Volume 5, Number 4 - April 1959
Life in a Stream
by Carl Prophet
THE COVER PICTURE and other photographs, taken by various members of the biology staff, were taken incidental to field trips. The drawing on page 8 was taken from the "Pond" issue of KSN; all other drawings were made by Nancy Unruh, Emporia State sophomore.
Prepared and Issued by
Editor: John Breukelman, Department of Biology
Editorial Committee: Ina M. Borman, Robert F. Clarke, Helen M. Douglass, Gilbert A. Leisman, Carl W. Prophet, Dixon Smith
The Kansas School Naturalist is sent upon request, free of charge, to Kansas teachers and others interested in nature education. Back numbers are sent free as long as the supply lasts, except Vol. 5, No.3, Poisonous Snakes of Kansas. Copies of this issue may be obtained for 25 cents each postpaid. Send orders to The Kansas School Naturalist, Department of Biology, State Teachers College, Emporia, Kansas.
The Kansas School Naturalist is published in October, December, February and April of each year by The Kansas State Teachers College, Twelfth Avenue and Commercial Street, Emporia, Kansas. Second-class mail privileges authorized at Emporia, Kansas.
Online edition by: Terri Weast
The value of an aquatic freshwater habitat, the place where an organism lives, as an outdoor laboratory for demonstrating relationships between organisms and their environment has been emphasized in an earlier issue of The Kansas School Naturalist (Life in a Pond, Vol. 3, No.3) . However, differences between organism-environment relationships are apparent when a pond habitat is compared to a stream habitat. The present issue of The Kansas School Naturalist
covers some of these differences and describes some of the more common stream organisms.
Kansas is divided into two major drainage basins, the Missouri River basin, draining the approximate northern half of the state and the Arkansas River basin draining the southern half. Kansas youngsters are familiar with the role our major rivers and streams have played in the exploration and development of our state, and an ordinary road map reveals that most of our major cities are located near the larger river and streams.
As one travels westward across Kansas, he sees changes in the dominant vegetation; more grass and fewer trees are seen. To one from eastern Kansas the sight of fairly large natural stands of trees is common, but in the western counties trees are restricted primarily to moist banks of meandering streams
or near edges of springs and ponds.
Approximately 1500 rivers and streams in Kansas have been named, but there are an additional 50,000 or more as large as the smallest of the named streams, each with countless thousands of still smaller streams and gullies serving as tributaries. It is readily seen that there is an abundance of these excellent outdoor laboratories waiting to be utilized by an alert teacher.
Limnologists, scientists who study the physical, chemical, and biological features of fresh waters, separate aquatic habitats into two categories, standing-waters such as ponds or lakes, and running-waters such as streams or springs. Although it is sometimes difficult to determine into which category a particular body of water should be classified, a definite continuous current is regarded as a characteristic of streams. However, conditions in parts of certain streams might more nearly duplicate those of a pond; and on windy days ponds with barren shorelines are often subjected to much wave action, during which time their shallow margins might more closely resemble the banks of a stream. With these similarities in mind, one is able to distinguish two major zones which alternate throughout the length of a stream, a rapids or riffles zone characterized by shallow water flowing rapidly over rocks, and a pond zone characterized by deeper water whose velocity is reduced, thus allowing silt and other loose materials to accumulate on the bottom.
That the current is an important environmental force is evident when one compares a rapid mountain stream of Colorado to a sluggish prairie stream of Kansas. For example, trout, which abound in many mountain streams, would not survive long in a prairie stream. What are some possible explanations? Water of a mountain stream comes from melting snow, therefore, it is usually colder than the water of the prairie stream. The gradient (amount of fall per linear unit) of a mountain stream is greater than that of a prairie stream, and as a result, the speed of the current of a mountain stream is greater. A given amount of cold water can contain more dissolved oxygen than warm water. This combination of current and water temperature results in a greater supply of dissolved oxygen for the animals of a mountain stream. Also, a rapid current prevents the accumulation of silt which might cover the trout eggs and stop their development. We can see that many environmental conditions are involved in our example, however, current is probably the principal factor. Even in our sluggish prairie streams the influence of current can be demonstrated. One need only compare organisms from a rapids zone with those from a pool zone to notice many differences in shape, structure, and occurrence.
