Invasion by land and sea
Facilitator: Good evening and thank you for being here. My name is Bill Gladstone. I'm the head of the department of environmental sciences. It's my great pleasure to introduce tonight's two speakers to you. I'd like to firstly welcome you to the University of Technology Sydney and to this Science Engage talk. It's particularly apt that the topic of tonight's talk is invasive species and that this is also the International Year of Biodiversity given the significance of invasive species and their impact on Australia's unique biodiversity. So this is a very appropriate talk for this year and our celebration of our unique biodiversity and what impacts we're having on it.
Before we start, I'd like to make a welcome to country. I'd like to show my respect and acknowledge the traditional custodians of the land of elders past and present on which this event takes place. I would like to acknowledge the Gadigal people who are traditional custodians of this land. I would also like to pay respect to the elders both past and present of the Eora nation and extent that respect to other Aboriginals present. I've got just a couple of announcements before we start. If you have a mobile phone, please switch it off. Make sure it's switched off completely rather than being on silent mode because I've been told that it interferes with the camera technology going on at the back there. If you happen to bring a glass of wine, champagne or something in here, when you finish your drinks please take yours glasses outside with you so they can be packed away.
It's my great - as I said, it's my great pleasure to introduce both Dr Brad Murray and Dr Paul Gribben, the speakers for tonight's series. I'm a newcomer to UTS. The main reason I came here was so that I could be amongst people of the calibre of Brad and Paul. They - and my other colleagues in the Department of Environmental Sciences. The department has a great international reputation for its research and is really going to be at the forefront of the university's endeavour to become a world-class research institution. So I haven't been disappointed in the people I have found myself working with. It's been a great pleasure.
It's my pleasure to acknowledge the contribution that both Brad and Paul make to the department and to the university's research reputation. I'll just give a brief intro or bio about both speakers before we start. Brad will begin and Paul will come second. At the end there will be a period of time for some questions. Brad graduated from the University of Sydney in 1993 and completed an honours research project with Professor Chris Dickman [unclear] in the Simpson Desert. He then completed a PhD at Macquarie University under the supervision of Professor Mark [Westerby] who also happened to be my PhD supervisor. So it's a nice connection there.
Three years were then spent as a post-doctoral researcher at CSIRO Plant Industry in Canberra. In both of these cases, his work focused on rare and threatened species. This was followed by a lectureship at UTS in 2001. Coming into his tenth year at UTS as a senior lecturer, Brad has developed a large research team working on the invasive species problem. Paul graduated from the University of Auckland in 2002 and completed his research in developing sustainable bivalve fisheries with Dr. Bob Creese. He then spent three years as a post-doctoral research fellow at UNSW investigating chemical cues for settlement in commercially important molluscs.
During this time he developed his interest in understanding the impacts of invasive species and saw the error of his ways and moved to UTS. as a chancellor's post-doctorate fellow investigating the impacting of invasive species on marine biodiversity in New South Wales. Paul continues this research within and other interesting animal behaviour as a research fellow in the Department of Environmental Sciences and the Plant Functional Biology and Climate Change Cluster research group. Thank you. Brad.
Brad Murray: Thanks for those kind words Bill. Thank you all for making the trip out on a cold winter's night to listen to Paul and I talk about invasion by land and sea, invasive species and the threat to biodiversity. Is that working? There we go. I'm Brad. That was Paul who's now sat down. I'm going to start the talk tonight with this quote from an all-around good guy, Dr. Peter [Pizak] from the Czech Republic. He is a world expert in the invasive species problem. He had a paper published last week in the influential Proceedings of the National Academy of Sciences. In this he said nations do not have a good track record in forsaking future economic prosperity for environmental benefits. I wanted to put this up at the front of the talk because it's an undercurrent for what Paul and I are going to be talking about.
But we want to try and build on this a little bit, in that if we actually look after environmental benefits we're actually ensuring our economic prosperity. Why are we here? Well, Bill mentioned that it's the International Year of Biodiversity this year. It was established by the United Nations in 2005 at the World Summit with two main aims. Firstly, to increase worldwide awareness of biodiversity and its importance. Secondly, to engage more people in biodiversity conservation. A key thrust of this is to try and reduce rates of biodiversity loss at national, regional and global levels.
