Coral reef microbes point to a new way to assess ecosystem health

A new study shows that ocean acidification is changing the composition of microbes in coral reef systems, which can be used to assess ecosystem health.

The study, published today microorganismThe researchers looked specifically at coral reefs, but the researchers say it could be broadly applicable as a method for measuring how ecosystems respond to human activities.

Understanding how ecosystems change in response to human activities allows predictions about their future and how to protect them. Although microbes are critical to ecosystems—supporting critical functions such as nutrition and immune system modulation—changes in microbial communities are rarely measured when assessing ecosystem health.

A team led by Imperial College London researchers tested whether measuring changes in whole communities of large (macro) organisms and microbes could provide a new measure of stress on coral reefs. In these ecosystems, microbes are particularly important and live not only on the macro-organisms but also in the surrounding sediment and water.

Coral and carbon dioxide

Some reefs grow near natural carbon dioxide (CO₂) vents on the seafloor, which can be used to understand the response of reefs to future oceanic CO₂ Conditions caused by human activities and resulting acidification. The researchers visited such a CO₂ used Automated Reef Monitoring Structures (ARMS) to collect samples of organisms and sediments from vents and various CO areas in Papua New Guinea.₂.

They used genome sequencing and mass spectrometry to determine the microbes and metabolites (small molecules produced by organisms that have various ecological functions) in each sample. They found that the amount of CO₂ As the ocean increased, the microbes and metabolites found in the reef macro-organism community became similar to those in the sediment, a phenomenon referred to as the collapse of „holobiont community specificity.”

The findings suggest that the way microbial communities are altered by macro-organisms can be used as an early indicator of environmental stress. They also highlight the importance of taking an 'ecological approach' to understanding the impact of human pressures.

Environmental stress

The new result is limited to one ecosystem under one source of stress (acidification), so the team is now testing this approach at more than 80 reef sites around the world that are subject to various human stressors.

First author Jack Williams, from the Department of Life Sciences at Imperial and ZSL's Institute of Zoology, said: „Intensification of human activities and climate crisis are increasing pressure on ecosystems around the world. But we lack common and robust ways of monitoring this pressure and how ecosystems are responding.

„Our findings suggest the possibility of developing such general and robust metrics based on the relationships between microbes and chemicals. Ideally, these metrics should not depend on what type of ecosystem you're looking at, but apply to every system. From coral reefs to rainforests.”

Lead researcher from the Department of Life Sciences at Imperial, Dr. Emma Ransom added, „A holistic approach is needed to accurately assess and predict impacts on coral reefs. Microbes are the most important and overlooked components of all our ecosystems. They are instrumental in understanding environmental impacts and achieving an ecologically sustainable future.”