minnow

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Lotic Communities

Lotic communities are groups of organisms found in systems of moving water such as creeks, streams, and rivers. Click the Begin button below to learn about the fish, mollusks, and invertebrates living in these communities.

Caddisfly larvae

Glossary

Medium streams/rivers

Lotic communities include aquatic life that live in moving water.Click through the menu buttons above to see examples of aquatic life in that part of the waterway.

Largerivers

Headwaterstreams

Large rivers

Intro

Headwater streams

Main

The headwaters are made up of temporary streams (streams that appear after a rain then sink below ground) and smaller, colder streams. The headwaters have a direct impact on the health of the water downstream.

Crayfish

Headwater Streams

Mayfly larva

Minnow

Close

The crayfish is a shredder species. Shredders shred, or breakdown, organic material like leaves, plants, and sticks into smaller material. It is food here and the rest is carried downstream.

There are 54 native species of crayfish in Kentucky. That makes up 10% of the world's crayfish population.

The mayfly larva is a collector species. They collect or filter small organic particles. Filtering the organic material improves the health of the stream.

Mayfly larvae

There are 111 native species of mayfly in Kentucky. They are a major source of food for larger species of aquatic life.

There are 64 native species of  minnows in Kentucky.  Most of them are less than  four inches long.

Minnows are the predator species in the headwaters of a stream. A predator hunts and eats other fish and animals. Predators help control the population of smaller species.

Snails

Mussels

Medium streams and rivers are wider than headwaters. The canopy above them is open, which allows more sunlight to warm the water, helping food production through in-stream photosynthesis. The animal community shifts to include grazers and collectors.

Darters

There are 67 native species of snails in Kentucky. Snails are  grazers. Grazing helps with the production of carbon, which benefits other organisms downstream.

Grazing species, like snails for example, feed on the algae and plant material attached to surfaces such as rocks and logs. They are particularly suited to the slower-moving water in this part of the waterway.

Mussels are collector species. Collectors gather and filter small organic particles.This improves the health of the stream by controlling the growth of organic matter.

There are 103 native species of freshwater mussels in Kentucky. They are from 1 to 10 inches long depending upon the species. They can be found, partially buried in gravel, sand, and mud.

There are 77 native species of darters in Kentucky. Like the minnow, they are small, ranging from 1 to 4 inches long. They are uniquely adapted to move about in the faster moving currents of shallow, mid-size streams and rivers.

Darters are one species of predators found in mid-sized streams and rivers. Predators eat other fish and animals. This helps control individual species populations.

Gar

Caddisfly larva

As it continues downstream, a waterway receives the input of many tributaries and becomes a large river. Due to bank erosion by the water, the river doesn't twist and turn as much. It is wider and the current is slower. Because the habitat is larger, there is greater species diversity.

Some caddis flies are collector species. They filter small food particles carried in slowercurrents by constructing tiny, fine-mesh nets made of silk. 

Caddisfly Larvae

There are 250 native species of caddisfly in Kentucky. Caddisflies are aquatic insects. They are an indicator species. That means their presence is  a sign the waterway is  healthy and diverse.

Gar are large predator fish. That meansthey hunt smaller fish and aquatic life  in the waterway. Because of their size and the fact they feed on other fish, they prefer the slower current and deeper waters of larger streams.

Most biodiverse regions have at least one species of predator. In large rivers, a gar is one such predator species. The predator plays a vital role in keeping species population in the region under control

lotic communities - groups of aquatic organisms that live in systems of flowing water such as a river,                                    stream, or creek

aquatic - of or referring to water

invertebrate - animals without a backbone such as insects, mussels, snails, and spiders

canopy - the uppermost trees, or branches of trees in a forest, forming a more or less continuous layer of                foliage

organic - of, relating to, or derived from living matter

habitat - the natural home or environment of an animal, plant, or other organism

larva - an immature form of some animals that undergo some changes in body structure (metamorphosis)             as they mature, such as a tadpole changing into a frog

tributary - a stream or river that flows into a larger river or lake