INCORPORATION OF STRESSED STREAM ANALYSIS INTO THE PROVIDENCE COLLEGE BIOLOGY CURRICULUM. Carol B. Crafts

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1 INCORPORATION OF STRESSED STREAM ANALYSIS INTO THE PROVIDENCE COLLEGE BIOLOGY CURRICULUM Subject keywords: biology, social sciences Technique keywords: biotic indices Carol B. Crafts Biology Department Providence College Providence, RI Pedagogy keywords: course-introductory, laboratory/unit, new course/program, student research Overview: Dr. Crafts developed a detailed stream sampling exercise for students in introductory biology laboratory and shared a new minor in Environmental Studies being developed at Providence College. Introduction The Biology Department and Providence College are beginning to respond to the need to address global, national and local environmental issues through curriculum change and development. Over the past ten years, more students are coming to the College and into the Department with an interest in and commitment to public service and environmental issues. My attendance at the Stressed Stream Analysis program was motivated by the need to develop my own skills and knowledge in this area, to respond to student needs and demands for environmental studies in and outside of the Department, and to find a context for the study of environmental concerns that was practical, accessible, and applicable at a number of different points in the biology curriculum. The SSA program was instrumental in my own efforts to begin to meet these objectives in the Biology Department. Additionally, I believe it will have a significant impact on other initiatives that the College has undertaken during the past academic year in its approval of an Environmental Studies Minor and the establishment of the Feinstein Institute for Public Service. BIO : General Biology Biology Department Initiatives Integration of environmental studies at the freshman level has been difficult to effect since General Biology has an enrollment of 100 students and five laboratory sections, each taught by a different member of the Department. This year we have added a stream

2 ecology laboratory, at the beginning of the fall semester, to this course, "Stream Ecology: Benthic Macroinvertebrates as Biotic Indicators of Stream Water Quality" (Appendix 1). Often, ecological studies are delayed until the end of general biology courses. Our rationale for inclusion of this laboratory early in the fall semester was to introduce students to levels of biological organization in ecosystems in the same manner that we introduce them to molecular and cellular levels of organization early in the course. Just as we attempt to show that functional characteristics of organisms and cells are determined by the interaction of their structural components, this lab introduces students to an ecosystem as a functional system composed of groups of organisms interacting with their environment. The laboratory exercise draws heavily from SSA materials on benthic macroinvertebrate and fish sampling in streams. Students are asked to complete a descriptive habitat evaluation, collect benthic macroinvertebrates using the kick-sampling method, identify them using the Isaac Walton pictorial key, and then to apply three biotic indices (EPT Value, Percent Model Affinity and Family Biotic Index) to assess the relative health of the Pleasant Valley Parkway Stream which meanders through a neighborhood near the College. This exercise allows a large number of students access to a stream ecosystem, experience with collection and identification of organisms most of them have not seen before, comparison of three different biological indices, and a context for discussion of environmental concepts such as homeostasis, pollution, and correlative and causative relationships. It provides them with a "macro" example of functional dependence of systems on their structural components, in this case, stream ecosystem rather than tissue, cell or molecule. The use of benthic macroinvertebrates as indicator organisms is both practical and effective as a teaching tool. They are large enough to see without a microscope. They can be identified to family using simple keys. They are plentiful and easy to collect. The students were both surprised and delighted to see what was living in the stream, even at the most impoverished sites. Beginning biology students were extremely positive and enthusiastic about this field experience. The use of three indices was a somewhat confusing but valuable lesson for students. Discussions of the relative significance of index scores, reliability of the various indices, and variability among results were generated during the lab sessions. The biological data collection sheet will be changed, however, so students can more clearly see phylogenetic relationships. They can then select the appropriate data from a single data sheet for application of each index to be used. Inclusion of three separate data collection tables was confusing to first semester freshmen and, in fact, obscured the relationship between the three biotic indices. In the academic year, we intend to utilize the stream site in a number of other exercises in the General Biology course. The macroinvertebrates that are collected will be retained for use in a functional morphology lab that is being developed. Examination of organisms that students have collected and identified will make the exercise more meaningful to them than one using commercial collections from unidentified locations.

3 The summer laboratory assistants for the Department are collecting water chemistry data from the stream site. This will provide a data set for discussion in General Biology lectures on stream ecology during the spring semester, again from a location that is familiar to the students. An additional lab exercise is being developed to introduce students to water chemistry sampling and testing methods. BIO 411: Biochemical Instrumentation and Techniques The Biology Department offers a senior elective, Biochemical Instrumentation and Techniques, in which one of the General Biology lab assistants was enrolled last fall. His interest in the freshman laboratory exercise was translated into a project proposal to electrophoretically examine the proteins of selected benthic macroinvertebrates. He did initiate the project and was able to obtain good electrophoretic separation of proteins from two species of "scud." The preparations were very crude and provided little in the way of meaningful or comparative information, however. It is our intention to refine this project so that electrophoresis may be used as a technique for species identification of some of the organisms collected at our stream site. Incorporation of SSA Ideas Elsewhere in the Biology Curriculum As more students become familiar with the Pleasant Valley Parkway Stream, I am hopeful that students will use the site for independent projects in other courses. Ecology, Invertebrate Zoology, Field Botany are three field courses offered by the Department that require independent student projects. Courses such as Microbiology might also use the site for microecology studies. We are making headway - slowly. Environmental Studies Minor Providence College Initiatives The Faculty Senate approved an Environmental Studies Minor in the spring of 1994 (Appendix 2). The program does not require, but may have, a science emphasis, and many of the Biology majors are interested in it. The objective of the minor is to familiarize students with environmental issues and to emphasize the necessity of a multidisciplinary approach to solving environmental problems. The minor requires completion of a capstone course, "ENV 470: Special Topics in Environmental Studies," that includes a hands-on field component. Even before the ink dried on the Senate legislation, one of the Biology majors interested in the minor developed a proposal to use the Pleasant Valley Stream Site for his field project. He is particularly interested in the study of chironomid deformities as pollution indicators. He intends to collect and examine chironomids in the stream and other nearby sites for deformities. Ultimately, he hopes to determine if any correlation between "pollution" and deformities exists. To date, the project is in a very preliminary stage.

