Aquatic Plants and Lakes Ecology home > Water Quality > Aquatic Plants, Algae & Lakes > Native Freshwater Plants - Aquatic Plants and Lakes Native Freshwater Plants Aquatic Plants and Lakes Introduction Plants growing in our lakes, ponds, and streams are called macrophytes. These aquatic plants appear in many shapes and sizes. Some have leaves that float on the water surface,while others grow completely underwater. In moderation, aquatic plants are aesthetically pleasing and desirable environmentally. Their presence is natural and normal in lakes, and in fact they are an important link in a lake's life system. In large quantities, plants can interfere with some water uses and may be seen as a problem. When lake users are confronted with too many plants in the wrong places, a common reaction is to remove the entire problem. Such hasty decisions are often made with little regard for the important role plants play in the water environment. Neglecting to see these interrelations often results in unintended impacts to wildlife, fish, and other forms of life. Unfortunately, the information required to make environmentally sound decisions is not always easily available. Without this information, how can anyone know what is best over the long term to do about aquatic plants?

The purpose of this information is to provide some general but pertinent information and insights regarding aquatic plants: (1) how they came to be where they are, (2) what beneficial contributions that they make to life in the lake, (3) how our activities can affect them, and (4) some things to consider if plant removal is planned. Acknowledgments: This information was taken from a brochure called About Aquatic Plants written by the Municipality of Metropolitan Seattle's (METRO) Water Resource Section (now King County). Life History of a Lake A question frequently raised regarding aquatic plants is why some lakes have them in abundance and others do not. An answer to this question lies in the explanation of the lake's aging cycle. Most of our local lakes came into being as a result of activity of glaciers in the most recent ice age, approximately 10,000 years ago. A lake bed is a natural depression or low spot in the terrain. In the Puget Sound lowlands they were often gouged out by movement of glacial ice. These depressions then became holding basins for water of the drainage area as it flowed toward sea level. As a lake detains water on its way downstream, it also becomes a settling pond for sediment.

Part of the sediment that settles in lakes is carried in by the flow of streams or other runoff, and part comes from the accumulation of the remains of organisms in the water and near the shoreline. Aquatic life includes visible plants and animals and also multitudes of microscopic plants and animals that can, over time, add significantly to the accumulation of sediment in the lake by dying and settling to the bottom. The microscopic plants in the water are nourished by plant nutrients (phosphorus and nitrogen) that originate in the watershed and are washed into the lake. Within the lake, a portion of these nutrients can be recycled indefinitely, while more continue to be washed in from the lake basin. Over time sediment accumulates in the lake as productivity gradually increases. When first formed, many of the lake beds were deep and clean (mostly free of sediment). Sediments that were first deposited were silty and had little organic material because there was little life in or around the lakes. Over time, hundreds or thousands of years, the sediment deposits became deeper and more favorable to the growth of rooted, aquatic plants (macrophytes).

As these plants (and the microscopic life in the water, now also more abundant) died back at the end of each growing season or life cycle, they enriched the sediments with organic material. Since macrophytes tend to grow better in organically richer sediments, this process set up a cycle of more growth in the lake causing richer sediments and these in turn favored even more growth of macrophytes As both microscopic and rooted plants continue to grow in increasing volumes and to enrich the bottom sediments of the lake, the lake ultimately fills in with silt and partially decomposed plant and animal material, forming a wetland and eventually a meadow. This occurrence marks the end of a lake's life. A lake's life generally extends over several hundreds or thousands of years under natural conditions. It can, however, be significantly shortened by human activities such as improper construction practices that disturb the soil and make it susceptible to erosional processes. As erosion increases in the watershed, quantities of sediment transported to the lake also increase. Consequently, the lake fills in faster and its life expectancy is reduced. The rate at which the process occurs varies with the size, shape, and flushing rate of the lake.

Human beings introduce to the watershed nutrient-rich materials such as fertilizers and wastes. Installing hard surfaces (roofs, roads, pavement) makes it easy for these nutrients to be washed into streams and lakes. These activities boost the continuing production of organisms that contribute to the filling of the lake as they die and become part of the organic sediment that favors macrophyte growth. Lake Aging and Macrophytes Aquatic plants are an integral part of the lake and its aging process. Although they may appear in deep, clear lakes, they generally grow most abundantly in shallow, productive lakes---old lakes that have accumulated thick sediments. An abundance of aquatic plants represents a sign of middle or old age. Conditions that favor macrophyte growth are fairly well documented. Many observations and studies have shown that conditions favoring their growth include an accumulation of organically enriched sediment and water that is shallow enough and clear enough for sufficient light to penetrate to the bottom. Algae, silt, or a natural amber or brown color in the water can interfere with transparency. Of course, the temperature range has to be acceptable to the plants, and there has to be enough stability in the sediments to permit plants to gain a foothold.