The reason Paul and I are here tonight is that we are in the Plant Functional Biology and Climate Change Cluster, also known as the C3. This is a priority research investment area for UTS. We're both teachers and researchers in the Department of Environmental Sciences in the Faculty of Science. We are in the biodiversity research group within this C3. We have a range of C3 primary objectives - what we call our C3P0s. In particularly, we look at the ecology of plants and animals. We look at plant and animal biodiversity. We focus specifically on terrestrial and marine systems - so we're not biased to one system or another. Paul has kind of convinced me a little bit that marine ecosystems might be a little bit important and he's winning me over.
One of our key research programs within the biodiversity research group is the area of biological invasions and invasive species. We like to ask questions like why do species such as Japanese honeysuckle and morning glory, why do they become so abundant and widespread? Why are they such invasive species? When we've got such large numbers of species coming into the country, why is it that ones like these do so well? Why are they so successful. The other sorts of questions we ask, why do species like Caulerpa - Paul will tell you more about this species in particular later in the talk - but why do species like Caulerpa do so well and what are their impacts on native biodiversity and the provisioning of ecosystem services?
What's an invasive species I hear you ask? A multitude of meanings are linked to invasive species. It's like the word rare. Rare can mean any number of things. So can invasive in relation to species. Noxious weeds, environmental weeds and so on. I like to stick to a simple definition - I'm a simple bloke and I like simple things. As an ecologist, we can describe an invasive species as something that occurs beyond its native range - so it's outside of where it naturally occurs - because of human activities - we've moved it somehow or other - purposefully, accidentally - whatever it might be, we've moved it. It forms self-sustaining populations - so it doesn't need us to keep it going - and it spreads rapidly across a novel landscape.
A good example is the cane toad you're all familiar with. This little - wonderful illustration here shows - I'm glad it's working actually - shows that in every five year increment - in five year increments - it's spread throughout northern Australia up until about I think 1980 [and then it avoided] the '80s. Invasive species do pose a threat to native biodiversity. Coutts-Smith and Downey from National Parks and Wildlife back in 2006 put together what they thought were the stats on this situation. These guys know their stuff. But they reckon that about - in New South Wales, about 45 per cent of all biodiversity is threatened by invasive species. Eighty nine per cent of endangered communities are threatened by invasive species - seventy one per cent of threatened plants and 13 per cent of native animal species.
Invasive species are a global phenomenon. They occur on every continent. I include Antarctica in this. So every continent. There's also the problem with invasive species of what we're calling synergistic effects. So there's a lot of hullabaloo at the moment about climate change and there's a worry that invasive species and climate change acting together will cause even more problems than we're seeing at the moment. Climate change, whether you're into it or not, is effectively a disturbance event and invasive species, they dig the disturbance events.
If you don't believe me about the impacts, check it out. This is Kudzu. You can't see any of the - I think it's up in Queensland - you can't see any of the native veg - perhaps something up the back there - but it's absolutely swamped the native vegetation. So that's a really good visual representation of the kinds of problems that we're trying to solve and work on.
Male: Sorry, what did you say that one was?
Brad Murray: I think that's Kudzu.
Male: Sorry.
Brad Murray: That's all right. I'll answer questions at the end. That's cool. So what I need to do is give you an idea of what biodiversity is. I've spoken about invasive species and we need to get an idea of what biodiversity is. A simple definition - again, simple - the variety of all life forms on earth, the different plants, animals and microorganisms and the ecosystems of which they are a part. Something to keep in mind about biodiversity is it's the results of millions of years of evolution. It didn't just pop up out of nowhere. It's taken a long time. So we're talking about some long temporal scales here that we're managing and dealing with.
Biodiversity ranges from small scales, or small levels, from say genes, to individuals, to populations - which are groups of individuals - to species such as the iconic spinifex hopping mouse and the perhaps less iconic but equally beautiful Hovea linearis, a member of the Fabaceae found around Sydney - to ecosystems from alpine sorts of environments down to the coast and so on - and, importantly, the interactions amongst these things. So we're talking about interactions like competition, predation and mutualism. So all of these are encompassed by biodiversity.
Where does Australia sit in relation to biodiversity? We're one of 17 megadiverse countries. Now megadiverse countries, these 17 countries occupy less than 10 per cent of the Earth's surface but they have more than 70 per cent of the species that occur on the Earth. In Australia, we have 600,000 to 700,000 species. So that's a lot of species. We've got a lot of endemism. Now, what endemism means is for a species it's something that occurs here and nowhere else. In terms of endemism, 84 per cent of our plant species are endemic, 83 per cent of our mammals, 45 per cent of our birds and for something that Paul worries about, the marine biodiversity, about 70 per cent of our biodiversity is endemic - it only occurs here.