Because of current and lack of depth in most Kansas streams, the water is usually so thoroughly mixed that marked variations in temperature, concentrations of oxygen and carbon dioxide, minerals, and other dissolved materials from surface to bottom do not occur. Thus in a stream the surface and bottom temperatures are usually within a degree or two of each other, and samples of surface and bottom water show almost exactly the same chemical composition. On the other hand, ponds often vary considerably from surface to bottom in respect to these same conditions. A farm pond may easily be eight or ten degrees warmer at the surface than at the bottom.
Considering the mass of water present in relation to its shoreline, a pond may be thought of as a closed natural unit in which the living and non-living components of the pond interact. Little interchange occurs between pond and surrounding land. However, because of its tremendous shoreline in relation to volume of water, a stream is more closely associated with the immediate land environment. The close association between these two different environments results in considerable interchange between them in respect to minerals and nutrients contributed to the stream and cover and food provided for some of the land organisms.
Streams usually contain a higher concentration of dissolved oxygen than do ponds. The lack of depth, large surface area exposed, and the mixing effect of the current in streams usually results in an adequate absorption of oxygen from the atmosphere. On the other hand, stream organisms generally cannot tolerate as great a reduction in the amount of available dissolved oxygen as can pond organisms.
Streams are often victims of municipal and industrial pollution. Decay of the organic materials causing the pollution uses excessive amounts of oxygen, thus pollution may kill many desirable organisms. Certain environmental conditions may be such that they prohibit the occurrence of an organism in a habitat; such conditions are said to be limiting. Thus a stream may be so muddy that trout cannot live in it, while carp thrive. Floating plants such as duckweed cannot establish themselves in the current, but only in the quiet pools - if such plants happen to drift into the current they are at once carried downstream. To the trout the limiting factor is the mud suspended in the water; to the duckweed the limiting factor is the movement of the water.
Most stream organisms have structural adaptations which better equip them for living in currents. Some of these adaptations are so apparent that we tend to overlook them. Others are less easily seen and may require some careful observation.
Almost without exception stream organisms have streamlined shapes. That is, their body shape is such that the least possible amount of resistance to the water develops as the organism swims. Also, many adaptations occur in external appendages to facilitate swimming and for exchange of respiratory gases. Some aquatic animals are covered with a slimy coat of mucus which might play a role in reducing friction between the body and the water, but it is perhaps even more important in helping to maintain a stable internal environment within the animal. Because of differences in the concentration of dissolved salts contained in their body fluids as compared to the water medium in which they live, water tends to enter most aquatic animals through their body surfaces. The animal must constantly eliminate this excess water or it becomes "waterlogged" and dies. The presence of a mucous covering slows the rate of diffusion of water into the animal's body. Other animals have hard exoskeletons rather than mucous coats which prevent the entrance of water.
Many stream animals that commonly live in riffles have flattened bodies which enable them to live under rocks and in tiny crevices; such shapes offer but a minimum of resistance to the current. Other animals have hooks or suckers which enable them to anchor to a rock or log. Even plants must have some means of attachment if they occur in rapidly flowing water. Most stream animals show a positive response to current; that is, they orient themselves so that their front ends face the direction of the current.
Streams differ from ponds in another interesting aspect, that of succession. Succession may be defined as a series of successive changes (seral stages) in respect to the vegetation and animal life occurring within a community; it is an orderly process of directional change resulting eventually in a final mature stage termed the climax which will remain stable under existing climatic conditions. The process of ecological succession is slow, usually requiring a period of many hundreds of years before the climax condition is reached.
