What role do algae play in marine ecosystems?

Algae are crucial components of marine ecosystems, serving primarily as primary producers. They undergo photosynthesis, utilizing sunlight to convert carbon dioxide and nutrients into energy, which results in the production of oxygen as a byproduct. This process not only supports the algae themselves but also provides food for various marine organisms, forming the foundation of the food web in aquatic environments.

The role of algae as primary producers means they are integral to energy transfer within marine systems, as they create organic material that sustains higher trophic levels, such as herbivorous fish and other marine animals. This function also makes algae vital for maintaining balanced ecosystems and supporting biodiversity.

The other options do not accurately capture the multifaceted ecological role of algae. While algae may contribute to some decomposition processes, their primary function is not as decomposers. The assertion that they are solely responsible for coral growth overlooks the complex interactions between corals and various organisms, including zooxanthellae, which are symbiotic algae that aid in the growth of corals. Additionally, while algae do absorb carbon dioxide, they do not exclusively consume it; they also play a part in oxygen production, which is essential for many marine organisms.