Kyle J. A. Zawada , Joshua S. Madin, Andrew H. Bair D, Tom C. L. Bridge, Maria Dornelas
Corals are responsible for building and maintaining huge areas of habitat for other organisms, but the role each coral plays depends on their shape. Massive boulder-like corals are slow growing but long-lived, and help to build the reef over generations, table-like corals provide shade and hiding spots for larger fish, and intricate branching colonies provide shelter for schools of smaller fish. Together, this variety of coral forms defines reef ecosystems.
However, there is a downside for corals with some shapes: they are more susceptible to human activity and extreme weather events. If we lose some coral forms, what are the consequences for other species that rely on them?
In this paper we outline three ways that corals vary in their shape and link each one to variation in how corals live, their roles in the ecosystem, and how they respond to changing environments. We then combine data from high resolution laser scans with field data collected over a 22-year period to track how coral communities have changed in response to cyclones and the 2016 coral bleaching event.
We show that there has been a shift in the number of complex branching corals and corals that have space underneath them across multiple sites around Lizard Island, Australia. Both cyclones and coral bleaching events are already increasing in severity worldwide, in addition to pressure from other human activities. With these shifts comes a change in the suitability of coral-built habitat to support other organisms.
Our approach allows for the broad variety and diversity of coral species to be summarised into easy to understand and quantifiable traits to track how reef ecosystems respond to human activity.
Life on earth is increasingly being shaped by human activity each year. Identifying ways to clearly track how ecosystems are affected by these changes is key if we are to work out how to coexist with the other species that also live in this new world.