Thus, the near-shore area cannot be too steep. Although considerable research has been done to determine specific characteristics of sediment and water where macrophytes grow, many fundamental questions remain unanswered. However, it has been documented that macrophytes are able to get most of their nutrition from the sediment and can grow abundantly even when the lake water is not high in nutrients. Macrophytes in a Lake Ecosystem In many lakes macrophytes contribute to the aesthetically pleasing appearance of the setting and are enjoyable in their own right. But even more important, they are an essential element in the life systems of most lakes. They perform a number of useful functions in maintaining the food chain of life in the lake. Macrophyte leaves and stems provide a habitat or home for small attached plants and animals. Some are microscopic in size and some are larger. These attached organisms are valuable in that they are food for animals higher in the food chain, for example, fish and birds. There is a vast variety of these attached organisms, which are often very particular in their habitat needs. The kinds of surfaces available for their attachment will help determine the kinds and amounts of organisms present. Logs, sticks, and rocks of various sizes, shapes, and textures provide different kinds of surfaces.

Different kinds of macrophytes---because they have a variety of sizes, shapes, and textures of stems and leaves, and because they assume various positions in the water---also provide different kinds of surfaces for attachment. Many types of small organisms live in the sediment. There are insects that spend the immature stages of life in the sediments, leaving when they become adults. Decomposing plant life provides part of the food supply for these sediment-dwelling organisms and the emerging insects, in turn, are food for fish. The submerged portions of macrophytes provide shelter and cover for small or young fish from larger fish that would feed on them. Types of plants that extend above the water can provide cover for waterfowl and their young. Many plants can serve directly as food for certain types of waterfowl. Macrophytes may have an impact on the amount of floating algae in the lake. They can provide a growing surface for an enormous amount of algae. These algae use up a portion of the nutrients dissolved in the water that might otherwise fertilize; the floating algae and increase their growth. On the other hand, the macrophytes themselves, as they die back and decay, contribute nutrients to the water and thus can promote algal growth.

So in many cases we cannot be sure (without very specific and detailed analyses) whether removing rooted plants would bring about more algae growth, or less, or no change. Macrophytes as Nuisances Thus far, we have described how macrophytes are necessary to life as we know it in lakes. The question then is one of degree: How much plant life is desirable? Can there be too much? How much is too much? The answers will be different for different types of lake users and may vary from one lake to another. Some uses of a lake are more affected by macrophytes than other uses, and some types of plants interfere with recreational activities more than others do. Generally, plants are not considered to be a problem unless they interfere with desired or accustomed uses of a lake. Some plants have special capabilities to become very abundant and are thus apt to become nuisances. An example of this type of plant is the nonnative noxious weed Eurasian watermilfoil (Myriophyllum spicatum). This plant: Has a broad tolerance in its environmental requirements and is capable of flourishing under what seems to be difficult conditions and is found in a wide range of environments.

It is a nonnative species and does not have significant natural controls in Washington. Its reproduction and growth habits are very efficient. Its highly effective process of vegetative reproduction by fragmentation enables it to spread rapidly. In milder western Washington, it can overwinter in an evergreen state and start growing early in the spring before the native plants get started. Recreational boaters unwittingly contribute to the spread of milfoil and other exotic waterweeds such as Brazilian elodea, by carrying fragments of the plant on their boats, trailers, or fishing gear to an uninfested waterbody. Some of these noxious weeds can spread rampantly from even a tiny sprig, creating an aquatic jungle within a couple of years. Problems frequently attributed to the growth of macrophytes in lakes used primarily for recreation include: Interference with recreational activities such as boating, fishing, water skiing, and swimming. Production of fish populations consisting of many small fish rather than fewer large fish as a result of the plant's protecting small fish too well against predators. Unsightly and odoriferous accumulations of plant material on the water surface or beach. Oxygen deficiencies in the water (perhaps causing death to fish populations) due to decay of plants and plant respiration.

Accelerated filling of lakes by accumulation of decomposing plant material. Minimizing Macrophyte Nuisances There are several ways (aside from direct control operations in the lake) that a homeowner and citizen can reduce the chances for macrophyte problems to develop or worsen. Since nutrients and sediments influence the presence and growth of macrophytes, curtailing their flow into a lake is important. Preventative maintenance or actions that can be taken include the following: Curtail fertilizer use. Apply no more than the amount recommended by the manufacturer. Use a phosphorus-free fertilizer on established lawns. Develop lake-friendly landscaping practices. Maintain septic tank systems to prevent failures and support enforcement of laws aimed at preventing construction of septic tanks in unsuitable soil types. Place garden and grass clippings in areas not draining directly into the lake. Allow drainage from this debris to flow over soil or grassy places so that nutrients from their decomposition can be absorbed. Use low-or no-phosphate soaps or cleaning/washing compounds when washing your car. If you have a septic tank, use low-or-no phosphate dishwasher detergents.

