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 »





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 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.

Bollocks.

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 »





More than leftovers: getting marine parks right in Australia

7 08 2011
Taken by user Hossen27

Image via Wikipedia

A few weeks back I cosigned a ‘statement of concern’ about the proposal for Australia’s South West Marine Region organised by Hugh Possingham. The support has been overwhelming by Australia’s marine science community (see list of supporting scientists below). I’ve reproduced the letter addressed to the Australian government – distribute far and wide if you give more than a shit about the state of our marine environment (and the economies it supports). Basically, the proposed parks are merely a settlement between government and industry where nothing of importance is really being protected. The parks are just the leftovers industry doesn’t want. No way to ensure the long-term viability of our seas.

On 5 May 2011 the Australian Government released a draft proposal for a network of marine reserves in the Commonwealth waters of the South West bioregional marine planning region.

Australia’s South West is of global significance for marine life because it is a temperate region with an exceptionally high proportion of endemic species – species found nowhere else in the world.

Important industries, such as tourism and fisheries, depend on healthy marine ecosystems and the services they provide. Networks of protected areas, with large fully protected core zones, are essential to maintain healthy ecosystems over the long-term – complemented by responsible fisheries management1.

The selection and establishment of marine reserves should rest on a strong scientific foundation. We are greatly concerned that what is currently proposed in the Draft South West Plan is not based on the three core science principles of reserve network design: comprehensiveness, adequacy and representation. These principles have been adopted by Australia for establishing our National Reserve System and are recognized internationally2.

Specifically, the draft plan fails on the most basic test of protecting a representative selection of habitats within the bioregions of the south-west. There are no highly protected areas proposed at all in three of the seven marine bioregions lying on the continental shelf3. Overall less than 3.5% of the shelf, where resource use and biodiversity values are most intense, is highly protected. Further, six of the seven highly protected areas that are proposed on the shelf are small (< 20 km in width)4 and all are separated by large distances (> 200 km)5. The ability of such small isolated areas to maintain connectivity and fulfil the goal of protecting Australia’s marine biodiversity is limited. Read the rest of this entry »





Disaster coming to a coastline near you

24 02 2011

Many of you already know that against all better judgement, the spectacularly audacious Australian Commonwealth government has granted BP offshore drilling rights in our southern waters.

You’d think that with all the evidence that BP is a company that cannot be trusted with this particular form of resource exploitation, we’d be a little bit more discerning when granting exploration permits to them. Apparently not.

In protest and within my rights as an Australian citizen, I wrote to the Minister responsible for the decision, MP Martin Ferguson (Federal Minister for Resources and Energy) to register my protest:

Dear Minister Ferguson,

As an ecologist, academic and citizen, I find it rather astounding that Australia has permitted the deep-sea exploration of oil by BP in our own back garden. The unreasonable environmental risk aside, it simply equates to poor economics – the very real probability of a disaster on the same scale (or larger) than the Gulf of Mexico’s fiasco last year will effectively destroy the commercial fishing and aquaculture industry of our southern coastline overnight. The loss of tourism dollars could arguably exceed even that.

This is most definitely not in Australia’s best interest, and will represent yet another blight on our already poor environmental record (see http://wp.me/phhT4-1cf and http://wp.me/phhT4-Zt). I urge you to reconsider your permission and revoke the licence to drill in our waters. It is a mistake you and your government will regret for decades, and will make the recent flooding disaster in Queensland appear mild in comparison.

Sincerely,
Professor Corey J. A. Bradshaw

I certainly wasn’t expecting the Minister to say suddenly “Oh my. You are right, Prof. Bradshaw. It is a bad decision. I’ll revoke that permission forthwith”, but I was expecting a little bit more than the jumbled form letter I received in reply: Read the rest of this entry »





Global erosion of ecosystem services

14 09 2010

A few months ago I was asked to give a lecture about erosion of ecosystem services to students in the University of Adelaide‘s Issues in Sustainable Environments unit. I gave that lecture last week and just uploaded a slidecast of the presentation (with audio) today.

I’ve reproduced the lecture here for your viewing pleasure. I hope you find the 45-minute presentation useful. Note that the first few minutes cover me referring to the Biodiversity film short that I posted not too long ago.

CJA Bradshaw





February Issue of Conservation Letters

13 02 2010

Diver at Great Barrier Reef, Australia

Hard to believe we’re already at Volume 3 – introducing the latest issue of Conservation Letters (Volume 3, Issue 1, February 2010). For full access, click here.

Note too we’ve jumped from 5 to 6 papers per issue. Congratulations to all our authors. Keep those submissions coming!

CJA Bradshaw

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