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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
Sandy beaches are categorised mainly in two groups based on their gradient. Analyse how the energy of the waves and currents influence the gradient of the beach.
Answer
Waves and currents are critical in shaping the gradient of sandy beaches.
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Wave Energy: Higher energy waves tend to create steeper beach gradients. Stronger waves can mobilize larger sediment particles, leading to a steep slope as the sediment is pushed up the beach.
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Current Action: Tidal currents also influence beach gradients. When currents are strong, they can carry finer sediments away from the shore, resulting in a steeper gradient.
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Sedimentation Rates: Where wave energy is lower, finer sediments accumulate, leading to a more gradual beach gradient.
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Gradient Categorization: Overall, beaches are characterized as either steep with strong waves and currents or gentle with calmer water, influencing local ecosystems and human activities.
Step 2
When visiting the beach, one often sees the plough snails (Bullia species) feeding on dead organisms close to the shoreline. Explain how these snails make use of the tides to get their food.
Answer
Plough snails utilize tidal movements effectively to feed.
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Tidal Movements: As the tide rises, the snails emerge from their burrows to feed on detritus and decomposing organisms brought to the shore.
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Surfing Technique: These snails can surf in the incoming tides, moving towards the high tide mark where they find abundant food sources.
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Feeding and Retreat: Once they have fed sufficiently, they retreat back into mid-tide burrows as the tide comes back in, thus protecting themselves from predation and harsh conditions.
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Adaptation: This adaptability to tidal changes allows them to maximize their food intake while minimizing risk.