Avoid using impervious ground covers (pavement, plastics) that will cause increased amounts of water to run off your property. More water tends to transport more nutrients and sediments and tends to cause erosion. Clean up after your pet. Animal wastes should be flushed down toilets connected to a sewer system or disposed of away from the lake. Keep livestock away from streams and the lake shore. Animal wastes introduce nutrients and hooves can cause bank collapse, which leads to heavy siltation. Don't feed the waterfowl. Canada geese can contribute a significant amount of nutrients to a lake. Support the adoption of ordinances designed to minimize surface water runoff and unnecessary land clearing during construction. Be on guard against introduction of new kinds of plants to your lake by fragments clinging to boats, trailers, or fishing gear, from aquarium plant discards, or by intentional ornamental plantings in the lake. Find ways to communicate your ideas on how the lake or lakes you are interested in ought to be managed. Form a lake association to communicate effectively with government agencies and other organized groups about how they feel lakes should be managed and protected. In some cases, these types of organizations have enough authority to share financial responsibility and thus participate directly in management activities.

Macrophyte Control In spite of efforts to control aquatic plants, they may proliferate along shores and in embayments. In situations where heavy plant growth interferes seriously with the use of a lake, the lake users are likely to think about getting rid of part or all of the plants. Because plants play an important role in the lake ecosystem any disturbance or removal of them will have an impact on the lake. This impact cannot be predicted accurately because of the complexity and differences in physical and chemical conditions and communities of organisms from lake to lake. Also some effects may be subtle and not recognized immediately. Once a lake's ecosystem is disturbed, a new balance must be achieved. What the new balance will look like or how rapidly it will occur is not always easy to know. Naturally, there is less cause for concern if a small portion of the lake is to be treated rather than a large area. Almost all methods of plant control have direct effects on plant life and organisms other than the targets of the control program. Depending on what is actually done to the lake, these side effects may or may not be extensive or long-lasting.

In cases where macrophyte control is planned, the probable effects of the proposed program can be predicted to some extent, if the lake is studied so that its physical, chemical, and biological systems are understood. Literature that reports the results of similar treatments on similar lakes can be helpful. Control methods should be chosen to minimize impacts. Hand pulling, for instance, has relatively limited side effects. However, there will generally be some uncertainties remaining as to how well the treatment will work and particularly on how extensive and significant its side effects may be. Glossary Algae- Single celled plants, most of which are microscopic. The kinds referred to here are either floating in the water or attached to solid surfaces of material in the water, such as rocks, logs, and plant stems and leaves. Decomposition - Decay of once-living material that releases back into the water some of the basic substances the living material was composed of. For example, decay of plants release plant nutrients back into the water. Ecosystem - The interacting system of all the living things in a biological community and all the parts of their environments. Food Chain - A succession of organisms starting with algae or other plants, followed by the animals that feed on them.

Next come the animals that feed on the animals that feed on plants, and so forth. A simplified example would be algae followed by tiny floating animals that eat the algae; larger floating animals (still small) that eat the tiny animals; small fish that eat the larger animals; big fish that eat the little fish; and humans who eat the big fish. Habitat - The environment in which a plant or animal lives. Different kinds of plants or animals have different requirements for their habitats and cannot survive in a habitat that provides too few of their required conditions. Macrophytes - Large plants that grow in the water. Most of the types we have are rooted in the sediment. Organic - Refers here to material that is living or once was part of a living organism. Organism - Any plant or animal including those of microscopic size. Plant Nutrients - Materials that plants use in growth such as phosphorus and nitrogen. Predators - Animals that prey on other animals, that is, use them for food. A particular kind of predator uses only certain other types of animals as food or prey. Respiration - The physical and chemical processes by which an organism supplies its body cells with needed oxygen and rids itself of waste carbon dioxide.

In some kinds of animals, respiration is also known as breathing; oxygen is used up and carbon dioxide is given off. Plants give off oxygen as a product of photosynthesis during daylight hours. Plants also respire, however, and at night when photosynthesis stops, they use up oxygen from the water rather than produce it as they do during the day. Sediment - Refers here to lake sediment, which is composed of (1) rock and soil particles and (2) particles of plant and animal materials. The first is the silt portion. and the second is the organic portion. Wetlands Wetlands Audience Objectives Content Glossary Activities Resources About the Author Audience This lesson is intended to be used with grades 9-12, but can be adapted as needed for grades 6-12. Objectives After completing the lesson the learner will: 1. correctly define a wetland 2. identify the three characteristics of wetlands 3. recognize the importance of wetlands 4. describe the ecological and economic functions of wetlands 5. distinguish between the five types of wetlands 7.

use an internet site to determine the types of wetlands in a choosen area (back to top) Take the pre-quiz below using your own notebook paper: 1. Define in your own words wetland: 2. What are five types of wetlands? 3. Choose the 15 states with the greatest percentage of wetlands: Description of Wetlands Wetlands are areas where water and land are mixed. They usually occur between dry land and deep water habitats. Wetlands can look very different throughout the world. The following map shows the location of wetlands throughout the United States: Three characteristics that all wetlands have in common: Water: In order for an area to be classified as a wetland the top 12 inches of soil must be saturated with water for at least 15 days during the growing season. There are two main sources of water for wetlands: 1. Surface water comes from streams, rivers, lakes, ponds, and oceans. 2. Ground water coming from cracks in sand, gravel, and rock beneath the earth's surface. The amount of water in any given wetland must be enough to support wetland plants.

