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Native/bugs tank log


Sophia

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these are the main critters that were caught today - I think ostracods and daphnia?

These are what i thought were daphnia but now I think they resemble a pod of some sort.

These crawl about on surfaces like beetles but they appear to have only the 2 legs out the front propelling them and do swim about as well.

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I took this so you could see the movements - excuse the quality and yes it should be rotated so they move up and down

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I think these are daphnia and there are 2 sizes. They seem to use their 'arms' to swim up and up a few times and then sink back down. A bit like the breaststroke. In the top circle there is a pod as well

th_morebugs004.jpg

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How curious - there is a mini water boatman swimming along with an ostracod stuck to it's head. It goes boing boing boing along and then his head sinks like 'you're heavy!'

Unless the ostracod is slowly sucking the other dry or some other slow death, there isn't any other sign of difficulty on the part of the boatman.

:o

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Garage tank set up – all available space utilised!

dec26001.jpg

No more oxygen weed, added small sponge filter and clip on 7watt 6500K light for 12 hours a day

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Caught more daphnia and ostracods today, and 2 or 3 swimming beetles that I am yet to figure out what they are. All bugs seem much more active with the filter and light on and the water boatmen seem to shoal in the current (though not happy if I turn the bubbles up :nilly: ). Temperature sits around 20 degrees during the day without a heater.

Hydra have not seemed to grow in numbers so I'm not so concerned. I've squashed a couple on the glass to see if they try to emerge again.

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In other news, I moved the 2 surviving shrimp from the killie tank back to the bug tank, and they seem quite happy. No sign of the 3rd shrimp, presumably the one that died was the one that was trying to lie down in the bug tank when I plucked it to 'safety' and it died anyway. :o

So the survivers went from stream to container, to rain water tank, to slightly salty killie tank, and back to partially water changed bug tank. Hardy little critters, very interested and alert.

Found a green hydra, actually saw it trying to catch an ostracod - ostracod went up to it, next thing ostracod leapt away like it had been burnt (stung).

Also I see there are some much fatter daphnia in among the others, these I presume are pregnant so that's good news for bug farmers :happy2:

Also trying to ID a swimming beetle. I don't think it's a diving beetle, it's round and black like a katipo spider with similar markings in pale colour and you can see the legs scampering away under water. About the size of a dressmakers pin head is the biggest.

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Your swimming beetle may be a mite: http://www.google.co.nz/images?q=aquati ... 80&bih=839

I have one in my bath-pond outside. It is the size of a pin-head and swims around crazily - 'scampering' is a really good description!

It turns out that the mites have a parasitic life stage, which are the little red blobs you see attached to the thorax of some boatmen and backswimmers. The adults are usually carnivorous, eating little critters of all types.

(I think you would enjoy this book: 'An introduction to the freshwater crustacea of NZ' (1976) by Chapman and Lewis. Often on Trademe for circa $45. Currently being updated for a reprint. A technical book but also quite readable and entertainingly written)

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Yes the big one looks like a mite in body shape. I wondered if it was some sort of killer beetle but I haven't seen it catch anything and doesn't seem to chase anything either. Maybe it eats at night or much smaller critters.

I will see if any of the libraries have that book - I am lucky to have the resources of the uni library available too, sounds like something they would have.

edit - yes the library has that book :happy2:

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  • 2 weeks later...

Today's update:

Have removed all suspected predators that I can identify and am now left with 2 shrimp, rotifers, daphnia, a few ostracods, a couple of snails and some things look like miniature limpets stuck to the glass. There is now a lump of bog wood with some baby java fern plantlets attached, and most of the native plants now removed.

What I find odd/interesting is that the ostracods seem to have mostly died out, and most of the small daphnia. I'm left with a group of about 20 fat daphnia from about 40-60 after the last trawl in the trough. Wondering whether the suspected predators got the small daphnia (backswimmers and mites) or whether they died naturally?? I haven't found a way to feed the tank successfully yet (still growing greenwater) so maybe everything starved??

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The 'limpets' are cool, I have a few. They are actually a snail :-?

The bugs that I have outside in buckets don't seem to have built up numbers at all so no easy live food for the little bullies in my native tank. The bugs in the little tank on my desk/window sill are doing well with the populations going up and down all the time, both of the diving beetles have gone but there are still some shrimp there.

Good luck with yours sophia

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backswimmers are pretty effective predators, they were probably the problem.

There are two types of freshwater 'limpet' that you might come across.

One only gets to ~3mm long and is fairly transparent. That is Ferrissia, possibly a native. Is pretty common in aquaria, moved in on plants.

The other gets up to 12mm and has a dark, strong shell. This is Latia neritoides, also native, evolved for fast-flowing water and secretes a glowing mucous when threatened - how cool is that!? Not sure how well they do in aquaria. They certainly don't do well with bullies.

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I think I must have the first kind of limpet, these haven't gotten any bigger and about 2-3mm max, quite transparent. They don't like being removed either, I think they die. At least when I took one off to inspect it, it didn't turn itself back over like a snail-snail.

I didn't realise the backswimmers were a problem till too late, and I think they ate each other as well. At one point I had 5 and all but one disappeared. I posted naively earlier that there was one swimming around with an ostracod on it's head but at that time I didn't realise it was a backswimmer, I thought it's legs were underneath. Now I know it must have caught one and was swimming about eating it. :o

If I can't get the bugs to grow back I will have to go trawling again, but I had sort of promised myself that I would not look like a crazy person with a fish net in the middle of the park again :roll: ... I'm sure I will be able to justify another trip soon :lol:

Charles, does the moss have those white blobs on it still? I am watching some that are growing on the glass, and on another strand of moss, odd things they are. They look like miniature cauliflowers or a roundish coral. About 2 mm around and the one that's on the moss is about twice that size. I don't think they are a hydra at all now.

Stella, I'm waiting for my library's copy of your book to arrive, I think it's been long enough by now. Did you also get a request from Auckland Uni as well?

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:an!gry :evil: :facepalm: :x

found a freaking damsel fly larvae in the tank. Thankfully it was resting on the filter or I wouldn't have seen it. That's been alive somehow since Dec 27th minimum as that is when I last caught bugs. Unfortunately for Mr DF he will not be in there very long if I can catch him.

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It was very small, as big as or less than a mm thick only, maybe the body was 5mm long not counting the tail feathers.

Anyway the other thing I am wondering about, in the thread I started called 'Live food found out and about' you posted some photos that were ID'd as copepods. I have those and they have multiplied somewhat. In this thread http://www.thekrib.com/Food/daphnia.html they refer to these as cyclops and say they are a threat to daphnia, they eat the eggs faster than they can lay them.

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http://fishweb.ifas.ufl.edu/planktonweb/taxonomy.htm":qh3asu2g]Copepods range in size from less than 500 um (microns) to over 2 mm in length. They have a cylinder-shaped segmented body with many small appendages on the head and thorax and two caudal setae at the end of the abdomen. They have a prominent exoskeleton, a large pair of first legs (antennae) that are used for swimming, and a single eye. The two most common types of copepods in lakes and ponds are Calanoida (calanoids) and Cyclopoida (cyclopoids)... Copepods feed on a wide range of food, ranging from small zooplankton to algae and bacteria. They are truly omnivores when one considers their position in the food web...

HTH

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Spotted another small damselfly last night. Smaller than the last, not much thicker than a hair. Gone to the pond in the sky now though.

The neighbour's cat knocked over my jar of green water as well :-?

Does anyone know can I just drop a couple of strands of activated yeast into the tank to feed the daphnia?

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