It’s not always best to be the big fish

3 02 2016

obrien_fish_2Loosely following the theme of last week’s post, it’s now fairly well established that humans tend to pick on the big species first.

From fewer big trees, declines of big carnivores, elephant & rhino poaching, to fishing down the web, big species tend to cop it hardest when it comes to human-caused ecological disturbance.

While there are a lot of different combinations of traits that make some species more vulnerable to extinction than others (see examples for legumes, amphibians, sharks & teleosts, and mammals), one of the main ones is species size.

Generally speaking, larger species tend to produce fewer offspring and breed later in life than smaller species. This means that despite larger species tending to live longer than their smaller counterparts, their ‘slow’ reproductive output means that they are generally more susceptible to rapid environmental change (mainly via human intervention). In other words, their capacity for self-replacement is often too low to counteract the offtake from direct exploitation or habitat loss.

Despite a reasonable scientific understanding of this extinction-risk principle, the degree to which human disturbance affects species’ distributions is much less well quantified, and this is especially true for marine species.

I’m proud to announce another fascinating paper led by my postdoc, Camille Mellin, that has just come out online in Nature CommunicationsHumans and seasonal climate variability threaten large-bodied coral reef fish with small ranges.

With the world’s largest combined dataset of coral reef fish surveys for the entire Indo-Pacific (including the coral reef fish biodiversity hotspot — the Coral Triangle), we examined which conditions best described the distribution of fishes over a range of body sizes. Read the rest of this entry »





No evidence climate change is to blame for Australian megafauna extinctions

29 01 2016

bw spear throwingLast July I wrote about a Science paper of ours demonstrating that there was a climate-change signal in the overall extinction pattern of megafauna across the Northern Hemisphere between about 50,000 and 10,000 years ago. In that case, it didn’t have anything to do with ice ages (sorry, Blue Sky Studios); rather, it was abrupt warming periods that exacerbated the extinction pulse instigated by human hunting.

Contrary to some appallingly researched media reports, we never claimed that these extinctions arose only from warming, because the evidence is more than clear that humans were the dominant drivers across North America, Europe and northern Asia; we simply demonstrated that warming periods had a role to play too.

A cursory glance at the title of this post without appreciating the complexity of how extinctions happen might lead you to think that we’re all over the shop with the role of climate change. Nothing could be farther from the truth.

Instead, we report what the evidence actually says, instead of making up stories to suit our preconceptions.

So it is with great pleasure that I report our new paper just out in Nature Communications, led by my affable French postdoc, Dr Frédérik SaltréClimate change not to blame for late Quaternary megafauna extinctions in Australia.

Of course, it was a huge collaborative effort by a crack team of ecologists, palaeontologists, geochronologists, paleo-climatologists, archaeologists and geneticists. Only by combining the efforts of this diverse and transdisciplinary team could we have hoped to achieve what we did. Read the rest of this entry »





Getting your conservation science to the right people

22 01 2016

argument-cartoon-yellingA perennial lament of nearly every conservation scientist — at least at some point (often later in one’s career) — is that the years of blood, sweat and tears spent to obtain those precious results count for nought in terms of improving real biodiversity conservation.

Conservation scientists often claim, especially in the first and last paragraphs of their papers and research proposals, that by collecting such-and-such data and doing such-and-such analyses they will transform how we manage landscapes and species to the overall betterment of biodiversity. Unfortunately, most of these claims are hollow (or just plain bullshit) because the results are either: (i) never read by people who actually make conservation decisions, (ii) not understood by them even if they read the work, or (iii) never implemented because they are too vague or too unrealistic to translate into a tangible, positive shift in policy.

A depressing state of being, I know.

This isn’t any sort of novel revelation, for we’ve been discussing the divide between policy makers and scientists for donkey’s years. Regardless, the whinges can be summarised succinctly: Read the rest of this entry »





Outright bans of trophy hunting could do more harm than good

5 01 2016

In July 2015 an American dentist shot and killed a male lion called ‘Cecil’ with a hunting bow and arrow, an act that sparked a storm of social media outrage. Cecil was a favourite of tourists visiting Hwange National Park in Zimbabwe, and so the allegation that he was lured out of the Park to neighbouring farmland added considerable fuel to the flames of condemnation. Several other aspects of the hunt, such as baiting close to national park boundaries, were allegedly done illegally and against the spirit and ethical norms of a managed trophy hunt.

