December 5th was World Soil Day. This does not mean a chance to reflect on any particular messes in our lives, but rather the substrate just outside our doors that is vital to our survival. Soil is composed of minerals, water, air, and bacteria. We would not say that soil itself is alive, but it is full of life and without that life we would not have all the wonderful plant diversity that sustains all other life on the planet. When I taught about natural resources to fourth graders I distinguished between renewable and nonrenewable resources and I explained that both forests (as opposed to trees) and soil are nonrenewable resources. Yes, we can compost, and generate some soil from the decomposition of our food and yard wastes in just a year or even a season, but this is small scale. The soil lost from flooding and deforestation can take hundreds of years to renew, and still may not harbor the same soil bacterial community needed to “replace” the original forest. This bacterial community can take even longer to return to its original composition. So many microscopic organisms impact our lives and yet we barely pay attention to them. How often do you think about your friendly gut compatriots? I hope World Soil Day can educate and influence more people to at least be aware of our soil and its need for our care.
Another ecological system that is probably thought of more readily is stream ecology. People love to play in streams, fish, or just listen to the sound of the water. And of course, streams and rivers are a source of drinking water. For that reason (and others just as important) streams need to stay clean. There is a community of small insects that can indicate water quality to us. They are visible to the naked eye; hence they are macro not micro. They are insects; hence they are invertebrates. And we could add that they are bottom dwellers of the streambed, hence they are benthic. If we put all these terms together, we get their official name: benthic macro invertebrates. These insects are much easier to collect and observe than soil bacteria, but I wonder still how many people know about them.
I am a citizen water monitor for Save Our Streams. Our local Rockbridge County group is called the Maury River Monitors. Certified monitors are assigned a stream in the county that they sample four times a year. Sampling involves placing a net in a riffle and rubbing the rocks and disturbing the streambed in front of the net to allow the capture of the macro invertebrates living in the riffle area. The critters are counted at the family level so that a monitor just needs to learn to distinguish mayflies from stoneflies, hellgrammites from fish flies, dragonflies from damselflies, etc., not how to distinguish between species of say mayflies, which requires much more skill and usually a microscope. The data is entered into the VA Save Our Streams website – http://www.vasos.org/ – and available to the VA DEQ if there is a pollution concern.
So why do we do this? Well, certain macro invertebrates will only thrive in clean, well-oxygenated streams and are therefore considered pollution intolerant. Examples of intolerant macro invertebrates are stoneflies, mayflies, and gilled snails. Other macro invertebrates, such as black fly larvae, midges, and lunged snails have adaptations that allow them to survive in polluted waters. By looking at the ratios of tolerant to intolerant critters, and insects to non-insects, we can generate a score that indicates overall health of the stream.
Kids always seem to gravitate to the crayfish in a net sample. Something about those big claws and the chance of getting pinched really fascinates them. They also tend to like water pennies. Water pennies tickle when they crawl across your hand and remind me of a tiny prehistoric version of a horseshoe crab. Another critter with a wow factor is the hellgrammite. Kids who have fished before recognize hellgrammites right away. Hellgrammites are large and fierce looking with pinchers rumored to cause some pain. I wouldn’t know. They are one organism, which I will not pick up with my fingers. Well, ok, I use tweezers on the crayfish too!
I have done countless stream samplings with kids. They are always excited, rarely squeamish, and they readily start to identify the critters after a few examples. I think it has to do with a chance to get in the water. Water play is fun. In the process they are introduced to a world they may not have known existed – a world that is readily available in any stream – or should be if we take care of the watershed. There are so-called dead streams in parts of Virginia because there is no macro invertebrate life, and therefore no fish life.
Soil is integral to stream health. As part of the watershed, any substance that is dumped on our soils has the potential to drain to a stream. Since it was World Soil Day in our late fall, but the southern hemisphere’s late spring, more people besides soil scientists in the southern hemisphere were perhaps aware of the day. Maybe if there was a World Soil Day during the spring season for the northern hemisphere its message could reach more people as we wake up our gardens or make mud pies with our kids. Maybe if we just spent more time awakening our inner child by playing in the soil or water, we wouldn’t need a special day to remind us of these valuable resources right in our own backyards. Happy soil health to you all!