Macro-invertebrates live in the water and the substrate of the stream bottom. They are an important part of the stream food web. The sun provides energy for plant growth in and around the stream. Bacteria and fungi feed on dead plant material. Herbivorous invertebrates feed on bacteria, fungi, algae, and partially decomposed leaves. These invertebrates provide food for predators, such as other invertebrates, fish, reptiles, amphibians and birds.

The location of stream invertebrate communities varies between three Kings Creek prairie stream habitats. As Kings Creek flows from the upland headwaters, to the middle reaches, and through the gallery forest, the stream channel, stream bed and streamside vegetation changes. Invertebrates prefer particular habitats depending on how they feed. The upper reaches of Kings Creek are surrounded by grassland. Little organic debris falls into the stream, so organisms called collectors must filter fine organic matter from the water. Other organisms called scrappers or grazers feed on diatoms and algae. The mid-reaches of the stream are surrounded by grasses and shrubs, and the lower reaches of the stream are surrounded by a gallery forest. In the gallery forest, trees such as bur oak, chinquapin oak, hackberry and elms shade the stream and drop their leaves into the water. Organisms called shredders dominate in the lower reaches and feed on the larger leaf and woody debris. Predators, which feed on animal tissue, such as insects, crustaceans, and fish live throughout Kings Creek.

Other factors that may affect the dispersion of stream invertebrates are patterns of stream flow and water temperature. Floods also affect stream invertebrate populations because the fast moving water scours the stream bed. Up to 95% of the macroinvertebrate population can be washed downstream in a high water event. Depending on the frequency of high water events, plant life, such as algae, and macroinvertebrates often fully recover within two weeks.

The life cycle of aquatic macro-invertebrates can span days to years, and while some species spend their whole lives in the water, others do not. Aquatic macro-invertebrates, such as caddisflies, true flies and beetles undergo complete metamorphosis, which includes four stages of growth: egg, larvae, pupa and adult. During complete metamorphosis, larval insects look very different from the adult and then go through a non-feeding pupal stage before emerging as adults. Stoneflies, mayflies, and dragonflies undergo incomplete metamorphosis and pass through three growth stages: egg, nymph and adult. All insects change and grow during metamorphosis. They molt, or shed their exoskeleton. Some aquatic insects emerge from the water as adults and live on the land, such as dragonflies and mosquitoes. Other adult aquatic insects continue to live in the water, like water striders.

Macro-invertebrates act as biological indicators because they react quickly to changing water quality conditions. Ecologists can determine if a stream is ecologically healthy by knowing which species live in a particular reach of the stream. For example, an abundance of pollution tolerant species such as oligochaetes, midge fly larvae, and leeches may indicate a high level of unwanted pollutants in the water. On the other hand, a healthy stream will have numerous pollution sensitive species such as mayflies, caddisflies and stoneflies.

LONG-TERM INVENTORIES OF KONZA STREAM INVERTEBRATES

PURPOSE: Researchers maintain a long-term inventory of diversity and abundance of stream invertebrates along reaches of King's Creek on Konza Prairie.  Student collections will benefit the LTER researchers by archiving these aquatic insects in a quantitative measure that will aid them in their work.

Click to view the Konza Prairie Biological Station aquatic macro-invertebrate species list.

METHODS: Students use Surber bottom samplers to collect stream invertebrates from selected areas along Kings Creek. Samples will be examined on white- bottomed trays used to carefully separate and identify the specimens.  This process is called "picking". Using forceps and plastic pipettes to pick all aquatic invertebrates, any collected insects will be placed in vials and labeled for date, location, and collector.  These specimens will be kept for future reference as part of the archive. Visit the aquatic macro-invertebrate species list to find the species found for the first time on Konza Prairie by students of the Schoolyard LTER program in 1999.