So why is it important? These big numbers - who cares? Why is it important? Why should be conserve it? Conservation has an aim to increase the probability that the earth's biodiversity will persist into the future - it's going to hang around. I argue here that biodiversity has value. It's not just one type of value either. It has consumptive use value - so natural products that don't pass through the markets. Seventy five per cent of the population of Ghana rely on fish from the sea - straight from the sea - for their diets. So it doesn't go through markets. So this is what we call consumptive use phase. Biodiversity is important in this regard.
Biodiversity is also important in terms of productive use value - things like commercially harvested biological resources that go through the markets. The drugs obtained for medicine that are obtained from rainforest plants in 2000 had a net US value of about USD150 billion. Biodiversity has also got intrinsic value. So regardless of our needs, desires or our wants, biodiversity exists and it has its own value. So that's something else that's worth mentioning.
Biodiversity is important for scientific and educational value. As environmental scientists and teachers here at UTS, biodiversity provides the basis of improved biological knowledge. So here are some of our students from last year down at La Perouse Bare Island. They're looking at marine biodiversity in the intertidal zone, having a lot of fun counting and identifying all the different types of organisms that occur in this intertidal zone. Biodiversity has experiential value. For many cultures, there's an enjoyment of nature. To get over the jitters of tonight's talk on the public holiday - Monday - I went for a nice walk in the Blue Mountains to clear the mind, body and soul. So it has experiential value.
Possibly more important than all of this is that it has ecosystem service value. These are the natural processes that sustain human life. Air purification, water purification - these kinds of processes that we get for free. Biodiversity provides us with ecosystem functioning which gives us these services. I would argue that intrinsic to ecosystem services is the idea that intact ecosystems and biodiversity are more valuable than the products derived destructively. A good example of this comes from mangroves in Thailand where coastal mangrove habitats are cleared to farm shrimp. An economic analysis was done of this situation. This analysis found that the value of shrimp farming was completely outweighed by these benefits from leaving the system intact - managing it sustainably.
Timber, charcoal production, offshore fisheries, storm protection - all valuable assets. In fact, by leaving the ecosystem intact it's worth about USD60,000 versus USD20,000 per year. So this was some pretty good economic evidence that leaving biodiversity ecosystems intact is very important. As my esteemed colleague Professor Derek Eamus will tell you as well, these economic analyses are very rare. There's not a lot of this sort of stuff done. Importantly, the sort of work that's being done in this area is looking at all or nothing contrasts - what do we get if it's there, what do we get if it's not there? So there's this real dichotomy used in these sorts of analyses.
Incredibly rare are economic valuations that look at slow changes in ecosystems - what I'm going to refer to as creeping ecosystem change. Invasive species and the spread of invasive species offer a great example of this. So this is asparagus fern creeping through the vegetation. The vegetation is still there and it's still green. So what's wrong? Well, we don't actually know the effects and impacts of this sort of creeping change on biodiversity and the provision of ecosystem services - or at least I should say that our knowledge is in its infancy.
Well, where do we start if we're trying to address these problems of invasive species and biodiversity? People like Paul and I start with these three questions? How do invasives get places - how do they move around? What makes a species invasive? What are the ecological impacts of invasive species? There's an idea called the invasion pathway and this is how species become invasive. They follow this pathway. First a species has to be introduced. It's got to get somewhere. An introduced species such as this Erowid morning glory is a species that survives transport to enter a new region through human mediation. This species has been recorded as occurring in Australia - it was introduced to Australia. We don't know anything more about that. We don't know if it's progressed further or not. It's just been recorded as being introduced.
Species can be introduced intentionally or accidentally. Ornamental species are a great example of things that are introduced intentionally. Japanese honeysuckle, rubber vine, wild ginger - I've got heaps of these growing in my backyard up in the Blue Mountains. I didn't plant it myself. But it's a major invasive weed. Very pretty but causes a lot of damage - but introduced specifically as an ornamental species. Species can also be introduced intentionally for agriculture or aquaculture. This here is Buffel grass that's a major weed in northern Australia. The interesting thing about this species is that it's very resistant to fire and it actually promulgates fire in areas where fire once wasn't supposed to be or didn't naturally occur.
Of course, the Pacific oyster is another good example of an intentional introduction. The Pacific oyster was introduced from Japan in the 40s as far as I'm aware. It's now competing so incredibly with native oysters it's causing major problems for the native oyster industry. Species can be introduced accidentally. Something like the black rat is the classic example. This map here - the bits in red, that's where the black rat occurs - yes, it's got a very, very wide distribution. It's actually native to these regions here. It spread throughout Europe and through Britain back in the good old days of the Romans.
