Question

Q8. Consider the following statements about Noctiluca:

1. A warming ocean means greater temperature differences among layers of the sea water and this slows the upward transport of nutrients like silicate from the ocean bottom, lowering its concentration at the surface.

2. Noctiluca consumes one of the most important planktonic organisms at the base of the fish-food chain, namely diatoms, and also excretes large amounts of ammonia, which is linked with massive fish mortalities.

Which of the above statements are correct?

• A. a) 1 only
• B. b) 2 only
• C. c) Both 1 and 2
• D. d) Neither 1 nor 2

Answer 1

The correct option is C

c) Both 1 and 2

• Noctiluca consumes one of the most important planktonic organisms at the base of the fish-food chain, namely diatoms, and also excretes large amounts of ammonia, which is linked with massive fish mortalities.
• A warming ocean means greater temperature differences among layers of the sea water and this slows the upward transport of nutrients like silicate from the ocean bottom, lowering its concentration at the surface.
• Diatoms growing in surface water need both sunlight and silicate to build their glass skeletons and thus, will fail to thrive when silicate becomes less available.
• On the other hand, Noctiluca remains unaffected by these changes and additionally will prey on the remaining diatoms.
• Intensifying global-warming conditions thus may be expected to disrupt the fish-food chain and cause a decline of fisheries in the region.