It couldn’t have been us!

29 05 2012

A few months ago I asked Chris Johnson of the University of Tasmania to put together a post on his recent Science paper regarding Australian megafaunal extinctions. It seems that it stirred, yet again, some controversy among those who refuse to accept (mainly archaeologists) that humans could have had anything to do with pre-European extinctions. Indeed, how could humans possibly have anything to do with extinctions?!

Like Corey, I am mainly interested in current environmental problems. But now and then I wade into the debate over the extinction of Australia’s Pleistocene megafauna [editor’s note: Chris literally wrote the book on Australian mammal extinctions over the last 50,000 years], those huge animals that wandered over the Australian landscape until about 40,000 years ago.

This is an endlessly fascinating topic. The creatures were wonderful and bizarre – it’s great fun doing work that lets you think about marsupial lions, giant kangaroos, geese bigger than emus, echidnas the size of wombats, and the rest. The cause of their extinction is perhaps the biggest mystery, and the most vexed controversy, in the environmental history of Australia. And for reasons that I will explain in a minute, solving this mystery is profoundly important for our understanding of contemporary Australian ecology.

The latest bit of work on this is a paper that a group of us (including Corey’s close colleague, Barry Brook) published in Science. You can see it here (if you don’t have access to Science, email me for a copy). So far, research on this problem has concentrated on dating fossils to find out when megafauna species went extinct. Several recent studies have found evidence for extinction between 40,000 and 50,000 years ago, which is about when people first came to Australia. But the conclusion that people caused a mass extinction of megafauna has been strenuously criticised, because so far it is based on only a few species with good collections of dates. The critics argue that other species disappeared before humans arrived, maybe in an extended series of extinctions caused by something else, like a deteriorating climate.

This argument over fossils will be with us for a long time. Because finding and dating fossils is such hard, slow work, the fossil record will inevitably give a seriously incomplete picture of what happened. One way around this problem would be to analyse the fossil record using mathematical approaches that take into account the problem of incomplete sampling. Corey is lead author of a recent paper that introduced a great new set of tools for this, and we are part of a group that is currently assembling a complete database of all recent dates on Australian fossils so that we can analyse them using these tools. Stay tuned for the result. Read the rest of this entry »

Ghosts of bottlenecks past

25 05 2012

© D. Bathory

I’ve just spent the last week at beautiful Linnaeus Estate on the northern NSW coast for my third Australian Centre for Ecological Analysis and Synthesis (ACEAS) (see previous post about my last ACEAS workshop).

This workshop is a little different to my last one, and I’m merely a participant (not the organiser) this time. Our task was to examine the mounting evidence that many Australian species appear to show a rather shallow genetic pool from a (or several) major past bottlenecks.

What’s a ‘bottleneck’? In reference to the form after which it was named, a genetic bottleneck is the genetic diversity aftermath after a population declines to a small size and then later expands. The history of this reduction and subsequent expansion is written in the DNA, because inevitably gene ‘types’ are lost as most individuals shuffle off this mortal coil. In a way, it’s like losing a large population of people who all speak different languages – inevitably, you’d lose entire languages and the recovering population would grow out of a reduced ‘pool’ of languages, resulting in fewer overall surviving languages.

Our workshop focus started, as many scientific endeavours do, rather serendipitously. Several years ago, Jeremy Austin noticed that devils who had died out on the mainland several thousand years ago had a very low genetic diversity, as do modern-day devils surviving in Tasmania. He thought it was odd because they should have had more on the mainland given that was their principal distribution prior to Europeans arriving. He mentioned this in passing to Steve Donnellan one day and Steve announced that he had seem the same pattern in echidnas. Now, echidnas cover most of Australia’s surface, so that was equally odd. Then they decided to look at another widespread species – tiger snakes, emus, etc. – and found in many of them, the same patterns were there. Read the rest of this entry »

Can Australia afford the dingo fence?

18 05 2012

I wrote this last night with Euan Ritchie of Deakin University in response to some pretty shoddy journalism that misrepresented my comments (and Euan’s work). Our article appeared first in The Conversation this morning (see original article).

We feel we have to set the record straight after some of our (Bradshaw’s) comments were taken grossly out of context, or not considered at all (Ritchie’s). A bubbling kerfuffle in the media over the last week compels us to establish some facts about dingoes in Australia, and more importantly, about how we as a nation choose to manage them.

A small article in the News Ltd. Adelaide Advertiser appeared on 11 May in which one of us (Bradshaw) was quoted as advocating the removal of the dingo fence because it was not “cost effective” (sic). Despite nearly 20 minutes on the telephone explaining to the paper the complexities of feral animal management, the role of dingoes in suppressing feral predators, and the “costs” associated with biodiversity enhancement and feral control, there wasn’t a single mention of any of this background or justification.

