Singin’ in the heat

9 03 2017
coqui & forest

Common coqui frog male (Eleutherodactylus coqui, snout-to vent length average ~ 3 cm) camouflaged in the fronds of an epiphyte in the El Yunque National Forest (Puerto Rico), along with an image of the enchanted forest of the Sierra de Luquillo where Narins & Meenderink did their study (4) – photos courtesy of Thomas Fletcher. This species can be found from sea level to the top of the highest peak in Puerto Rico (Cerro Punta = 1338 m). Native to mesic ecosystems, common coquis are well adapted to a terrestrial life, e.g., they lack interdigital webbing that support swimming propulsion in many amphibians, and youngsters hatch directly from the egg without transiting a tadpole stage. The IUCN catalogues the species as ‘Least Concern’ though alerts recent declines in high-altitude populations caused by chytrid fungus – lethal to amphibians at a planetary scale (9). Remarkably, the species has been introduced to Florida, Hawaii, the Dominican Republic and the Virgin Islands where it can become a pest due to high fertility rates (several >20 egg clutches/female/year).

Frog songs are species-specific and highly useful for the study of tropical communities, which host the highest amphibian diversities globally. The auditory system of females and the vocal system of males have co-evolved to facilitate reproductive encounters, but global warming might be disrupting the frequency of sound-based encounters in some species..

It is a rainy night, and Don (Gene Kelly) has just left his love, Kathy (Debbie Reynolds), at home, starting one of the most famous musical movie scenes ever: Singin’ in the rain 

Amphibians (see Amphibians for kids by National Geographic) also love to sing in rainy nights when males call for a partner, but now they have to do it in hotter conditions as local climates become warmer. Vocal behaviour is a critical trait in the life history of many frog species because it mediates recognition between individuals, including sexual selection by females (1).

With few exceptions, every species has a different and unique call, so scientists can use call features to identify species, and this trait is particularly useful in the inventory of diverse tropical communities (2). Differences in call frequency, duration and pitch, and in note, number, and repetition pattern, occur from one species to another. And even within species, songs can vary from individual to individual (as much as there are not two people with the same voice), and be tuned according to body size and environmental temperature (3). Read the rest of this entry »





Fertilisers can make plants sicker

25 01 2017

sick-plantLast year we reported experimental evidence that the dilution effect was the phenomenon by which greater biodiversity imparts disease resistance in plant communities. Our latest paper shows the mechanism underlying this.

In my ongoing collaboration with the crack team of plant community ecologists led by Shurong Zhou at Fudan University in Shanghai, we have now shown that nitrogen-based fertilisers — in addition to causing soil damage and environmental problems from run-off — reduce a plant community’s resistance to fungal diseases.

This means that prolonged use of artificial fertilisers can lead to the extinction of the most resistant plant species in a community, meaning that the remaining species are in fact more susceptible to diseases.

Continuing the experimental field trials in alpine meadows of the Tibetan Plateau, we tested the biodiversity resilience of an isolated  plant community to increasing concentrations of nitrogenous fertilisers. In this diverse and pristine ecosystem, we have finally established that extended fertilisation of soils not only alters the structure of natural plant communities, it also exacerbates pathogen emergence and transmission. Read the rest of this entry »





Rich and stable communities most vulnerable to change

16 08 2016

networkI’ve just read an interesting new study that was sent to me by the lead author, Giovanni Strona. Published the other day in Nature Communications, Strona & Lafferty’s article entitled Environmental change makes robust ecological networks fragile describes how ecological communities (≈ networks) become more susceptible to rapid environmental changes depending on how long they’ve had to evolve and develop under stable conditions.

Using the Avida Digital Evolution Platform (a free, open-source scientific software platform for doing virtual experiments with self-replicating and evolving computer programs), they programmed evolving host-parasite pairs in a virtual community to examine how co-extinction rate (i.e., extinctions arising in dependent species — in this case, parasites living off of hosts) varied as a function of the complexity of the interactions between species.