Hydric Soils: Wetland soils are different then the soils found in dry lands. Wetland soils are called hyrdric soils because the spaces between each grain of soil is filled with water. Wetland soils are anaerobic. Anaerobic means that the soil lacks oxygen. The color of wetland soils is usually dark brown to black due to the presense of mineral or organic matter. Wetland soils may also have a rotten egg smell due to the presense of sulfur. Hydric Soil Wetland vegetation: Wetland plants have adaptations that allow them to live in an area that is saturated with water at various times in the year. Saltwater wetland plants have special adaptations that allow them to tolerate varying degress of salt. Wetland plants are called hydrophytes. Major Wetland Functions and Values In the past wetlands have been viewed as wasted land. They have been viewed as swampy, bug infested waters. Wetlands were also blamed for causing diseases. Malaria is an Italian word that means "bad air" because it was believed that the air of the swamps caused this terrible disease. For these reasons it became common practise to drain, fill, or build over many wetlands.

In the past 200 hundred years America has lost half of her wetlands. Fortunately, scientists have realized that wetlands have tremendous value. The following message was given by President Jimmy Carter in 1977: The nation's coastal and inland wetlands are vital natural resources of critical importance to the people of this country. Wetlands are areas of great natural productivity, hydrological utility, and environmental diversity, providing natural flood control, improved water quality, recharge of aquifiers, flow stabilization of streams and rivers, and habitat for fish and wildlife resources. Wetlands contribute to the production of agricultural products and timber and provide recreational, scientific, and esthetic resources of national interest. Although only about 5% of the nation's total land area is wetlands, almost 35% of the nation's rare or endangered plants and animals are found there and over 900 species of vertebrates (in the United States) spend at least part of their life in wetland habitats. (Olson, Margaret. Georgia's Wetland Treasures. (Graphic Creations Publication) The major functions and values of wetlands are the following: The habitats of numerous fish and wildlife are found in the wetlands.

A great percentage of fresh and salt water fish depend on the wetlands for spawning and nursery grounds. Wetlands are used by ~80% of all waterfowl for nesting, feeding, and breeding. Over half on the migratory birds of the South spend at least part of their time en route in wetlands. Other animals spend some portion of their life in the wetlands for shelter, feeding, or water. Rockfish The water in a wetland itself serves valuable purposes in the environment. The functions of water in a wetland are called hydrologic functions. Water in wetland serves the following functions: 1. Flood control 2. Buffers the effects of waves on the land 3. Controls the amount of erosion 4. Stores water that refurbishes the groundwater 5. Discharges of groundwater into lakes, rivers, and streams during dry periods Wetlands play an important role in maintaining the quality of water of deep water habitats. Wetlands carry out the following functions: 1. 80%-90% of all suspended soil that passes through wetlands is trapped by wetland plants. This function is called sediment trapping. 2.

Much of the world's oxygen is produced in wetlands by microscopic plants called phytoplankton. 3. Wetlands are capable of removing 85%-90% of the nitrogen and phosphorous as water flows through them. The removal of nitrogen and phosphorous prevents the eutrophication of nearby ponds or lakes. 4. Some wetland plants can change the makeup of viruses, certain bacteria, and suspended solids in waste water so that the substances are no longer harmful. Phytoplankton Wetlands also have a socioeconomic function due to the many products for which they are directly or indirectly responsible. The products are the following: 1. Timber 5. Fur and other wildlife products 6. Food Wetlands are categorized into five different types based on four different factors: 1. Type of vegetation present 2. Pattern of flooding 3. Chemistry of the water 4. Type of soil A brief description of each of the five wetland types will follow: Marine: Includes beaches, bars, and shorelines that are alternately exposed and flooded by tidal action of the open ocean. This area also includes the "splash zone". Algae is the only characteristic plant of these wetlands.

Marine wetland animals must be able to withstand the crashing waves of saltwater during high tide and the hot sun at low tide. Some of the animals of these wetlands are the polychaete worm, coquina clam, mole crabs, isopods, amphipods, and sand dollars. Estuarine: Includes wetlands that contain a mixture of both fresh and salt water. Examples of estuarine wetlands are saltmarshes, brackish marshes, intermediate marshes. These three are separated by the degree of salt in the water and by the type of vegetation. 1. Intertidal marshes have woody vegetation and are flooded periodically by water that has a salinity of 5 ppt. This category is composed mainly by the mangrove swamps located Florida and Louisianna. 2. Salt marshes occur extensively in South Carolina and Georgia. Plants are found in distinct zones depending on the type of soil, salinity, temperature fluctuations, and tidal fluctuations. One of the dominant plants in salt marshes is cord grass. 3. Brackish marshes are saltwater wetlands that occur in North Carolina, Florida, and Louisianna.

