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The function of fungi

Janice WilliamsJanice Williams
Email: janice.williams@latrobe.edu.au

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Matt Smith:

Welcome to the La Trobe University Podcast! I would be your host Matt Smith. And I'm here today with Janice Williams who's a PhD student in the Department of Environmental Management and Ecology. Thank you for joining me, Janice!

Janice Williams:

Hi. Pleased to meet you.

Matt Smith:

Your PhD focuses on the break down of organic material and fungi, is that right?

Janice Williams:

That's right, specifically looking at floodplain wetlands. How fungi contribute to breakdown of plant that thrives on dead plant material and how that contributes to moving carbon around the environment and also through food chains.

Matt Smith:

Is fungi really important to the carbon cycle?

Janice Williams:

They're a component. And they're a component of the carbon cycle that we haven't really focused on before. They work at the same level as bacteria do. And we've done a lot of work on bacteria in wetlands, but we haven't looked at the fungi, so we don't know what they're doing. They're an important part of the equation we need to take into account.

Matt Smith:

If we're going to some baby steps, first, can you give us a bit of a brief of what the carbon cycle is and what the fungi's role on this has been?

Janice Williams:

The carbon cycle is really about life cycles. It's about how carbon is taken in from the air by plants. It's made into a biomass. Then, consumers like animals who eat that carbon make it into their biomass. And then, what is not eaten by other consumers is decomposed. So, decomposition is where fungi and bacteria come in. They take dead plant and animal material. They make part of it into their bodies, their biomass, and other parts of it, they respire.

So, you're getting this cycle of carbon in form of carbon dioxide or methane from the atmosphere into plants and animals when being decomposed. Then, gas is either going back to the atmosphere or carbon being stored in soils and sediments. So, that balance between what goes back to the atmosphere and what gets stored is really important to things like global warming. We want to know how much is going back to the Earth and could possibly contributing to global warming, how much is going into soils and into biota. But also, carbon in soils is an indicator of soil health.

Matt Smith:

So, it's a circle of life, Simba, sort of thing?

Janice Williams:

Yeah, yeah.

Matt Smith:

Where does your research come into it?

Janice Williams:

I'm focused specifically on floodplain wetlands because they are an environment that's really quite interesting to me. And then, I'm focusing on the decomposition part of the carbon cycle. And, since we already know what the bacteria are doing in terms of decomposition, I'm going to focus on what the fungi are doing, which has been difficult because fungi are interesting organisms that we've sort of avoided because they're hard.

Matt Smith:

Why are they hard?

Janice Williams:

The fungi are hard to count because they're multi-cellular organisms that branch out within their food source. So, it's very hard to separate their biomass from their food source to measure it. It's very hard to determine how many of them there are - like with bacteria you can count individual bacteria cells. But, with fungi they are these branched out, interlocking spaghetti on an organism within their food source interspersed with other organisms that are similar in bacteria. And it can be very difficult to just say how much is there, so we've had to resort to chemical methods. So, we extract biomarkers so a chemical that's specific to fungi figure out how much of that's there. And then, we use that as a measure of how much fungi are there.

So, that's a method that's only been developed in the last 20 years. So, up until that point, figuring out how much fungi was there was a headache. They're quite unique organisms. In fact, when we're talking about kingdoms, you know there's a plant kingdom, animal kingdom, there's actually taxonomic now three kingdoms of fungi. So, we've got three groups of organisms that we call fungi and they're all quite different. And we've ignored them a lot because we've sort of try and kill them because of causing mould in our bathrooms or infections on our animals. But, they have a function in our ecosystem that's important, that we need to know about.

Matt Smith:

You're studying them specifically in wetlands, but what sort of conditions can they leave in? Is there a potentially different fungi for every living environment?

Janice Williams:

There's potentially fungi in every living environment, but they're likely to be different ones because they have specific adaptations to their food sources. For instance, one of the food sources that I've been focusing on is River Red Gum leaves, and because they have oils and tannins that make it difficult for all sorts of organisms to eat them. There's a specific group of fungi that like to colonize them. If you looked at for instance, Maple leaves, you will find a completely different group of fungi that colonize them. There's probably normally 20 or 30 species, but they'll be different between different places and different food sources, so leaves and sticks and dead animals.

Matt Smith:

We're in Albury-Wodonga at the moment, which is well-known for its river systems and wetlands. So, how important is fungi here to the ecosystem?