Another News Ltd. article denouncing Ritchie’s work on the role of predators in Australian ecosystems appeared in The Weekly Times the day before, to which Ritchie responded in full.

So it’s damage control, and mainly because we want to state categorically that our opinion is ours alone, and not that of our respective universities, schools, institutes or even Biosecurity SA (which some have claimed or insinuated, falsely, that we represent). Biosecurity SA is responsible for, inter alia, the dingo fence in South Australia. Although our opinions differ on its role, we are deeply impressed, grateful and supportive of their work in defending us from biological problems. Read the rest of this entry »

Conservation value of paddy wagon currency: civil disobedience by scientists

12 05 2012

A couple of years ago, James Hansen visited Adelaide and I was fortunate enough to attend dinner with him and his lovely wife Anniek. A truly inspiring scientist in all respects. His academic track record is unbeatable, and he puts his money where his mouth is in terms of climate change activism.

In a similar vein, but something I’m not used to publishing on Conservation Bytes, my colleague Alejandro Frid requested I publish his essay here. I’m a firm advocate for standing up for evidence-based policy, and Alejandro (inspired by James Hansen), shows us how it’s done.

I am addressing this letter to colleagues with research careers because I am compelled to share what I learned recently by crossing a new threshold. For years I have been talking and writing about the climate change crisis. As intellectually rewarding and therapeutic as it has been, these letters to government, meetings with Members of [the Canadian] Parliament, and articles for conservation-minded audiences have accomplished nothing of substance.

Others feel similarly. Prominent academics, fed up with governments that ignore science and heed the priorities of corporations, have turned to civil disobedience. James Hansen, a senior climate scientist with NASA’s Goddard Institute for Space Studies, led by example last year when he got himself arrested in front of the USA’s Whitehouse to protest the proposed Keystone Pipeline that would carry oil from the Alberta Tar Sands to the USA. That was his third arrest in three years; the previous two involved civil disobedience against the mining of coal, a huge contributor to greenhouse gases.

In the wake of Hansen’s arrests, on 05 May 2012, Mark Jaccard—a prominent economist, IPCC member, and professor at the Energy and Materials Research Group of Simon Fraser University—got himself arrested in White Rock, British Columbia, for blocking a coal train carrying US coal for export to China via British Columbia ports. There were 12 others with Jaccard, among them a man in his 80s, several men in their 60s and 70s, and a few youngsters like myself and my good friend Lynne Quarmby. Lynne happens to be chair of the Department of Molecular Biology at Simon Fraser University.

Shortly before the arrest, as we sat on the tracks, I told Jaccard that I had been teetering on the decision to come, but his announcement to participate sealed my decision. Jaccard replied that, given what he knew about the climate crisis and the consequences of inaction, it was impossible for him to not be here. He was echoing sentiments shared by all 13 of us on the tracks. Later, as we were released from jail, Jaccard wondered out loud whether the arrest would affect his ability to travel for work. Then he said something to the effect that, “You can forever come up with excuses, or you can get real and just do it.”

Read the rest of this entry »

No more ecology

9 05 2012

To all ecology people who read this blog (students, post-docs, academics), this is an intriguing, provocative and slightly worrying title. As ecology has matured into a full-fledged, hard-core, mathematical science on par with physics, chemistry and genetics (and is arguably today one of the most important sciences given how badly we’ve trashed our own home), its sophistication now threatens to render many of the traditional aspects of ecology redundant.

Let me explain.

As a person who cut his teeth in field ecology (with all the associated dirt, dangers, bites, stings, discomfort, thrills, headaches and disasters), I’ve had my fair share of fun and excitement collecting ecological data. There’s something quaintly Victorian (no, I am not referring to the state next door) about the romantic and obsessive naturalist collecting data to the exclusion of nearly all other aspects of civilised life; the intrepid adventurer in some of us takes over (likely influenced by the likes of David Attenborough) and we convince ourselves that our quest for the lonely datum will heal all of the Earth’s ailments.


As I’ve matured in ecology and embraced its mathematical complexity and beauty, the recurring dilemma is that there are never enough data to answer the really big questions. We have sampled only a fraction of extant species, we know embarrassingly little about how ecosystems respond to disturbance, and we know next to nothing about the complexities of ecosystem services. And let’s not forget our infancy in understanding the synergies of extinctions in the past and projections into the future. Multiply this uncertainty by several orders of magnitude for ocean ecosystems.

Read the rest of this entry »

Sharks: the world’s custodians of fisheries

5 05 2012

Today’s post comes from Salvador Herrando-Pérez (who, incidentally, recently submitted his excellent PhD thesis).

