Listening Practice Question#5

Theme: Coral Bleaching, Ocean Acidification, Climate Change Impacts on Marine Ecosystems, Coral Reef Conservation Efforts, Greenhouse Gas Emissions

Questions

Scenario:

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Questions:

1. What is the primary cause of coral bleaching mentioned in the lecture?
   • (A) Pollution from coastal cities
   • (B) Overfishing near coral reefs
   • (C) Rising sea temperatures
   • (D) Increased tourism in reef areas
2. According to the lecture, what role do zooxanthellae play in the health of corals?
   • (A) They protect corals from predators.
   • (B) They provide food to corals through photosynthesis.
   • (C) They help corals maintain their structure.
   • (D) They clean the water around the coral reefs.
3. What is ocean acidification, and how does it affect coral reefs, as described in the lecture?
   • (A) It makes the water warmer, causing corals to bleach.
   • (B) It increases the amount of sunlight reaching the corals.
   • (C) It weakens coral skeletons by lowering the pH of the water.
   • (D) It results in more frequent storms that damage coral reefs.
4. Which of the following is mentioned as an indirect effect of climate change on coral reefs?
   • (A) The introduction of invasive species
   • (B) A decrease in the salinity of seawater
   • (C) Changes in weather patterns leading to more storms
   • (D) The migration of fish species away from reefs
5. What efforts are being made to protect and restore coral reefs, according to the lecture?
   • (A) Reducing the amount of sunlight that reaches the reefs
   • (B) Creating marine protected areas and restoring damaged reefs
   • (C) Preventing the acidification of oceans through chemical treatments
   • (D) Limiting the movement of fish around coral reefs
6. What does the professor suggest is the most critical action needed to ensure the future of coral reefs?
   • (A) Expanding coral nurseries worldwide
   • (B) Increasing global tourism to reef areas
   • (C) Reducing greenhouse gas emissions
   • (D) Banning all fishing near coral reefs

Transcripts

Lecture Script: The Impact of Climate Change on Coral Reefs

Professor:
Good afternoon, everyone. Today, we’re going to discuss the impact of climate change on coral reefs, one of the most important and fragile ecosystems on our planet. Coral reefs are not only stunningly beautiful, but they are also crucial for marine biodiversity. They provide habitat for countless species and protect coastlines from storms and erosion. However, climate change poses a significant threat to these ecosystems.

One of the most immediate and visible effects of climate change on coral reefs is coral bleaching. Coral bleaching occurs when corals are stressed, primarily due to rising sea temperatures. When the water becomes too warm, corals expel the symbiotic algae, called zooxanthellae, that live in their tissues. These algae are crucial for coral health because they provide the corals with food through photosynthesis and give them their vibrant colors. Without these algae, the corals turn white, or “bleach,” and if the stress continues for too long, the corals can die.

The rise in sea temperatures is largely due to increased levels of greenhouse gases in the atmosphere, particularly carbon dioxide. As the concentration of these gases increases, more heat is trapped in the Earth’s atmosphere, which in turn raises the temperature of the oceans. Studies have shown that even a slight increase in sea temperature, by just 1 or 2 degrees Celsius, can trigger coral bleaching.

But rising temperatures aren’t the only problem. Ocean acidification is another serious issue that results from the absorption of excess carbon dioxide by the oceans. When carbon dioxide dissolves in seawater, it forms carbonic acid, which lowers the pH of the water, making it more acidic. This acidification can weaken coral skeletons, making it harder for corals to build and maintain their structures. Weaker corals are more susceptible to damage from storms, and the overall reef structure can become compromised.

In addition to these direct impacts, climate change also indirectly affects coral reefs through changes in weather patterns. For example, more intense and frequent storms can physically damage coral reefs. Furthermore, the increase in sea levels, another consequence of climate change, can reduce the amount of sunlight that reaches shallow-water corals, inhibiting their growth and making it harder for them to recover from bleaching events.

It’s not all doom and gloom, though. There are ongoing efforts to protect and restore coral reefs. For instance, marine protected areas have been established around many reefs to reduce human impacts such as overfishing and pollution. Additionally, some scientists are working on coral restoration projects, which involve growing corals in nurseries and then transplanting them back onto damaged reefs. There are even research initiatives focused on breeding heat-resistant coral strains that can better withstand rising temperatures.

However, while these efforts are important, they can only go so far. The most critical action that needs to be taken is to address the root cause of climate change by reducing greenhouse gas emissions. Without significant global action to mitigate climate change, the future of coral reefs remains uncertain.

Answers and Explanations

1. Question: What is the primary cause of coral bleaching mentioned in the lecture?
   Answer: (C) Rising sea temperatures
   Explanation: As explained in the lecture, coral bleaching is primarily caused by the increase in sea temperatures. Specifically, a temperature rise of just 1 or 2 degrees Celsius can stress corals, causing them to expel the symbiotic algae (zooxanthellae), which is the direct cause of bleaching.
2. Question: According to the lecture, what role do zooxanthellae play in the health of corals?
   Answer: (B) They provide food to corals through photosynthesis.
   Explanation: The lecture emphasizes that zooxanthellae play a crucial role by providing food to corals through photosynthesis. These algae are essential for maintaining coral health and their vibrant colors.
3. Question: What is ocean acidification, and how does it affect coral reefs, as described in the lecture?
   Answer: (C) It weakens coral skeletons by lowering the pH of the water.
   Explanation: The lecture describes ocean acidification as a process where dissolved carbon dioxide forms carbonic acid in seawater, lowering the pH. This acidification weakens coral skeletons, making it more difficult for corals to maintain their structures, thereby threatening the entire reef ecosystem.
4. Question: Which of the following is mentioned as an indirect effect of climate change on coral reefs?
   Answer: (C) Changes in weather patterns leading to more storms
   Explanation: The lecture mentions that climate change alters weather patterns, leading to more frequent and intense storms. These storms can physically damage coral reefs, making their recovery more difficult, which is an indirect effect of climate change on coral reefs.
5. Question: What efforts are being made to protect and restore coral reefs, according to the lecture?
   Answer: (B) Creating marine protected areas and restoring damaged reefs
   Explanation: The lecture explains that efforts to protect and restore coral reefs include establishing marine protected areas and restoring damaged reefs. These efforts aim to protect coral reefs from human impact and promote their regeneration.
6. Question: What does the professor suggest is the most critical action needed to ensure the future of coral reefs?
   Answer: (C) Reducing greenhouse gas emissions
   Explanation: The professor identifies reducing greenhouse gas emissions as the most critical action needed to address the root cause of climate change. This is essential for ensuring the future of coral reefs.