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South Africa has a coastline of about 3 650 km - NSC Marine Sciences - Question 3 - 2021 - Paper 1
Question 3
South Africa has a coastline of about 3 650 km. Many different ecosystems are found along this coastline. About 27% are rocky shore, 42% sandy beach and 31% mixed sh... show full transcript
Worked Solution & Example Answer:South Africa has a coastline of about 3 650 km - NSC Marine Sciences - Question 3 - 2021 - Paper 1
Step 1
3.1.1 Analyse how the energy of the waves and currents influence the gradient of the beach.
Answer
The gradient of a sandy beach is influenced significantly by wave energy and currents.
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Waves and Their Energy: Stronger waves lead to steeper beach gradients as they transport larger amounts of sediment towards the shore. This process compacts the sand, creating a slope. Conversely, weaker waves result in gentler gradients, often seen on beaches with light wave action.
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Currents: The influence of currents can also shape the beach gradient. If currents flow parallel to the shore, sediment may be eroded or deposited in a manner that affects the beach gradient. For instance, longshore currents can narrow the beach by eroding sediment from one section and depositing it in another, resulting in varying gradient levels.
Step 2
3.1.2 Explain how these snails make use of the tides to get to their food.
Answer
Plough snails, or Bullia species, utilize the tidal movements to access their food in the following ways:
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Emerging and Burrowing: As the tide rises, the snails emerge from their burrows in the sand to feed on organic matter, such as dead organisms that are washed ashore.
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Tidal Surfing: They are adapted to 'surf' to the high tide mark, allowing them to access areas where food is abundant without being washed away. This behavior not only maximizes their feeding opportunities but also minimizes the risk from predators.
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Retreating with the Tide: After feeding, as the tide goes out, the snails retreat back to their burrows to avoid desiccation and predators, ensuring their safety and survival.