UNIT 4

1. UNIT 4 WATER AS AN ECOSYSTEM

2. 4.1 AQUATIC ENVIROMENTS • A watershed is the land area that is drained when drops of rain join others to flow into a particluarstream,river,lake, or wetland. • What happens on the land in a watershed affects the quality of water in the aquatic enviroments and the organisms that live there. • Two types of aquatic enviroments are freshwater and saltwater ecosystems. • Freshwater ecosystems can be divided into two groups: lotic(fast moving water) and lentic (slow moving water)

3. Examples of lotic ecosystems are rivers, streams, brooks, and creeks. • Examples of lentic ecosystems are lakes, ponds, and wetlands

4. Stream Classification Streams are classified by their size. The smallest streams are first-order streams. When two first-order streams meet they form a second-order stream. The place where the two streams meet is the confluence. The stream formed at the confluence of two second-order streams is a third-order stream. The process continues until the stream or river empties into a lake or the ocean. The place where the river system ends is its mouth.

5. REACHES • River systems are divided into 3 different regions- upper, middle, and lower reaches. • The beginning of a stream is called the headwaters. • As the water moves from the headwaters to the mouth of the river system the physical characteristics of the stream change. • The riparian zone ( ecosystem along the river or stream) aslo changes.

6. UPPER REACHES • This includes regions of the stream with the greatest slope. The channel is straight and V shaped. • The riparian zone is narrow and the trees form a conopy shading the stream. Little sunlight reaches the stream. • Rapids, riffles, and waterfalls are abundant in the upper reaches. • Boulders and cobble stones cover the bottom of the stream. • Organisms that live here must constantly fight the fast current. • The upper reaches contain fewer species of plants and animals than other regions of the river system.

7. MIDDLE REACHES • The middle reaches include the sections of the river system with 3rd and 4th order streams. Here the slope is moderate and the U shaped channel is wider. • The bottom is covered with boulders, cobble, and gravel. • The riparian zone widens to form a floodplain, and the path of the stream has more curves or meanders. • Trees and other rooted plants along the stream’s edges provide food and shelter for some species. • There is less canopy and therefore more sunlight gets to the water thus increasing the growth of algae and aquatic plants. • The middle reaches have the greatest variety of habitats with a combination of shallow areas of riffles and deeper pools.

8. LOWER REACHES • The lower reaches include sections of the river system with a gentle steady flow. • The slope has a low slant and the river meanders across a wide valley. The U shaped channel is wider and deeper than the middle reaches. • The erosional material from the upper and middle reaches is deposited here. The bottom is covered with gravel, sand, and silt. • There are no rapids, riffles, or waterfalls; the surface is smooth. • The riparian zone is a broad floodplain often several miles wide. • The depth and turbidity of the water prevents sunlight form reaching the bottom which limits photosynthesis. The community of plants and animals is much like a pond.

9. HABITATS • There are a variety of habitats where organisms can live in aquatic enviroments. • The habitats found in streams depend upon volume of flowing water and slope. • Habitats include: • Surface film- The place where water meets the air. Animals found here include air-breathing insects that walk on or hang on to the surface of the water. • Open water- The area where rooted plants do not reach the surface. (fish,turtles,birds, and plankton)

10. Bottom- The area of rocks,sand, or mud that is the habitat for a variety of small organisms ( bacteria, snails, worms, sponges, crayfish, and larvae) • Water’s edge- is where the water meets the land. This is home for greatest number of species of plants and animals.

11. MACROINVERTEBRATES • Macroinvertebrate surveys are an important part of monitoring the water quality of an aquatic water system. • The benthic macroinvertebrates are aquatic insects or other small organisms that have no backbone and are large enough to be seen without a microscope. • A benthic macro survey can tell us if the aquatic ecosystem is healthy. Since these organisms do not move very far or very fast they can’t escape pollution. • They can also indicate the water quality of a long period of time since some of their larvae remain at the bottom for 2-3yrs before they surface.

