From left: Australian Rivers Institutes Dr Jan Warnken and Ms Shafagh Kamal, HDR student, Professor Shing Yip LeeAccording to marine ecologists, mangroves may be endangered by a small number of crustaceans and molluscs for each ecological function.An international study has shown that even a small loss of invertebrates can have serious consequences.Professor Shing Yip, from the Chinese University of Hong Kong, and Adjunct to the Australian Rivers Institute at Griffith University said that mangrove forests are disappearing at alarming rate worldwide."The relationships between individual animal and plant components determine the ecological functions and services they provide."A healthy community of invertebrates is essential for sustaining a mangrove forest that is viable"Mangrove ecosystems are home to a wide range of specialist invertebrates. However, very little is known about how deforestation and the human impact can affect the functional diversity of these fauna.The team created a database of 209 and 155 mollusc species, from 16 mangrove forests across the globe, to answer this question. When compared to other ecosystems, mangroves had the lowest number of animals fulfilling the same ecological function.Professor Lee stated that a high level of functional redundancy can be a kind of "ecological insurance" for a forest because if one species dies, another can fulfill its function, keeping the ecosystem alive."The low redundancy in mangrove invertebrates indicates that the coastal vegetations are one the most fragile ecosystems in the globe in the face the recent anthropogenic change."Based on their feeding habits, behaviour traits and micro-habitat, the authors divided the species into 64 functional categories.The functional redundancy of more than 60% of sites was not evident, which means that only one species could fill each functional niche.Professor Lee stated that even a small loss invertebrate diversity can have serious consequences on mangrove resilience and functionality. Invertebrates are essential for nutrient cycling as well as providing oxygen to tree roots.Mangrove forests are not able to function without local invertebrate fauna. This will rob humanity of many of their valuable services. A few patches of mangrove with more invertebrates in each ecological niche, like those in Hong Kong or Mozambique may be critical biodiversity reservoirs that will help to ensure future conservation efforts.It is essential to study the functional diversity of resident animals in mangrove forests. This will help determine the vulnerability of these forests to environmental change."The current assessment of the health and resilience mangrove forests worldwide is based on their area growth. However, this method doesn't take into account the true viability or functionality of these forests."Our findings suggest that the traditional indicator of forest size, which is based on faunal functional diversity, may not be as good a measure of mangrove resilience as it was ours.""Mangrove management and rehabilitation projects must consider not only the growth in mangrove size, but also the stability or redundancy its faunal component."The Proceedings of the National Academy of Sciences (PNAS) published the findings.Explore more Mangrove forests are more diverse and store more carbon.More information: Stefano Cannicci and colleagues, A functional analysis uncovers extremely low redundancy worldwide mangrove invertebrate fauna. Proceedings of the National Academy of Sciences (2021). Information for the Journal: Proceedings of National Academy of Sciences Stefano Cianicci et. al., A functional analysis uncovers extremely low redundancy among global mangrove invertebrate species, (2021). DOI: 10.1073/pnas.2016913118