Starting from a single ancestor digital organism, the authors let evolve several artificial life communities for hundred thousands generation under different, stable environmental settings. Such communities included both free-living digital organisms and ‘parasite’ programs capable of stealing their hosts’ memory. Throughout generations, both hosts and parasites diversified, and their interactions became more complex. Read the rest of this entry »





Higher biodiversity imparts greater disease resistance

12 03 2016

fungal infection

Is biodiversity good for us? In many ways, this is a stupid question because at some point, losing species that we use directly will obviously impact us negatively — think of food crops, pollination and carbon uptake.

But how much can we afford to lose before we notice anything bad is happening? Is the sort of biodiversity erosion we’re seeing today really such a big deal?

One area of research experiencing a surge in popularity is examining how variation in biodiversity (biowealth1) affects the severity of infectious diseases, and it is particularly controversial with respect to the evidence for a direct effect on human pathogens (e.g., see a recent paper here, a critique of it, and a reply).

Controversy surrounding the biodiversity-disease relationship among non-human species is less intense, but there are still arguments about the main mechanisms involved. The amplification hypothesis asserts that a community with more species has a greater pool of potential hosts for pathogens, so pathogens increase as biodiversity increases. On the contrary, the dilution hypothesis asserts that disease prevalence decreases with increasing host species diversity via several possible mechanisms, such as more host species reducing the chance that a given pathogen will ‘encounter’ a suitable host, and that in highly biodiverse communities, an infected individual is less likely to be surrounded by the same species, so the pathogen cannot easily be transmitted to a new host (the so-called transmission interference hypothesis).

So I’ve joined the ecological bandwagon and teamed up yet again with some very clever Chinese collaborators to test these hypotheses in — if I can be so bold to claim — a rather novel and exciting way.

Our new paper was just published online in EcologyWarming and fertilization alter the dilution effect of host diversity on disease severity2. Read the rest of this entry »





Biowealth

24 02 2016

frogWhile I’ve blogged about this before in general terms (here and here), I thought it wise to reproduce the (open-access) chapter of the same name published in late 2013 in the unfortunately rather obscure book The Curious Country produced by the Office of the Chief Scientist of Australia. I think it deserves a little more limelight.

As I stepped off the helicopter’s pontoon and into the swamp’s chest-deep, tepid and opaque water, I experienced for the first time what it must feel like to be some other life form’s dinner. As the helicopter flittered away, the last vestiges of that protective blanket of human technological innovation flew away with it.

Two other similarly susceptible, hairless, clawless and fangless Homo sapiens and I were now in the middle of one of the Northern Territory’s largest swamps at the height of the crocodile-nesting season. We were there to collect crocodile eggs for a local crocodile farm that, ironically, has assisted the amazing recovery of the species since its near-extinction in the 1960s. Removing the commercial incentive to hunt wild crocodiles by flooding the international market with scar-free, farmed skins gave the dwindling population a chance to recover.

redwoodConservation scientists like me rejoice at these rare recoveries, while many of our fellow humans ponder why we want to encourage the proliferation of animals that can easily kill and eat us. The problem is, once people put a value on a species, it is usually consigned to one of two states. It either flourishes as do domestic crops, dogs, cats and livestock, or dwindles towards or to extinction. Consider bison, passenger pigeons, crocodiles and caviar sturgeon.

As a conservation scientist, it’s my job not only to document these declines, but to find ways to prevent them. Through careful measurement and experiments, we provide evidence to support smart policy decisions on land and in the sea. We advise on the best way to protect species in reserves, inform hunters and fishers on how to avoid over-harvesting, and demonstrate the ways in which humans benefit from maintaining healthy ecosystems. Read the rest of this entry »





High-altitude ecology

28 08 2014
A constant hazard in the Tibetan Plateau - yakjam

A constant hazard in the Tibetan Plateau – yakjam

I’ve been out of the social-media loop for a few weeks, hence the abnormally long interval since my last post. As you might recall, I’ve been travelling overseas and most recently blogged from Monterey, California where I was attending a symposium on invasion genetics.

The next phase of my travels couldn’t have been more different.

The reason I couldn’t access the blog was because I was well behind the Great Firewall of China. I was, in fact, in the Tibetan region of Gansu and Sichuan Provinces in western China for most of the last 10 days. While I’ve travelled to China many times before, this was by far the most evocative, interesting and unique experience I’ve ever had in this country. Reflecting on the past 10 days while waiting in Hong Kong for my flight back to Australia, I am still reeling a little from what I saw.