4 Feinstein Institute for Public Service Providence College was awarded a $5 million grant by Alan Shawn Feinstein to establish a public service program last year. As a result, the Feinstein Institute for Public Service has been established and ranks as the only service learning program of its kind in the country. Among the initiatives taken by the Institute is the design of concentration "tracks" that students might pursue in a community service major. One is an environmental track (Appendix 3). I have submitted a course proposal (Appendix 4) to the Feinstein Institute for inclusion in the environmental track. The course follows the SSA multi-focal approach to environmental problem solving. Ideally, students would identify a real local or state environmental problem or project and become involved with appropriate agencies; for example, Department of Environmental Management, Save-The-Bay, Better Business Bureau, in assessment of the environmental impact of the project. Ultimately, students would regroup to generate an environmental impact statement. The Feinstein Institute provides an excellent opportunity to train students as leaders in public service and to direct their efforts toward solving environmental problems.

5 Appendix 1 Lab 5 Stream Ecology: Benthic Macroinvertebrates as Biotic Indicators of Stream Water Quality By now in your study of biology, it should be clear that functional characteristics of organisms and cells are determined by the interaction of their structural components. Cells as units perform certain functions because of their structural components and organization. Multicellular organisms perform certain functions that are dependent on their structural organization and interactions. Ecosystems are composed of interacting groups of organisms with their environments. Just as cells and organisms can be characterized by their interacting structures and functions, ecosystems function because of the organization and interaction of their component parts, both biotic (living) and abiotic (non-living). An ecosystem is healthy when its components are homeostatic (balanced within an acceptable range of biotic and abiotic parameters). When some component is absent or altered by the addition of pollutants, for example, the health of the ecosystem becomes impaired. This laboratory is designed to familiarize you with a way to assess the health of an aquatic ecosystem, a local stream, using benthic macroinvertebrates as indicators of relative stream health. Benthic, or bottom, communities are known to be excellent indicators of the health of a water body. The resident instream biota reflect the integrated effects of substances intermittently discharged, substances reacting synergistically with each other, or substances present in levels too low for chemical detection. Benthic macroinvertebrates are ideal instream monitors because of their sedentary nature, their vital position in the food web, and their ease of collection. In short, stream macroinvertebrates are very sensitive monitors of pollution. Macroinvertebrates die off rapidly in response to pollution because of their sensitivity to pollution and their short life cycles. Most invertebrates live one year or less. This allows a comparison of population studies over a short period of time. There are seasonal population changes because many of the adult forms are terrestrial. However, any abnormal change in their population numbers is the result of a recent change in water quality and not merely a case of older organisms finally succumbing to a pollution problem that occurred a few years earlier. Also some toxins only effect one stage of an organism's life cycle. The adults may survive but the eggs or immature stages will be affected. Because an invertebrate rapidly progresses through all of its life stages, each stage will be exposed to any pollutants resulting in a measurable difference in the population. Lastly, invertebrates are good indicators because they are not very mobile. The aquatic immature stage cannot move to a different body of water and they do not travel very far within the stream or waterway. Even the flying adult forms usually lay their eggs within the same stream. Therefore, an abnormal change in the population is caused by a change in the water quality of that stream and not from changes in other waterways.

6 We will in this laboratory: 1. Evaluate the habitat of the stream being monitored, 2. Sample the macroinvertebrates using a standard traveling kick method which will be demonstrated by your instructor, 3. Become familiar with other sampling techniques, and 4. Assess the stream quality based on three biological indices (measurement of stream health using quantity and type of macroinvertebrates rather than physical or chemical water testing methods). The indices we will use are 1. The EPT Value Method, 2. a modification of Hilsenhoff s Biotic Index Score (Bode, Biological Stream Testing, 1990) and 3. the Percent Model Affinity. A. HABITAT EVALUATION To assess a site using biological indices, it is necessary to review the habitat, to identify and use appropriate sampling protocols, to preserve and sort specimens properly, to identify and quantify collected organisms, and to synthesize the collected data into meaningful biotic indices. Stream habitats that can be assessed using the three methods indicated above are typically characterized as riffles and pools. Whenever habitats are sampled and assessed, it is important to compare data from comparable habitats, i.e. not riffle to pool or vice versa. We will be sampling primarily riffles. Within riffles, microhabitats also exist, i.e. the habitats are different on the bottom, top, subsurface, etc. We will be looking at the bottom or benthic habitats. Therefore, the benthic habitat must be evaluated and characterized. Using the Stream Assessment Field Data Form, fill in all the information on the first page, except dissolved oxygen, ph and conductivity. Type (diameter) 1. Some of the measurements are self-explanatory. 2. Velocity can be measured by measuring the time it takes a float to travel a fixed distance. Several replicate times should be taken and average velocity determined. 3. Canopy cover is defined as the percent of the water surface directly beneath riparian vegetation or bridge structure. 4. Substrate composition is designated by visual determination of percentage of each particle size as defined by EPA (Environmental Protection Agency). Particles may be categorized as follows: Bed rock or solid rock - Boulders >256 mm (10 in) Rubble mm (2 1/2-10 in) Gravel 2-64 mm (1/2-2 1/2 in) Sand mm Silt mm Clay less than mm Size