In May 2015, a Texan legally shot a critically endangered black rhino in Namibia, which also generated considerable online ire. The backlash ensued even though the male rhino was considered ‘surplus’ to Namibia’s black rhino populations, and the US$350,000 generated from the managed hunt was to be re-invested in conservation. Together, these two incidents have triggered vociferous appeals to ban trophy hunting throughout Africa.

These highly politicized events are but a small component of a large industry in Africa worth > US$215 million per year that ‘sells’ iconic animals to (mainly foreign) hunters as a means of generating otherwise scarce funds. While to most people this might seem like an abhorrent way to generate money, we argue in a new paper that sustainable-use activities, such as trophy hunting, can be an important tool in the conservationist’s toolbox. Conserving biodiversity can be expensive, so generating money is a central preoccupation of many environmental NGOs, conservation-minded individuals, government agencies and scientists. Making money for conservation in Africa is even more challenging, and so we argue that trophy hunting should and could fill some of that gap. Read the rest of this entry »





Game bird madness

4 11 2015

Gamecart_largeI just returned to Paris after a brief visit to the University of Aberdeen over the weekend. My hosts, Xavier Lambin and Beth Scott, were not only marvellously welcoming, I also learned a lot about the travesty that is game bird management in the United Kingdom, and especially in Scotland.

As you might already know, the Great Britons are a little cuckoo for birds — I’d even wager that the country produces more twitchers than any other country on Earth. The plus side is that there are few national taxa better censused and studied that British birds, because so many non-scientists get into the spirit of data collection. Hell, I’ve even had a play with some of their datasets.

The other side of this bird madness is not so good — I’m talking about the massive biomass of game birds reared, released and shot every year in the United Kingdom. It’s not the hunting per se with which I take issue, it’s the insane manipulation of an entire ecosystem for the benefit of a few species. Read the rest of this entry »





Ice Age? No. Abrupt warmings and hunting together polished off Holarctic megafauna

24 07 2015
Oh shit oh shit oh shit ...

Oh shit oh shit oh shit …

Did ice ages cause the Pleistocene megafauna to go extinct? Contrary to popular opinion, no, they didn’t. But climate change did have something to do with them, only it was global warming events instead.

Just out today in Science, our long-time-coming (9 years in total if you count the time from the original idea to today) paper ‘Abrupt warmings drove Late Pleistocene Holarctic megafaunal turnover‘ led by Alan Cooper of the Australian Centre for Ancient DNA and Chris Turney of the UNSW Climate Change Research Centre demonstrates for the first time that abrupt warming periods over the last 60,000 years were at least partially responsible for the collapse of the megafauna in Eurasia and North America.

You might recall that I’ve been a bit sceptical of claims that climate changes had much to do with megafauna extinctions during the Late Pleistocene and early Holocene, mainly because of the overwhelming evidence that humans had a big part to play in their demise (surprise, surprise). What I’ve rejected though isn’t so much that climate had nothing to do with the extinctions; rather, I took issue with claims that climate change was the dominant driver. I’ve also had problems with blanket claims that it was ‘always this’ or ‘always that’, when the complexity of biogeography and community dynamics means that it was most assuredly more complicated than most people think.

I’m happy to say that our latest paper indeed demonstrates the complexity of megafauna extinctions, and that it took a heap of fairly complex datasets and analyses to demonstrate. Not only were the data varied – the combination of scientists involved was just as eclectic, with ancient DNA specialists, palaeo-climatologists and ecological modellers (including yours truly) assembled to make sense of the complicated story that the data ultimately revealed. Read the rest of this entry »





Earth’s second lung has emphysema

19 02 2015
© WWF

© WWF

Many consider forests as the ‘lungs’ of the planet – the idea that trees and other plants take up carbon and produce oxygen (the carbon and oxygen cycles). If we are to be fair though, the oceans store about 93% of the Earth’s carbon pool (excluding the lithosphere and fossil fuels) and oceanic phytoplankton produces between 50 and 80% of the oxygen in the atmosphere. For comparison, the terrestrial biosphere – including forests – stores only about 5% of the Earth’s carbon, and produces most of the remainder of atmospheric oxygen.

So there’s no denying that the biggest player in these cycles is the ocean, but that’s not the topic of today’s post. Instead, I’m going to focus on the terrestrial biosphere, and in particular, the carbon storage and flux of forests.

Now it’s pretty well established that tropical forests are major players in the terrestrial carbon cycle, with the most accepted estimates of about 55% the terrestrial carbon stock stored therein. The extensive boreal forest, covering most of the northern half of North America, most of Scandinavia and a huge chunk of Russia, comes in globally at about 33%, and temperate forests store most of the remainder.

That is, until now. Read the rest of this entry »








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