Research from Swansea University indicates that when the marine megafauna that is threatened with extinction today goes extinct it could result in a much larger deterioration of the functional diversity of the ecosystem as previously expected.
Scientists define marine megafauna as animals with a body mass of 45 kilograms or over. At this moment 4 out of 10 species of marine megafauna are threatened with extinction, mainly due to overfishing and ecological impact from human activity. Marine megafauna is divided into 40% bony Fishes, 20% sharks and rays, 36% mammals like whales and dolphins, and the rest of animals like penguins and giant oysters.
These animals play a key role in balancing the ecosystem. They eat a large amount of biomass, like plankton and seaweeds, and bring nutrients from one place to another by e.g. excretion.
The researchers made a computer stimulation of different extinction models of marine biofauna and used it to gauge the possible effects on the entire ecosystems. In the first model the team of scientists followed the current trajectories of extinction. Following this model would mean that 18% of species go extinct and 11% of ecological functions are lost within the next 100 year. In a worst case scenario where all threatened species were to go extinct, 40% of the species are extinct and 48% of ecological funcions are lost.
Dr. John Griffin, a co-author on the team researching the effects of the possible extinction of marine megafauna of the Swansea University says: “Our results show that among the largest animals in the oceans, this so-called “redundancy” is very limited — even when you roll in groups from mammals to mollusks. If we lose species, we lose unique ecological functions. This is a warning that we need to act now to reduce growing human pressures on marine megafauna, including climate change while nurturing population recoveries.”
Citation: BY C. PIMIENTO, F. LEPRIEUR, D. SILVESTRO, J. S. LEFCHECK, C. ALBOUY, D. B. RASHER, M. DAVIS, J.-C. SVENNING, J. N. GRIFFIN SCIENCE ADVANCES17 APR 2020: EAAY7650