Conservationists are increasingly moving imperilled marine plants and animals to new locations to prevent species and ecosystems from dying out, according to the first global review of marine conservation translocations, co-authored by IUCN’s Dr Axel Moehrenschlager.
Conservation translocations are being used to boost marine species such as sea otters, oysters, corals or seagrasses, mostly to reinforce depleted populations or reintroduce species where they have become locally extinct, the review found.
“Translocations in oceans are on the rise, particularly in coastal environments, where human impacts are greatest. There is a critical need to prevent the collapse of coastal ecosystems such as coral reefs, mangrove forests, and seagrass meadows, given the great importance of these habitats to marine species and to people,” said Dr. Axel Moehrenschlager, Chair of IUCN’s Species Survival Commission Reintroduction Specialist Group.
Around two-thirds of the projects examined by the review focused on conserving whole ecosystems rather than individual species, with ‘ecosystem engineer species’ such as corals or mangroves common. These species provide foraging and nursery habitat for many others, so ‘planting’ them in a new location can recreate an entire ecosystem. Planting corals onto denuded reefs to allow them to recolonise the area and rebuild a habitat for other species is one example.
The technique also involves risks, however, especially when species are moved to new habitats where they have never been found in the past, the authors said. If not carefully planned, these 'assisted colonisations' could disturb population dynamics or introduce diseases.
In rare cases, a species can be moved to an entirely new habitat to replace another, extinct, species – a process known as ‘ecological replacement.’ The review noted only a single such case, where the yellow crowned night heron was brought in to fulfil the role of the extinct Bermuda night heron in keeping crab numbers in check on the island.
To minimise the risks and ensure translocations are implemented responsibly, governments should adopt IUCN Guidelines for Reintroductions and Other Conservation Translocations, the authors suggested.
They also warned that translocations will not prevent the disappearance of many marine species and ecosystems without adequate action to tackle habitat destruction, carbon dioxide pollution, climate change and overfishing.
The review, a collaboration between Canada’s Calgary Zoological Society and New Zealand’s University of Otago, due to appear in Conservation Letters, is based on a comprehensive search for marine translocation publications over the years 1883 - 2013. It identified 487 marine translocation projects (involving 242 species) motivated by conservation objectives over that period, the earliest involving seagrasses being planted in Atlantic North America in 1947, and an increasing frequency of such efforts since.
While only a fraction of marine species have been assessed to date, 1,206 marine species are classified as critically endangered, endangered or vulnerable on the IUCN Red List.