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Difficulty: HardEcological Factors and Their Measurement

An ecologist studying abiotic factors in a lotic freshwater habitat estimated the surface water velocity by timing a float that travelled a distance of 60 m60\text{ m} downstream in 24 s24\text{ s}. To record a precise, depth-specific measurement of this ecological factor across different river strata, which calculated velocity and instrument choice are correct?

  1. A
    0.40 m s−10.40\text{ m s}^{-1} measured using a hydrometer
  2. 2.50 m s−12.50\text{ m s}^{-1} measured using a water current meterAnswer
  3. C
    2.50 m s−12.50\text{ m s}^{-1} measured using an anemometer
  4. D
    1440 m s−11440\text{ m s}^{-1} measured using a Secchi disc

Answer

The stream velocity is 2.50 m s−12.50\text{ m s}^{-1} and the appropriate instrument for depth-specific measurement is a water current meter.
Dividing the distance of 60 m60\text{ m} by the time of 24 s24\text{ s} yields a velocity of 2.50 m s−12.50\text{ m s}^{-1}. A water current meter (flow meter) is the standard ecological instrument for measuring water velocity at different depths in lotic habitats.

Step-by-Step Solution

1
Calculate the water current velocity using the formula Velocity=DistanceTime\text{Velocity} = \frac{\text{Distance}}{\text{Time}}.
Velocity=60 m24 s=2.50 m s−1\text{Velocity} = \frac{60\text{ m}}{24\text{ s}} = 2.50\text{ m s}^{-1}.
Velocity represents the rate of movement of water per unit time.
2
Identify the proper ecological instrument for measuring water current velocity at specific depths.
A water current meter (or flow meter) is designed to record current speed across various aquatic depths.
Surface floats only measure surface speed, whereas current meters submerged at defined depths give precise strata measurements.

Key Concept

Measurement of Aquatic Ecological Factors
Estimated Time:2m 0s
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Topics

Ecological Factors and Their Measurement

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