Around the time of the First Fleet it - it was spread through to Australia. This funny little red blob down here, I don't know - Paul, what's - oh, is that called New Zealand is it? Right. Another accidentally introduced species is whiskey grass. This was introduced from south-eastern USA accidentally. It's seeds were transported around the packaging of bottles of whiskey. So all us whiskey drinkers, we're a little bit to blame for the introduction of this major invasive species in Australia.
I thought I'd show you a little bit of work that we've been doing in my lab in relation to introduction patterns. In particular we've focussed on exotic vines. These are a particularly problematic group of exotic plant species. This is some work done by a PhD student who went through my lab a couple of years ago - Carla Harris. The work was - the impetus for the work came about because the New South Wales Scientific Committee recognised invasion by exotic vines as a key threatening process. I was on the committee at the time and I thought to myself wow, we don't actually know a lot about how many or what types of these things are in Australia.
So Carla picked up the reins on this and did a fantastic PhD project where she put together for the first time an inventory of all the exotic vine species in Australia. Along the way she gathered a bunch of information for species like Bridal creeper. She found that most of them - this is the number of species here and their reasons for introduction - most of them were introduced for ornamental purposes. So we brought them in because we liked the look of them. A fairly large number - a proportion of all these vines - were introduced for agricultural purposes.
It wasn't possible to find out reasons for introduction for about 40 of these species, which probably means that they were accidentally introduced. This is a pattern that's shown in exotic vines and it appears to be reflected overall for all exotic plant species in Australia. What Carla also found was that vines seemed to be introduced from all over the world. South America, Europe, Africa, Asia, North America and Oceania - in different proportions here - but again, that's reflected in exotic species across - all types of exotic species, not just vines, across Australia, in that they've come from all over the world.
Some work we're doing at the moment, we've been lucky enough to get a database from the Department of Agriculture, Fisheries and Forestry which has an enormous amount of information on when plant species or exotic plants were introduced to Australia. Working with my colleague Peter Pizak we're looking at temporal patterns of introduction to Australia and a number of other things as well. But some of our early results are showing that if we look at time since introduction - so back in the 1800s up to about now - and the number of species introduced, there are these temporal patterns of introduction that are really cool.
So you'll notice that there are two spikes. These ones - this spike here, 1840 to 1880, coincides with the gold rush. So a lot of people coming in - early colonisation - the gold rush people coming in and bringing in lots of exotic plants to make the world Britain. The second spike relates to increased rates of travel around the world - big super jets and so on - also the internet. So you can see these two big spikes. Those observant amongst you will note this other little spike here just around the late 1930s and 1940s which probably coincides - because this is - sorry, I should say these are species from Europe - from Central Europe in particular.
But this coincides with immigration to get away from the horrors of World War II I'd imagine. So we're starting to look at these patterns, break them down and see if these patterns are related to the types of growth forms of plants and so on. But these are patterns of introduction. Some species that are introduced remain pretty casual. A casual species is a species that's only sustained through direct human care and it can't establish in the wild. So it will exist nicely in pots like Blue Dawn Flower in your garden but it won't move outside of that and establish in the wild.
Of all introduced species, there's a thing called the rule of 10. About 10 per cent of all introduced species become naturalised. A naturalised species is something that reproduces and self-sustains in native habitat. So without our influence, it will get into the native - it might get there through our influence but it can sustain itself. It will sit there comfortably in native vegetation. Digging into some of Carla's work again for the exotic vines, she actually showed that if you look through time and the cumulative number of exotic species that are naturalising, the number is increasingly pretty lineally and it's ongoing. So this is a continuing problem. Exotic plant species are coming into the country still.
If a species makes it through this invasion pathway to become invasive - I described an invasive species before. It's a naturalised one that actively reproduces and spreads quickly across the landscape and it forms established populations - something like coastal morning glory. If it reaches this point we call it invasive. This is something that our lab works on in a lot of detail. We ask questions like if you have a bunch of naturalised species that don't become invasive and a bunch that do become invasive, what separates them? So we do comparative ecological work to try and understand what separates out the invasives from the non-invasives.
