Guest blog by Ursa Heidinger, who did her science project today on the Westfield River with a group of parents & kids organized by Sienna Wildfield, of Hilltownfamilies.org.
When you go to a stream or river, you might not notice, but there are small hard-working bugs, called Benthic Macro Invertebrates on the bottom, that if you looked close enough you could see with your naked eye. The phrase ‘Benthic Macro Invertebrates ‘ seems pretty specific if you don’t know what those words mean, but actually there are many different species. Benthic is pretty much anything that is on the bottom of a body of water. Macro means something that you can see with the naked eye (ex. You don’t need a microscope to see it). Finally, invertebrate means a living organism that has no backbone or spinal chord. Thus, Benthic Macro Invertebrates are living organisms that you can see with your naked, that have no backbone, and live on the floor of a body of water.
These small creatures are very important to testing water quality. They are important because some of them can only live in highly oxygenated water. So, volunteers go out into rivers, brooks, and streams and collect these organisms. If there are a lot of Benthic Macro Invertebrates that live only in very clean bodies of water, then you have a clean, oxygenated river. If you only find very common ones that can live in virtually any kind of water quality then you probably will have a pretty un-oxygenized river. You would also probably find a limited variety of fish, because most fish eat Benthic Macro Invertebrates, so with limited species of Benthic Macro Invertebrates you will find a limited spectrum of fish variety.
Benthic Macro Invertebrates are pretty much the bottom of the food chain. A lot fish eat them (ex. Brook Trout eat Stoneflies), and if a bigger species of fish doesn’t eat Benthic Macro Invertebrates they most likely eat a fish that eats Benthic Macro Invertebrates. If you visited a river with a small spectrum of Benthic Macro Invertebrates you would also probably find a limited variety of fish, because most fish eat Benthic Macro Invertebrates.
In my collection you will see a variety of species of Benthic Macro Invertebrates. There are; Minnow Mayflies, Case Builders, Giant Stoneflies, Fingernet Caddis Flies, Michelin-Man Caddis Flies, Fishflies, and Penny Beetles. All of these I collected (with my father and a few other volunteers) in the Westfield River below Stevenson Brook. I collected them by placing a net into the river, and scrubbing the rocks and gravel, within a foot from the net opening, so all the Benthic Macro Invertebrates will fall in the net. After we caught them, we placed them in a bucket. Then, we repeated that process in a place roughly ten feet away from where we did it before, and placed the organisms in a different bucket. We then repeat the process once more. After that, we move the process inside and separate the creatures (from the leaves, gravel, and what ever else fell into the net) in ice cube trays. After that, we identify the species of the Benthic Macro Invertebrates and put them in according plastic vials. Then, we pour in rubbing alcohol (the same stuff used to sterilize wounds) to preserve them. Later, my dad and I will send the specimens to the Massachusetts Department of Environmental Protection (MassDEP).