Given a scientific passage and an answer, generate a question for the given answer.

Passage: Multicellular seaweeds called kelp may grow as large as trees. They are the food base of ecosystems called kelp forests (see Figure below ). Kelp forests are found throughout the ocean in temperate and arctic climates. They are highly productive ecosystems. Answer: kelp
Which forests are found throughout the ocean in temperate and arctic climates?