New Pond Critter Tank

[Stella]

On Saturday I finally set up a spare 3ft tank as a pond.

I had a 1ft cube tank set up as a pond for a year or so, it worked really well and I wanted to scale it up.

So, the idea is I add random bugs to watch, and random collections of things that I pull out of ponds over time, and some will form self-sustaining populations - everything eating each other. The basis of the ecosystem is a combination of sunlight (the tank is half against a window) to feed algae and plants and peat and leaf litter decomposition. Occasional waterchanges and plant thinning will be needed, but generally it will be pretty low-maintenance.

The current population:

Water beetles (two species, I love water beetles!)

Backswimmers and boatmen

Daphnia

Snails

Pea mussels (tiny filter-feeding mussels)

Tubifex

Copepods

Ostracods

Plants:

Nitella (native branched algae that looks like a plant)

Lemna (duckweed, will also try Azolla fern later)

It doesn't look like much, but it is fascinating to watch. Still a bit cloudy from setting up, but the pea mussels should deal to that in time.

(the big dots are backswimmers, the little dots near the surface are daphnia, everything else is too small)

The backswimmers eat insects - they suck their juices! They had been there since the weekend and tonight I added some daphnia. Talk about CARNAGE! The backswimmers clearly chase the daphnia, then to catch them they do this dramatic circle around them. Within a minute of putting the daphnia in the tank, almost every backswimmer was sucking daphnia juice through a straw!

:bounce:

Next I want to get more beetles (love beetles!), some damselfly and dragonfly larvae, and maybe see if some tadpoles can survive the beetles over summer. The backswimmers have already covered the nitella with eggs!

A neat simple experiment in community and ecosystem ecology

[Artem]

Yoah! Cool tank! I'd be careful about adding too much dragonfly/damselfly larvae, or just keep watch for when they decide to hatch/molt(I'm not sure what its called..). You may consider adding some shrimp or small crayfish, but these are from streams so I don't know if you'll want to ruin the 'look'

Good Luck with this set up it looks really cool right now!

[Josh_S]

Watch out for the mozzies when trying to get to sleep!

Very nice!

[Moya]

What a brilliant idea! I'm totally going to try something like this. Thanks for the inspiration

[Stella]

Artem, why the caution about adding too many dragonfly/damselfly larvae? I was thinking only adding in a few - certainly the top-down control by too many predators would muck everything up.

I might put some shrimp in at some point, and maybe some mayflies or caddiesflies, just to see if they can deal with it. Yes I would like to keep it pond-focused, but it is also an excuse to learn more about any critter

Josh_S, last summer I had a mudfish tank set up but had no fish in it (peat substrate, so lovely tannined water that the mossies love). The wrigglers were going nuts! Finally I managed to get the fish in there before they all simultaneously hatched and sucked me dry

[Jennifer]

Great idea Stella, I am inspired. I am just wondering about the high concentration of organisms for that small space - is that the way it is in ponds?

[Artem]

It wont matter if its just a few. I was meaning that when they hatched you may have a problem. When I had frogs I decided to try hatching some dragonflies, except then one morning I wake up to around 10 buzzing in the tank and the frogs didn't even eat them Then when I went to get them out they escaped! My cockatiel got a real fright >.>

Same thing goes for mozzies they can be a real pain because they're harder to see. In general if you keep a lid on it you should be fine, mozzies cant get in and lay the eggs and hatchings cant get out, everyone wins, and hopefully you don't wake up with bites all over you!

Another thing is to make sure is that you don't get the giant dragonfly larvae. Ive seen ones with a 15cm wingspan! beautiful insects :]

Anyway, I'm no expert so don't take me too seriously

[Stella]

LOL Artem, that sounds awesome! I wanna grow my own dragonflies! :bounce:

The window above the tank is always open, so the mossies will get in. In summer I rely on keeping the doors closed, pulling the sheets up tight and earplugs... :roll: (Actually it usually works out fine. And with the 'pond' I can just add more backswimmers if the mossies get out of control, but the increase in food should lead to a natural increase in predators)

Thanks Jennifer. The 1ft cube sustained an amazingly high diversity of critters, and certainly the tiny ones (copepods and ostracods) were in really high numbers. I do expect that the backswimmers will die back quite a bit, not in the least due to me harvesting them for the fish But everything will find their own natural balance, and that is the interesting part of this as a long-term project.

(I am a postgrad ecology student and my applied theory geekgland is having a fun workout tonight )

[Nymox]

Want me to send a couple of these Stella?

I was told they are dragon fly larvae, I still have that one in my paludarium its been about 3 months since I put it in there, eats guppy fry but it hasnt changed at all, just gotten alot bigger, its now close to 3cm.

