Year 9 Science · Unit 2 · Lesson 19
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Learning Goals
Scenario
A polar fleece jacket made of polyester sheds approximately 1,700 plastic microfibres per wash. These fibres are too small to be caught by standard washing machine filters and pass through most wastewater treatment plants, entering rivers and the ocean as primary microplastics. Research published in 2021 found that zooplankton in Sydney Harbour ingest up to 22 microfibres per individual per day.
(a) Trace the complete pathway of a single microfibre from a fleece jacket to a bottlenose dolphin living in Sydney Harbour. Use the concept of biomagnification to name at least three steps in the food chain.
(b) Predict why a bottlenose dolphin at the top of the Sydney Harbour food chain would have a much higher concentration of microfibres per gram of tissue than a single zooplankton, even though the zooplankton ingests fibres directly from the water.
Because… chain
Fill in the missing effects in the chain below. Each cause leads to the next step. The shaded boxes are given, fill in the white boxes.
Overall outcome:
1. CSIRO research has found microplastics in the tissues of Australian sea turtles, whales, and seabirds. Using your knowledge of bioaccumulation, explain why marine mammals and seabirds are particularly at risk compared with the zooplankton they ultimately eat.
2. Tyre wear is described in the lesson as the single largest global source of microplastics. Explain how tyre wear particles enter the ocean, and describe ONE reason why this source of microplastics is particularly difficult to reduce.
Wrap Up
In one sentence, what was the main idea of this lesson?