Top bloke: Jiajia Liu of Fudan University

Top bloke: Jiajia Liu of Fudan University

What the hell was I doing at 3500-4000 m elevation on the Tibetan Plateau? Good question. I have been most fortunate to be included in a crack team of Chinese ecologists who have designed and implemented a most impressive set of experiments in plant community ecology. The team, led by Professor Shurong Zhou and Dr. Jiajia Lui of Fudan University, has been working relentlessly to put together some of the sexiest plant ecology experiments going in China.

Having now so far published two papers from the some of the experiments (see here and here), my Chinese colleagues thought it was high time I visited the famous site. Situated at 3500 m in the Tibetan region of Gansu Province in western China, the Lanzhou University research station Azi Shi Yan Zhan is about a 20-hectare area of meadow fenced off from the grazing of the ubiquitous domestic yaks herded by the local Tibetans. If that sounds pretty exotic, let me assure you that it is. Read the rest of this entry »





South Australia’s tattered environmental remains

16 04 2014
State budget percentage expenditures for health, education and environment

South Australia State budget percentage expenditures for health, education and environment

Yesterday I gave the second keynote address at the South Australia Natural Resource Management (NRM) Science Conference at the University of Adelaide (see also a brief synopsis of Day 1 here). Unfortunately, I’m missing today’s talks because of an acute case of man cold, but at least I can stay at home and work while sipping cups of hot tea.

Many people came up afterwards and congratulated me for “being brave enough to tell the truth”, which both encouraged and distressed me – I am encouraged by the positive feedback, but distressed by the lack of action on the part of our natural resource management leaders.

The simple truth is that South Australia’s biodiversity and ecosystems are in shambles, yet few seem to appreciate this.

So for the benefit of those who couldn’t attend, I’ve uploaded the podcast of my slideshow for general viewing here. I’ve also highlighted some key points from the talk below: Read the rest of this entry »





More species = more resilience

8 01 2014

reef fishWhile still ostensibly ‘on leave’ (side note: Does any scientist really ever take a proper holiday? Perhaps a subject for a future blog post), I cannot resist the temptation to blog about our lab’s latest paper that just came online today. In particular, I am particularly proud of Dr Camille Mellin, lead author of the study and all-round kick-arse quantitative ecologist, who has outdone herself on this one.

Today’s subject is one I’ve touched on before, but to my knowledge, the relationship between ‘diversity’ (simply put, ‘more species’) and ecosystem resilience (i.e., resisting extinction) has never been demonstrated so elegantly. Not only is the study elegant (admission: I am a co-author and therefore my opinion is likely to be biased toward the positive), it demonstrates the biodiversity-stability hypothesis in a natural setting (not experimental) over a range of thousands of kilometres. Finally, there’s an interesting little twist at the end demonstrating yet again that ecology is more complex than rocket science.

Despite a legacy of debate, the so-called diversity-stability hypothesis is now a widely used rule of thumb, and its even implicit in most conservation planning tools (i.e., set aside areas with more species because we assume more is better). Why should ‘more’ be ‘better’? Well, when a lot of species are interacting and competing in an ecosystem, the ‘average’ interactions that any one species experiences are likely to be weaker than in a simpler, less diverse system. When there are a lot of different niches occupied by different species, we also expect different responses to environmental fluctuations among the community, meaning that some species inherently do better than others depending on the specific disturbance. Species-rich systems also tend to have more of what we call ‘functional redundancy‘, meaning that if one species providing an essential ecosystem function (e.g., like predation) goes extinct, there’s another, similar species ready to take its place. Read the rest of this entry »





Fast-lane mesopredators

29 07 2013

Another post from Alejandro Frid (a modified excerpt from a chapter of his forthcoming book).

I fall in love easy. Must be my Latino upbringing. Whatever it is, I have no choice on the matter. So for five years and counting, I have been passionate about lingcod (Ophiodon elongatus) and rockfish (Sebastes spp.), upper- and mid-level predatory fishes on rocky reefs of the Northeast Pacific.