Brackish marshes form upstream from saltmarshes and contain a higher percentage of freshwater. The plants of brackish marshes depend on the degree ofsalinity in the area. Some of the plants characteristic of these wetlands are cord grass, common reed, saw grass, and knotgrasses. Cordgrass Palustrine wetlands are freshwater wetlands that are dominated by woody vegetation greater than 20 feet in height. Floodplain wetlands make up the dominant portion of this category. Trees common to palustrine wetlands are oaks, green ash, sweet gum, ironwood, cypress, water tupelo, willows, water hickory, and maples. Lacustrine wetlands contain freshwater and border lakes and reservoirs. They are permanently flooded with water deeper than 6.6 feet and are usually in an area larger than 20 acres. Plants consist of submersed floating plants and non-persistent emerging plants. Some examples of lacustrine wetlands are stream levees, beaver dams, limesinks, and barrier island lakes. Beaver Dam Riverine wetlands also contain freshwater and are contained within a channel of moving water. They are found along rivers and streams.

Riverine wetlands are permanently flooded and contain the same type of vegetation as Lacustrine wetlands. Some examples of riverine wetlands are mountain streams, brown water streams, tidal streams, and springs. Mountain Stream In his book, My First Summer in the Sierra, John Muir says, "Every rain-cloud, however fleeting, leaves its mark, not only on trees and flowers whose pulses are quickened, and on the replenished streams and lakes, but also on rocks are its marks engraved whether we can see them or not". (Muir, John. My First Summer in the Sierra. California: Sierra Club, 1988.) Let us never underestimate the effect of any aspect of nature on every other aspect of nature. Algae - photosynthetic, plantlike protists important in oxygen production Amphipoda - order of crustacean that live in the ocean Coquina clam - type of two shelled mollusk Isopod - order of crustacean that live on land ex.

rolly polly Malaria - a disease marked by recurring chills and fever and caused by a protozoan transmitted by the anopheles mosquito Polychaete worm - class of segmented worm that usually live in burrows, under rocks,in tubes of hardened mucous, and inside shells Salinity - condition of containing salt Spawning - process of producing eggs or offspring esp. in large numbers Vegetation - plant life Making A Wetland Map Purpose: Each group will use an internet site to determine the location of wetlands within a chosen area. The internet site will also be used to determine the types of wetlands in the area. Students will print a colored map that includes a key describing the wetlands in their chosen area. The internet site that will be used to produce the wetlands map is a site produced by the U.S. Fish and Wildlife Service. Digital maps have been made from photographs taken from the air. Data has not been completed for the whole U. S. yet. Students will first need to go to a site that identifies the states with complete digital date. Identifying States with Complete Digital Data 1. Go to the following web address: 2. Scroll down to the following item: "NWI map status - continental U.

S." 3. Left click on this item 4. Print this map on a color printer. The map is color coded to inform you of the states for which wetland digital maps are complete. Every area that is colored red has complete digital maps. The states that are completely red will be the best states for you to choose to make a wetland map. 5. Close out this internet site. The internet site that you will use to produce a wetland map works best on narrowly defined areas. Because of this it is best if you use a zipcode for an area rather than a whole county. Choose a state that is colored red from the map produced in the first web site. If you do not know a zip code for a city within the state you can use the web site below to find one: 2. Type a city and state abbreviation 3. Left click on "process" 4. Print the zip codes that are given Making the Wetland Map 1. Go the internet site: 2. Scroll down to the menu item on the lefthand side of the page and left click the mouse on the item entitled "Wetlands Interactive Mapper" 3.

Scroll to the bottom of the page entitled "National Wetlands Inventory" 4. Click the icon "Wetlands Interactive Mapper" 5. Scroll to "zip code" and left click on it under "Area Query" 6. Type in the zip code for an area in the U. S. in which digital maps of wetlands have been completed 7. Left click the mouse on the icon "Submit" 8. Check the zip code and submit it again 9. A box will appear on the top left hand side of the screen. Choose the following items to view on the map: wetlands, roads, streams by left clicking on them 10. Left click on "Submit" 11. The map can be viewed by left clicking on the arrow at the right side of the map 12. Any gray areas in the map represent areas for which there is no digital data 13. There is a dialogue box at the bottom of the page that can not be seen if you have a 15" monitor. In order to view this you need to move the mouse to the top horizontal line of the box (you should be able to see a portion of the box).

When the mouse icon changes to a double arrow drag the box to the top of the page. You can now view everything in this box which is entitled "More Descriptive Wetlands Legend". 14. Left click on the title "More Descriptive Wetlands Legend". This is a key to the colors on your map. Print this page on a color printer. 15. Close out this box by left clicking on the X in the right hand corner 16. Left click on "Format Map for Printing" 17. Print a copy of the map 18. Return to the map utilities page 19. Scroll down to the title "View Wetland Acreage Summary" 20. Look at the topic "Entire Map View" and double click on "General Type" 21. This page gives you a list of the types of wetlands in your zipcode. Print this page. Some of the wetland terminology in the key for your map may be hard to understand. Go to the following web address and print that page: The page gives you the common descriptions for each term. Presentation 1. Make an overhead transparency of your wetland map 2.