7 5. Aquatic vegetation should be designated as percent cover of the stream bottom. the 6. Turbidity may be notable. Indicate the depth of visibility. Generally it will be depth of the stream at this particular site. When you have completed the stream assessment form, review the data against the following criteria for habitat suitability for use of the indices we have selected. The sampling site should be a riffle with a substrate of rubble, gravel and sand. Depth should be one meter or less, and the current speed should be at least 0.4 meters per second. Any replicate sites should have comparable current speed, substrate type, embeddedness (degree to which large substrate is surrounded by finer substrates), and canopy cover. Sites should have a safe and convenient access. Valley Parkway between Academy Avenue and the Culvert on the Parkway. The topographic map from US Geological Survey shows the location. Notice that this is in an urban area and the buildings, roads, and people in the area have very likely had an impact on the stream water quality. Figure 5.1: Topographic Map of Pleasant Valley Parkway Stream

8 B. SAMPLING There are a number of devices and methods that can be used to sample benthic macroinvertebrates. Before we venture into the field, we will consider a number of these that are presented on video by Dr. V.H. Resh of University of California at Berkeley. We will be sampling macroinvertebrates using the standardized traveling kick method in riffles. A "D" Frame net is positioned in the water at arms' length downstream and the stream bottom is disturbed by foot so that the dislodged organisms are carried into the net (Figure 5.2). Sampling is continued for a specified time and for a specified distance in the stream. Usually this is 2 minutes along a 5 meter length diagonally across the stream bed moving in an upstream direction. This may be adjusted depending on the stream site selected. The net contents should be emptied into a pan of stream water. Larger rocks, sticks, and plants should be removed from the sample after organisms are first removed from them. The contents of the pan should then be poured through a No. 30 sieve, emptied back into the pan and preserved with 95% ethanol. The preserved material can now be poured into a quart jar to return to the lab. Be careful to rinse the sieve and pan well with ethanol so that all organisms collected find their way into the collection jar. Refer to the photographs in the lab that illustrate the traveling kick sample collection method. A sample label should be prepared using pencil only to indicate the collection site, date of collection, name of collector. Place the label in inside the sample jar. Your specimens are now preserved for storage until you return to the lab for identification of the organisms you have collected. C. SAMPLE SORTING AND ORGANISM IDENTIFICATION Each of the three methods used for assessment of stream quality depends upon the numbers and kinds or benthic invertebrates found in our samples. Some organisms are tolerant of pollutants and others are not. Thus it is important to determine what organisms and how many of each kind we have collected. It is not necessary to count all the organisms collected. We can instead randomly select 100 individuals from each sample for sorting and identification.

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10 Figure 5.2: The Traveling Kick Sample Method. Rocks and sediment in the stream riffle are dislodged by foot upstream of a net; dislodged organisms are carried by the current into the net. Sampling is continued for a specified time, gradually moving downstream to cover a specified distance. 1. Sample Sorting Pour your sample back into a large, white pan. Try to distribute the material over the entire surface and then randomly select 100 organisms. Move these to a finger bowl, watch glass, petri dish or other container that you find it comfortable to work with. Be sure to keep the specimens covered with ethanol at all times. They will be useless if they dry out. When you are finished sorting or working with them, they may be stored in a small jar of 70% ethanol almost indefinitely. Now it is necessary to identify the organisms in your sample of 100. It is easier than you think if you first begin by simply examining them under a dissecting microscope and sorting them into groups that are alike. Once all the different groups of similar