Three species co-occurring in the Gulf of Mexico and involved in the trophic cascade examined by Myers et al. (8). [1] Black-tips (Carcharhinus limbatus) are pelagic sharks in warm and tropical waters worldwide; they reach < 3 m in length, 125 kg in weight, with a maximum longevity in the wild of ~ 12 years; a viviparous species, with females delivering up to 10 offspring per parturition. [2] The cownose ray (Rhinoptera bonasus) is a tropical species from the western Atlantic (USA to Brazil); up to 2 m wide, 50 kg in weight, and 18 years of age; gregarious, migratory and viviparous, with one single offspring per litter. [3] The bay scallop (Agropecten irradians) is a protandric (hermaphrodite) mollusc, with sperm being released a few days before the (> 1 million) eggs; commonly associated with seagrasses in the north-western Atlantic; shells can reach up to 10 cm and individuals live for < 2 years. In the photos, a black-tip angled in a bottom long-line off Alabama (USA), a school of cownose rays swimming along Fort Walton Beach (Florida, USA), and a bay scallop among fronds of turtle grass (Thalassia testudinum) off Hernando County (Florida, USA). Photos by Marcus Drymon, Dorothy Birch and Janessa Cobb, respectively.

The hips of John Travolta, the sword of Luke Skywalker, and the teeth of Jaws marked an era. I still get goose pimples with the movie soundtrack (bass, tuba, orchestra… silence) solemnizing each of the big shark’s attacks. The media and cinema have created the myth of man’s worst friend. This partly explains why shark fishing does not trigger the same societal rejection as the hunting of other colossuses such as whales or elephants. Some authors contend that we currently live in the sixth massive extinction event of planet Earth (1) 75 % of which is strongly driven by one species, humans, and characterized by the systematic disappearance of mega-animals in general (e.g., mammoths, Steller’s seacow), and predators in particular, e.g., sharks (2, 3).

The selective extirpation of apex predators, recently coined as ‘trophic downgrading’, is transforming habitat structure and species composition of many ecosystems worldwide (4). In the marine realm, over the last half a century, the main target of the world’s fisheries has turned from (oft-large body-sized) piscivorous to planctivorous fish and invertebrates, indicating that fishery fleets are exploiting a trophic level down to collapse, then harvesting the next lower trophic level (5-7).

Myers et al. (8) illustrate the problem with the fisheries of apex-predator sharks in the northeastern coast of the USA. Those Atlantic waters are rife with many species of shark (> 2 m), whose main prey are smaller chondrichthyans (skates, rays, catsharks, sharks), which in turn prey on bottom fishes and bivalves. Myers et al. (8) found that, over the last three decades, the abundance of seven species of large sharks declined by ~ 90 %, coinciding with the crash of a centenary fishery of bay scallops (Agropecten irradians). Conversely, the abundance of 12 smaller chondrichthyes increased dramatically over the same period of time. In particular, the cownose ray (Rhinoptera bonasus), the principal predator of bay scallops, might today exceed > 40 million individuals in some bays, and consume up to ~ 840,000 tonnes of scallops annually. The obvious hypothesis is that the reduction of apex sharks triggers the boom of small chondrichthyans, hence leading to the break-down of scallop stocks. Read the rest of this entry »

If a tree falls… preventing deforestation with insurance

3 05 2012

As CB readers will know, I’ve reported a few times on our iREDD idea, and it got a little pick-up overseas. Here’s a great article by Rachel Nuwer covering the concept, published in

Almost everything we own – our houses and cars and our very health – is insured. It works on a simple principal: the higher the risk, the higher the premium. It’s an age-old concept that ecological modelers have decided to apply to a new area: forest preservation.

A new proposal, published in the journal Conservation Letters, would create forest insurance to make the U.N. forest preservation program Reduced Emissions from Deforestation and forest Degradation, or REDD, more effective. REDD is generally supposed to function by paying developing countries to protect their forests in exchange for carbon pollution credits. Currently the program has 42 partner countries across the globe. The program is crucial to the fight against climate change since deforestation and forest degradation accounts for about 20 percent of global greenhouse gas emissions and threatens biodiversity.

“REDD is a fantastic idea,” said Corey Bradshaw, director of ecological modeling at the University of Adelaide and co-author of the study. “You get a carbon advantage and biodiversity doesn’t get wiped out at the same time, it seems perfect.”

But it has a few major flaws that the insurance scheme, called iREDD, seeks to remedy.

REDD only works if the parties are honest and stick to the agreement. Bradshaw doesn’t have much faith that will happen. “If there’s a way to cheat, people will cheat. That’s the nature of all life, not just humans, but we excel at it,” he said. If, for example, a country is paid to conserve one forest but moves its deforestation efforts to an adjacent forest in order to get both money and timber, in terms of carbon offsets, that transaction was a failure. This phenomenon is called “leakage.”

Carbon-capture also only works if it’s maintained indefinitely. If a country accepts money for ten years and then cuts its forest the day after the agreement expires, then all of that conservation was for naught. This issue is called “permanence,” usually translated into an arbitrarily defined period of time set by countries in terms of decades or centuries. Read the rest of this entry »