So here's just a little taster - I don't want to spend too long on it because Paul's champing at the bit to talk about the impacts I'm sure - here's some of our work on comparing invasives and non-invasives. This comes from work that Megan Phillips, a PhD student, has been working on. This graph shows you residence time. Residence time is how long something's been here. These are different regions of the world. The non-invasive species are in the dark bars and the invasive are in the light bars. All you've got to take away from this is that the light bars are higher in every instance than the dark bars. What this says is that invasive species have longer residence times - they've been here longer. If you interpret this, what this means is that the longer you're here the more chance you've got to become a problem.
So if you leave naturalised species too long in the wild it's more likely that they're going to become a problem - not always - there are other factors involved. But this is a key trait for - this is for all of Australia - but this is a trait that's found in many different regions of the world as well. This is what we call an introduction history trait - so it's a trait related to how these species are introduced. We're also looking at biological traits. This is a graph of dispersal investment. Now, dispersal investment is how much a plant invests in something to disperse its seed into the environment.
Broad-leaf privet is a great example. You've got a seed within here but there's this big fleshy fruit that birds love. They'll eat this, they'll move away, they'll defecate and drop the seed somewhere else and you've got dispersal of your seed. What we've found recently - again, invasives and non-invasives in the different colours - if you measure the percentage that a species invests in dispersing its seeds, we've found that the invasive species invest more.
We've found this really neat correlation between how much you invest in dispersing your seed and how likely you are to be an invasive species. That's regardless of whether you're a grass, a herb or a shrub. So controlling for growth form, as we call it, invasive species invest more in dispersing their seeds. This is just a taster or some of the stuff we're doing to give you an idea of what we're doing to try and identify invasive species and traits related to them so that we can then predictably - pre-emptively manage in the invasive species problem.
This is my last slide before Paul takes over. I wanted to end with a little bit of an inventory of what we've got in terms of invasive species. Flora, fauna - we've actually had a total of 26,242 exotic plants in Australia. This many have naturalised. This many have become invasive. We've got 20 WONS, which are Weeds of National Significance. There's such big problems continentally that they've got this status. As you can see, we've got a number of different animal species that have been introduced as well. Undoubtedly, these are underestimates. Getting hold of these numbers is very difficult and there's a lot of work yet to be done trying to identify and count - even get an inventory of the numbers of exotics.
Dr Paul Gribben: What Brad's done a fantastic job of is explaining how species get here and how they spread once they're here. Now, what I'm going to do is follow up with an extension of this [pathway] and talk more about some of the impacts of invasive species and how we go about managing them. Now, make no mistake - invasive species are very, very expensive. The US alone spends about USD140 billion managing terrestrial weeds annually. In the marine environment, ballast water and biofouling are estimated to cost in the tens of billions of dollars.
In Australia, we spend an estimated $7 billion on managing invasive species. Terrestrial weeds cost about $4 billion. Terrestrial vertebrates about $120 million - sorry, $720 million. We spend about $175 million on red fire ants alone. For the marine environment, there's - some of the data is very hard to get hold of - but we spent - recently spent $2 million removing the black-striped mussel from Darwin. It's one of the few known successful marine eradications in the world. The Pacific oyster is a - has been costing the native oyster industry up to $90 million annually. Now, these economic impacts come from direct losses to production and costs to control and management. But they don't account for environmental damage. They don't account for loss of biodiversity, species extinctions or loss of ecosystem services. So the actual estimated costs are drastically low.
We also find that there's a very large disparity between spending on economic versus environmental pests. I know this data is old but it just serves to highlight a point. In 1996 the Victorian Government spent approximately $200 million managing agricultural weeds. They spent less than $2 million on environmental weeds. Now, this is probably - this great disparity is probably because the economic benefits of biodiversity are poorly known.
So what are some of the biological costs? Terrestrial invasive pests have caused more animal extinctions in Australia than any other factor. Twenty two mammals and foxes have been - 22 mammals have been lost to foxes, cats and rabbits. Five bird species on Lord Howe alone have been lost to black rats. We've lost seven species of endemic frogs to an invasive fungal disease. Now, I couldn't find any comparative information on marine extinctions. We simply don't know whether invasive species in the marine environment are causing extinctions.
So what are some of the traits of invasive species? Well, invasive species often have - often are voracious predators. On the left hand side we have two examples from the marine environment. We have the Northern Pacific seastar, Asterias amurensis, and the European green crab, Carcinus maenas. Now, these two species are munching their way through vast quantities of commercially important bivalves in Tasmania and Victoria. Here we have the terrestrial example - the domestic cat. It now occurs in most habitats across Australia. It's caused some extinctions of some species on islands. It's thought to be have contributed to the disappearance of many ground dwelling birds and mammals on the mainland.