12. The macroinvertebrates are essential to healthy fish populations. They are eaten by smaller fish while larger fish eat both small fish and macroinvertebrates. • FEEDING GROUPS • *Collectors: feed on decomposing organic matter. • -gathering collectors: feed on the bottom where organic matter accumulates • -filtering collectors: filter feeders, use structures to trap and strain the water

13. Scrapers: graze on algae that is attached to surfaces of submerged rocks and other objects • Shredders: break large pieces of dead plant material into smaller pieces. • Predators: have adaptations for capturing other organisms • Parasites: have structures for attaching to and drawing fluids from other organisms

14. Plants in an Aquatic Ecosystem • Types of Algae: • Plankton algae- very small, usually microscopic and floats in water • Pond scum- a floating mat of filamentous algae. Grows as long strands( filaments) as opposed to floating cells. • Sonewort algae- found on the bottom of ponds or lakes in areas with limestone soil. Easily identified by a central stem with branches of up to 3ft.

15. Importance of algae • Please put your name on your notes and turn it in when we are done today for a 100. • Algae are the most important producers in any aquatic ecosystem. Some algae are the first link in the food chain, they are also important for their production of oxygen. • Too many algae can be a problem though (algal bloom) because they use up all the oxygen in the water( kills fish) and may also be toxic to animals (cattle, sheep, ducks, humans)

16. IMPORTANCE OF FLOWERING PLANTS • TYPES: • Submerged plants- grow in deep water and usually are rooted in the muddy bottom. Except for the flower they are entirely submerged. • Emerging plants- grow in shallow water. Most of the stems, leaves and flowers grow above water. • Floating plants- have floating leaves and flowers, or their leaves and flowers only slightly rise above the surface.

17. The submerged stems and leaves of flowering plants provide habitats for many small organisms. • The surfaces of leaves and stems provide homes for bacteria,fungi,algae,diatoms,protozoa,insectlarvae,aqautic worms and other small organisms. • Fish and amphibians deposit their eggs among the plants. • The plants provide protection from predators • Emerging plants along the shore help prevent erosion and provide cover for fur-bearing animals (beaver, muskrats, and mink)

18. Plants at the waters edge provide nesting sites for many birds. WATER POLLUTION AND PLANT GROWTH Some pollutants inhibit the growth of aqautic plants while others stimulate the growth. Many ponds and lakes are polluted with chemicals that stimulate plant growth. This is due to increased levels of chemicals in fertilizers, particularly nitrates and phosphates.

19. Controling Plant Growth • When the presence of aqautic plants interferes with the planned use of the water, it’s necessary to control their growth. • Physical removal: This method is most effective for small quantities at the water’s edge. • Animals: Ususally not very helpful because the leftover parts of plants develop into new plants. Some exotic species of fish have been brought in to control aqautic plants but lead to new problems ( invasive species grass carp)

20. Chemicals: Herbicides are very effective in controling unwanted plant growth but the following steps must be taken to provide the most effective control and least enviromental damage- • 1. identify the plants causing the problem • 2. select the correct herbicide • 3. determine the most effective time to use (usually late spring or early summer) • 4. determine surface area and avg. depth of pond or lake, this is necessary to determine the amount of chemcial to use. • Some states require the use of a permit to apply herbicides to any body of water (Pennsylvannia)

21. WATER QUALITY • Water quality is determined by a number of chemical,physical, and biological factors. • The designated use is also important when judging the quality of water. Ex: High quality drinking water would not be good for goldfish. • Water is polluted when conditions are present in the water in amounts that are harmful to the organisms living in or using the water.

22. DISSOLVED OXYGEN • Aquatic organisms absorb dissolved oxygen from the water. • Dissolved oxygen enters the water by diffusion from the atmosphere. • When water is mixed with the air as it moves over rocks and waterfalls the level of DO is increased. • Standing or slow moving bodies of water have lower levels of DO. • The types of organisms in a lake or pond may be limited by the amount of DO.