I have about 10 of them in my daphnia tank outside so can send ya them if you like, they are just eating my daphnia so not really good for me lol, I suppose I could feed them to the Birchirs.

It looks like a fun project Have fun! :bounce:

[antwan]

Nice work, good to see something a bit different

[Stella]

Thanks, Nymox, but I don't know how well such things would post. I am happy to keep poking around in streams and finding things randomly. It gets me out there and keeps things interesting

Last night I watched for about 20 minutes:

Saw boatmen mating (man they go for ages!)

And one boatman trying to hit on another (didn't work)

Saw a huge daphnia swim away from a predation attempt, like Beaker on the Muppets! Almost head the "memememe!"

Most of the previous day's daphnia have been eaten

Turns out I have two damselfly larvae

Was watching some things mosying around the plants, could be a huge ostracod or a bivalve-like cladoceran...

Some of the backswimmers have bright red mites on their thoraxes

Not sure where the small ramshorn snail came from

Note to self: USB microscope!

[Insect Direct]

Ive just noticed red mite like things on some backswimmers here.

Have you used a usb microscope? They look perfect for close up photos

[Insect Direct]

http://www.youtube.com/watch?v=EGPOA5AJIKk

are the red things mites?

[Sophia]

I think I had those. I also had ostracods 'riding' backswimmers before I realised it was the backswimmer swimming along eating the ostracod :lol:

[Stella]

yes they would be aquatic mites. Very often seen on the thorax of backsimmers. They are parasitic for part of their lifecycle.

[ally07]

Just curious, Stella:

1. Is the lack of aeration going to be a problem?

2. Does it smell like a stagnant pond?

:-?

[Stella]

Hi Ally,

The lack of aeration hasn't been a problem. Actually aeration would have been a problem for the beetles and backswimmers that breathe at teh surface.

It smells fresh and nice actually (I had to go check!). Things go stagnant when the oxygen is used up and decomposition goes anaerobic (I think, someone might correct me on this). The peat is fairly inert and the thick growth of nitella and floating lemna and azolla are providing plenty of oxygen. The amount of decomposition in pretty low, and it is all just providing nutrients for the plants.

I haven't waterchanged it in a few months (naughty!) and I really ought to test the water, especially for nitrates, will be interesting to see just how balanced it is!

[ally07]

That's so cool, lol. I assumed (naughty!) that in nature, ponds would have natural aeration, eg wind/ rain, thus an artificial pond would also need the same. Expanding on that logic, I thought that if there is no oxygen, everything dies and gives off a really funky smell, as I've experienced with an old canister filter that I forgot to clean out lol. Interesting idea for a tank, much less "artificial" than the rest of us haha.

[Sophia]

All my outdoor buckets are aerated naturally in the breeze and are always fresh. The only one that went stagnant is the one that started with pureed peas to get the green water started.

[Stella]

Well, that is true about the natural aeration, but it is also a balance. The term is 'biological oxygen demand'. If the bacteria in the system need more oxygen than is available then aerobic bacteria will die and be replaced by anaerobic bacteria and get manky and stinky very quickly, and it is rather hard for it to recover from that.

[Squirt]

Hey

Where did you get tublifex? I was thinking of culturing them for fish food. Is this a good or bad idea?

Thanks

[Stella]

no idea! I assume they just came with a collection of trough bugs. There are thousands in there but they are invisible most of the time except when it gets low in oxygen and they stick their tails out of the peat and form these amazing waving meadows (good indicator species!)

I have no idea how you would separate them from the substrate.

I took some odd things into uni last week for my supervisor to identify using a microscope. Turns out they are the ciliate protozoan Stentor http://en.wikipedia.org/wiki/Stentor_(protozoa)

The cilia (little moving hairs) are all around the edge of the trumpet and beat so fast you can't really see them, just looks like a sort of glowing halo. The 'bodies' also wave around a little and they can swim quite effectively using the cilia. When disturbed they 'flinch' and contract into a ball. Pretty cute for a single celled organism!

The green is the nitella they are living on, the little trumpets are the Stentors:

[Sophia]

are those the same little greeblies you found that retracted when you poked them in the other thread we had going a few months ago, or something new?

[Stella]

nice memory!

These look quite different to the 'chandelier' retracting things, but appeared in the tank at the same time. There seem to be heaps of 'trumpets' but I couldn't find any 'chandeliers' when I wanted to take a sample to uni. They could well be a similar thing, or a different form of the same thing.

This is the original thread, with photos: viewtopic.php?f=41&t=50080&hilit=ufo

[Sophia]

yep those! In some ways it's a shame I don't have a glass Bug-quarium anymore, I can't see all the smaller critters.