It may seem obvious that coral reefs boast an abundance of fish and invertebrate species, but what causes them to support such lively ecosystems? Some researchers believe size might have something to do with it. Reef size-- meaning vertical, horizontal, and diagonal, 3-Dimensional structure of a reef.
Nooks & Crannies
Coral reefs are complex ecosystems that support a variety of benthic and mobile organisms. Reefs' structures determine what habitat and functional niches are available for organisms to occupy. Coral build intricate limestone structures that create homes, shelter, and hunting locations for many organisms, both small and large. Reefs' organic design contain cryptic holes, too, meaning critters can hang out inside, when not swimming or roaming around the reef.
Different corals species grow into different shapes (e.g. branching structures, boulder structures, etc), which influence the shape and size of reefs. These shapes are also important determinants of the species that inhabit the reefs.
In general, reef structural complexity positively correlates with higher diversity and increased species abundance of both fish and invertebrates on reefs! Therefore, more structure, more fish and coral species. That means, when it comes to 3D structure, size matters... a lot.
Seas Need 3D
Without this complex combination of 3D shapes and structures, reefs lack the habitats and diversity that support the thriving ecosystems we see them as today. Therefore, artificial structures aren't capable of bringing back the natural mix of species we see on coral reefs. Live coral is essential to sustaining both the environmental processes and marine life in the region, maintaining the ecosystem.
These ecosystems support more than just the fish and organisms within them- they support us.
So Do We...
Over 500 million people directly depend of coral reefs for the resources and services they provide. Reefs are a source of food, livelihood, coastal protection, and more. Many people indirectly rely on reefs for income, food, pharmaceutical drugs and medicines, recreation, skincare products, and other products.
Human-induced environmental changes are threatening the sustainability of coral reefs around the world. Reefs are becoming continually flatter, and less structurally complex. Decreasing 3D structural complexity will likely come with consequences.
Keep the Sea 3D!
Don't fret -- though this is likely to cause rippling effects throughout reef ecosystems, there are some ways you can help! Check out our post on ways to Keep the Sea 3D for more information.