Tropical biology and conservation overview

28 07 2010

Last week I attended the 2010 International Meeting of the Association for Tropical Biology and Conservation (ATBC) in Sanur, Bali (Indonesia). I only managed one post on the real-world relevance of conservation research (that attracted quite a lot of comment) while there, but I did promise to give a conference overview as I did for the International Congress for Conservation Biology earlier this month. So here goes.

This was my first ATBC meeting despite having co-written ‘the book’ on tropical conservation biology (well, one of very, very many). I no longer live in the tropics but am still managing to keep my hand in many different aspects of tropical research. After all, tropical regions represent ground zero for conservation biology – they have the highest biodiversity (no matter which way you measure it), some of the greatest threats (e.g., most people, most rapid development, most corruption) and some of the most pressing human problems (disease, hunger, socio-political instability). Ironically, most of the world’s conservation ecologists work in temperate realms – it should really be the other way around. Read the rest of this entry »





Faraway fettered fish fluctuate frequently

27 06 2010

Hello! I am Little Fish

Swimming in the Sea.

I have lots of fishy friends.

Come along with me.

(apologies to Lucy Cousins and Walker Books)

I have to thank my 3-year old daughter and one of her favourite books for that intro. Now to the serious stuff.

I am very proud to announce a new Report in Ecology we’ve just had published online early about a new way of looking at the stability of coral reef fish populations. Driven by one of the hottest young up-and-coming researchers in coral reef ecology, Dr. Camille Mellin (employed through the CERF Marine Biodiversity Hub and co-supervised by me at the University of Adelaide and Julian Caley and Mark Meekan of the Australian Institute of Marine Science), this paper adds a new tool in the design of marine protected areas.

Entitled Reef size and isolation determine the temporal stability of coral reef fish populations, the paper applies a well-known, but little-used mathematical relationship between the logarithms of population abundance and its variance (spatial or temporal) – Taylor’s power law.

Taylor’s power law is pretty straightforward itself – as you raise the abundance of a population by 1 unit on the logarithmic scale, you can expect its associated variance (think variance over time in a fluctuating population to make it easier) to rise by 2 logarithmic units (thus, the slope = 2). Why does this happen? Because a log-log (power) relationship between a vector and its square (remember: variance = standard deviation2) will give a multiplier of 2 (i.e., if xy2, then log10x ~ 2log10y).

Well, thanks for the maths lesson, but what’s the application? It turns out that deviations from the mathematical expectation of a power-law slope = 2 reveal some very interesting ecological dynamics. Famously, Kilpatrick & Ives published a Letter in Nature in 2003 (Species interactions can explain Taylor’s power law for ecological time series) trying to explain why so many real populations have Taylor’s power law slopes < 2. As it turns out, the amount of competition occurring between species reduces the expected fluctuations for a given population size because of a kind of suppression by predators and competitors. Cool.

But that application was more a community-based examination and still largely theoretical. We decided to turn the power law a little on its ear and apply it to a different question – conservation biogeography. Read the rest of this entry »





Protecting Australian wilderness

1 10 2009

Today I highlight a new paper just out online in Diversity and Distributions by James Watson and colleagues: Wilderness and future conservation priorities in Australia. It’s certainly one for the Potential list.

KNP

Jim Jim Falls, Kakadu National Park

Australia has a pretty bad biodiversity conservation track record – we have some of the worst mammal extinction trends in the world, and we’ve lost at least 50 % of our forested area since European colonisation. Despite our relatively large system of parks and reserves, things aren’t going to well (even in the parks!).

Our rapidly expanding influence means that we have to start protecting larger and larger areas if we want to have any chance of slowing the modern extinction crisis. This means we have to go beyond dedicated biodiversity reserves and sequester more ‘wilderness’ (defined as “…large areas that have experienced minimal habitat loss“). Watson and colleagues therefore used Australia as a good example to determine the extent to which the national protected area network captures ‘wilderness’, and how Australia’s planned expansion of the reserve system will include ‘wilderness’ in the future.

Although there wasn’t much planning involved initially, Australia (like many other countries) started to take biodiversity conservation seriously in the mid-1990s, such that now we have about 11 % of our 7.7 million km2 land area within a National Reserve System. Planning didn’t feature heavily in the early years, but it has been embraced now by nearly all planning bodies within government.

© Wiley-Blackwell

© Wiley-Blackwell

Using estimates of the total wilderness area in Australia (Fig. a), Watson and colleagues determined how much was included in the Reserve System (Fig. b), and how this value changed between 2000 and 2006.

Of the 2.93 million km2 of wilderness (38 % of land area, mostly in northern and western Australia), only 14 % was protected in 2000. This value increased marginally to 19 % by 2006 as the size of the Reserve System itself increased by 37 % (i.e., from 652597 to 895326 km2).