11 (or preferably identical) organisms have been sorted, it will be much easier to identify them in these sets. 2. Specimen Identifications Begin your identification by comparing your sets of specimens to the diagrams and descriptions on the Izaak Walton League "Stream Insects & Crustaceans" Identification guide. This will probably get you through most of the identifications required for application of the three biological indices we have selected. Commonly found aquatic macroinvertebrates are also profiled for you. These profiles (supplement) are useful in developing an understanding of the life cycles and interactions among the organisms found in a stream habitat. Note that midge fly larvae (Suborder Nematocera) include the family Chironomidae. These two designations are used interchangeably in this exercise. If you need additional help with identification of your specimens, refer to the appended key at the end of this exercise. Use The Stream Assessment Biologic Data form to list all the taxa you have identified from your sample. The Assessment Form is organized to help you apply the biological indices to your sample data. Note that it is organized for two sets of data. You will be completing only half of the form for one sample. Part 1 includes all the major groups that are considered in the Percent Model Affinity and the EPT methods. The Biotic Index requires that some additional identifications to family be made. Any specimens that do not fit into the major groups in part one of the Assessment Sheet should be noted in part two. 3. Stream Assessment Using the Biological Indices The EPT VALUE denotes the total number of species of mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera) found in an average 100 organism sample. These are considered to be mostly clean-water organisms, and their presence generally is correlated with good water quality. We are using a qualitative version of this method, so that the EPT Value obtained will be designated excellent, good, fair, or poor. Determine the number of organisms you identified in each of the three indicator groups. Refer to Figure 5.3 and find the EPT Value for your sample. Enter this value in the Stream Assessment Form. Figure 5.3: EPT Values Excellent Good Fair Stoneflies, Mayflies and Caddisflies are present. Mayflies and Caddisflies present. Stoneflies are absent. Caddisflies are present. Stoneflies and Mayflies are absent. Poor All three groups are absent

12 The Percent Model Affinity is a measure of similarity to a model non-impacted community based on percent abundance in 7 major groups. Percentage similarity is used to measure similarity to an ideal community of 40% Ephemeroptera, 5 % Plecoptera, 10% Trichoptera, 10% Coleoptera, 20% Chironomidae, 5 % Oligochaeta, and 10% Other. Ranges for the levels of impact are: > 64% similarity, non-impacted; 50-64%, slightly impacted; 35-49%, moderately impacted; and <35%, severely impacted. To Calculate the Percent Model Affinity determine the percent contribution for each of the 7 major groups. These numbers should already be entered on your Stream Assessment Form in the first column labeled "#(%)". These must add up to 100. For each group, find the absolute difference in percentage from the model value for that group. For example, if the #(%) for Oligochaeta is 8, the difference is 8-5 = 3. Enter these differences in the column labeled "diff." Add up these differences and enter the total on the form. Multiply the total of differences by 0.5 and subtract this number from 100. Enter this number on your Stream Assessment Form. It is the Percent Model Affinity value. The Biotic Index is based on a quantitative Index called the Hilsenhoff Biotic Index. The number of individuals of each species is determined and multiplied by an assigned pollution tolerance value. The tolerance values range from 0 (intolerant) to 10 (tolerant). The Hilsenhoff method requires identification of specimens to species. We will, be using a revised version of the Hilsenhoff method based on a system which classifies invertebrates into three categories. These categories are indicated in Figure 5.4. If you compare Figure 5.4 with the Izaac Walton Identification Guide, you will note that Class I, II and III are roughly equivalent to Group I, II and III Taxa. Because there are a few differences, you should use the classification system in Figure 5.4. This will provide you with a more quantitative assessment. Figure 5.4: Biotic Index Values Class I Biotic Class II Biotic Class III Biotic Value Value Value Stonefly Larvae 10 Beetle Larvae 8 Midge Larvae 5 Mayfly Larvae 10 Cranefly Larvae 8 Snails 4 Hellgrammite 10 Scud 6 Sowbug 2 Water Penny 10 Clams, Mussels 6 Leach 2 Riffle Beetle. 10 Crayfish 6 Aquatic Worms 0 Caddisfly Larvae 10 Dragonfly Larvae 6 Damselfly Larvae 6 Blackfly Larvae 6

13 To calculate the Biotic Index Value, multiply the Biotic Value (shown in Figure 5.4) times the number of each type of organism in each of the groups represented in your sample. Add up all the numbers and divide by 10. Enter the Biotic Index Value on Sheet 2 of the Stream Assessment Biologic Data sheet where it reads "Family Biotic Index". This value will allow you to rate the stream. A Biotic Index Value of > 62 indicates a rating of excellent, as good, as fair, and < 31 as poor. Note these ratings on your Stream Assessment sheet. When you have obtained your three index values you should determine if they appear to confirm one another. Then submit your Stream Assessment Biologic Data sheets to your instructor so that all data for the samples collected and examined can be combined. Discuss among yourselves and then with the lab group as a whole, what each index value means in terms of the stream's health. What do you believe are some of the contributing factors to the condition of the stream? How might you go about studying the stream further? What other parameters need to be considered?. Stream Assessment Field Data.:...::: i... STREAM COUNTY STATE LOCATION DATE (Month/Day/Year) FIELD PERSONNEL Station Number Location Time Width (ft.) Depth (ft.) Velocity (ft./sec.) Banks - Describe Canopy - % Cover Stream - Describe Substrate (Bottom) - Describe Aquatic Vegetation

14 Turbidity Water Temperature Dissolved 02 (PPM) ph Conductivity Photo Taken Biologic Sample Remarks Completed By: Stream Assessment Biologic Data STREAM COUNTY STATE LOCATION DATE (Month/Day/Year) Field Personnel Station Number Location Time Taxa Sorted (List) #(%) Model Diff. #(%) Model D Oligochaeta 5 5 Ephemeroptera Plecoptera 5 5 Coleoptera Trichoptera 10 10

