Sleuthing the Chinese green slime monster

21 10 2009

greenslimemonsterI just returned from a week-long scientific mission in China sponsored by the Australian Academy of Science, the Australian Academy of Technological Sciences and Engineering and the Chinese Academy of Sciences. I was invited to attend a special symposium on Marine and Deltaic Systems where research synergies between Australian and Chinese scientists were to be explored. The respective academies really rolled out the red carpet for the 30 or so Australian scientists on board, so I feel very honoured to have been invited.

During our marine workshop, one of my Chinese counterparts, Dongyan Liu from the Yantai Institute for Coastal Zone Research, presented a brilliant piece of ecological sleuthing that I must share with readers of ConservationBytes.com.

The first time you go to China the thing that strikes you is that everything is big – big population, big cities, big buildings, big projects, big budgets and big, big, big environmental problems. After many years of overt environmental destruction in the name of development, the Chinese government (aided by some very capable scientists) is now starting to address the sins of the past.

Liu and colleagues published their work earlier this year in Marine Pollution Bulletin in a paper entitled World’s largest macroalgal bloom caused by expansion of seaweed aquaculture in China, which describes a bloody massive outbreak of a particularly nasty ‘green tide’.

What’s a ‘green tide’? In late June 2008 in the coastal city of Qingdao not far from Beijing (and just before the 2008 Olympics), a whopping 1 million tonnes of green muck washed up along approximately 400 km2 of coastline. It took 10,000 volunteers 2 weeks to clean up the mess. At the time, many blamed the rising eutrophication of coastal China as the root cause, and a lot of people got their arse kicked over it. However, the reality was that it wasn’t so simple.

The Yellow Sea abutting this part of the Chinese coast is so named because of its relatively high productivity. Warm waters combined with good mixing mean that there are plenty of essential nutrients for green things to grow. So, adding thousands of tonnes of fertilisers from Chinese agricultural run-off seems like a logical explanation for the bloom.

Qingdoa green tide 2008 © Elsevier

Qingdao green tide 2008 © Elsevier

However, it turns out that the bulk of the green slime was comprised of a species called Enteromorpha prolifera, and it just so happens that this particularly unsavoury seaweed loves to grow on the infrastructure used for the aquaculture of nori (a.k.a. amanori or zicai) seaweed (mainly, Porphyra yezoensis). Problem is, P. yezoensis is grown mainly on the coast hundreds of kilometres to the south.

Liu and colleagues examined both satellite imagery and detailed oceanographic data from the period prior to the green tide and not only spotted green splotches many kilometres long, they also determined that the current flow and wind direction placed the trajectory of any green slime mats straight for Qingdao.

So, how does it happen? Biofouling by E. prolifera on P. yezoensis aquaculture frames is dealt with mainly by manual cleaning and then dumping the unwanted muck on the tidal flats. When the tide comes back in, it washes many thousands of kilos of this stuff back out to sea, which then accumulates in rafts and continues to grow in the warm, rich seas. Subsequent genetic work also confirmed that the muck at sea was the same stock as the stuff growing on the aquaculture frames.

Apart from some lovely sleuthing work, the implications are pretty important from a biodiversity perspective. Massive eutrophication coupled with aquaculture that inadvertently spawns a particularly nasty biofouling species is a good recipe for oxygen depletion in areas where the eventual slime monster starts to decay. This can lead to so-called ‘dead’ zones that can kill off huge numbers of marine species. So, the proper management of aquaculture in the hungry Goliath that is China becomes essential to reduce the incidence of dead zones.

Fortunately, it looks like Liu and colleagues’ work is being taken seriously by the Chinese government who is now contemplating financial support for aquaculturists to clean their infrastructure properly without dumping the sludge to sea. A simple policy shift could save a lot of species, a lot of money, and a lot of embarrassment (not to mention prevent a lot of bad smells).

CJA Bradshaw

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This post was chosen as an Editor's Selection for ResearchBlogging.org

ResearchBlogging.orgLiu, D., Keesing, J., Xing, Q., & Shi, P. (2009). World’s largest macroalgal bloom caused by expansion of seaweed aquaculture in China Marine Pollution Bulletin, 58 (6), 888-895 DOI: 10.1016/j.marpolbul.2009.01.013





How to make an effective marine protected area

22 09 2009

Here’s a nice little review from the increasingly impressive Frontiers in Ecology and the Environment which seems to be showcasing a lot of good conservation research lately.

© USGS

© USGS

As we know, the world’s oceans are under huge threat, with predictions of 70 % loss of coral reefs by 2050, decline in kelp forests, loss of seagrasses, over-fishing, pollution and a rapidly warming and acidifying physical environment. Given all these stressors, it is absolutely imperative we spend a good deal of time thinking about the right way to impose restrictions on damage to marine areas – the simplest way to do this is via marine protected areas (MPA).

The science of MPA network design has matured over the last 10-20 years such that there is a decent body of literature now on what we need to do (now the policy makers just have to listen – some  progress there too, but see also here). McLeod and colleagues in the latest issue of Frontiers in Ecology and the Environment have published a review outlining the best, at least for coral reefs, set of recommendations for MPA network design given available information (paper title: Designing marine protected area networks to address the impacts of climate change). Definitely one for the Potential list.