But invasive species are also often very good competitors. Again we have the Pacific oyster on the left hand side. This was, as Brad said, deliberately introduced for aquaculture. It now out-competes native oysters and affects native oyster production. Here's another example that should be familiar to you all - rabbits. Rabbits degrade vegetation that provides valuable food and resources for native animals. This is something that's pretty typical of good competitors - good invasive competitors. They're often very good at utilising a resource such as space or food and they're much better at doing that than native species.
But some of the most damaging invasive species are these ones that we call ecosystem engineers. They don't target single species but they have the ability to transform entire ecosystems by changing the surrounding environment. So they can actually completely alter biodiversity in these systems. Now, on the left hand side we have a couple of graphs. We have an estuarine example - this is the invasive saltmarsh Spartina anglica in the Tamar Estuary in Tasmania.
What we can see is it's forming this very, very complex habitat structure in what should be intertidal mudflats. What we can see here in this dark brown area is the extent of the invasion in this estuary. All this area should be quite valuable intertidal mudflat. On the right hand side we have a terrestrial example. We have a eucalypt forest with no lantana invasion. On the left hand side we have a eucalypt forest that's been invaded with lantana. You can see the complex structure it now forms within the canopy.
What I want to do now is bring this talk a little bit closer to home. I want to talk - I want to spend a little bit of time talking about the impacts of this ecosystem engineer, the green algae Caulerpa taxifolia, and its impacts on biodiversity in New South Wales. But first a little bit of background about Caulerpa. It's got a pretty interesting history. It was first found outside the [Monaco] Museum in 1984. Now, they had an opportunity to get rid of it. There was only one square metre. They left it and they didn't touch it. Now it occupies more than 30,000 hectares of the Mediterranean - vast quantities of open space. It's now invaded four temperate regions worldwide.
This species is spread by the aquarium trade. Like all things bad, it's native to Queensland. It's also been the focus of this book here, Killer Algae, by this guy Alexandre Meinesz. He's been a tireless advocate of doing something about this species. If any of you can get a hold of this book, it's an excellent treatise on French bureaucracy. Now, Caulerpa was first discovered in New South Wales in 2000 in Port Hacking. It's since gone on to invade 14 estuaries, from Lake Macquarie in the north to Wallagoot Lake in southern New South Wales.
So what are some of the impacts of Caulerpa. Well, Caulerpa is one of the top 100 most invasive species. It says so on the list. Now, globally the focus has been on understanding its impacts on seagrass because it commonly occurs in vegetated sediments next to seagrasses. But globally the results are ambiguous. Generally it appears that if seagrasses are really healthy they'll take care of themselves and Caulerpa can't get in. What it does invade is vast tracts of vegetated sediment. People say well, why should we care about unvegetated sediment? There's nothing there. We can't see it. But that's not true.
These are incredibly important habitats for maintain biodiversity and ecosystem functions in estuarine environments. They improve water quality. They often have large invertebrate fisheries within them. Despite the fact we can't see them, they have very high biodiversity. They also provide habitat and food for other larger species. So this is where I've done a lot of my work. It's a beautiful spot down south - about 200 kilometres south of Sydney - called Lake Conjola. It's a barrier spit estuary. Now, Caulerpa was first found here in 2001, 2002. It's thought that the first infestation was caused by some guy that lived on the estuary here who dumped all his unwanted aquaria out into the estuary.
So the invasion and the impacts you see are anecdotally caused by this one idiot. Once in Lake Conjola it spread rapidly. New South Wales [INI] now - which was DPI - identified Conjola as a key at risk area and they desperately needed studies on its impacts. So Caulerpa spreads through a process called asexual fragmentation. It's a big word for a little process. Simply put, little fragments break off and they float around to new regions. They can also be transported to different estuaries on boating equipment.
Once in a new region the fragments quickly establish and, if you're really lucky, you'll end up with a complete mess like this which has happened in Lake Conjola. So this is a colleague of mine that I've done a lot of this coming up - this work I'm going to show you - with Dr Jeff Wright. These are two lantern nets that we put out - one in unvegetated sediments and one in Caulerpa sediments. So this overgrowth here was after one month only. This is how quickly it can spread. It also infects the face.
So unlike Brad who's shown you some lovely graphs on his labs' work, I'm going to show you this rather childish cartoon. But hopefully it will illustrate the purposes of my research. So what we have here is a normal functioning ecosystem and unvegetated sediments and estuarine environments in New South Wales and globally. So we have a very diverse fauna of clams, worms, other crabs and other organisms within there - highly diverse. We'll have some other higher order organisms such as predatory crabs, stingrays and octopi which will feed on these animals.