15 Chironomidae Other Total ` Percent Model Affinity EPT Value (2)Families Sorted # Tol Subtotal # Tol GO TO SHEET 2 STATION # Families (con t) # Tol. Subtotal # Tol. Subtotal

16 Total Family Biotic Index Above Completed by:

17 SUPPLEMENT PROFILES OF COMMON AQUATIC AWERTEBRATES This supplement (developed by Dr. Joseph K. Buttner, SUNY College at Brockport; now at Salem State University, Salem, MA) consists of descriptive profiles of the common orders of invertebrates you and your group are likely to find on our stream safari. If you become especially interested in a particular aquatic invertebrate, this section will give you background information that you may not gather in one or two observations alone. There are many diverse aquatic organisms to discover. Observation is ultimately the best tool that you can use to learn more. Because such a wide variety of life inhabits streams and the shallow areas of ponds, no one aquatic exploration will be exactly like another. You will begin to recognize familiar creatures in your samples; but because populations of invertebrates are always changing--depending on the season, time of day, stage in the organism's development, and natural and human-made disturbances-- different creatures will dominate your samples at different times. If you and your group sample a body of water over a period of weeks or months, you can record these changes and, through your own observations, gain a better understanding of the aquatic world. Caddisfly (Order: Trichoptera) The caddisfly is a close relative of the butterfly. Butterflies, with few exceptions, spend their entire lives, from caterpillar to winged adult--on land. The life cycle of the caddisfly is different. It includes an aquatic larval stage. Caddisfly larvae are soft bodied and look very much like small caterpillars or inchworms. Caddisfly larvae are unique, as well as easy to identify, because most build and live in tubelike cases made out of twigs, leaves, small pebbles, or small grains of sand. Caddisfly larvae glue the cases together with a sticky silk that they spin from their mouths. Some larvae make their cases entirely from this material. The cases serve several purposes. Most importantly, they protect the soft larvae from predators. They also help camouflage the larvae. In addition, a stone case adds extra weight to the caddisfly, preventing it from being swept downstream. Other types of caddisflies do not build cases but live freely in the water, usually where the current is not strong. Caddisfly larvae can be found in both still ponds and flowing streams. Those that live in ponds make cases out of pond grasses and weeds. Those that live in streams make cases out of sand and small pebbles. Caddisfly species that live in streams generally require higher levels of oxygen dissolved in the water than do species that live in ponds. Different species of caddisfly larvae have different feeding habits. Many species eat dead leaves and very small dead animals, often by filter feeding. Others eat plants such as algae, and still others are predators, which means they eat living creatures.

18 The caddisfly larva molts about five times. As it gets bigger and fatter, its skin becomes too tight. Like a snake, it sheds the skin that is too small. Some species rebuild their cases after each molt. When the caddisfly larva is ready to become an adult, it seals itself inside its case. At this stage the larva is called a pupa. Over a period of days or weeks, the pupa rearranges its body inside the case. When the caddisfly emerges, it is a winged adult. Caddisfly adults live for about two months and mate during this time. Females lay their eggs along the water's edge. Caddisfly larvae are eaten by a number of fish and are therefore very important in aquatic food webs. When the adult caddisfly emerges from its case, it flies through the water to the air, where it dries its wings. This is a very vulnerable stage because the caddisfly no longer has its protective case nor does it fly well in water. Escape from predators is difficult. Fish, knowing an easy meal, feed readily on emerging caddisflies. Fly fishing enthusiasts have found that imitation flies that are highly attractive to fish look like newly formed caddisfly adults. Mayflies (Order: Ephemeroptera) Mayflies were around when dinosaurs lived on earth. Except for becoming smaller, they have changed little in the past 300 million years. Today, most mayfly nymphs live in fresh running water. The approximately 700 species of mayflies in North America are a major part of the diets of fish that live in streams. You can find mayfly nymphs hiding under and on submerged rocks, burrowing in the silt, and swimming in the water. Mayflies that live on and under rocks are well adapted to that environment; they are often very flat. Swimming mayflies, however, have a streamlined shape, much like that of a small minnow. One way to distinguish a mayfly nymph from other nymphs is to look for gills. Seven pairs of gills, located along the length of the abdomen, help the mayfly nymph absorb oxygen from the water. Gill shapes vary from species to species. Some gills are short, some are long and tapered like leaves, and others are forked. Mayflies wave their gills to create a current, which increases the amount of dissolved oxygen passing over the gills. Mayfly nymphs generally have three tails attached to the end of their abdomens. The tails help the mayfly swim. You also can see tails on adult mayflies, trailing behind them as they fly. The presence or lack of three tails, however, cannot be used to identify a mayfly. Some species have two tails, and some mayflies may have lost a tail. To identify a nymph accurately, always check for gills along the sides of the abdomen. (Stoneflies, which also have two tails, do not have gills down the sides of their abdomen (some have tufty gills in their "armpits"). Damselfly nymphs have three tail-like appendages at the end of their abdomens, but they do not nave gills along their sides. Always look for gills when you make an identification.) Mayfly nymphs have certain adult characteristics: e.g., wing pads are visible. As the nymph gets older, the wing pads get larger and darker. Also, their legs are fully developed.

