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"Few will doubt that humankind has created a planet-sized problem for itself.
No one wished it so, but we are the first species to become a geophysical force,
altering Earth's climate, a role previously reserved for tectonics, sun flares, and glacial cycles."
E. O. Wilson, 1998. Consilience: The Unity of Knowledge
p. 277-278

Microbial loops

Monday 13th March 2017.

Scientist Angus Rawleinvestigates microbial loops in fresh water systems
and how these may change with big rain events.

Angus is studying freshwater ecology in the School of Life Sciences,
University of Technology Sydney.

TRANSCRIPTION

AR: I'm Angus Rawle and I'm looking at bacterial carbon interactions in the microbial loop.

LR: Now what the hell does that mean?

AR: Ha ha, no it's not exactly so straightforward. So basically you've got this concept called the microbial loop and it's pretty fundamental to a lot of aquatic ecology. The idea is that you've got algae in the water and these algae, they eat up all the sunlight and they absolutely love it and pump out all these nice things, essentially algae poo... and everything else likes it, and this...

LR: I thought algae were plants!

AR: Yeah, they're a photosynthetic bacteria.

LR: How do they poo? I didn't know plants pooed.

AR: They're cells, so they just let stuff out.

LR: Stuff.

AR: Stuff.

LR: This is a whole new idea for me.

AR: Yeah. It's where they, they just excrete stuff, like plants do... see I'm not a plant biologist.

LR: Stuff. Sap comes out of trees.

AR: Yeah I don't know what sap is.

LR: OK. Don't you?

AR: I think it's like, sugary...

LR: Yeah.

AR: I always thought that...

LR: Sticky stuff.

AR: [like] blood

LR: So, algae poo...

AR: OK, so when the algae kind of explodes essentially, like if something ruptures the cell it will let all the stuff outside the cell, just go. And that's just these really simple little carbon molecules on it, like sugar. In our experiments we use glucose as a substitute for algal carbon. So it's just sugar really. And the bacteria munches the sugar up, and absolutely loves it, and then these bigger ones, these sort of lurkers called nanoflaggellates, they eat the bacteria which have eaten the carbon, and they're these weird things. They're tiny, almost little pods with little wriggly tails so they can move themselves around wherever they want to go. And then they're eaten by something called the cilliates which are these almost big hairy ball things. ...

LR: And they do this (wiggling fingers).

AR: Yeah, they just sort of hang around and do (wiggling fingers)... and they can also use their fuzzy things to sort of eat the water towards themselves. Like, 'Come to me, come to me.' Ultimate laziness. I quite like it. And then the cilliates are eaten by these things called the zooplankton which ... they're planktonic, which means thay don't really control where they go. They just go with the flow essentially. Literally. And they do the same thing, they eat water towards themselves, and they'll eat these cilliates which are quite small compared to them. So this is just a gradient of size, so things just keep getting bigger and bigger and bigger...

LR: So we start with the algae poo...

AR: Yeah.

LR: That's the tiniest element in the loop?

AR: Yeah.

LR: And we finish with the zooplankton?

AR: Well! That's, that's...

LR: That's just the start of another loop?

AR: The question we're trying to figure out is whether it ends with the zooplankton... (listen...)