Now, as I said before, Caulerpa comes in and it very readily establishes in unvegetated sediments. Now, when we first started doing this work in Lake Conjola one of the surprising things that we found was that Caulerpa was initially increasing biodiversity. So what we found, there was a whole bunch of organisms that were living in, on and amongst Caulerpa that were increasing biodiversity in the system. It was doing this because it was excluding the large predators. The large predators didn't like foraging in Caulerpa. So this habitat was actually acting as a habitat refuge for these species.
But what we found is that as the invasion process progressed we found that Caulerpa was completely degrading the sediment quality. What we were finding was very, very high levels of toxic sulphides. Now, sulphides are toxic to most organisms on the planet. It was removing most of the oxygen within the sediments as well. So there was no oxygen down there for the organisms that live in there to respire. So as these sediments continued to degrade we started seeing decreases in biodiversity and abundance and we're probably seeing ecosystem function being compromised as well because these sediments will no longer be functioning as they're supposed to do.
But wait - as it further progressed and Caulerpa biomass got very, very high, it started sucking oxygen out of the overlying water column as well. So all those species that were initially facilitated died. So we have very, very large scale effects below the ground and very, very large scale effects above the sediments within the Caulerpa canopy itself. So we may actually start - begin to start seeing some localised extinctions of some species. Now, one of the species that I've worked a lot with is this soft-sediment bivalve Anadara trapezia. This is the most abundant mollusc in New South Wales estuaries.
Organisms such as these are really, really important for removing excess nutrients from the water column. This particular species is a growing fishery. But one of its problems in New South Wales is that it commonly occurs in areas that have been invaded by Caulerpa. Now, just a brief graph to show you some of the effects that Caulerpa is having on this. In 2006 we measured the abundance of clams in good habitat - like this - and bad habitat Caulerpa. In 2006 we see that there's four-fold loss of species in Caulerpa - sorry, of abundances of Anadara in Caulerpa compared to unvegetated sediments. We went back in 2009. There are now no clams in unvegetated sediments because there are no unvegetated sediments. It's all now colonised by Caulerpa.
What we see is the abundances are now reduced to about three or four per metre squared. We will see local extinctions of this species within five to 10 years. So - and I would put this out there - that Caulerpa is potentially one of the greatest ecological disasters in New South Wales estuaries. If it can have these effects in Lake Conjola it can do this in any estuary that it invades in New South Wales or where it's present. But Caulerpa itself is only one of many habitat forming invasive species that we have both in the terrestrial and the marine environment. But we don't know a lot about their impacts. We don't know a lot about what's happening to biodiversity and the environmental changes associated with them. Globally, their environmental impacts are underestimated.
So how do we manage invasive species? Well, up until 2005 Australia lacked a coherent framework for managing invasive species. Now, two things happened in 2005. We developed two policies independently. One for the terrestrial environment - the Invasive Weeds, Pests and Diseases: Solutions to Secure Australia policy - and one for the marine environment - the National System for the Prevention and Management of Marine Pest Incursions. Now, big documents - it took me a while to read them - but essentially, both of these independent documents had three main objectives. The first was to reduce pest incursions. The second, restrict their spread. The third, to reduce their impact once they're established.
These policies were developed primarily in response to increasing invasions in the last 1980s and 1990s. The marine policy even went as far as developing a national monitoring network. So these people identified 18 key - at key - sorry, at risk - key at risk locations. The sites were chosen based on their risk of new introductions, translocations of existing pests and to provide a good geographical spread around Australia. The terrestrial framework aimed to cover all taxa, including plants, animals and diseases.
It was also developed to fix some contradictory policies amongst states and territories. Some states would - had a policy of one species but not others and vice-versa in other states and territories. But one of the things it did do is it makes - it did make quarantine, surveillance, cost-sharing, eradication and control arrangements equivalent for both environmental and agricultural needs. So despite the fact that we still don't know a lot about the economic worth of intact environments, it was put on the same footing as the agricultural needs where we know what some of the direct impacts that invasive species have.
Problems - well, the cost for implementing these strategies fell squarely on the states and the territories and both of these policies are expensive. So as a result, no state or territory has yet implemented these policies. So - in fact, we have no comprehensive national framework. That's not to say that there aren't national policies for some individual species. In the marine environment we do have a national policy that's administered by AQIS for monitoring biofouling and ballast water for incoming international vessels. So most of the management is done at the state level.