Lingcod are beautiful and fierce. Rockfish are cosmic. Both taste mighty good and—surprise, surprise—have been overfished to smithereens throughout much of their range. Howe Sound, my field site near Vancouver, British Columbia, is no exception, although new protective legislation might be starting to give them some slack.

Our dive surveys1 and earlier studies, in combination, have pieced together a story of ecosystem change. In the Howe Sound of today, lingcod rarely exceed body lengths of 80 cm. But up to 30 years ago, when overfishing had yet to inflict the full extent of its current damage, lingcod with lengths of 90 to 100 cm had been common in the area. There is nothing unique about this; most fisheries target the biggest individuals, ultimately reducing maximum body size within each species of predatory fish.

As predators shrink, the vibrant tension of predation risk slips away. The mechanism of change has a lot to do with mouth size. Predatory fishes swallow prey whole, usually head or tail first, so it is impossible for them to eat prey bigger than the width and height of their open jaws. And bigger fishes have bigger jaws, which makes them capable not only of consuming larger prey, but also of scaring bigger prey into using antipredator behaviours, such as hiding in rocky crevices. As predators shrink, big prey enter a size refuge and only small prey remain at risk, which can alter trophic cascades and other indirect species interactions. Read the rest of this entry »





Crying ‘wolf’ overlooks the foxes: challenging ‘planetary tipping points’

28 02 2013

tipping pointToday, a paper by my colleague, Barry Brook, appeared online in Trends in Ecology and Evolution. It’s bound to turn a few heads.

Let’s not get distracted by the title of the post, or the potential for a false controversy. It’s important to be clear that the planet is indeed ill, and it’s largely due to us. Species are going extinct faster than the would have otherwise. The planet’s climate system is being severely disrupted, so is the carbon cycle. Ecosystem services are on the decline.

But – and it’s a big ‘but’ – we have to be wary of claiming the end of the world as we know it or people will shut down and continue blindly with their growth and consumption obsession. We as scientists also have to be extremely careful not to pull concepts and numbers out of our bums without empirical support.

Specifically, I’m referring to the latest ‘craze’ in environmental science writing – the idea of ‘planetary tipping points‘ and the related ‘planetary boundaries‘. It’s really the stuff of Hollywood disaster blockbusters – the world suddenly shifts into a new ‘state’ where some major aspect of how the world functions does an immediate about-face. Read the rest of this entry »





No need for disease

7 01 2013

dead or alive thylacineIt’s human nature to abhor admitting an error, and I’d wager that it’s even harder for the average person (psycho- and sociopaths perhaps excepted) to admit being a bastard responsible for the demise of someone, or something else. Examples abound. Think of much of society’s unwillingness to accept responsibility for global climate disruption (how could my trips to work and occasional holiday flight be killing people on the other side of the planet?). Or, how about fishers refusing to believe that they could be responsible for reductions in fish stocks? After all, killing fish couldn’t possibly …er, kill fish? Another one is that bastion of reverse racism maintaining that ancient or traditionally living peoples (‘noble savages’) could never have wiped out other species.

If you’re a rational person driven by evidence rather than hearsay, vested interest or faith, then the above examples probably sound ridiculous. But rest assured, millions of people adhere to these points of view because of the phenomenon mentioned in the first sentence above. With this background then, I introduce a paper that’s almost available online (i.e., we have the DOI, but the online version is yet to appear). Produced by our extremely clever post-doc, Tom Prowse, the paper is entitled: No need for disease: testing extinction hypotheses for the thylacine using multispecies metamodels, and will soon appear in Journal of Animal Ecology.

Of course, I am biased being a co-author, but I think this paper really demonstrates the amazing power of retrospective multi-species systems modelling to provide insight into phenomena that are impossible to test empirically – i.e., questions of prehistoric (and in some cases, even data-poor historic) ecological change. The megafauna die-off controversy is one we’ve covered before here on ConservationBytes.com, and this is a related issue with respect to a charismatic extinction in Australia’s recent history – the loss of the Tasmanian thylacine (‘tiger’, ‘wolf’ or whatever inappropriate eutherian epithet one unfortunately chooses to apply). Read the rest of this entry »





Essential predators

21 11 2012

© C. Hilton

Here at ConservationBytes.com, My contributors and I have highlighted the important regulating role of predators in myriad systems. We have written extensively on the mesopredator release concept applied to dingos, sharks and coyotes, but we haven’t really expanded on the broader role of predators in more complex systems.

