IELTS Reading Practice: How Climate Change is Impacting Marine Ecosystems

Climate change is one of the most pressing issues of our time, with far-reaching consequences for our planet’s ecosystems. In this IELTS Reading practice, we’ll explore how climate change is impacting marine ecosystems through a series of passages and questions. This practice will help you improve your reading skills while learning about an important environmental topic.

Climate Change Impact on Marine Life

IELTS Reading Practice Test

Passage 1 – Easy Text

The Warming Oceans

The world’s oceans are experiencing significant changes due to global warming. As greenhouse gases trap heat in the atmosphere, much of this excess heat is absorbed by the oceans. This warming trend has profound implications for marine life and ecosystems.

One of the most visible effects of warming oceans is coral bleaching. Corals have a symbiotic relationship with tiny algae called zooxanthellae, which provide them with food and their vibrant colors. When water temperatures rise too high, corals expel these algae, leading to a white, “bleached” appearance. If high temperatures persist, corals can die, devastating entire reef ecosystems.

Rising ocean temperatures also affect the distribution of marine species. Many fish and other sea creatures are moving towards cooler waters near the poles. This shift can disrupt food webs and impact fishing communities that rely on certain species.

Moreover, warmer waters hold less dissolved oxygen, creating “dead zones” where marine life struggles to survive. These areas of low oxygen can lead to mass die-offs of fish and other organisms, further destabilizing marine ecosystems.

The warming of oceans also contributes to sea level rise through thermal expansion. As water warms, it expands, taking up more space and causing sea levels to rise. This phenomenon, combined with melting ice caps, threatens coastal habitats and human communities.

Questions 1-5

Do the following statements agree with the information given in the passage? Write

TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this

1. Oceans absorb most of the excess heat caused by global warming.
2. Coral bleaching is caused by pollution in the oceans.
3. Some marine species are moving towards the poles due to warming oceans.
4. Dead zones in the ocean are areas with high levels of dissolved oxygen.
5. Sea level rise is solely caused by melting ice caps.

Questions 6-10

Complete the sentences below. Choose NO MORE THAN TWO WORDS from the passage for each answer.

6. Corals have a __ __ with tiny algae called zooxanthellae.
7. When water temperatures rise too high, corals __ the algae.
8. The movement of marine species towards cooler waters can disrupt __ __.
9. Areas of low oxygen in the oceans can lead to __ __ of fish and other organisms.
10. The warming of oceans causes sea level rise through __ __.

Passage 2 – Medium Text

Ocean Acidification: The “Other CO2 Problem”

While much attention has been focused on the warming effects of carbon dioxide (CO2) emissions, there is another equally serious consequence of rising atmospheric CO2 levels: ocean acidification. Often referred to as “the other CO2 problem,” ocean acidification occurs when the ocean absorbs excess CO2 from the atmosphere, leading to a decrease in seawater pH.

The ocean has absorbed approximately one-third of the CO2 produced by human activities since the beginning of the Industrial Revolution. When CO2 dissolves in seawater, it forms carbonic acid, which increases the acidity of the ocean. Since the Industrial Revolution, the average pH of surface ocean waters has fallen by 0.1 units, representing a 30% increase in acidity.

This change in ocean chemistry has profound implications for marine life, particularly for organisms that build shells or skeletons out of calcium carbonate, such as corals, mollusks, and some plankton species. In more acidic waters, these organisms struggle to extract the calcium carbonate they need from seawater, leading to thinner shells, slower growth rates, and in some cases, dissolution of existing shells.

The impacts of ocean acidification ripple through the entire marine food web. For example, pteropods, tiny sea snails also known as “sea butterflies,” are a crucial food source for many fish species, including salmon. As ocean acidity increases, pteropods’ shells become thinner and more fragile, potentially leading to population declines that could have cascading effects on their predators.

Moreover, ocean acidification threatens coral reefs, which are already under stress from rising temperatures. Acidification reduces corals’ ability to build their skeletons, making them more susceptible to erosion and storm damage. This poses a significant risk to the incredible biodiversity supported by coral reef ecosystems and the millions of people who depend on them for food, income, and coastal protection.