Be able to describe all of the colors in your map using the page printed from the "More Descriptive Wetlands Legend" 3. Describe the acreage for each type of wetland 4. Identify wetland areas using the common descriptions 5. Describe each type of wetland in your area using the information from your lesson 6. Describe five different living organisms that would be found in each type of wetland in your area. You need to have a picture to show for at least two living organisms per wetland. 7. Your presentation should last 8-10 minutes. (back to top) Olson, Margaret. Georgia's Wetland Treasures. (Graphic Creations Publication) Muir, John. My First Summer in the Sierra. California: Sierra Club, 1988. Online Resources Food Chains and Webs | Teaching Great Lakes Science Teaching Great Lakes Science Search Food Chains and Webs All living organisms depend on one another for food. By reviewing the relationships of organisms that feed on one another, this lesson explores how all organisms— including humans—are linked.

If students understand the relationships in a simple food chain, they will better understand the importance and sensitivity of these connections, and why changes to one part of the food chain almost always impact another. Grade level: 4-8th grades Performance Expectations: MS-LS2-1 Ecosystems: Interactions, Energy and Dynamics. Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem. MS-LS2-2 Ecosystems: Interactions, Energy and Dynamics. Construct an explanation about how the different parts of the food chain are dependent on each other. MS-LS2-3 Ecosystems: Interactions, Energy and Dynamics. Develop a model to describe the cycling of matter and flow of energy among living parts of the food chain. MS-LS2-4 Ecosystems: Interactions, Energy and Dynamics. Construct an argument, supported by evidence gathered through observation and experience, showing how changes to physical or biological components of an ecosystem affect populations. MS-LS2-5 Ecosystems: Interactions, Energy and Dynamics. Evaluate competing design solutions for maintaining biodiversity and ecosystem services. MS-ESS3-3 Earth and Human Activity.

Answer questions about how pollution affects food chains by applying scientific principles to design a monitoring plan for minimizing the human impact on the environment. For alignment, see: NGSS Summary Lesson Objectives Describe the difference between herbivores, carnivores and producers. Answer questions about the interdependence of herbivores, carnivores and producers as members of a food chain. Answer questions about how pollution affects food chains. Background A food chain is a simplified way to show the relationship of organisms that feed on each other. It’s helpful to classify animals in a simple food chain by what they eat, or where they get their energy. Green plants, called producers, form the basis of the aquatic food chain. They get their energy from the sun and make their own food through photosynthesis. In the Great Lakes, producers can be microscopic phytoplankton (plant plankton), algae, aquatic plants like Elodea, or plants like cattails that emerge from the water’s surface. Herbivores, such as ducks, small fish and many species of zooplankton (animal plankton) eat plants. Carnivores (meat eaters) eat other animals and can be small (e.g., frog) or large (e.g., lake trout).

Omnivores are animals (including humans) that eat both plants and animals. Each is an important part of the food chain. In reality, food chains overlap at many points — because animals often feed on multiple species — forming complex food webs. Food web diagrams depict all feeding interactions among species in real communities. These complex diagrams often appear as intricate spider webs connecting the species. This lesson demonstrates that changes in one part of a food chain or web may affect other parts, resulting in impacts on carnivores, herbivores, and eventually on producers. An example of this might be the harmful effects of pollution. The point that should be made is that when something disrupts a food web, humans should try to understand and minimize the disturbance. Students should also come to recognize that humans, too, are part of this complex web of life. Food Chains and Food Webs – Parts and Pieces Food Chains Producers Plants form the base of Great Lakes food chains. They’re called producers, because they make their own food by converting sunlight through photosynthesis. They also act as food, providing energy for other organisms. In the Great Lakes, most producers are phytoplankton, or microscopic floating plants. An example of phytoplankton is green algae.

Large rooted plants, another type of producer, provide food and shelter for different organisms, fish and wildlife. Primary Consumers The next level in the food chain is made up of primary consumers, or organisms that eat food produced by other organisms. Examples of primary consumers include zooplankton, ducks, tadpoles, mayfly nymphs and small crustaceans. Secondary Consumers Secondary consumers make up the third level of the food chain. Secondary consumers feed on smaller, plant-eating animals (primary consumers). Examples of secondary consumers include bluegill, small fish, crayfish and frogs. Top Predators Top predators are at the top of the food chain. Top predators eat plants, primary consumers and/or secondary consumers. They can be carnivores or omnivores. Top predators typically sit atop the food chain without predators of their own. Examples include fish such as lake trout, walleye, pike and bass, birds such as herons, gulls and red tailed hawks, bears—and humans! Food Webs In reality, many different food chains interact to form complex food webs. This complexity may help to ensure a species’ survival in nature. If one organism in a chain becomes scarce, another may be able to assume its role.

