Question

Coral reefs are found primarily in tropical and subtropical shallow seaways. Which of the following statement(s) is/are correct?

• A. Corals require plenty of sunlight for photosynthesis and sunlight is abundant in the tropical and subtropical latitudes.
• B. Corals grow optimally in seawater unsaturated in carbonate, which is found only in the tropical and subtropical oceans.
• C. Corals grow optimally in fresh low-salinity water.
• D. Corals grow optimally in water temperatures between 23°C and 29°C.

Hint:

Corals need specific environmental conditions, such as sufficient sunlight, the right temperature, and proper salinity, to thrive and grow.

Answer 1

The Correct Option is A, D

(A) Corals require plenty of sunlight for photosynthesis and sunlight is abundant in the tropical and subtropical latitudes:
This statement is true. Corals rely on a symbiotic relationship with zooxanthellae (a type of algae) that live within their tissues. These algae carry out photosynthesis, providing energy to the corals. Sunlight is essential for this process, and the tropical and subtropical latitudes, where coral reefs are found, receive abundant sunlight throughout the year, making these areas ideal for coral growth. (B) Corals grow optimally in seawater unsaturated in carbonate, which is found only in the tropical and subtropical oceans:
This statement is false. Corals actually require seawater that is saturated with carbonate ions because the calcium carbonate (CaCO3) used by corals to form their skeletons comes from the carbonate in the seawater. Seawater in the tropical and subtropical oceans is typically saturated with carbonate ions, which is why these regions are favorable for coral growth. (C) Corals grow optimally in fresh low-salinity water:
This statement is false. Corals require water with a salinity range of about 30-40 parts per thousand (ppt). They cannot grow optimally in fresh or low-salinity water because such conditions can stress the corals and the zooxanthellae, leading to coral bleaching or death. (D) Corals grow optimally in water temperatures between 23°C and 29°C:
This statement is true. The optimal temperature range for coral growth is between 23°C and 29°C. This temperature range is typically found in the tropical and subtropical oceans, which is why coral reefs thrive in these regions. Water temperatures outside this range can cause stress and lead to coral bleaching, where the corals expel their zooxanthellae, resulting in a loss of their color and vitality. Thus, the correct answers are (A) and (D). Final Answer: \[ \boxed{\text{(A) Corals require plenty of sunlight for photosynthesis and sunlight is abundant in the tropical and subtropical latitudes.}} \text{and} \boxed{\text{(D) Corals grow optimally in water temperatures between 23°C and 29°C.}}. \]