The rate of acidification is accelerating as CO2 emissions continue to rise. If current trends continue, by the end of this century, ocean acidity could increase by 150% compared to pre-industrial levels. This rapid change gives marine organisms little time to adapt, potentially leading to widespread ecosystem disruption and biodiversity loss.

Questions 11-15

Choose the correct letter, A, B, C, or D.

11. Ocean acidification is caused by:
    A) Pollution from industrial waste
    B) Absorption of excess CO2 from the atmosphere
    C) Rising ocean temperatures
    D) Increased algae growth

12. Since the Industrial Revolution, the acidity of surface ocean waters has increased by:
    A) 0.1 units
    B) 30 units
    C) 30%
    D) One-third

13. Which of the following is NOT mentioned as an effect of ocean acidification on shell-building organisms?
    A) Thinner shells
    B) Slower growth rates
    C) Increased shell strength
    D) Dissolution of existing shells

14. Pteropods are important because:
    A) They regulate ocean acidity
    B) They are a food source for many fish species
    C) They build coral reefs
    D) They absorb excess CO2

15. By the end of this century, ocean acidity could increase by:
    A) 30%
    B) 100%
    C) 150%
    D) 200%

Questions 16-20

Complete the summary below. Choose NO MORE THAN TWO WORDS from the passage for each answer.

Ocean acidification occurs when the ocean absorbs excess (16) __ from the atmosphere. This process leads to a decrease in seawater (17) __. The change in ocean chemistry affects organisms that build shells or skeletons out of (18) __, such as corals and mollusks. These impacts can (19) __ through the entire marine food web. Coral reefs are particularly at risk, as acidification reduces their ability to build their skeletons, making them more susceptible to (20) __ and storm damage.

Passage 3 – Hard Text

The Cascade Effect: Climate Change and Marine Ecosystem Dynamics

The impact of climate change on marine ecosystems is far more complex and interconnected than initially perceived. As researchers delve deeper into the intricate web of marine life, they uncover a cascade of effects that ripple through entire ecosystems, often with unexpected and far-reaching consequences.

One of the most striking examples of this cascade effect is the relationship between sea ice, phytoplankton, and higher trophic levels in polar regions. Arctic sea ice has been declining at an unprecedented rate due to global warming. This decline not only affects ice-dependent species like polar bears but also alters the entire marine food web. As sea ice retreats, it exposes more open water to sunlight, potentially increasing phytoplankton productivity in some areas. However, this apparent benefit is offset by increased stratification of the water column due to freshwater input from melting ice, which can limit nutrient upwelling and ultimately reduce overall productivity.

The changes in phytoplankton abundance and distribution have ramifications for zooplankton, small fish, and eventually, larger predators. For instance, in the Southern Ocean, krill populations, which are crucial to the Antarctic food web, are shifting southward as waters warm. This movement affects not only local predators like penguins and seals but also migratory species such as whales that depend on krill for sustenance during their long journeys.

Climate change is also altering the timing of ecological events, a phenomenon known as phenological shifts. In many marine ecosystems, the timing of phytoplankton blooms is changing, often occurring earlier in the year due to earlier ice melt or changes in water temperature. This can lead to a mismatch between the availability of food and the breeding cycles of zooplankton and fish, potentially causing population declines and disrupting entire food webs.

Moreover, the combination of ocean warming and acidification is having synergistic effects on marine ecosystems. While each stressor alone poses significant challenges, their combined impact can be even more severe. For example, many coral species are already at their thermal tolerance limits due to warming waters. The additional stress of acidification further compromises their ability to build and maintain their calcium carbonate structures, making them more susceptible to bleaching events and less resilient to recovery.

The cascade effect extends to biogeochemical cycles as well. Changes in ocean circulation patterns due to warming can alter the distribution of nutrients and oxygen in the water column. This, in turn, affects primary productivity and can lead to the expansion of oxygen minimum zones, areas of low dissolved oxygen that are inhospitable to most marine life. The expansion of these zones can compress the habitable space for many species, forcing them into smaller areas and potentially increasing their vulnerability to predation and overfishing.