Bottom line – our growth in reserve area didn’t really capture the necessary wilderness; instead, gains were made in areas largely modified by humans. Even where wilderness has been captured, it’s predominately in ‘multiple use’ regions (incorporating mining, forestry and grazing, for example).

This isn’t a bad thing really – by focussing on areas of high biodiversity value that are under relatively high threat embraces the biodiversity hotspot approach to conservation and emphasises restoration. This is, of course, needed. But not incorporating a wider component of the habitats within wilderness could bias conservation toward range-restricted species.

© Wiley-Blackwell

© Wiley-Blackwell

Watson and colleagues therefore make a number of recommendations:

  1. We should strive to quantify and map spatially the  important ecological and evolutionary processes that drive the distribution and abundance of biodiversity so they can be explicitly incorporated into reserve area prioritisations.
  2. We should focus on predicting the magnitude and distribution of future threats and incorporate them into the spatial prioritisation framework.
  3. We should incorporate realistic constraints (e.g., financial costs) into prioritisation.
  4. We need to map and analyse a range of social and economic factors that define opportunities for conservation in conjunction with information on conservation values, threats and costs.

The bottom line is that we need to find a better balance between planning that protects threatened species and ecosystems in already highly fragmented (threatened) landscapes, and planning that protects large areas of wilderness that still contains most of its conservation values (wilderness). We’re getting there, but slowly, and hopefully in time to save our remaining threatened species from extinction.

CJA Bradshaw

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ResearchBlogging.org

Watson, J., Fuller, R., Watson, A., Mackey, B., Wilson, K., Grantham, H., Turner, M., Klein, C., Carwardine, J., Joseph, L., & Possingham, H. (2009). Wilderness and future conservation priorities in Australia Diversity and Distributions DOI: 10.1111/j.1472-4642.2009.00601.x





The rarity of commonness

18 08 2009

I’m attending the 10th International Congress of Ecology (INTECOL) in Brisbane this week and I have just managed to find (a) an internet connection and (b) a small window to write this post.

I have to say I haven’t been to a good plenary talk for some time – maybe it’s just bad luck, but often plenary talks can be less-than-inspiring.

Not so for INTECOL this year. I was very pleased to have the opportunity to listen to biodiversity guru Professor Kevin Gaston of the University of Sheffield give a fantastic talk on… common species (?!).

clones

If you have followed any of Kevin’s work, you’ll know he literally wrote the book on rarity – what species rarity is, how to measure it and what it means for preserving biodiversity as a whole.

Now he’s championing (in a very loose sense) the importance of common species because it is these taxa, he argues, that provide the backbone to the persistence of all biodiversity.

Yes, we conservation biologists have tended to focus on the rare and endemic species to make certain we have as much diversity in species (and genetic material) as possible when conserving habitats.

There are a lot more rare species than common ones, and the most common species (i.e., the ones you most often see) tend to have the broadest distributions. We know from much previous work that having a broad distribution reduces extinction risk, so why should we be concerned about common species?

Kevin made a very good point – if you turn the relationship on its head somewhat, you can state that the state of ‘commonness’ is itself ‘rare’. In fact, only about 25 % of the most common species account for about 90-95 % of ALL individuals. He used an interesting (and scary) example to show what this can mean from an extinction perspective. Although very back-of-the-envelope, there are about 2000 individual birds in a km2 of tropical forest; we are losing between 50000 and 120000 km2 of tropical forest per year, so this translates into the loss of about 100 to 240 million individual birds per year; this is the sum total of all birds in Great Britain (a bird-mad country). Yet where do we have the best information about birds? The UK.

Commonness is also geologically transient, meaning that just because you are a common species at some point in your evolutionary history doesn’t mean you have always been or always will be. In fact, most species never do become common.

But it is just these ‘rare’ common that drive the principal patterns we see globally in community structure. The true ‘rare’ species are, in fact, pretty crap predictors of biodiversity patterns. Kevin made a good point – when you look at a satellite image of a forest, it’s not all the little rare species you see, it’s the 2 or 3 most common tree species that make up the forest. Lose those, and you lose everything else.

Indeed, common species also form most trophic structure (the flow of energy through biological communities). Take away these, and ecosystem function degrades. They also tend to have the highest biomass and provide the structure that supports all those millions of rare species. Being common is quite an important job.

Kevin stated that the world is now in a state where many of the so-called common species are in fact, “artificially” common because of how much we’ve changed the planet. It is these benefactors of our world-destroying machinations that are now in decline themselves, and it is for this reason we should be worried.

When you start to see these bastions of ecosystems start to drop off (and the drop is usually precipitous because we don’t tend to notice their loss until they suddenly disappear), then you know we’re in trouble. And yet, even though once common, few, if any, once-common species have come back after a big decline.