This week comes an elegant experimental study (and how I love good experimental evidence of complex ecological processes and how they affect population persistence and ecosystem stability, resilience and productivity) demonstrating, once again, just how important predators are for healthy ecosystems. Long story short – if your predators are not doing well, chances are the rest of the ecosystem is performing poorly.

Today’s latest evidence comes from on an inshore marine system in Ireland involving crabs (Carcinus maenas), whelks (Nucella lapillus), gastropd grazers (Patella vulgata, Littorina littorea and Gibbula umbilicalis), mussels (Mytilus edulis) and macroalgae. Published in Journal of Animal Ecology, O’Connor and colleagues’ paper (Distinguishing between direct and indirect effects of predators in complex ecosystems) explains how their controlled experimental removals of different combinations of predators (crabs & whelks) and their herbivore prey (mussels & gastropods) affected primary producer (macroalgae) diversity and cover (see Figure below and caption from O’Connor et al.). Read the rest of this entry »





No-extinction targets are destined to fail

21 09 2012

I’ve been meaning to write about this for a while, and now finally I have been given the opportunity to put my ideas ‘down on paper’ (seems like a bit of an old-fashioned expression these days). Now this post might strike some as overly parochial because it concerns the state in which I live, but the concept applies to every jurisdiction that passes laws designed to protect biodiversity. So please look beyond my navel and place the example within your own specific context.

As CB readers will appreciate, I am firmly in support of the application of conservation triage – that is, the intelligent, objective and realistic way of attributing finite resources to minimise extinctions for the greatest number of (‘important’) species. Note that deciding which species are ‘important’ is the only fly in the unguent here, with ‘importance’ being defined inter alia as having a large range (to encompass many other species simultaneously), having an important ecological function or ecosystem service, representing rare genotypes, or being iconic (such that people become interested in investing to offset extinction.

But without getting into the specifics of triage per se, a related issue is how we set environmental policy targets. While it’s a lovely, utopian pipe dream that somehow our consumptive 7-billion-and-growing human population will somehow retract its massive ecological footprint and be able to save all species from extinction, we all know that this is irrevocably  fantastical.

So when legislation is passed that is clearly unattainable, why do we accept it as realistic? My case in point is South Australia’s ‘No Species Loss Strategy‘ (you can download the entire 7.3 Mb document here) that aims to

“…lose no more species in South Australia, whether they be on land, in rivers, creeks, lakes and estuaries or in the sea.”

When I first learned of the Strategy, I instantly thought to myself that while the aims are laudable, and many of the actions proposed are good ones, the entire policy is rendered toothless by the small issue of being impossible. Read the rest of this entry »





The invader’s double edge

15 06 2012

The Ogasawara Archipelago (Bonin Islands,) encompasses several tens of small islands ~ 1000 km from mainland Japan. In 2011, UNESCO declared this archipelago a World Heritage Site. Some regard them as the “Galapagos of the Orient”, owing to their biological singularity, e.g., endemism rates of ~ 50 % of > 500 species of plants, or ~ 90 % of > 100 species of terrestrial snails. Photos show patches of native scrub (left) and introduced sheoak forest (right), close-ups of the two study species Ogasawarana discrepans (left) and O. optima (right), and empty shells with (top right, bottom) and without (top left) rat scars (Courtesy of Satoshi Chiba).

Another great post by Salvador Herrando-Pérez that challenges our views on invasive species (some would do well to heed his words when it comes to species like dingos). I mentioned in his last post that he had just recently submitted his PhD thesis, and now I’m proud to say that it has been examined with no recommended changes required. What a truly rare accolade. Congratulations, Salva.

A blunt instrument of ecological restoration is the elimination of introduced species. However, when introduced species become custodians of native wildlife, a dilemma emerges between re-establishing historical ecosystem conditions or instead, accepting foreign species for the benefits they might also bring.