19 The mayfly belongs to the insect order Ephemeroptera. This name tells us something about its adult life. Ephemeral means short-lived. Although mayfly nymphs live for about a year, adult mayflies live only three days at the most. Their sole purpose as adults is to mate and lay eggs, adding to the next generation of mayflies. Sometimes thousands of mayflies emerge as adults at the same time, and then they all die within hours of each other. Dead mayflies on shores, roads, and bridges can pile up several inches thick. Although mayfly nymphs eat live and decaying plants, adults do not have the ability to eat. Imitations of mayfly nymphs and adults are popular ties for fly fishers because mayflies are a. common food of trout. Mayflies are especially vulnerable to being eaten by trout either as the nymphs emerge from the water's surface, as the egg-laying females rest on the top of the water, or just after the females die following egg laying. Dragonflies and Dannselflies (Order: Odonata) Another very ancient order of insects includes dragonflies and damselflies. Three hundred million years ago, their ancestors ruled the air. With wingspans of up to 30 inches (75 cm), they were the most formidable flying predators around. Flying dinosaurs or birds had not yet evolved. Today, dragonflies and damselflies are much smaller, but they are still effective predators, both as nymphs and as adults. Dragonfly and damselfly nymphs are found almost exclusively in ponds, marshes, and along lake shores, although you may see a few in a slow-moving portion of a stream. Equipped with huge compound eyes, these insects have nearly a 360-degree view of the world around them. This range of vision helps them strike at prey. The lower "lip" of the dragonfly or damselfly nymph is also adapted to predation. It is hinged in two places and has grasping pincers on the end. A nymph can snatch prey in only a few hundredths of a second. It then folds its lip back in and stuffs the food item into its mouth. The color of dragonfly and damselfly nymphs is also well suited for stalking prey. Camouflaged by their brown or green bodies and often covered with algae, they blend into the background as they cling to a plant or lie waiting in the mud at the bottom of a pond. Dragonflies and damselflies eat a variety of foods, including mollusks, insects, crustaceans, worms, and some times even small fish. In fish hatcheries, dragonflies can be an economic threat. As adults, dragonflies and damselflies are equally good predators. Dragonflies, capable of spurts of speed of up to 60 miles per hour, commonly fly at about 25 miles per hour. The legs of damselflies and dragonflies are far forward, close to their heads. A dragonfly, with its sharp eyesight, can capture a flying insect on the wing. The six front legs reach down forming a basket to capture the prey. The dragonfly then eats its meal as it flies. Nymphs of dragonflies and damselflies are sometimes the prey of fish. Some dragonfly nymphs are called bass bugs by anglers and are used as bait. Adults are the prey of birds and frogs.

20 Although both use gills, dragonflies and damselflies obtain oxygen in different ways. The damselfly has three leaflike gills at the end of its abdomen. The dragonfly has gills too, but they are located inside its body. To get water to pass across the gills, the dragonfly nymph draws water in through an opening at the end of its abdomen. As water passes over the gills, the gills absorb the dissolved oxygen. Then the nymph forces the used water out of its body. The expelled water propels the dragonfly nymph through the water. The body of a dragonfly nymph can be long and torpedo-shaped or round and spiderlike. As you would expect, the torpedo-shaped nymphs move through water much more swiftly than do the spiderlike nymphs, which creep along on their long legs. Damselfly nymphs are generally long, thin, and more delicate. Although in prehistoric times dragonfly and damselfly nymphs sometimes exceeded 1 foot in length, now they are seldom more than 2 inches (5 cm) long. When adult dragonflies and damseflies mate, the male grasps the female behind her head with a pair of pincers at the end of its abdomen, and the two fly in tandem for many hours. The males are territorial and can reach inside the female to clean out sperm deposited by other males, increasing their own chance of fatherhood. Beetles (Order: Coleoptera) Beetles are a large order of insect. In North America, more than 1,000 beetle species spend at least part of their lives in war. Some, such as whirligig beetles and predaceous diving beetles, live in water or on the water's surface for almost their entire lives, although they can fly from one pond or stream to another. Others, such as the water penny, are aquatic as larvae and then terrestrial, or land dwelling, as adults. Beetles have adapted to live in many different environments. Therefore, unlike caddisfly larvae or mayfly nymphs, which are easily distinguished by key characteristics, beetle larvae have diverse life histories as well as physical characteristics. Water pennies are adapted to lie in cold, fast-running streams. Up to 1/2 inch (12 mm) in diameter and less than 1/8 inch (3 mm) high, their plate-like, streamlined shape protects them from being swept away by the current. Their body shape and color help camouflage them from most predators. Water pennies attach themselves to the undersides of rocks, where they are out of sight and difficult to pry loose. It is possible to pick up a rock and not see one until it slowly begins to move. As they move over stones, water pennies graze on microscopic algae and other encrusted material. Water pennies obtain oxygen from the water through small white tufty gills behind their third set of legs. To become adults, water pennies go through a complete metamorphosis and emerge looking like typical beetles. Although adults don't live in water, they spend much of their time along the shores of streams. Predaceous diving beetles comprise more than 40 percent of the beetle species in North America. They have dramatically different life-styles compared with their slow-moving cousin, the vegetarian water penny. Predaceous diving beetles are aggressive and even cannibalistic as both larvae (often called water tigers) and adults. They can even eat small

