Dataset: Macroinvertebrates and Stream Hydraulics
Introduction to Macroinvertebrates and Stream Hydraulics
Video: Caddisflies, Engineering an Ecosystem
Transcript: "Imagine living in a world where food was floating all around you, but you had no way to grab it. This problem is one that underwater insects deal with daily. To figure out a way to catch all of this yummy food swirling all around them, net-spinning caddisflies have developed a clever way to trap and eat that food. Net-spinning caddisflies of the famiy Hydropsyche are aquatic insects that produce silk thread into a mesh net. Using painstaking detail and precision, each thread is placed into just the right spot to create mesh webbing that will fill up with food.
When they aren't harvesting food off their silk net, they hunker down in what's called a retreat or hom where they can hid from being prey for fish and other predators in the stream Net-spinning caddisflies draw the interest of fishermen who spend hours tying flies that mimic these special critters. Net-spinners are typically very abundant downstream of dams and may play their most important role in human-altered rivers. But they can also be found in almost all the streams and rivers near you.
Scienstist have found that these silk threads also play an important role in modifying erosion and water flow in the streams. Although it is not as strong as spider silk, each thread must still be strong enough to stand up to forceful water currents. The silk holds together gravels that are as big as the size of an orange. By holding these rocks together, they can reduce erosion during floods and make the riverbed more stable. Changing erosion patterns can be important for predicting how much gravel will move in a flood, how much fine sediment will build up, and maintaining the available healthy habitats for sensitive animals such as trout.
The silk structure that the caddisfly builds also sticks up on the surfaces of rocks and acts as a barrier to rushing water. By slowing down the water at the streambed, the caddisfly can make living in this powerful environment easier for other aquatic insects. Animals and plants like net-spinning caddisflies that modify their environment are called ecosystem engineers, which means that they create or modify their physical environment through their activities. You might recognize some of these common engineers. Beavers build dams that change flow conditions. Crayfish use their claws to move gravels around while they burrow or look for food. Ecosystem engineers are of conservation concern because without them habitats that support so many other critters would not be the same.
Net-spinning caddisflies are very important for modifying how stream ecosystems function and stay healthy. Researchers at Montana State University study how net-spinning caddisfly silk regulates erosion and water flow patterns. Using experiments and surveying patterns of caddisfly abundances, they investigate just how big of a role these small insects play in the beautiful and dynamic rivers. Net-spinners are monitored in natural streams, in the laboratory where they can be watched very carefully, and in models that simulate how these ecosystem engineers modify erosion and water flow. By filtering food, sticking their silk threads to gravel, and slowing down flow, these small insects play a big role, and they do all of this important work under the water."
Data
- Data for Figure 2 in Maguire et al., 2020 (see article under Additional Resources below)