confidence: 99%

Standard hemispheres as indicators of flow characteristics in lotic benthos research

Statzner¹,

Müller²

1989

Freshwater Biology

130

117

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Effect of Changes in Streamflow on the Microhabitat Use and Movements of Sympatric Juvenile Coho Salmon (Oncorhynchus kisutch) and Chinook Salmon (O. tshawytscha) in a Natural Stream

Shirvell¹

1994

Can. J. Fish. Aquat. Sci.

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The microhabitats at positions selected by juvenile coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) following a change in streamflow differed from microhabitats occupied at normal streamflows. At drought streamflow (37% mean seasonal streamflow (MSF)), juvenile coho salmon selected slower, darker, and higher sites above the streambed (P < 0.05) than sites selected at normal (75% MSF) or flood (159% MSF) flows. Juvenile chinook salmon microhabitat use changed similarly with changes in streamflow, but the differences were not significant. Up to one fifth of the fish chose positions with faster water velocities than those available either 30 cm above or 30 cm lateral to them. These fish chose positions inconsistent with the hypothesis of optimal position selection based on maximizing net energy gain. On average, fish moved 6.8 m following a change in streamflow. Juvenile coho salmon generally moved upstream in response to decreasing streamflows and downstream in response to increasing streamflows. Juvenile chinook salmon tended to move offshore and downstream in response to all streamflow changes. These results show that juvenile coho and chinook salmon will move to find suitable microhabitat following a change in streamflow and that the microhabitats are not the same at all streamflows.

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Source of Error in Water Velocity Measurement for Aquatic Studies

Cited by 2 publications

References 3 publications

Standard hemispheres as indicators of flow characteristics in lotic benthos research

Standard hemispheres as indicators of flow characteristics in lotic benthos research

Effect of Changes in Streamflow on the Microhabitat Use and Movements of Sympatric Juvenile Coho Salmon (Oncorhynchus kisutch) and Chinook Salmon (O. tshawytscha) in a Natural Stream

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