21 fish. The larvae have mouthparts, with specialized channels, that can puncture prey and suck out their fluids. Most predaceous diving beetles live in still fresh water, although some species are found in running water. The bodies of predaceous diving beetle larvae are very different from those of water pennies. They are slender and range from 3 inches (70 mm) to 1/4 inch (5 mm) in length. Three obvious pairs of legs extend to the side, and the abdomen narrows to almost a point at its end. Of the aquatic beetles in North America, 20 percent are water scavenger beetles. Depending on the species, water scavenger beetles eat decaying matter or other animals. Adult water scavenger beetles are distinguished from predaceous diving beetles by their behavior. Predaceous diving beetles move their legs in unison when they swim. Water scavenger beetles surface for air head first and move their legs alternately. Also, the larvae of water scavenger beetles have wrinkled body surfaces. The whirligig beetle is a fascinating insect, most often found in ponds and in the still areas of streams. The shiny black adult whirligigs congregate in groups, spinning around each other like bumper cars. If disturbed, they scatter in every direction and then recongregate. Adults are almost always found on the surface of water. Whirligig beetles have two pairs of eyes, one pair above the water and one pair below. The adults use their below-water eyes to hunt for small prey. The adults protect themselves from predators with an odor. Some emit a foul odor, and one type secretes a milky substance that smells like apples. Although the smell of apples might not be offensive to you, it fends off their predators. Watch an adult aquatic beetle swim. It is much better adapted to life in water than to life on land. Its body is smooth and streamlined. The middle and hind legs often have long swimming hairs, which make the legs look and work like oars. You also may notice a silvery shine to the insect's body or a small silvery bead trailing behind as it swims. This is an air bubble, which the beetle carries with it under the water. Because it carries a supply of oxygen with it when it swims, the beetle only needs to surface for air infrequently. Stoneflies (Order: Plecoptera) Have you ever seen an insect flying on a mild winter's day or crawling on the snow? Chances are, that insect was not confused or sick. It was probably a stonefly. Stonefly nymphs, like many other aquatic insects, are active all winter long, feeding and moving in icy cold streams. Stoneflies, in fact, do a lot of their growing in water during the winter. When they get big enough, they emerge as winged adults. Most other insects wait until spring or summer to become adults, but some stoneflies do not. In some areas, nymphs of larger stonefly species grow for as many as four years before they become adults. Stoneflies require high levels of dissolved oxygen. Therefore, they do well in cold stream water because it can hold more oxygen. Some stoneflies also live along the wave-swept shores of large cold lakes, where the water is also highly oxygenated. Warm water with low levels of dissolved oxygen means death to a stonefly nymph.

22 The flattened shape of the stonefly nymph is one adaptation for crawling among the stones and gravel of a creek. Stonefly nymphs are not strong swimmers, and the current in open water can be swift. Therefore, most of their foraging takes place along a quiet bottom, not in the open water. Many stoneflies are predators and actively search for prey, relying on touch, vibrations in the water, or the detection of chemicals released by the prey to locate a meal. A number of stonefly nymphs prefer to eat decaying plants and animals. It is not the decaying matter that the nymphs find so appetizing, however. Scientists believe that the stoneflies are actually going after the protein-rich bacteria and fungus that live on dead plants and animals. Stonefly nymphs breathe either through the surface of their skin or through single or tufty gills under their legs, in their "armpits." When the oxygen level of water begins to drop, stonefly nymphs do "push-ups," which increase the flow of water (and therefore oxygen) over their bodies. Stonefly nymphs have very obvious wing pads. Two tails, which remain when the nymph becomes an adult, also help identify it. When identifying a two-tailed nymph, be sure to look for leaf-like gills down both sides of its abdomen. These gills are a distinctive characteristic of the mayfly nymph; if you see them, the nymph is not a stonefly. Some mayfly nymphs may have two tails, but their gills are always obvious. Trout eat stoneflies, and fly fishers use flies that imitate the nymphs. True Bugs (Order: Hemiptera) True bugs are another type of insect. The word bug has been used to describe all insects, so it's important to clarify this term when talking about insect identification. One common feature of all true bugs living in water is a beak, with which they pierce their prey and then suck out the body's juices. Although it sounds gory, all aquatic true bugs are extremely efficient predators and a very important part of aquatic food chains. They consume many other aquatic insects, including mosquito larvae, and many are a source of food for fish. The nymphs of aquatic true bugs look very similar to the adults. Only their size and underdeveloped wings distinguish them from the adults. Aquatic true bugs have adapted to their habitats in a variety of ways. One common true bug that you are likely to see in ponds and calm areas of streams is the water strider. Water striders, sometimes called water spiders because of their long legs, skate across the surface of water, but magically do not fall through. The tiny feet of the water strider have a coating of water repellant wax, which helps keep the body above the surface. The feet are also sense organs that can pick up vibrations of other organisms in the water. The predatory water strider can then zip over and eat them. Because water striders are almost always above the water's surface, they get oxygen, as do most land-dwelling insects, through specialized holes in the surface of their skin called spiracles. Some species of water striders live only in the open ocean. No other kind of insect can survive in such a difficult and dangerous environment. Marine water striders congregate in