Here’s what they recommend:

Size

  • bigger is always better
  • minimum diameter of an MPA should be 10-20 km to ensure exchange of propagules among protected benthic populations

Shape

  • simple shapes best (squares, rectangles)
  • avoid convoluted shapes to minimise edge effects

Representation

  • protect at least 20-30 % of each habitat

Replication

  • protect at least 3 examples of each marine habitat

Spread

  • select MPA in a variety of temperature regimes to avoid risk of all protected reefs succumbing to future climate changes

Critical Areas

  • protect nursery areas, spawning aggregations, and areas of high species diversity
  • protect areas demonstrating natural resilience or rapid recovery from previous disturbances

Connectivity

  • measure connectivity between MPA to ensure replenishment
  • space maximum distance of 15-20 km apart
  • include whole ecological units
  • buffer core areas
  • protect adjacent areas such as outlying reefs, seagrass beds, mangroves

Ecosystem Function

  • maintain key functional groups of species (e.g., herbivorous fishes)

Ecosystem Management

  • embed MPA in broader management frameworks addressing other threats
  • address and rectify sources of pollution
  • monitor changes

Of course, this is just a quick-and-dirty list as presented here – I highly recommend reading the review for specifics.

CJA Bradshaw

ResearchBlogging.orgMcLeod, E., Salm, R., Green, A., & Almany, J. (2009). Designing marine protected area networks to address the impacts of climate change Frontiers in Ecology and the Environment, 7 (7), 362-370 DOI: 10.1890/070211





August issue of Conservation Letters

6 08 2009

© Discovery Channel/W. Sloss

© Discovery Channel/W. Sloss

The latest edition of Conservation Letters is now out. Click here for full access (yes, all articles are still free!).

Papers in this issue:





Underwater deforestation

26 05 2009
© C. Connell

© S. Connell

I’ve been meaning to blog on this for a while, but am only now getting around to it.

Now, it’s not bulldozers razing our underwater forests – it’s our own filth. Yes, we do indeed have underwater forests, and they are possibly the most important set of species from a biodiversity perspective in temperate coastal waters around the world. I’m talking about kelp. I’ve posted previously about the importance of kelp and how climate change poses a threat to these habitat-forming species that support a wealth of invertebrates and fish. In fact, kelp forests are analogous to coral reefs in the tropics for their role in supporting other biodiversity.

The paper I’m highlighting for the ConservationBytes.com Potential list is by a colleague of mine at the University of Adelaide, Associate Professor Sean Connell, and his collaborators entitled “Recovering a lost baseline: missing kelp forests from a metropolitan coast“. This paper is interesting, novel and applied for several reasons.

First, it sets out some convincing evidence that the Adelaide coastline has experienced a fairly hefty loss of canopy-forming kelp (mainly species like Ecklonia radiata and Cystophora spp.) since urbanisation (up to 70 % !). Now, this might not seem too surprising – we humans have a horrible track record for damaging, exploiting or maltreating biodiversity – but it’s actually a little unexpected given that Adelaide is one of Australia’s smaller major cities, and certainly a tiny city from a global perspective. There hasn’t been any real kelp harvesting around Adelaide, or coastal overfishing that could lead to trophic cascades causing loss through herbivory. Connell and colleagues pretty much are able to isolate the main culprits: sedimentation and nutrient loading (eutrophication) from urban run-off.

Second, one might expect this to be strange because other places around the world don’t have the same kind of response. The paper points out that in the coastal waters of South Australia, the normal situation is characterised by low nutrient concentrations in the water (what we term ‘oligotrophic’) compared to other places like New South Wales. Thus, when you add even a little bit extra to a system not used to it, these losses of canopy-forming kelp ensue. So understanding the underlying context of an ecosystem will tell you how much it can be stressed before all hell breaks loose.

Finally, the paper makes some very strong arguments for why good marine data are required to make long-term plans for conservation – there simply isn’t enough investment in basic marine research to ensure that we can plan responsibly for the future (see also previous post on this topic).

A great paper that uses a combination of biogeography, time series and chemistry to inform about a major marine conservation problem.

CJA Bradshaw

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Realising you’re a drunk is only the first step

11 05 2009

© A. Savchenko

© A. Savchenko

I recently did an interview for the Reef Tank blog about my research, ConservationBytes.com and various opinions about marine conservation in general. I’ve been on about ‘awareness’ raising in biodiversity conservation over the last few weeks (e.g., see last post), saying that it’s really only the first step. To use an analogy, alcoholics must first recognise and accept that they are indeed drunks with a problem before than can take the (infamous AA) steps to resolve it. It’s not unlike biodiversity conservation – I think much of the world is aware that our forests are disappearing, species are going extinct, our oceans are becoming polluted and devoid of fish, our air and soils are degraded to the point where they threaten our very lives, and climate change has and will continue to exacerbate all of these problems for the next few centuries at least (and probably for much longer).

We’ve admitted we have a disease, now let’s do something about it.

Read the full interview here.

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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Toilet Torrens II: The Plot Sickens

14 02 2009
© CJA Bradshaw

© CJA Bradshaw

A few days into the Torrens ‘River’ disaster, and we see very little in the way of a truly dedicated, organised clean-up. With some token efforts to clean up the more obvious rubbish in the lake section itself (i.e., cars, fridges, etc.), there is nothing suggesting the true problems are going to be addressed. Indeed, the authorities are desperately trying to ‘find’ water to cover the problem up rather than deal with it.

Instead of a catchment-wide mass clean-up, the removal of the water-sucking invasive plants that line the river’s edge (see photos below), the implementation of a water neutrality scheme, and the removal of hundreds of untreated drainage pipes, they are willing to spend over $1 million to pipe in water from elsewhere.

I can’t believe it.

This is the best opportunity Adelaide has ever had to rectify the problem and clean the mess up once and for all; instead, the investment is going toward a cosmetic cover-up that will effectively fix nothing. Toothless. Some images I took today while cycling along the Torrens path follow:

© CJA Bradshaw

© CJA Bradshaw

© CJA Bradshaw

© CJA Bradshaw

© CJA Bradshaw

© CJA Bradshaw

CJA Bradshaw

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