In general, the diversity of organisms that do similar things provides a type of safety, and may allow an ecological community to continue to function in a similar way, even when one species becomes scarce. However, some changes in one part of the food web may have effects at various trophic levels, or any of the feeding levels that energy passes through as it continues through the ecosystem. At the base of the aquatic food web are: Plankton Plankton are microscopic plants and animals whose movements are largely dependent upon currents. Plankton are the foundation of the aquatic food web. Plankton are vital in the food supplies of fish, aquatic birds, reptiles, amphibians and mammals. Phytoplankton Plant plankton are called phytoplankton and may be single cells or colonies. Several environmental factors influence the growth of phytoplankton: temperature, sunlight, the availability of organic or inorganic nutrients, and predation by herbivores (plant eaters). Zooplankton Animal plankton are called zooplankton. Zooplankton can move on their own, but their movement is overpowered by currents.

Zooplankton may be herbivores or plant-eaters (eat phytoplankton), carnivores or meat eaters (eat other zooplankton) or omnivores, which eat both plants and animals (eat phytoplankton and zooplankton). What is a red tide? Home Ocean Facts What is a red tide? What is a red tide? A "red tide" is a common term used for a harmful algal bloom. VIDEO: Learn about "red tides" and human health in this video from the U.S. Integrated Ocean Observing System® . Harmful algal blooms, or HABs, occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds. The human illnesses caused by HABs, though rare, can be debilitating or even fatal. While many people call these blooms 'red tides,' scientists prefer the term harmful algal bloom. One of the best known HABs in the nation occurs nearly every summer along Florida’s Gulf Coast.

This bloom, like many HABs, is caused by microscopic algae that produce toxins that kill fish and make shellfish dangerous to eat. The toxins may also make the surrounding air difficult to breathe. As the name suggests, the bloom of algae often turns the water red. HABs have been reported in every U.S. coastal state, and their occurrence may be on the rise. HABs are a national concern because they affect not only the health of people and marine ecosystems, but also the 'health' of local and regional economies. But not all algal blooms are harmful. Most blooms, in fact, are beneficial because the tiny plants are food for animals in the ocean. In fact, they are the major source of energy that fuels the ocean food web. A small percentage of algae, however, produce powerful toxins that can kill fish, shellfish, mammals, and birds, and may directly or indirectly cause illness in people. HABs also include blooms of non-toxic species that have harmful effects on marine ecosystems. For example, when masses of algae die and decompose, the decaying process can deplete oxygen in the water, causing the water to become so low in oxygen that animals either leave the area or die.

Scientists at the National Ocean Service have been monitoring and studying this phenomenon for a number of years to determine how to detect and forecast the location of the blooms. The goal is to give communities advance warnings so they can adequately plan for and deal with the adverse environmental and health effects associated with these 'red-tide' events. Search Our Facts Water Biomes | The Water Page Water Biomes Water Biomes The earth is filled with a variety of climates that give life to different plant species. A large area that shares the same weather patterns and plant species is known as a biome. Many experts agree that seven biomes make up our world. Water makes up three-fourths of Earth’s surface and creates two of its biomes: the freshwater biome and the marine or saltwater biome. The freshwater biome includes ponds, rivers, streams, and other bodies of water with little salt in them. The marine biome consists of the oceans, which contain plenty of saltwater. Ponds and Lakes The freshwater biome consists of many unmoving bodies of water known as ponds and lakes. A pond is a shallow hole where water builds up over time from falling rain.

Plants grow around the pond and often spread across the bottom of the pond since the water is still shallow enough for sunlight to reach its depths. Temperature is consistent throughout and the water is still, with no waves. Due to its shallow depth, a pond may freeze solid in the winter or completely evaporate in the summer. When a body of water grows larger and deeper than a pond, it becomes a lake . Lakes can stretch to thousands of square kilometers in size. Plants survive only near the shoreline because further out the water is too deep for adequate sunlight. Some lakes have waves. The temperature of a lake varies widely from top to bottom. Middle Layer: 8-19°C Bottom Layer: 4-8°C Since a lake is so deep, it cannot freeze solid. The top layer can freeze, however, and cut down on oxygen levels. This causes some plants and animals to die off, known as winterkill. In the summertime the opposite occurs. Algae , a plant-like organism found in lakes, can overproduce and die off in large numbers. The decaying algae lowers oxygen levels and kills off some of the plants and animals, known as summerkill. Summerkill and Winterkill can be a problem for those raising fish.