23 groups in the ocean. It has been suggested that these groups of tiny water striders give the impression of being one large creature, which is less vulnerable to predators. Several other true bugs get oxygen by breathing air through snorkel-like breathing tubes that extend from their bodies to the water's surface. These include the giant water bug and the water scorpion. Giant water bugs have two short breathing tubes at the end of their abdomen. By tipping their backsides up toward the water's surface, they take in oxygen from the air. The giant water bug sometimes grows up to 3 inches (7.5 cm) long. It is also known as the toe biter because of the painful bite it can inflict. The bite is only painful to humans, but it can be lethal to smaller animals such as frogs, ducklings, other insects, and fish. A giant water bug was once observed eating a woodpecker! The bite injects a poison into the prey, and special chemicals in the poison cause the internal body parts of the prey to dissolve. In only minutes the giant water bug can suck out the juices. Another interesting fact about giant water bugs is that the males carry a pad of fertilized eggs on their backs and stroke the eggs to keep a flow of fresh water over them. Water scorpions have much longer breathing tubes than do giant water bugs. The water scorpion is often seen quietly hanging from the surface of water with its breathing tube just barely breaking the surface. Water scorpions have excellent camouflage and look much more like sticks than insects. But the bite that the water scorpion can inflict on its prey makes it worthy of its name. Water scorpion bites are not as painful, however, as those of the giant water bug. Water boatmen are the largest group of aquatic true bugs in North America. Water boatmen have adapted to many habitats, including running and calm waters and salty intertidal ocean waters. They are more tolerant of pollution than are most aquatic insects. Water boatmen, as their name implies, are adept swimmers. Their middle and hind legs are covered with long swimming hairs, which increase their surface area and make them act more like paddles than legs. Water boatmen differ from many other true bugs in that they eat not only animals but plants and decaying matter as well. Another aquatic bug, which looks like a water boatman, is the backswimmer. Backswimmers do just that--they swim on their backs. Unlike most other insects, which are dark on their backs and sometimes lighter underneath, the backswimmer has a whitish back and a dark underside. This is an adaptation for avoiding predators. Viewed from below, the backswimmer's light back blends in with the glare from daylight above. From above, the dark surface of the bug's underside (facing up) blends in with the dark surface of the water. The backswimmer's legs have swimming hairs similar to those of the water boatman. Dobsonflies, Fishflies, Alderflies (Order: Megaloptera) Dobsonflies, fishflies, and alderflies are all members of the same order of insects. All three are important in aquatic food webs. All have an aquatic larval stage and then emerge 1 to 3 years later as land dwelling adults, which live only a few days. They are large (looking a lot like a character in a science fiction movie), predaceous, and sometimes even cannibalistic.

24 The larvae of dobsonflies, or hellgrammites, are well known to anglers. They are good bait for fish because they are so large and lively. The larvae of these insects are distinguished by their stout body shape and the pointed filaments along the edge of their abdomens. The abdomens end with either a single long filament or a pair of short hooked prolegs. The larvae absorb oxygen through the surface of their bodies or through gill tufts along the sides of their abdomen. Dobsonflies are predators, and their diet consists mainly of other stream dwellers such as caddisflies and black flies. Dobsonflies, fishflies, and alderflies possess powerful chewing mouthparts, and the male dobsonflies have extremely long, tusklike mandibles, which are used for self-defense and in courtship. As ferocious as the larvae are, they also are very shy. You are much more likely to see the larvae of mayflies or stoneflies than you are to see these larvae crawling in streams. Flies (Order: Diptera) Not many people know that a number of flies have aquatic stages early in their lives. In fact, nearly 3,500 species of flies begin their lives in water. These includes black flies, mosquitos, horse and deer flies, crane flies, and midges. Black fly larvae are usually found in the cool headwaters of streams. In late spring the larvae become adults. The female adults need a blood meal to nourish them as they prepare to lay eggs, and this is when black flies become such vicious biters. You have probably encountered these pests if you have ever camped or hiked in the mountains during May or June. Black flies lay their eggs in the cool rapids of streams because the larvae require high levels of dissolved oxygen and food particles are carried to them by the current. Black fly larvae do not swim. They attach themselves to the rocky bottom of a stream by small hooks at the ends of their abdomens. First the black fly larva spins a small pad of sticky silk on a rock. Then the hooks grab onto the pad affixed to the rock. If a larva is knocked off a rock, it can often use the silk as a lifeline and reel itself back in. Sometimes you may see rows and rows of tiny black fly larvae attached to the bottom of a stream, lined up so they are oriented to the flow of food and oxygen. Black fly larvae are a good source of food for trout and other fish that live in cool streams. Mosquitos, which as adults can be as annoying as black flies, are found in a much different habitat. When you think about mosquitos, does an image come to mind? Do you think of a swamp? Mosquito larvae live in still or stagnant water. They are commonly found in ponds, marshes, swamps, and lakes. Unlike black fly larvae, mosquito larvae do not require high levels of dissolved oxygen. This is because mosquito larvae have a snorkel-like breathing tube that pokes through the water's surface and draws in oxygen from the air. Because of this adaptation, mosquitos and their larvae can live in polluted water, which has low levels of dissolved oxygen. Another fly larva that is very tolerant of polluted water is the rat-tailed maggot. This larva has a long snorkel-like tail that draws in oxygen from the air.