My most recent piece for RiAus 🙂
The story of the cane toad is one of many from history that involves the misguided introduction of exotic animals to vulnerable areas. When Europeans first arrived in Australia they missed the sights and sounds of the homeland and brought over many animals for familiarity and comfort, some of which are now considered to be the most destructive in Australia. But the deliberate introductions of animals for aesthetics and agriculture are not the only pathways for invasive species. Lots of organisms sneak through customs and immigration as stowaways and by human carelessness.
As we reported in our article in the journal PLOS ONE this year, paradise destination Lord Howe Island has become yet another recent victim of the carelessness of trade and transport. The World Heritage listed group of islands comprises stunning volcanic mountains surrounded by the world’s most southern coral reef. It sits several hundred kilometres off the coast of New South Wales and is home to only a few hundred residents that work in tourism and local industries.
Far-flung islands like Lord Howe are frequently protected by the vast oceans that surround them, but the isolation that protects them also makes them vulnerable. Volcanic islands rise from the sea and the animals and plants that live there are restricted from breeding with organisms on the mainland. In many cases, wildlife on remote volcanic islands is endemic – meaning it’s found there and nowhere else. Lord Howe Island has remained largely pristine since it was settled, with lots of untouched forest and a lagoon teeming with wildlife. Sadly though, lots of the endemic wildlife of Lord Howe has been devastated by introduced animals.
Despite this knowledge, the march of invasive animals continues. The bleating tree frog, a small noisy amphibian from south-eastern Australia, was introduced to Lord Howe Island accidentally – likely with a boat load of supplies, in the 1990s. To investigate how the frog got to the island, we took genetic samples from the Lord Howe population of frogs and compared them with the genetic information of the bleating tree frogs on the mainland to find their closest relatives. We were able to determine that the Lord Howe Island population originated in northern coastal New South Wales. While we were there we also collected data on the distribution of the frogs across Lord Howe Island, their breeding activity and habitat use. We found that the frog is widespread and successfully making use of most habitats on the island, including the forested areas, cattle pastures and buildings.
Due to their intolerance of seawater, amphibians are rare on volcanic islands such as Lord Howe. They must be introduced by humans to be able to colonise such isolated places. The bleating tree frog has been the only frog that has successfully invaded Lord Howe Island so far, but without careful consideration for the future, other animals may follow its path. Although it remains to be seen if the bleating tree frog will be a disaster to the Lord Howe Island wildlife, scientists continue to call for greater biosecurity controls and awareness to help prevent further animals and plants slipping through the net and destroying native systems.
Citation: Plenderleith TL, Smith KL, Donnellan SC, Reina RD, Chapple DG (2015) Human-Assisted Invasions of Pacific Islands by Litoria Frogs: A Case Study of the Bleating Tree Frog on Lord Howe Island. PLoS ONE 10(5): e0126287. doi:10.1371/journal. pone.0126287
This work is published in an open access journal, which means anybody can read it! Find it here.
Celebrate biodiversity on its own international day!
Finishing up a Ph.D. takes up valuable blogging time. I did manage to squeeze this in for RiAus though:
Sharks swim in human-infested waters. Our fair weather relationship with the sea, our disrespect for our marine environment and our fear of the unknown, fuelled by media sensationalism puts undue stress on all ocean-going creatures. More recently, sharks have taken the brunt of this issue*, to the point where we have started to appease swimmers with inhumane and unethical treatments of sea life, causing death, disruption and suffering. All this, despite opposition from marine biology experts.
Sharks do not represent a real risk to us; even when we swim in their habitat. Not a real risk. A quick browse of the The International Shark Attack File will show how small the risk really is. Not like driving a car or getting married (to someone who might kill or injure you) and certainly not like cigarettes or fatty food. The act of swimming in the ocean is more likely to kill you through drowning than shark attacks.
Killing sharks offers a visible reduction in their numbers and therefore a perceived reduction in the perceived threat. Rare, endangered species (such as white sharks) are actually targets of the programmes. It also reduces numbers of all animal “bycatch”. Sometimes more so than the target species, as recognised by the authorities that continue to implement the programmes.
Sharks are bioindicators (a living being, or group thereof, that signifies the health of an ecosystem). They eat dead matter in the oceans. They are incredibly diverse. They perform the tasks of an apex predator, keeping the species below them in the food web healthy and in equilibrium. Sharks are more useful than the credit they are afforded. Sharks are more important than I have space to write.
A recent study showed that sharks could be removed and released, safely and successfully whilst reducing shark attacks and eliminating the need for killing, inhumane or otherwise. The location of the study, Brazil, has one of the largest number of shark attacks in the world and this is a promising step in reducing shark attacks and respect for the life of our oceans.
We need sharks more than we realise, but perhaps more importantly, right now they need us. So spread the word about the low low risk of shark attacks. Sign petitions to stop the drumlines and write to your politicians about reducing the harm we are doing to the oceans. We will miss them if they go.
*Most of this research appears to be open access (which means you can read it for yourself) and I implore you to see what the scientists have to say on the issues addressed briefly here.
Hazin, F. H. V. & Afonso, A. S. (2014) Response: A conservation approach to prevention of shark attacks off Recife, Brazil. Animal Conservation, 17(4), 301-302.
House, D. (2014). Western Australian Shark Hazard Mitigation Drum Line Program 2014-17.
Meeuwig, J. J., & Ferreira, L. C. (2014). Moving beyond lethal programs for shark hazard mitigation. Animal Conservation, 17(4), 297-298.
Shiffman, D. (2014). Keeping swimmers safe without killing sharks is a revolution in shark control. Animal Conservation, 17(4), 299-300
P.S. I make no excuse for three marine-centric articles in a row. The saltwater portion of our planet is the most significant, the most endangered and the least known. Because we don’t live within its limits we are foolish enough not to protect it to the standards we should.
Lord John Krebs is a scientist for whom I have the utmost respect. This interview is definitely worth a listen. It starts by talking to Lord Krebs about his career and then asks his professional opinion of the badger culls. He raises some very interesting points about sample size and unreported data (namely the effect of the culls outside the study area).
All in all, this harks back to my original point that with or without badger culls, more has to change to help prevent diseases and improve conditions in farming methods everywhere.