crawfish – Schnarr's Blog

Aquatic Macro Invertebrates at Litzinger Road Ecology Center

Aquatic Macro Invertebrates are animals without a backbone that live in water and can be seen with the naked eye. I’ve had an interest in these creatures ever since I can remember. When I was young I caught a variety of water invertebrates such as water beetles, clams, crawdads and snails and attempted to maintain them in my aquariums. I was thrilled when my brother’s aquarium started to grow hydra even though they predate on tiny fish, because I’d read about them but never thought I’d see any. I currently have small colonies of freshwater shrimp in three of my aquariums. Many aquatic invertebrates are insects that live part of their life cycles in water but have an adult flying stage.

When the Litzinger Road Ecology Center offered a training workshop for volunteers on how Aquatic Macro Invertebrates are used to monitor water quality, of course I had to attend. Master Naturalist and Stream Team member Cliff Parmer taught us some Aquatic Entomology facts then we went outside to Deer Creek to learn how to take a scientific sample of water invertebrates.

sampling aquatic invertebrates — Volunteer collectors chose two spots in the stream for collecting samples – one in a riffle, and one in a calm area. The stream bottom was disturbed while a seine caught the small animals that were swept downstream.

collecting water invertebrates — We examined the contents of the seine for small invertebrates which we placed in ice cube trays filled with stream water.

aquatic invertebrates in Deer Creek — Here are some of our finds – there is a nice leech in there (yuck). One of the animals in the right tray is a Mayfly nymph – something I was happy to see because the purpose of sampling is to check water quality. Mayfly nymphs are one of the animals found only in healthier streams. Stream team sample findings are reported to the Missouri Department of Conservation so they can use the data to check stream health.

identifying aquatic invertebrates — Although macro invertebrates can be seen with the naked eye, a microscope is useful to see small details to help identify each species. We were provided with identification charts to show us what to look for.

Mother crawdad with babies under the tail — I used my childhood crawdad catching skills to hand-catch the most “Macro” invertebrate of the day – a large mother crawdad with tiny babies clinging to the underside of her tail. We released all the animals back into the water after we had a look at them.

If your garden has a water feature, at some point you may encounter aquatic invertebrates. A common example is the mosquito, very undesirable and needs to be eliminated. A strain of BT (Bacillus thuringiensis) will kill mosquitoes without harming any other life forms (except some gnats, which I don’t think anyone will be sad about – except maybe hummingbirds which eat them). Most other aquatic invertebrates are harmless or downright beneficial. For example, dragonflies live the first stages of their lives in water and are one of the best predators of mosquito larvae. When dragonflies emerge as flying adults they have a voracious appetite for adult flying mosquitoes – they also add beauty and color to the garden. Others, like caddisfly larvae or water beetles are not exactly beautiful in a conventional sense but have interesting lifestyles that are fun to observe and study.

Even if your garden does not include a water feature, there are ways that your garden can impact aquatic invertebrates. Water that runs off your garden and yard into a storm sewer is eventually released into natural bodies of water. If you can keep excess pesticides and fertilizer out of storm runoff you can help invertebrates to survive. Excess fertilizer harms invertebrates by causing algae blooms that reduce oxygen in the water and kill off more sensitive animals. Life forms higher up on the food chain such as fish and birds depend on a steady supply of invertebrates for food.

If your property is adjacent to a body of water, you can further aid the water quality by implementing a riparian corridor or creek corridor vegetative buffer. Such a corridor does many things for water quality, including temperature regulation. By cooling the water, streamside vegetation helps maintain higher oxygen levels in the water.

Backyard wildlife increases my enjoyment of the outdoors and my garden. If you feel the same way, an appreciation for small but vital water animals can be rewarding!