In ponds, succession is predominantly horizontal as shown in the diagram. The youngest seral stage shown in this diagram is the open deep water or limnetic zone which is characterized by the absence of rooted plants. As one progresses through the littoral zone, water becomes more shallow, sunlight is able to penetrate to the bottom and certain submerged rooted aquatic plants are able to grow. As the water becomes still more shallow, the vegetation again changes with rooted, floating plants occurring. This zone of floating plants in turn gives way to a zone of emergent plants. As one leaves the shore and moves inland other differences in vegetation occur until finally the climax community is reached. The climax community is determined by the prevailing climatic and soil conditions of any geographic region; in the diagram, tall mixed grassland represents the climax condition. Theoretically, as silt slowly fills the pond, the younger seral stages are gradually replaced by older stages until finally all of this area would become grassland. It should be kept in mind that as the vegetation of each zone or community changes the associated animal life also changes.
In streams, succession occurs in a longitudinal direction, that is from source to mouth. As one travels from the mouth towards the source of the stream, it is as though he were passing backwards in time. In other words, the younger or pioneer stages of the stream are those areas nearer its source, while the older, more mature regions are those near its mouth. Unlike most ponds, streams do not have a continuous uniform change from region to region. It is not uncommon for specific communities to reoccur at intervals throughout the length of a stream. In general, it can be said that changes are more distinct near the source than near the mouth. Study the photographs on pages 7 to 9; they show how communities may vary along the length of a stream.
|"pioneer" stage of stream, near source||"older" or more mature stage, farther downstream|
|water flowing from pool into riffle||farther downstream, water flowing over riffle into another pool|
Depending on the role each organism plays in any community, the ecologist classifies organisms into one of three categories. Those organisms containing chlorophyll and therefore capable of producing their own food from inorganic (non-living) materials are termed producers. Other members of the community are dependent upon the producers for their food; without producers the basic link of the food chain is broken and there would be no way to replenish the food supply of a community. Animals of the community constitute a second category, the consumers; depending upon their feeding habits, consumers obtain food either by feeding directly upon the producers of a community or by preying upon other animals. Bacteria and fungi comprise the third category, the reducers. These organisms obtain their food from the dead organic matter in a community and in the process return valuable and essential compounds, minerals, and elements to the community so that they can be utilized once again by the producers. It is helpful to the student to become aware of these categories for it enables him to develop a better understanding of the interdependence of the plants and animals of a community.
|Water primrose, Jussiaea, forming a boundary between current (right) and marshy pool (left)|
|Flood water-swift current instead of the normally quiet pool|
|Collecting salamanders in a rocky stream bed|
|Mountain stream with rocky bottom, forming continuous riffle|
|Small grassland creek undercutting sod|
Space does not permit an extensive discussion of all plants which occur in Kansas streams, but a few of the more commonly occurring plants are mentioned. Those who are familiar with the Life in a Pond will no doubt recognize many of these plants as also being common in ponds. Additional references for the identification of aquatic plants are listed on page 15.
|1. CLADOPHORA (No common name)
This branched filamentous green alga is perhaps the most common of stream algae and is characteristically found in riffles attached to stones by special structures called holdfasts. Each cell is elongated, cylindrical, and contains many nuclei; unlike Spirogyra, Cladophora is not slimy. During spring months its long dark green filaments are easily observed streaming in the riffles' current and often become so abundant that it looks like a thick green carpet.
|2. SAGITTARIA (Arrowhead)
This plant gets its name from the shape of its leaves. It is commonly found growing along the margins of many of our streams. A perennial, arrowhead spreads by means of an underground stem called a rhizome. Arrowhead is utilized as food by waterfowl, and in the past the potato-like underground stems were roasted and eaten by Indians.