Furthermore, climate change is facilitating the spread of invasive species and pathogens in marine environments. Warmer waters allow species to expand their ranges into previously inhospitable areas, potentially outcompeting native species and altering ecosystem structure. Similarly, rising temperatures can increase the virulence and transmission rates of marine pathogens, leading to more frequent and severe disease outbreaks among marine organisms.

The cascading effects of climate change on marine ecosystems highlight the need for a holistic approach to marine conservation and management. Single-species or single-issue approaches are insufficient to address the complex, interconnected challenges posed by climate change. Instead, ecosystem-based management strategies that consider the full range of interactions and feedbacks within marine systems are essential for building resilience and mitigating the impacts of climate change on our oceans.

Questions 21-26

Complete the summary below. Choose NO MORE THAN TWO WORDS from the passage for each answer.

The impact of climate change on marine ecosystems involves a complex (21) __ of effects. In polar regions, the decline of sea ice affects not only ice-dependent species but also alters the entire marine (22) __. Changes in phytoplankton affect zooplankton and fish, ultimately impacting larger predators. Climate change is also causing (23) __ shifts, which can lead to mismatches between food availability and breeding cycles. The combination of ocean warming and acidification has (24) __ effects on marine ecosystems, particularly affecting coral species. Changes in ocean circulation patterns can alter the distribution of nutrients and oxygen, potentially expanding (25) __ zones. Climate change is also facilitating the spread of (26) __ and pathogens in marine environments.

Questions 27-32

Do the following statements agree with the claims of the writer in the reading passage? Write

YES if the statement agrees with the claims of the writer
NO if the statement contradicts the claims of the writer
NOT GIVEN if it is impossible to say what the writer thinks about this

27. The decline of Arctic sea ice uniformly increases phytoplankton productivity across all areas.
28. Krill populations in the Southern Ocean are moving northward as waters warm.
29. Phenological shifts can cause population declines in marine species.
30. Ocean warming and acidification always have additive effects on marine ecosystems.
31. The expansion of oxygen minimum zones can increase species vulnerability to overfishing.
32. Single-species approaches are sufficient to address the challenges posed by climate change to marine ecosystems.

Questions 33-40

Complete the sentences below. Choose NO MORE THAN TWO WORDS from the passage for each answer.

33. The retreat of sea ice exposes more open water to __, potentially increasing phytoplankton productivity.
34. Increased __ of the water column due to freshwater input from melting ice can limit nutrient upwelling.
35. Krill are crucial to the __ in the Antarctic region.
36. Phenological shifts can lead to a __ between food availability and breeding cycles.
37. Many coral species are already at their __ limits due to warming waters.
38. Changes in ocean circulation patterns can alter the distribution of __ and oxygen in the water column.
39. The expansion of oxygen minimum zones can compress the __ for many species.
40. Rising temperatures can increase the __ and transmission rates of marine pathogens.

Answer Key

Passage 1

1. TRUE
2. FALSE
3. TRUE
4. FALSE
5. NOT GIVEN
6. symbiotic relationship
7. expel
8. food webs
9. mass die-offs
10. thermal expansion

Passage 2

11. B
12. C
13. C
14. B
15. C
16. CO2
17. pH
18. calcium carbonate
19. ripple
20. erosion

Passage 3

21. cascade
22. food web
23. phenological
24. synergistic
25. oxygen minimum
26. invasive species
27. NO
28. NO
29. YES
30. NO
31. YES
32. NO
33. sunlight
34. stratification
35. food web
36. mismatch
37. thermal tolerance
38. nutrients
39. habitable space
40. virulence

Conclusion

This IELTS Reading practice test on “How Climate Change is Impacting Marine Ecosystems” provides a comprehensive overview of the complex interactions between climate change and ocean systems. By working through these passages and questions, you’ve not only improved your reading skills but also gained valuable knowledge about one of the most pressing environmental issues of our time.

Remember, success in the IELTS Reading test comes from regular practice and familiarizing yourself with various question types. Keep practicing with diverse topics to enhance your reading speed, comprehension, and test-taking strategies.

For more IELTS practice and tips, check out our related articles on how climate change is affecting the food industry and the impact of climate change on global water resources.