How can babies tell us about their environment? Recently, I visited three locations and collected macroinvertebrates (small and mostly immature insects still visible to the naked eye) from the ponds at Borders Farm in Foster, Buck Hill Wildlife Management Area in Pascoag, and Trustom Pond in Matunuck. Different species have different pollution tolerances, so certain species would indicate how clean the water was.
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| Abstract art or animals? Maybe water pennies? Very tiny. |
I first collected at Borders Farm, which has a small retainer pond with cattails, grasses, lily pads, algae, and lots of frogs. I was there to run an insect workshop and in the past another collector found a number of insects as well as leeches. I went into the shallow water with my rain boots and clean white plastic tubs, swishing my net back and forth through the fairly clear water. It was teeming with water boatmen and I dumped every scoop into one of the tubs I had added pond water to. I picked out the plants, swirling them one more time in the water and examining them before returning them to the pond. I added clear pond water to the other tub and brought them both over to the table. Then I waited for the sediment to settle.
Photographing these creatures posed its own challenges. It was a sunny day and we were set up in the shade. The sun was in my eyes most of the time, plus I was running a workshop. But I did get a few shots of some of the creatures.
Very pollution-tolerant are aquatic worms, blood worm midge larva, left-handed snails, and red-tailed maggots. I'm sure I didn't find every species in that pond, but I saw all but the maggot larva.
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| This snail looks like it's holding a balloon! |
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I didn't know to check which side the hole is on. I think this is a left-handed
snail, which breathes air. (Right -handed snails have gills.) |
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| Backswimmer from the pond. Shadow of my camera lens? Fairly tolerant species. |
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| Even another species? |
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| Mysterious newcomer! I later identified it as a phantom midge. |
Next in tolerance are the midge larva, like the phantom midge above, planar (flatworms), black fly larva, and leeches. Moderately intolerant to pollution are the damselfly nymphs, dragonfly nymphs, sowbug, crankily larvae, clams, and scuds or amphipods. We found two dragonfly larva and a few scuds. At the least tolerant tier are the stonefly and mayfly nymphs, riffle beetles (adult and nymph), caddisfly and dobsonfly larva, water penny larva, and the right-handed snail. Below, see the mayfly nymph!
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| Mayfly nymph. |
This was so exciting and I wanted to do it again with more time to improve the photography. At Buck Hill, I repeated my collecting with my cleaned, bleached, and rinsed bins to have another look. I moved the bins to a sunnier spot, still struggling against glare and shadows cast by either me or the sides of the bins. But I got a few better photos and a few people interested in what I was doing, including an older couple walking their dog and a man from the USFS! ("No, I wasn't with DEM. I was just taking pictures before I let them go. Do you know...")
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| Another oarman. |
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| Dragonfly larva! |
I did the usual sweep through the plants and dump. With the many oarsmen at Borders, I was looking for movement. But then I saw something big drop out... What WAS this? I saw the long projection and guessed water scorpion, my guides left at home. And it was!
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A water scorpion! Not actually a scorpion, but a predatory insect
found in slow-moving water. This guy did not move fast, so I easily
moved him to the clearer tub for the photo. |
On to Trustom Pond, a much larger body of water with frogs and painted turtles. There were oarsmen again, and my first leech! It was on a turtle we caught and stubbornly clung first to the turtle's shell, then to the boardwalk, then the tub. (The turtle snapped the stick with its beak and hissed at us, but after a few quick photos, we let it go.) Doing more sweeps, I brought up a lot of muck. As I swished through it, we found many aquatic sowbug (isopods). There were also dragonfly and mayfly larva. All three locations were quite clean!
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| Blood midge. Very tolerant. |
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| A clam! Moderately intolerant. |
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| Aquatic sowbug. |
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| Eat dead plant matter. |
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| Can indicate a recovering ecosystem. |
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| Got a cool shadow with this backswimmer. |
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Still dealing with bin shadow.
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| A whirligig beetle. Moderate pollution tolerance. Just briefly out of water. |
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| The LEECH!!!! |
Basic rule of thumb is the cleaner the water, the more biodiversity you will see. The air-breathing species are more tolerant because they don't breathe the water. Gilled creatures are thus more sensitive. Seeing a pollution-tolerant species does not mean the water is polluted unless that's all you find. Here's a good guide:
https://scioly.org/wiki/index.php/Water_Quality/Macroorganism_List
But I know you're wondering about that turtle...
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| "Hiss! Boo! Put me down!!!" |
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| "I still don't like this!" |
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| One more pic! |
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| Back at home! |
If you'd like to schedule a workshop in RI, MA, or CT, message me in the comments or at 15minutefieldtrips @ gmail.com. (Spaced to stop robots from messaging me, lol!) I also cover other insects, birds, fish, turtles, seeds, plants, and composting. See you outside!
