Size doesn’t matter in ecosystem resilience, study in PNAS shows

Mangrove forests were once dominant in the tropics, but they have disappeared at alarming rates around the world. Little is known, however, about the impact of this deforestation on the functional diversity and resilience of resident fauna. A team including Farid Dahdouh-Guebas of VUB’s Ecology & Biodiversity Research Unit Researchers addressed this question and found that mangroves have among the lowest faunal diversity of any of the planet’s ecosystems, making them especially vulnerable to environmental change. The study i s published in PNAS, the Proceedings of the National Academy of Sciences of the United States of America.

Farid Dahdouh-Guebas: "The findings suggest that studying the diversity may be a better measure of mangrove resilience than the conventional indicator of forest size. This is crucial for designing effective management and conservation plans."

The research team compiled a dataset of crustaceans and molluscs from 16 mangrove forests around the world. They classified 209 crustacean and 155 mollusc species into 64 functional entities based on unique combinations of three traits: feeding habits, behavioural traits potentially affecting ecosystem characteristics, and micro-habitat position.

More than 60% of the locations studied showed no functional redundancy on average, i.e., most of the entities at those locations consisted of only one species, with notable exceptions in South America, the eastern Indian Ocean and western Pacific Ocean. On average, 57% of the functional entities are represented by a single species, suggesting that even a modest local loss of invertebrate diversity could have significant negative consequences for mangrove functionality and resilience.

Some small mangrove patches, such as those in Hong Kong and Mozambique, harbour multifunctional invertebrate clusters that may serve as biodiversity reservoirs, which could prove critical for future conservation efforts. By contrast, some large forests, such as those in Cameroon, were characterised by low invertebrate functional diversity.

"It was the late VUB-Prof. Philip Polk, prominent biologist and advocate of marine scientific research in Belgium, who established the mangrove zoology research link between VUB and UNIFI, the home university of first author Stefano Cannicci. I did my Erasmus exhange there back in 1993 and then visited my first mangroves in Kenya", reminisces Prof. Dahdouh-Guebas. "It is since that time nearly 30 years ago, and for many more fieldwork expeditions, that data were collected that made this data mining paper possible."

Farid Dahdouh-Guebas +32 486 213 888 (via whatsapp only - in Kenya) Lies Feron Persrelaties Vrije Universiteit Brussel Vrije Universiteit Brussel is an internationally oriented university in Brussels, the heart of Europe. By providing excellent research and education on a human scale, VUB wants to make an active and committed contribution to a better society.

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