Question

A part of the North Atlantic Ocean is covered by free-floating brown algae. It is –
A) Dictyota
B) Alaria
C) Ectocarpus
D) Sargassum

Answer 1

Algae are often called seaweed, but they range from simple photo-synthetic unicellular organisms to larger multicellular plant-like structures. They are generally found in aquatic environments.

Complete Answer:
- Dictyota is a kind of brown algae found in the ocean, however it prefers tropical to subtropical waters. This algae is most commonly found in the Mediterranean as well the southern parts of the Atlantic around Europe. Answer A is incorrect.
- Alaria is a kind of algae that has large leaf-like portions. It is commonly known as kelp and is found more in the North Pacific, though it may be found in parts of the North Atlantic, but it doesn’t cover a large section of the ocean. Option B is incorrect.
- Ectocarpus is again a filamentous brown algae with a wide distribution which is one of the model organisms used in genetic research due to the short time in which it can complete its life cycle. However it is not responsible for covering the North Atlantic ocean. Option C is incorrect.
- A part of the North Atlantic Ocean is known as the Sargasso sea. This is because it is covered by the holopelegi algae, Sargassum. This reproduces vegetatively while floating, unlike other algal species which need to reproduce on the ocean floor. The Sargasso sea is unique in that it is not land bound on any side. Option D is correct.

Hence the correct answer is option D.

Note: Algae can be good indicators of climate change or pollution. For example, the red tides that are often seen where the algae produce toxins that kill aquatic animals. These often appear after storms due to nutrients being stirred up. Detergent run-off can also cause algal blooms.