Rivers and Streams Moving freshwater comes in the form of rivers and streams . The bottom of a river is the riverbed and the sides form its banks. Rivers are larger than streams and eventually flow out into the ocean. Combined, rivers and streams make up 3% of earth’s freshwater and help drain excess water away from the land. Qualities of Rivers: More abundant in areas of heavy rain Qualities of Streams: Join other stream to form rivers Known as tributaries when they form large rivers When rivers, streams, and rainfall all flow to a single point where they then empty out into a large body of water, such as a lake or ocean, this is known as a watershed . Watersheds can carry pollution from inland and deposit it into these larger bodies of water. When a river meets the ocean, this point is known as the mouth of the river. It carries soil with it and the soil is deposited at the mouth of the river, where it slowly builds up into land over long periods of time. This new land is called a delta . The last of the freshwater is found trapped inside glaciers. These frozen rivers are located in places such as Antarctica. It is a common misconception that glaciers don’t move, but the opposite is actually true.

Though their progress is slow, glaciers found on high ground slowly move down toward the lower ground. The Ocean The ocean covers most of our planet and accounts for 97% of the water found on earth. It provides the fish we catch for food and many of the plants we use in cosmetics and even toothpaste. The ocean also works to regulate the temperature of our air and provides the moisture needed to create rainfall. While the ocean may look smooth on the surface, the ocean floor is actually covered in mountains, valleys, and even volcanoes, just like on dry land. Our Oceans: Pacific Ocean – The Pacific Ocean separates North and South America from Asia and Australia. It is further divided into the North Pacific Ocean and the South Pacific Ocean. Atlantic Ocean – The Atlantic Ocean separates the coasts of North and South America from the coasts of Europe and Africa. Indian Ocean – The Indian Ocean separates Africa and southern Asia from Australia and stretches down toward the South Pole. Arctic Ocean – The Arctic Ocean is found in the Arctic, the area where the North Pole is located. Southern Ocean – The Southern Ocean encompasses Antarctica at the South Pole. Some argue that the Southern Ocean should not be considered a separate ocean at all, but generally it is included on the list.

The ocean is about 4,000 meters deep on average, but it can go quite deeper in some spots. The deepest known point in the ocean is the Mariana Trench . Located north of New Guinea, this trench stretches 2,500 kilometers long and varies in width from 70 kilometers to 338. The deepest point of this trench, called Vitjazdepth, is an astounding 11,035 meters deep. It’s not only the deepest known point in the ocean, but also the deepest known point on the entire planet. The ocean contains varying levels of sodium chloride , the salt we use to season our foods. Salt flows into the ocean from the land. Rain runs through rocks and sand, collecting salt and other minerals on its journey to the ocean. When that water reaches the ocean, it deposits the salt and minerals. When water evaporates out of the ocean, the heavy salt is left behind. Wetlands Areas formed from a mixture of water and land, known as wetlands , occur near rivers and in places with heavy rainfall. Swamps , marshes , and bogs all fall under the title of wetlands. Wetlands are both water and land.

While they consist of water, they also have thick vegetation growing in them. Often trees grow out of swamps and animal life is abundant. Wetlands occur along rivers, streams, and other large bodies of water. When it rains, a river can overflow its banks and fill low-lying areas of land to form wetlands. In dry seasons the wetland may dry up completely. To be considered a wetland , the water must be present for part of the year. In the past, people drained wetlands and filled them in to prevent them from filling with water. More recently people have begun to recognize the wetlands for the natural resources they provide. Many plants and animals call the wetlands home. Birds often migrate from wetland to wetland on their migration path, and some even go there to nest. The wetlands also prevent flooding by collecting overflow from rivers during heavy rain and prevent rivers and lakes from drying up by dumping water back into the river or lake during dry seasons. Despite these benefits , some people still drain wetlands. Water Biomes Information The World’s Biomes – Learn what a biome is and what biomes make up our planet. The Aquatic Biome – A detailed look at the aquatic biomes.

Marine Biome – Discover the animals and plants that live in the marine biome, along with the health issues they’re facing. Aquatic Biome – Learn about the aquatic biome and see images of the plants and animals that call it their home. Life’s Little Essential – PBS explains why water is vital to the formation and survival of all living things. The Water Cycle – An animated diagram of the water cycle. Find out where water comes from. Why is the Ocean Salty? – Find out why the ocean is salty and just how salty it is. Where is Earth’s Water Located? – Find out how the water on our planet is distributed and how much is usable versus unusable. Marine Life – Learn about marine life and see what plants and animals live in the ocean. Wetland Life – Discover the plants and animals that thrive in the wetlands. Lake Information – Find out how lakes form and what changes their water levels. Physical Features of the Ocean – The ocean holds many surprised. Find out what the ocean floor is actually like. Freshwater – The Encyclopedia of Earth presents detailed facts and graphs on freshwater and everything there is to know about it.

All About Glaciers – The National Snow and Ice Data Center offers a breath-taking look at glaciers and facts about their attributes. Icefields and Glaciers – Learn where glaciers and icefields come from, along with what kinds of plant and animal life exist near glaciers.

Question: What name is given to the microscopic plants found in great numbers in rivers, lakes, and oceans?
Answer: Algae