|3 . TYPHA (Cattail)
Cattails are commonly found growing in continually moist spots in Kansas. The cattail is characterized by long sword-shaped leaves and a long stalk bearing the "cattail" or female flowers. Like Sagittaria, cattails spread by means of underground stems, which also may be eaten.
|4. SALIX (Willows)
Willows are among the most commonly occurring trees along the banks, sand bars, and flood islands of Kansas streams. In that they are often so abundant along our stream banks, willows play an important role in the prevention of erosion. The leaves are simple, alternate, with long-pointed, usually curved tips, and finely serrated margins.
|5. HYDRODICTYON (Water Net)
This green alga is often found in still pools of many streams. It forms a fine green net which can easily be recognized. If the colony is not disturbed, the nets may attain lengths of one foot or more, but when the nets attain this size, new nets are formed by the breaking up of the old. Each net contains about one hundred cells.
|6. SPIROGYRA (Pondscum)
A common fresh-water green alga, Spirogyra forms bright green, unbranched strings (filaments) which feel characteristically slimy or slippery. With the aid of a microscope, one may see one or more coiled, springshaped green bodies (chloroplasts) in each cell of a filament. Spirogyra often occurs as floating or attached masses which appear as a greenish scum upon the pond surface. This scum is sometimes called "frog spit." In streams, Spirogyra appears mainly in pool zones.
|7. CAREX (Sedges)
This large group of moist soil plants may be found growing in shallow water along the banks of streams and on mud flats that are covered by water in late fall or winter. The leaves are more coarse and rough than those of most grasses; and the fruits are usually borne on the solid, triangular stems which are characteristic of all sedges. Sedges are important to man as soil anchors and land builders in lowlands.
|8. LEMNA (Duckweed )
These midget seed plants are among the smallest flowering plants in the world. Duckweeds are free-floating on the surfaces on ponds and streams throughout the state; they form dense mats late in summer. Leaves are but two to five millimeters (from one-twelfth to one-fifth of an inch) long, radiating from a center point which bears tiny roots. In a classroom aquarium they offer good examples of quick vegetative reproduction. They are used as food by wildlife.
9. JUSSIAEA (Water Primrose)
Both invertebrate (without backbones) and vertebrate animals abound in Kansas streams. Since most of our streams are shallow, except when in flood, it is often easier to collect the aquatic plants and animals which commonly inhabit streams rather than those occurring in ponds. Although a myriad of animal forms can be found in our streams, it is impossible to mention more than a few of the most frequently observed and most easily collected forms. Additional references which are helpful in the identification of aquatic animals are listed on page 15.
|1. BRYOZOA (Moss Animals)
Colonies of these tiny delicate animals may be found attached to stones and twigs primarily in riffles of many Kansas streams. Each individual of the colony is surrounded by a limy protective case secreted by the animal. Hydra-like, bryozoans feed by extending their ciliated tentacles which produce a current to drive microorganisms towards their mouths located within the ring of tentacles. At the slightest disturbance, bryozoans withdraw into their protective cases and appear more plant-like than animal-like.
|2. DINEUTES (Whirligig Beettle)
Found in "flocks" on the surface of both ponds and streams, these common beetles are characterized by a flat, oval body up to one-half inch long, blue-black or brown and black, with four compound eyes. Forelegs extend forward in a reaching position, rear two pairs of legs flattened for swimming. Whirligig beetles swim in erratic paths, some species give off an odor of apples. They are primarily animal feeders and are valuable in mosquito control.
|3. GERRIS (Water Strider or Pond Skater)
These are usually found in groups on the surface of quiet waters. They have elongated bodies about one-half inch long, first pair of legs short for grasping, other two pairs of legs long, spider-like. Both winged and wingless species occur. Even though they feed on other insects, water striders are of no significant value to man. Although this insect literally walks on the water's surface demonstrating surface tension, it is a poor aquarium specimen.
