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13.7 Understanding The Issue

CHECK YOUR UNDERSTANDING

Question 13.1

Which of the following is TRUE about ocean acidification?

CO₂ emissions have reduced the ocean’s pH by about 0.1, which corresponds to a 300% increase in ocean water acidity.

Ocean pH has now dropped below a pH of 7.0.

Ocean acidification is harmful, as CO₂ forms carbonic acid when dissolved in water, which eats away at existing calcium-based materials.

In a more acidic ocean, the increase in key nutrients such as nitrogen and iron stabilizes almost all marine ecosystems, counteracting the effects of global warming.

Question 13.2

Organisms that live on the ocean floor are said to live in the:

benthic zone.

abyssopelagic zone.

hadal zone.

pelagic zone.

Question 13.3

An estuary is:

a shallow coastal region affected by the tides, where organisms are adapted to strong currents.

the only ecosystem on Earth that does not depend on photosynthesis.

a pitch-black, cold, high-pressure zone where few organisms live.

a productive marine ecosystem in a region where rivers empty into the ocean, bringing nutrients from land runoff.

Question 13.4

Which of the following threats to ocean ecosystems currently has the biggest impact on coral reefs?

Overfishing

Coastal development

Sediment runoff from land

Oil spills

Question 13.5

What is/are the consequence(s) of coral bleaching for coral reefs and other ocean ecosystems?

Coral reefs attract coral larvae via visual cues, so when reefs lose their colour, larvae have difficulty attaching to the top of existing coral skeletons.

Coral bleaching occurs when corals under stress expel their zooxanthellae: corals can only survive for a short period of time without their photosynthetic algae partners.

Although coral reefs are home to many species, if bleaching occurs, most of these species can move to other marine ecosystems such as estuaries and kelp forests, thus tempering the impact on ocean ecosystems.

All of the above are consequences of coral bleaching for coral reefs and other ocean ecosystems.

Question 13.6

The highest percentage of destroyed coral reefs are found in the ________ while the _____ has the lowest percentage of destroyed coral reefs.

Arctic Ocean; Atlantic Ocean

Indian Ocean; Pacific Ocean

Caribbean Sea; Mediterranean Sea

Middle East; Asian South Pacific

WORK WITH IDEAS

Question 13.7

What are coral reefs and where are they found? Explain the symbiotic relationship the polyp shares with its resident zooxanthellae.

Question 13.8

What is ocean acidification? Describe the causes and consequences of this phenomenon.

Question 13.9

Besides ocean acidification, what threats do coral reefs and other ocean ecosystems face? Describe the causes and consequences of these threats.

Question 13.10

How can we reduce the threats to coral reefs and other ocean ecosystems? Discuss three strategies.