Janice Williams:

I t's an important component. There are few different roles that fungi has in the ecosystem. So, there's the breaking down of these leaves. In many ecosystems, the aquatic vegetation is too hard for insects to consume. They don't have the ability to eat it directly. So, what happens is reeds and sages they can get eaten, they die and they fall into the water. And then, they get colonized by fungi and bacteria. In the process of being colonized by fungi and bacteria, all the things that make it hard for animals to eat those plants start to disappear.

And what's more, fungi and bacteria, mostly fungi, improve that dead vegetation, in terms of nutrition, like more protein, more essential fats and acids and stuff like that. So, when aquatics insects come along and try to eat that colonized plant material, they actually are able to consume it and live on it and reproduce and have a full life cycle. So, fungi and bacteria are important in being able to channel energy from the plants into the insects and they're not the food chain. There's like an important stick there that could be broken if the fungi disappear.

Matt Smith:

So, is the fungi OK? Should we be concerned about it?

Janice Williams:

Like any organism, it's dependent on its ecosystem. So, where I say that a lot of these species are specific to their plant substrate. If we for instance, lost a River Red Gum, we would probably lose a lot of the fungi and colonized leaves there with the Red Gum.

Matt Smith:

Right. Things like pH levels and salinity in the water.

Janice Williams:

These are things that fungi adapt to, so you'll find that a different pH or a different species there. Yeah, they don't like salinity. And there in the research that I'd like to look into how some rising wetlands due to rising of the tables is going to affect these fungal decomposition processes. But, it's not something I've looked at yet.

Matt Smith:

That's a whirlwind of fungi. So, what's going to be the end result of your PhD? What sort of thing are you going to contribute to fungi kind?

Janice Williams:

I think it's important just to know what they're doing so that we can determine what types and variables influence the rate of their processes. So, for instance, one of the important things that, in terms of our land's rivers' regulation, if we change the season that we fill floodplain wetlands from winter when we normally would get flood, to summer when we send early out irrigation flows, how is that going to affect floodplain wetlands and the way that fungi are behaving in.

It appears that it's going to have some major effects in terms of the River Red Gum because the River Red Gum loses its leaves in summer, which means that if we have summer flooding basically lose it for straight off the tree into the water, means that more carbon comes out of then directly into the water. Those oils and tannins go directly into the water. And also, the aquatic fungi aren't able to colonize them straight away because those things like Eucalyptus oil are anti-fungal agents. That's why we use them in a medicinal way. So, they're not able to colonize the leaves, which means they're not able to provide food source for insects for at least three or four weeks. So, because it's hot at summer, the water holds less oxygen anyway. So, what we get is leaves fall into the water, there are a lot of carbon, the bacteria use that up, they use up the oxygen at the same time. And then, we have no oxygen in our water, we get fish dying.

This is an important thing to think about because we're potentially, it's not being tested, but we're potentially looking at food chain problems, we're potentially looking at water colony problems, and we're potentially looking at fish kills and "blackwater" events and other sorts of problems as well. So, knowing how the fungi deal with these sorts of situations, like what's the process, how do they fit in. We need to put water dam in the summer. We need to have irrigation. But maybe, we need to make sure we don't fill our floodplain wetlands in the summer. And maybe, we need to make sure that we do fill them when we get our high rainfall period in the winter. The important management decision is could this really help to inform.

Matt Smith:

It just goes to show how fragile the ecosystem is of those small things can just tip over the edge.

Janice Williams:

Yeah. Changing the seasonality of different events like flooding really does impact heavily upon aquatic ecosystems where all the biota are adapted to those season times. When fish reproduce, for instance, is often stimulated by flood events. So, if you change the seasonality of that, you're changing that their breeding them when it's not really viable. So, it's all very sensitive.

Matt Smith:

And what is it about fungi that you said "that's an interesting topic I want to research that"?

Janice Williams:

Why I was interested was because I did a project a few years ago looking at "blackwater" events. So, the botany of the forest is a Red Gum floodplain forest. It's pretty much just Red Gum over the floodplain. And it floods on a seasonal basis, so usually winter-spring, maybe around every year. But, sometimes when it floods the water turns black. And when the oxygen gets used up, then all the fish die.

And we wanted to know why that happens, and we were looking for the data that we needed to figure out who's using up all the oxygen and under what conditions would that happen. But, there was no information at all about fungi. It was just a really important black box that we weren't able to figure out where the numbers went. So, we're trying to make a model. We didn't have that information. So, the model was made and it works and it's useful. But, it just seemed to me to be a really big hole in our scientific knowledge. And I sort of thought that I could contribute that.

Matt Smith:

Janice Williams, thank you for your time today.

Janice Williams:

Thank you.

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