|4. LlBELLULA (Ten-spot Dragonfly)
Dragonflies are distinguished from damselflies in that the former always keep their wings horizontal when at rest while the latter fold them vertically over their backs. Libellula is identified by three blackish-brown spots on each wing of the adult. Wingspread of the adult may exceed three inches. Metamorphosis is incomplete, the egg develops into an immature aquatic stage called a nymph which eventually develops into the adult. The nymph is approXimately one inch
long and like the adult, devours many less desirable insects such as mosquitoes.
|5. ARGIA (Damselfly)
Like the dragonfly, damselflies belong to the insect order Odonata, have characteristic nymphs, and are beneficial to man, feeding on mosquitoes, flies, and gnats. The nymph of the damselfly differs from that of the dragonfly by having a more elongated body about one inch long and three leaflike tracheal gills on the posterior end of their abdomen. Note the three pairs of jointed walking legs of the nymph which are typical of adult insects.
|6. CORYDALIS (Dobson Fly)
The predaceous larvae of the dobson fly, sometimes called "hellgrammites," "crawlers," or "toe biters," are often found under stones in riffles. The life cycle of the dobson fly requires three years to complete. Hellgrammites are easily identified by their brownish segmented centipede-like appearance. Often reaching a length of two or more inches, hellgrammites have strong conspicuous biting jaws and paired lateral abdominal gills; they are frequently used as fish bait.
|7. HEXIGENIA (Mayfly)
Although mayfly nymphs are sometimes found in ponds, they are in Kansas more typical of running water. The nymph is about one inch long, respires through feathery gills attached somewhat dorsally on abdominal segments, and has three tail filaments. Mayflies pass the winter in the nymph state emerging as adults during spring and summer months. This is the only group of insects to molt after reaching the adult winged state. It might be said that the only function of adult mayflies is to reproduce, for they never feed and live only a few days. Metamorphosis is incomplete (egg.....nymph..... adult); nymphs feed only on plants and are eaten by other consumers of the stream.
|8. ACRONEURIA (Stonefly)
The stonefly larva is an abundant inhabitant of Kansas streams. Like most other aquatic insect larvae, the body of the stonefly is flat, adapted to its existence under stones in riffles. BaSically, the stonefly nymph resembles that of the mayfly, hut it may be distinguished by (1) two claws on each foot, (2) two divergent tail filaments, (3) thread-like gills on the underside of the body. Stonefly nymphs feed on other insects and in turn fall prey to fishes and other stream consumers.
9. ORCONECTES (Crayfish)
10. LEPOMIS (Sunfish)
11. ETHEOSTOMA (Darter)
12. NECTURUS (Mudpuppy)
13. ACRIS (Cricket Frog)
14. NATRIX (Common Water Snake)
15. CHELYDRA (Snapping Turtle)
|16. CHRYSEMYS (Painted Turtle)
The painted turtle is also a common inhabitant of Kansas streams and may be identified by the following characteristics. The plastron (lower "shell") of 12 plates has no moveable parts; the upper "shell" or carapace is flattened, without ridges, and bears red markings along its margin, although difficult to capture, the painted turtle is a good classroom pet.
Perhaps the handiest piece of equipment for collecting stream animals is a small seine. A durable seine can be constructed from plastic window screening, heavy twine, wooden floats, and lead weights. Pool animals are easily captured by pulling the seine through the water for short distances, but in the riffles as specimens are most easily collected by weighting the bottom of the seine with stones just below a riffle and then turning over stones and churning the bottom with one's feet a short distance above the seine. In this manner, the animals normally living under the stones will be dislodged and carried into the seine.
It is best to select pool organisms for the classroom aquarium because an aquarium is more like a pool than a riffles. The temperature, current, and oxygen requirements of most riffles organisms are such that they cannot be maintained in the classroom unless special equipment such as aerators are available. Information concerning the food habits of most of the animals discussed in this issue can be found in the references listed on page 15.
Breukelman, John. 1942. The Biology of a Stream. American Biology Teacher, 4(5) :143-149.