So what does this mean for the way we do biodiversity research? Kevin proposes that we need a lot more good monitoring of these essential common species so that we can understand their structuring roles in the community and more importantly, be able to track their change before ecosystem collapse occurs. The monitoring is crucial – it wasn’t the demise of small companies that signalled the 2007 stock market crash responsible for the Global Financial Crisis in which we now find ourselves, the signal was derived from stock data obtained from just a few large (i.e., ‘common’) companies. All the small companies (‘rare’) ones then followed suit.

A very inspiring, worrying and somewhat controversial talk. Watch out for more things ‘Gaston’ on ConservationBytes.com in the near future.

CJA Bradshaw

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Eastern Seaboard Climate Change Initiative

30 04 2009
© A. Perkins
© A. Perkins

I’ve just spent the last few days in Sydney attending a workshop on the Eastern Seaboard Climate Change Initiative which is trying to come to grips with assessing the rising impact of climate change in the marine environment (both from biodiversity and coastal geomorphology perspectives).

Often these sorts of get-togethers end up doing little more than identifying what we don’t know, but in this case, the ESCCI (love that acronym) participants identified some very good and necessary ways forward in terms of marine research. Being a biologist, and given this is a conservation blog, I’ll focus here on the biological aspects I found interesting.

The first part of the workshop was devoted to kelp. Kelp? Why is this important?

As it turns out, kelp forests (e.g., species such as Ecklonia, Macrocystis, Durvillaea and Phyllospora) are possibly THE most important habitat-forming group of species in temperate Australia (corals and calcareous macroalgae being more important in the tropics). Without kelp, there are a whole host of species (invertebrates and fish) that cannot persist. The Australian marine environment is worth something in the vicinity of $26.8 billion to our economy each year, so it’s pretty important we maintain our major habitats. Unfortunately, kelp is starting to disappear around the country, with southern contractions of Durvillaea, Ecklonia and Hormosira on the east coast linked to the increasing southward penetration of the East Australia Current (i.e., the big current that brings warm tropical water south from Queensland to NSW, Victoria and now, Tasmania). Pollution around the country at major urban centres is also causing the loss or degradation of Phyllospora and Ecklonia (e.g., see recent paper by Connell et al. in Marine Ecology Progress Series). There is even some evidence that disease causing bleaching in some species is exacerbated by rising temperatures.

Some of the key kelp research recommendations coming out of the workshop were:

  1. Estimating the value of kelp to Australians (direct harvesting; fishing; diving)
  2. Physical drivers of change: understanding how variation in the East Australian Current (temperature, nutrients) affects kelp distribution; understanding how urban and agricultural run-off (nutrients, pollutants, sedimentation) affects distribution and health; understanding how major storm events (e.g., East Coast Lows and El Niño-Southern Oscillation) affects long-term persistence
  3. Monitoring: what is the distribution and physical limits of kelp species?; how do we detect declines in ‘health’?; what is the associated biodiversity in kelp forests?
  4. Experimental: manipulations of temperature/nutrients/pathogens in the lab and in situ to determine sensitivities; sensitivity of different life stages; latitudinal transplants to determine localised adaption
  5. Adaptation (management): reseeding; managing run-off; managing fisheries to maintain a good balance of grazers and predators; inform marine protected area zoning; understanding trophic cascades

The second part of the discussion centred on ocean acidification and increasing CO2 content in the marine environment. As you might know, increasing atmospheric CO2 is taken up partially by ocean water, which lowers the availability of carbonate and increases the concentration of hydrogen ions (thus lowering pH or ‘acidifying’). It’s a pretty worrying trend – we’ve seen a drop in pH already, with conservative predictions of another 0.3 pH drop by the end of this century (equating to a doubling of hydrogen ions in the water). What does all this mean for marine biodiversity? Well, many species will simply not be able to maintain carbonate shells (e.g., coccolithophore phytoplankton, corals, echinoderms, etc.), many will suffer reproductive failure through physiological stress and embryological malfunction, and still many more will be physiologically stressed via hypercapnia (overdose of CO2, the waste product of animal respiration).

Many good studies have come out in the last few years demonstrating the sensitivity of certain species to reductions in pH (some simultaneous with increases in temperature), but some big gaps remain in our understanding of what higher CO2 content in the marine environment will mean for biota. Some of the key research questions in this area identified were therefore:

  1. What is the adaptation (evolutionary) potential of sensitive species? Will many (any) be able to evolve higher resistance quickly enough?
  2. In situ experiments outside the lab that mimic pH and pCO2 variation in space and time are needed to expose species to more realistic conditions.
  3. What are the population consequences (e.g., change in extinction risk) of higher individual susceptibility?
  4. Which species are most at risk, and what does this mean for ecosystem function (e.g., trophic cascades)?

As you can imagine, the conversation was complex, varied and stimulating. I thank the people at the Sydney Institute of Marine Science for hosting the fascinating discussion and I sincerely hope that even a fraction of the research identified gets realised. We need to know how our marine systems will respond – the possibilities are indeed frightening. Ignorance will leave us ill-prepared.

CJA Bradshaw

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