Right after birth, we all enter a culture where what is ‘good’ or ‘bad’ has already been determined. Later on, if those values remain unchallenged, individuals assume them to be true and act accordingly (which is neither ‘good’ nor ‘bad’ necessarily… it is just so). Science is therefore the only recourse humans have to check such values by  reducing the subjectivity of our judgements about why natural phenomena occur.

But scientists also work in a context of ‘pre-established truths’ (because, believe it or not, most of us are human too). The late Larry Slobodkin referred to our professional biases as ‘reifications’; i.e.,

“…reification consists of accepting a designation as if it has empirical meaning when, in fact, its existence has either never been tested or it has been found empty” (1).

Slobodkin underlined invasive species as an icon of reification. Indeed, people (with and without a scientific background) tend to demonise species that are not native and extremely abundant – experts even debate whether this is another sort of xenophobia (2). Thus, zebra mussels (Dreissena polymorpha), cane toads (Rhinella marinus) or caulerpa algae (Caulerpa taxifolia) are commonly referred to as ‘alien’, ‘invasive’ or ‘noxious’. Technically, we now call them ‘biological pollution’ (3). Such epithets are loaded with moral and pejorative connotations to qualify organisms that affect the range of facets of human well-being (aesthetics, economy, ethics, health). Read the rest of this entry »





Costs and benefits of a carbon economy for conservation

12 06 2012

I’ve had the good fortune of being involved now in a several endeavours funded by the Australian Centre for Ecological Analysis and Synthesis (ACEAS); two of those were workshops targeting specific questions regarding estimating modern extinction rates and examining the effects of genetic bottlenecks on Australian biota. The third was a bit different, to say the least – it was a little along the lines of ‘build it, and they will come‘. In other words, what happens when you bung 40 loosely associated researchers in a room for two days? Does anything of substance result, or does it degenerate into a mere talk-fest. I’m happy to say the former. The details of the ACEAS ‘Grand Workshop‘ are now being finalised in a paper that should be submitted by the end of the month. The ACEAS report is reproduced below.

The Grand ACEAS Workshop was something of an experiment: what will happen when we bring 30 of Australia’s top scientists working on land management issues into the same room?

The Grand Workshop participants came from academia, research institutions and the government, and had all received ACEAS funding for working groups. David Keith, Ted Lefroy, Jasmyn Lynch, Wayne Meyer and Dick Williams were amongst the attendees of the two-day workshop.

And when this group of people came together wanting to analyse and synthesise ecological data, great things happened.

“We decided to focus on how carbon pricing legislation will affect land use change and how will that spill over into biodiversity persistence”, said Professor Corey Bradshaw, Director of Ecological Modelling at The University of Adelaide, who led the synthesis activity at the Grand ACEAS Workshop.

“Will carbon pricing lead to good outcomes for biodiversity, or negative ones, or will it have no bearing whatsoever?”

The workshop participants broke into five groups to discuss how the carbon tax legislation will change land use when it is introduced in July 2012, and the potential impact on biodiversity.

Some of the questions asked included:

  • Is it enough simply to allow plants to re-grow to be eligible for carbon credits?
  • How will an increase in forestry plantations impact biodiversity, water catchments and fire regimes?
  • Will there be more kangaroo grazing to reduce methane emissions and erosion, replacing hard-hoofed livestock?
  • Can you receive carbon credits for shooting large feral animals like goats, camels, deer and boars?

The groups found many opportunities for positive biodiversity outcomes with the carbon sequestration activities encouraged by carbon pricing, but there are also many potential ‘bio-perversities’. 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 »





Biowealth – a lexical leap forward for biodiversity appreciation

17 12 2010

Here’s a little idea I’ve been kicking around in my head that I’d like to invite you to debate. Call it an ‘Open Thread’ in the spirit of BraveNewClimate.com’s successful series.

© The Economist

Let’s face it, ‘biodiversity’ is a slippery and abstract concept for most people. Hell, even most ecologists have a hard time describing what biodiversity means. To the uninitiated, it seems simple enough. It’s just the number of species, isn’t it?

Well, no. It isn’t.