Breukelman, John. 1957. What have I caught? 4th printing, Bull. no. 7. Forestry, Fish, and Game Commission, Pratt, Ks. (Free)
Conant, Roger. 1958. A Field Guide to Reptiles and Amphibians. Houghton Mifflin Co., Boston. ($3.95)
Jacques, H. E. 1947. How to know the insects. Wm. C. Brown Co., Dubuque, Iowa. ($2.00)
Jacques, H. E. 1947. Living things; how to know them. Wm. C. Brown Co., Dubuque, Iowa. ($2.00)
Jacques, H. E. 1949. Plant Families how to know them. Wm. C. Brown Co., Dubuque, Iowa, ($2.00 )
Morgan, Ann Haven. 1930. Fieldbook of Ponds and Streams. G. P. Putnam's Sons. 210 Madison Avenue, N.Y. 16, N.Y. ($3 .. 50)
Needham, James G. and Paul R. Needham. 1953. A Guide to the Study of Freshwater Biology. Comstock Publishing Assoc., 124 Roberts Place, Ithaca, New York. ($1.00)
Odum, Eugene P. 1953. Fundamentals of Ecology. W. B. Saunders Co., Philadelphia, pp. 217-252.
Prescott, G. W. 1954. How to know Freshwater Algae. Wm. C. Brown Co., Dubuque, Iowa. ($2.25)
Smith, Hobart M. 1956. A Handbook of Amphibians and Reptiles of Kansas. Museum of Natural History, University of Kansas, Lawrence, Kansas. ($1.50)
Stevens, Wm. C. 1948. Kansas Wild Flowers. University of Kansas Press, Lawrence, Kansas. ($7.50)
Zim, Herbert S. and H. M. Smith. 1953. Reptiles and Amphibians. Simon and Schuster. ($1.00)
Zim, Herbert S. and H. H. Shoemaker. 1956. Fishes-A Guide to Fresh and Salt 'Water Species. Simon and Schuster. ($1.00)
Oct. 1958, Watersheds in Kansas
Dec. 1958, Let's Build Equipment
WORKSHOP IN CONSERVATION
Plan now to attend the 1959 Workshop in Conservation, which will be a part of the 1959 Summer Session of the Kansas State Teachers College of Emporia, June 2 to 19, and June 22 to July 10, 1959.
As in the past several years, the Workshop will cover water, soil, grassland, and wildlife conservation teaching. Such topics as geography and climate of Kansas, water resources, soil erosion problems and control, grass as a resource, bird banding, wildflowers, conservation clubs, and conservation teaching in various grades will be discussed. There will be lectures, demonstrations, discussion groups, films, slides, field trips, projects, and individual and group reports. You may enroll for undergraduate or graduate credit.
Any interested person may enroll in the first section; enrollment in the second section is limited to those who have an established interest in conservation and some teaching experience.
Fee for first section (3 hours credit): Residents of Kansas, $22.9.5; non-resident, $42.45
Fee for second section (1, 2, or 3 hours credit): Residents of Kansas, $7.65 per hour; non-resident, $14.15 per hour
For other information about the Workshop write Robert F. Clarke, Department of Biology, KSTC, Emporia, Kansas.
Issues for which some work has been done are: Nature Hobbies, Lizards of Kansas, Wind Erosion in Kansas, as well as issues dealing with the sparrow family, with experiments for elementary science, and with wildlife areas in Kansas. Other subjects may be developed by the 1959 Workshop in Conservation. Suggestions are always welcome, both for topics and for possible authors and sources of information.
IF YOU WILL BE at a different address in 1959-60, be sure to notify us. The Kansas School Naturalist is sent by secondclass mail, and cannot be forwarded.
|The Kansas School Naturalist||Department of Biology|
|College of Liberal Arts & Sciences|
|Send questions / comments to
Kansas School Naturalist.
|Emporia State University|