What are artificial reefs NOT typically made from?

Artificial reefs serve a significant purpose in marine ecosystems by providing habitats for marine life and promoting biodiversity. They can be constructed from a variety of materials, each selected to enhance their structural integrity and ecological function.

The correct answer indicates that artificial reefs are not typically made from organic coral material. While live coral is crucial for natural reef systems, it is not practical or ethical to use organic coral material in the construction of artificial reefs. The goal of artificial reefs is to mimic the conditions of natural reefs using materials that can withstand oceanic conditions and support marine life.

Materials such as concrete and stone blocks are favored because they are durable, non-toxic, and can encourage the growth of algae and other organisms that support marine life. Similarly, large sacks filled with sand can provide structure and can be easily deployed. Sunken ships, often used for their complex shapes and submerged surfaces, can attract various species due to the niches they create. In contrast, organic coral material is typically protected under environmental regulations and not used in reef construction.