Unfortunately, it’s far, far more complicated. First, the somewhat arbitrary pigeon-holing of organisms into Linnaean taxonomic boxes doesn’t really do justice to the genetic gradients within species, among populations and even between individuals. We use the pigeon-hole taxonomy because it’s convenient, that’s all. Sure, molecular genetics has revolutionised the concept, but to most people, a kangaroo is a kangaroo, a robin is a robin and an earthworm is an earthworm. Hierarchical Linnaean taxonomy prevails.

Then there’s the more prickly issue of α, β and γ diversity. α diversity essentially quantifies species richness within a particular area, whereas β diversity is the difference in α diversity between ecosystems. γ diversity is used to measure overall diversity for the different constituent ecosystems of a region. Scale is very, very important (see our recent book chapter for more on this). Read the rest of this entry »





The lost world – freshwater biodiversity conservation

6 09 2010

Even the most obtuse, right-wing, head-in-the-sand, consumption-driven, anti-environment yob would at least admit that they’ve heard of forest conservation, the plight of whales (more on that little waste of conservation resources later) and climate change. Whether or not they believe these issues are important (or even occurring) is beside the point – the fact that this particular auto-sodomist I’ve described is aware of the issues is at least testament to growing concern among the general populace.

But so many issues in conservation science go unnoticed even by the most environmentally aware. Today’s post covers just one topic (I’ve covered others, such as mangroves and kelp forests) – freshwater biodiversity.

The issue is brought to light by a paper recently published online in Conservation Letters by Thieme and colleagues entitled Exposure of Africa’s freshwater biodiversity to a changing climate.

Sure, many people are starting to get very worried about freshwater availability for human consumption (and this couldn’t be more of an issue in Australia at the moment) – and I fully agree that we should be worried. However, let’s not forget that so many species other than humans depend on healthy freshwater ecosystems to persist, which feed back in turn to human benefits through freshwater filtering, fisheries production and arable soil accumulation.

Just like for the provision of human uses (irrigation, direct water consumption, etc.), a freshwater system’s flow regime is paramount for maintaining its biodiversity. If you stuff up the flow regime too much, then regardless of the amount of total water available, biodiversity will suffer accordingly.

Glen Canyon Dam

Image by James Marvin Phelps (mandj98) via Flickr

Thieme and colleagues focus specifically on African freshwater systems, but the same problems are being seen worldwide (e.g., Australia’s Murray-Darling system, North America’s Colorado River system). And this is only going to get worse as climate change robs certain areas of historical rainfall. To address the gap in knowledge, the authors used modelled changes in mean annual runoff and discharge to determine fish species affected by 2050.

The discharge/runoff results were: Read the rest of this entry »





Sick environment, sick people

30 10 2009

sickplanetA quick post to talk about a subject I’m more and more interested in – the direct link between environmental degradation (including biodiversity loss) and human health.

To many conservationists, people are the problem, and so they focus naturally on trying to maintain biodiversity in spite of human development and spread. Well, it’s 60+ years since we’ve been doing ‘conservation biology’ and biodiversity hasn’t been this badly off since the Cretaceous mass extinction event 146-64 million years ago. We now sit squarely within the geological era more and more commonly known as the ‘Anthropocene’, so if we don’t consider people as an integral part of any ecosystem, then we are guaranteed to fail biodiversity.

I haven’t posted in a week because I was in Shanghai attending the rather clumsily entitled “Thematic Reference Group (TRG) on Environment, Agriculture and Infectious Disease’, which is a part of the UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR) (what a mouthful that is). What’s this all about and why is a conservation ecologist (i.e., me) taking part in the group?

It’s taken humanity a while to realise that what we do to the planet, we eventually end up doing to ourselves. The concept of ecosystem services1 demonstrates this rather well – our food, weather, wealth and well-being are all derived from healthy, functioning ecosystems. When we start to bugger up the inter-species relationships that define one element of an ecosystem, then we hurt ourselves. I’ve blogged about this topic a few times before with respect to flooding, pollination, disease emergence and carbon sequestration.

Our specific task though on the TRG is to define the links between environmental degradation, agriculture, poverty and infectious disease in humans. Turns out, there are quite a few examples of how we’re rapidly making ourselves more susceptible to killer infectious diseases simply by our modification of the landscape and seascape.

