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Human Impact Analysis Worksheet

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Human Impact Analysis Worksheet

You are advising a community group in Aotearoa New Zealand about pressures on a freshwater ecosystem. Use the case file and data below to trace human impacts, evaluate evidence and recommend a response. Support conclusions with specific details.

Case file: Te Rimu Stream

Te Rimu Stream runs through farmland before joining a larger river. The upper site is beside native bush; the lower site is downstream of a dairy farm and a small town. After heavy rain, runoff can carry soil and nutrients into the stream. A volunteer team sampled both sites on the same day in late summer. These fictional results are provided for analysis; they are not a claim about a real stream.

Observation / measurement

Upper site

Lower site

Nitrate concentration (mg/L)

0.4

2.1

Water clarity (cm; greater means clearer)

Dissolved oxygen (mg/L)

9.2

5.3

Sensitive mayfly larvae found

Many

Few

1.Which site has higher nitrate concentration, and by how many mg/L? Show or state the comparison.

2.Complete this explanation: fertiliser or animal waste on land → ______ enters the stream → ______ may increase → dissolved oxygen may ______. Explain the final link.

3.The lower site has 5.3 mg/L dissolved oxygen compared with 9.2 mg/L upstream. Give one possible ecological consequence and explain which result supports it.

4.Write one cautious claim about how conditions differ between the two sites. Include two pieces of data and avoid claiming that the results prove a single cause.

5.True or false: Sampling each site once on the same day is enough to prove that farming caused every difference. Correct the statement.

TrueFalse

6.Which change would make the evidence more reliable?

Take repeated samples at both sites on several dates and record rainfall and flow.
Measure only the lower site once more.
Ask people whether the stream looks clean.
Remove the mayfly results because they are not chemical measurements.

7.Apart from nutrient runoff, identify one plausible human activity in this catchment that could reduce water clarity. Explain a pathway from the activity to the stream.

8.Recommend one realistic action for the farm or community. Link it to a mechanism and name one measure the volunteer team could monitor to check whether it helps.

9.A farmer is considering fencing off a strip beside the stream for planting. Describe one possible ecological benefit and one practical cost or trade-off.

10.In 3–4 sentences, advise the community group whether the lower site should be investigated further. Refer to at least three observations and include one limitation of the evidence.