23. Photosynthesis in algae and aquatic plants produces oxygen. Therefore the level of DO is higher during the day than at night. • If you write yoda on your notes and turn it in after I’m done you get +10 on next test • Water polluted with organic matter has less dissolved oxygen than clean water because the bacteria and other decomposers use much of the oxygen for the process of decay. • A large variety of organisms usually indicates water with a high level of DO.

24. During photosynthesis, plants release oxygen into the water. During respiration, plants remove oxygen from the water. Bacteria and fungi use oxygen as they decompose dead organic matter in the stream. The type of organisms present (plant, bacteria, fungi) affect the DO concentration in a water body. If many plants are present, the water can be supersaturated with DO during the day, as photosynthesis occurs. Concentrations of oxygen can decrease significantly during the night, due to respiration. DO concentrations are usually highest in the late afternoon, because photosynthesis has been occurring all day. For an example of how DO can vary from day to night, select here .

25. TEMPERATURE AND D.O. • Solubility is the ability of a substance to dissolve in a liquid. The solubility of a gas decreases as the temperature of a liquid increases. • Fish are cold-blooded animals. As the temp of the water increases, more oxygen is needed to maintain their normal body functions. The warmer water may not hold enough oxygen to supply the fish’s needs. • Most water used by factories is used for cooling, esp electrical plants, pollution occurs when hot water is dumped into aquatic ecosystems.

26. TOO MUCH OXYGEN? • When a liquid holds all of the gas that can be dissolved at a given temperature it is said to be saturated. • Under certain situations more gas is dissolved in water than would be normally. This is called supersaturated. • A healthy aquatic ecosystem should have water that is between 80 and 125% oxygen saturation. • Gas bubble disease is an example of what can happen to fish if there is too much oxygen present.

27. pH • Few organisms live in water with a pH lower than 4 or higher than 9. • Most species have a very narrow range of tolerance when it comes to pH. • The pH of the water often determines what types of organisms can live there. A pH between 6.5 and 8.2 supports a wide variety of organisms. Under 6.5 the snails and tadpoles start to die. Under 5.5 the decomposers start to die. • A pH higher than 9 can be harmful to fish.

28. The pH of the water is affected by several factors. Lakes and ponds are usually alkaline when they are first formed. • As organisms start to die and decompose they give off Carbonic acid which then lowers the pH of the water. • Water that enters from a factory may contain chemicals that alter the pH. • Strip mining exposes sulfur to the the air and rain. • Runoff from these mines contains sulfuric acid. Acid mine drainage is the single biggest pollutant in Pennsylvania’s streams.

29. Acid lakes are formed in old strip mine pits. • During heavy rains they can over flow and drain into nearby creeks. • As many as 60,000 fish have been killed when a lake overflows. • Some streams drain watersheds that have natural buffers. They contain a higher level of alkalinity.

30. Hardness • The rocks and soil in the watershed determine the hardness of water. • If there is a lot of granite which doesn’t dissolve easily the water will be soft, or lack certain mineral. • If there is a lot of limestone then that water may contain high levels of calcium and magnesium and is said to be hard water. • Water with a hardness of less than 10ppm can support very little life.

31. Rivers on the Land 4.10 • When water reaches the top of the bank of a river floods occur. • The low, flat land that is periodically flooded is called a floodplain. • Some of this water infiltrates the soil and restores groundwater. The rest returns back to the river as the water level drops. • When the water is gone a thick new carpet of fertile loam soil is left behind. Some of the worlds best farmland is found along the banks of rivers that have seasonal floods.

32. Cities along the river • The valleys along rivers and streams are some the most convenient and profitable places to live. • People have chosen to live along rivers because the river provided a cheap and easy means of transportation. • The rich level land was the most suitable for farming. • The river also provided water power that attracted industries. • In regions with a good supply of raw materials, small communities grew into large cities.

