Bright spots take out top science prize
A team of scientists led by the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) won one of the nation’s top science awards at tonight’s ‘Oscars of Australian science’, the Eureka P
Understanding of the links between coral reef ecosystems, the goods and services they provide to people, and the wellbeing of human societies.
Examining the multi-scale dynamics of reefs, from population dynamics to macroevolution
Advancing the fundamental understanding of the key processes underpinning reef resilience.
ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia
Phone: 61 7 4781 4000
Rat control should be considered an urgent conservation priority on many remote tropical islands to protect vulnerable coral reefs, according to an international team of scientists.
New research has confirmed that invasive rats decimate seabird populations, with previously unrecognised consequences for the extensive coral reefs that encircle and protect these islands.
Invasive predators such as rats – which feed on bird eggs, chicks, and even adults birds – are estimated to have decimated seabird populations within 90% of the world’s temperate and tropical island groups, but until now the extent of their impact on surrounding coral reefs wasn’t known.
The new study, led by researchers at Lancaster University (UK), ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University and Dalhousie University (Canada), examined tropical ecosystems in the northern atolls of the Chagos Archipelago to uncover how rats have impacted surrounding reefs.
Lead author Professor Nick Graham of Lancaster University, said: “Seabirds are crucial to these kinds of islands because they are able to fly to highly productive areas of open ocean to feed. They then return to their island homes where they roost and breed, depositing guano – or bird droppings – on the soil. This guano is rich in the nutrients, nitrogen and phosphorus. Until now, we didn’t know to what extent this made a difference to adjacent coral reefs.”
An extraordinary set of remote tropical islands in the central Indian Ocean, the Chagos islands provided a perfect ‘laboratory’ setting as some of the islands are rat-free, while others are infested with black rats – thought to have been introduced in the late 1700s and early 1800s. This unusual context enabled the researchers to undertake a unique, large-scale study directly comparing the reef ecosystems around these two types of islands.
By examining soil samples, algae, and counting fish numbers close to the six rat-free and six rat-infested islands, scientists uncovered evidence of severe ecological harm caused by the rats, which extended way beyond the islands and into the sea.
Rat-free islands had significantly more seabird life and nitrogen in their soils, and this increased nitrogen made its way into the sea, benefiting macroalgae, filter-feeding sponges, turf algae, and fish on adjacent coral reefs.
Fish life adjacent to rat-free islands was far more abundant with the mass of fish estimated to be 50% greater.
The team also found that grazing of algae – an important function where fish consume algae and dead coral, providing a stable base for new coral growth – was 3.2 times higher adjacent to rat free islands.
“These results not only show the dramatic effect that rats can have on the composition of biological communities, but also on the way these vulnerable ecosystems function (or operate),” said co-author Dr Andrew Hoey from Coral CoE at James Cook University.
“Critically, reductions in two key ecosystem functions (grazing and bioerosion) will likely compromise the ability of these reefs to recover from future disturbances.”
Professor Graham said: “The results of this study are clear. Rat eradication should be a high conservation priority on oceanic islands. Getting rid of the rats would be likely to benefit terrestrial ecosystems and enhance coral reef productivity and functioning by restoring seabird derived nutrient subsidies from large areas of ocean. It could tip the balance for the future survival of these reefs and their ecosystems.”
Associate Professor Aaron MacNeil from Dalhousie University said: “These results show how conservation can sometimes be a bloody business, where doing right by the ecosystem means there is a time to kill. For these invasive rats, that time is now.”
The paper “Seabirds enhance coral reef productivity and functioning in the absence of invasive rats,” is published in the prestigious journal Nature.
The research was led by Lancaster University (UK) with the ARC Centre of Excellence for Coral Reef Studies (Australia), Dalhousie University (Canada), Department of Biodiversity, Conservation and Attractions, Perth, Australia, University of Western Australia, Australia, Zoological Society of London, UK, University of Exeter, UK, and the International Council for the Exploration of the Sea, Denmark.
Note to Editors
Additional key points from the study:
Citation: Graham, NAJ, Wilson, SK, Carr, P, Hoey, AS, Jennings, S, MacNeil, MA (2018), Seabirds enhance coral reef productivity and functioning in the absence of invasive rats. Nature 559: 250-253
Link to video and images here. Please credit as marked.
Contacts for interviews
Prof Nick Graham
Lancaster University, Lancaster Environment Centre
P: +44 (0) 7479 438 914 (GMT/UTC)
Dr Andrew Hoey
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Townsville, QLD AUSTRALIA
P: +61 7 4781 5979 (AEST/UTC +10)
A/Prof Aaron MacNeil
Dalhousie University, Department of Biology
Halifax, NS, CANADA
P: +1 902 402-1273 (ADT/UTC -3)
For further information
Beth Broomby (U.K.)
Head of Press Office, Lancaster University
P: +44 (0) 1524 593719, +44 (0) 7881 813 831 (GMT/UTC)
Catherine Naum (AUSTRALIA)
Communications Manager, ARC Centre of Excellence for Coral Reef Studies
P: +61 (0) 7 4781 6067, +61 (0) 428 785 895 (AEST/UTC +10)
Niecole Comeau (CANADA)
Communications, Faculty of Science, Dalhousie University
P: +1 (902) 494-8443, +1 (902) 223-2446 (ADT/UCT -3)
An analytical tool will be used to assess the climate risks facing historic World Heritage sites in Africa—the ruins of two great 13th century ports and the remains of a palace and iron-making indus
A world-first study on the Great Barrier Reef shows crown-of-thorns starfish have the ability to find their own way home—a behaviour previously undocumented—but only if their neighbourhood is stoc
An international team of scientists has found leaving more big fish in the sea reduces the amount of carbon dioxide (CO2) released into the Earth’s atmosphere. When a fish dies in the ocean it si
Abstract: Invasive species management can be the the subject of debate in many countries due to conflicting ecological, ethical, economic, and social reasons, especially when dealing with a species s
Abstract: Ocean acidification, the increase in seawater CO2 with all its associated consequences, is relatively well understood in open oceans. In shelf seas such as the Great Barrier Reef, processe
Abstract: The backdrop of legends and movies, the deep sea has always been unfathomable because we had no idea what existed there. Once thought to be barren of life, we now know this couldn’t be
Abstract: Coral reefs provide economic and environmental services for millions of people but undergoing significant ecological decline due to local (i.e., sedimentation, land-based pollution, invas
Abstract: Increasing human populations around the world’s coastline have caused extensive loss, degradation and fragmentation of coastal ecosystems. Swift losses of coastal ecosystems have been rec
Abstract: CHE is not a particular theory or a single approach but a collection of lines of research that address human-environmental interactions in coastal and marine systems at the local scale
Abstract: How can we care about something we never see or experience? Virtual reality has the potential to connect people with far-away places, and is an effective medium to generate empathy and sel
James Cook University Townsville
Queensland 4811 Australia
Phone: 61 7 4781 4000