But most of these departments have limited funds for management and they generally manage a very small list of very bad species. The management tends to work best when it engages with the community. If I go back to the Caulerpa example, New South Wales INI are continuing to monitor infestations and they attempt to eradicate where they're feasible. But what's happened in Wallagoot Luke - Wallagoot Lake. For goodness sake, you have to be Australian to say that well I'm afraid - is that New South Wales INI went in. They did a broad scale eradication plan and they got community volunteers to come up and mop up all the little fragments that remained that INI couldn't afford to come back and monitor. So it seems to be working really, really well in this instance.
So what's the good news and the bad news about invasive species in Australia? Well, Australia has many of the most invasive species in the world. Some of the good news - well, we know a lot about how species get here now. We're learning more about which ones will become invasive and spread. So our predictive ability is increasing. The rate of arrival and establishment of new species should slow. Having said that, we're discovering 20 new exotic species in Australia every year. In Port Phillip Bay alone, we're finding three new marine exotic species. The bad news - the established species will continue to have major effects on biodiversity. The implications of biodiversity loss are still very poorly known.
So where do we go from here? Well, I guess it depends on this top question - whether we have the political will to do anything about it. Now, management only really occurs if the known economic benefits outweigh the costs of management, such as control. So we need to better understand the true economic benefits of biodiversity and ecosystem services per se. One of the other questions we need to ask ourselves is what is the economic cost of not doing something? Should we just assume that biodiversity and healthy ecosystems are worth a tremendous amount of money economically? I suspect we should. I think it's naive to think that the environment, biodiversity and economics are decoupled in some way. But one of the things that I really - also really want to stress is it's very, very hard to get large scale funding for impact studies. These are the studies that ultimately tell you what the costs of these invasive species are. Most of the money goes into the front end about stopping species get here - you can see why they do that - and how to stop them spreading once they are here. I'll throw this in there but sometimes I can't help but think that there's this mentality of if we don't know about it or we don't know about the impacts then we don't have to fix them.
I just want to finish with this quote because I think it's pertinent. Thirty or 40 years ago we didn't even think it was possible to remove invasive species from small islands. Now this is commonly done and it's done globally. We even have some very successful mainland reserves that are now completely free of invasive species. So I think that there is some hope for managing invasive species and protecting our biodiversity against them. Thanks.
16 June 2010 51:22
Tags: environmental science, Australian plants and wildlife, biodiversity, ecosystems
Will Australia’s iconic plant and wildlife survive foreign invasion?
Australia's biodiversity makes a significant contribution to our national identity, our culture and our tourism industry. Over the past 200 years we have suffered the largest decline in biodiversity of any continent in the world. Despite efforts to manage these threats and pressures impacting our unique ecosystems, the rapid decline continues.
Focusing on a selection of invasive species in Australia, this public lecture reveals the extent of the threat and suggest what we could be doing to safeguard the future of our plants and wildlife.
About the speakers
Senior Lecturer, Dr Brad Murray is an ecologist whose motivation and passion lies in the conservation of biodiversity. He is particularly interested in ecological theory, concepts and their application to conservation issues. His scientific research has covered the spread and ecological impacts of exotic plant species, the ecology of rare and threatened species and large-scale ecological and evolutionary patterns in terrestrial assemblages.
Currently in the Department of Environmental Sciences at the University of Technology Sydney since 2001, Brad heads up the Biodiversity Research Group within the centre for Climate Change Cluster (C3).
Post Doctoral Research Fellow, Paul Gribben is a marine biologist with a broad range of research interests including invasion biology, larval and community ecology. His main research focus is in the processes structuring marine communities. This includes why marine invertebrates make the habitat choice decisions they do, what the consequences of habitat choice decisions for individual fitness are, and how anthropogenic stressors affect population processes and community organisation.
Paul is a Research Fellow in the Biodiversity Research Group within the centre for Climate Change Cluster (C3).
UTS Science in Focus is a free public lecture series showcasing the latest research from prominent UTS scientists and researchers.
Related videos
Marine microbes: the ocean's lifeblood?
Dr Martina Doblin and Dr Justin Seymour reveal how understanding marine microbes' ecology is essential for predicting the consequences of an over-exploited ocean and its impact on climate change.
The end of growth?
Australian entrepreneur Dick Smith and Professor Paul Ehrlich discuss several economic, environmental and political factors that reveal a global system far more fragile than we imagined.