33. Raindrops falling on the city • The more land is developed the less water that can be absorbed. • Buildings, streets, and parking lots cover the land and prevents infiltration of water. • Storm sewers are used to channel excess water to the nearest river. • When the storm sewers can’t keep up the city streets are flooded. • According to the Red Cross, flash floods are the number one weather related killer in the U.S.

34. Straight and narrow channels • Sometimes the meandering paths of rivers and streams are replaced by man made channels that are shorter, straighter, and have steeper slopes. • This increases the amount of water that can be carried away. • Channels may solve the flooding problem in one area but may increase the risk in other areas down stream.

35. Johnstown PA • Located at the point where two mountain streams meet to form the Conemaugh River. It is an important manufacturing area in western Penn. • Of the 3,500 people killed in Penn. during the last 100yrs 2,300 were killed in floods that hit the Johnstown area. • One flood in 1889 killed 2,100. After a flood that killed 25 in 1936 the US Corps of Engineers straightened the the channels of the two mountain streams and built dikes. • Although in 1977, 75 people were killed in another flood it was a much bigger flood (12in of rain) and the dikes helped protect the city.

36. The value of a floodplain • The floodplain provides a natural storage area for the excess water that the river can’t carry. • It’s also an important recharge area for the groundwater supply • But the value of land is not determined by its ecological value but by how much it can be bought and sold for. Residential and commerial development is big business. $400 per acre undeveloped as opposed to $10,000-40,000 developed.

37. The cost of using a floodplain • 50yrs after the adoption of the national flood control policy the US has spent $50 billion for flood protection. • But floods are still major disasters. Between 1993-1997 floods killed nearly 500 people and destroyed $33 billion in homes and property. • A region is eligible for federal assistance if the President of the US declares it a disaster area. • In addition to property damage and loss of life, floodwaters also destroy bridges, roads, and railroads. • Another problem is the lack of safe drinking water. Floodwaters often carry raw sewage, dead animals, and toxic chemicals that contaminate the water supply.

38. Different approach to flood control • In 1960 St. Louis County Missouri adapted a land-use plan in which all land subject to flooding by major rivers and streams was zoned as open space. • The use of this land for agriculture and parks would not be severely affected by periodic flooding. • The financial loss when cropland is flooded is much less than the loss when floods destroy developed land. • In 1965 Congress asked the Corps of Engineers to develop a plan to control flooding along the Charles River in Massachusetts. After a 5yr study They recommended to buy a large section of undeveloped wetlands to absorb excess water and provide better protection than additional levees or reservoirs.

39. An act of Congress • In 1973 Congress passed the Federal Flood Disaster Protection Act. • The law encourages communities to use floodplains in ways that will not result in loss of life or property damage when floods do occur.

40. 4.12 Cleaning up the Rivers • Reviving the Thames: • In the mid 1800’s 25,000 people died along the River Thames from cholera. This was caused by a bacteria in wastes in the Thames. • Sewers were built to take the waste out to sea (only moved sewage from one location to another) • Sewer treatment plants were damaged during WWII and by 1950 the River Thames was declared dead. • After 10yrs wastewater was treated before it entered the Thames and the solid waste was dumped at sea. • Today the salmon have returned, the smell is gone and a host of recreational activities are enjoyed.

41. Restoring America’s Rivers • The first sewers were constructed in New York City during the 18th century. They carried untreated sewage and dumped it into rivers. In the 1970’s 290 million gallons of raw sewage flowed into the Hudson and East Rivers! • The Charles river near Boston was so polluted in 1900 that the shad had disappeared. • The Charles is still polluted today but its condition is improving. Every month it gets tested for fecal coliform bacteria. It showed significant improvement from 1997-1998

42. Fishable and swimmable rivers • There is no river too small or so polluted that its not worth saving. This is why Congress passed the Clean Water Act in 1972.