Some examples are required to illustrate the point. Schistosomiasis is a snail-borne fluke that infects millions worldwide, and it is on the rise again from expanding habitat of its host due to poor agricultural practices, bad hygiene, damming of large river systems and climate warming. Malaria too is on the rise, with greater and greater risk in the endemic areas of its mosquito hosts. Chagas (a triatomine bug-borne trypanosome) is also increasing in extent and risk. Some work I’m currently doing under the auspices of the TRG is also showing some rather frightening correlations between the degree of environmental degradation within a country and the incidence of infectious disease (e.g., HIV, malaria, TB), non-infectious disease (e.g., cancer, cardiovascular disease) and indices of life expectancy and child mortality.

I won’t bore you with more details of the group because we are still drafting a major World Health Organization report on the issues and research priorities. Suffice it to say that if we want to convince policy makers that resilient functioning ecosystems with healthy biodiversity are worth saving, we have to show them the link to infectious disease in humans, and how this perpetuates poverty, rights injustices, gender imbalances and ultimately, major conflicts. An absolute pragmatist would say that the value of keeping ecosystems intact for this reason alone makes good economic sense (treating disease is expensive, to say the least). A humanitarian would argue that saving human lives by keeping our ecosystems intact is a moral obligation. As a conservation biologist, I argue that biodiversity, human well-being and economies will all benefit if we get this right. But of course, we have a lot of work to do.

CJA Bradshaw

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1Although Bruce Wilcox (another of the TRG expert members), who I will be highlighting soon as a Conservation Scholar, challenges the notion of ecosystem services as a tradeable commodity and ‘service’ as defined. More on that topic soon.





Classics: Invasion Meltdown

26 10 2008

One for the Classics page…

melting_rat_by_xenatalhaoui-d71xr1yDaniel Simberloff is probably best known for his work on the implications of invasive (non-indigenous) species for biodiversity, although he has contributed to a wide range of conservation disciplines.

A seminal paper that he co-wrote with Betsy Von Holle is one I consider to be a conservation Classic: their 1999 paper in the inaugural issue of Biological Invasions entitled Positive interactions of nonindigenous species: Invasional meltdown?

The establishment of non-indigenous species can have severe negative impacts on ecosystems. Introduced species that become invasive (widespread and locally dominant) transform habitats, degrade ecosystem services, reduce biodiversity and are some of the greatest threats to ecosystems today (perhaps nearly as important as habitat loss and over-exploitation).

The so-called ‘invasion meltdown‘ describes the process by which the negative impacts induced on native ecosystems by one invading non-indigenous species are exacerbated by interactions with another exotic species.

Although there isn’t a lot of information on invasion meltdowns, one good example comes from Christmas Island in tropical Australia. The introduced yellow crazy ant (Anoplolepis gracilipes) exploded in numbers when another exotic species, a scale insect, was introduced about the same time that a native scale insect species also had a local outbreak.  Because ants protect scale insects from predators and parasites in return for scale honeydew, the crazy ant suddenly had a much more abundant food source, leading to the huge increase in the ant population. This large ant population devastated the population of native red crab (Gecarcoidea natalis) and resulted in massive increase in forest undergrowth due to reduced herbivory by crabs (see O’Dowd et al. 2003). The great decline in red crabs may also make the island more vulnerable to other plant invasions.

What did Simberloff & Van Holle’s idea and subsequent examples of invasion meltdowns teach us? I believe their paper really hit home the idea that invasive species were not only a threat to biodiversity, but the self-reinforcing mutualisms of invasive species could rival other forms of human-induced biodiversity decline. Indeed, many of the effects of invasive species will be reinforced by global climate change through increasing temperatures, rising sea levels and changing rainfall patterns that increase the potential range and spread of invading species, so the problem is only going to get worse. This is why the U.N. began the Global Invasive Species Programme (GISP), and world-wide, countries are attempting to restrict the flow of invasive species so that their negative effects are lessened. Identifying the extent of the problem has stimulated a lot of people to act accordingly.

CJA Bradshaw

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