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By C. Kohn Agricultural Sciences, Waterford WI. * Aquatic ecosystems include oceans, lakes, rivers, streams, estuaries, and wetlands. * These ecosystems.

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Presentation on theme: "By C. Kohn Agricultural Sciences, Waterford WI. * Aquatic ecosystems include oceans, lakes, rivers, streams, estuaries, and wetlands. * These ecosystems."— Presentation transcript:

1 By C. Kohn Agricultural Sciences, Waterford WI

2 * Aquatic ecosystems include oceans, lakes, rivers, streams, estuaries, and wetlands. * These ecosystems are easily distressed by pollution. * Surface water ecosystems are those found in rivers, wetlands, and lakes. * All precipitation eventually finds its way into a surface water ecosystem. * The area of land from which a body of water gets its water is known as a watershed. * Surface water ecosystems are critical to the survival of other kinds of ecosystems found on dry land.

3 * Surface water ecosystems are vital for land-based animals. * Wildlife depends upon surface water ecosystems for food, shelter, and breeding. * They also can provide much needed water for birds and wildlife. * Surface water ecosystems are also important to the watershed connection. * They capture rainwater as it flows over the ground, reducing erosion and flooding. * By holding stormwater, ponds allow nutrients and other chemicals to be filtered from the water by plants and animals before it moves into rivers and lakes. * Source:

4 * Plants are vital to a functioning aquatic ecosystem. * At the base of the food chain are small aquatic algae called phytoplankton. These algae use sunlight to convert CO2 and H2O into sugar. * Tiny animals in the water, called zooplankton, use phytoplankton as a food source. * Zooplankton are consumed by aquatic insects called macroinvertebrates. * Larger animals such as fish, use zooplankton and macroinvertebrates as a food source. Source:

5 * Discussion: How can you tell if a body of water is healthy? * What signs indicate whether or not an aquatic ecosystems is affected by a disturbance? * Visible signs of pollution, odor, dead fish, and poor taste (for drinking water) are all signs that a body of water has been affected by a disturbance. * Often, indications of pollution are much more subtle and require more testing than simply observing the water. * When determining if a body of water is affected by a pollutant, we cannot wait until the signs of are obvious and visible before we take action. * To wait this long could put the aquatic ecosystem at risk of irreparable damage. * Sometimes signs of a pollutant are not obvious even at dangerous levels. * For example, we cannot see, smell, or taste toxic levels of mercury.

6 * Pollution is defined as the introduction of a substance into a natural environment that causes instability, disorder, or harm to the ecosystem * Aquatic pollutants can be divided into two categories: * Point Source Pollution – this is pollution that originates from a single source * This could be a factory, failing sewage treatment plant, or a damaged sewer pipe. * Non-point Source Pollution – this is pollution that cannot be traced to a specific point because it comes from many individual places over a large, widespread area. * Agriculture is the largest source of non-point water pollution. * Parking lots, suburban lawns, and roads also are common sources of non-point pollution.

7 * Some pollutants are more of a concern because of the process of biomagnification. * Biomagnification: the process in which pollutants become more and more concentrated in living tissue. * Biomagnification enables a pollutant that is found in small amounts in the environment to become highly concentrated in the tissues of large organisms. * This can cause those organisms to become adversely affected by what may seem like a small problem in the environment.

8 * Biomagnification occurs because the pollutant will become stored in the bodily tissue of every organism that consumes it. * A toxin will first be absorbed in small amounts by phytoplankton. * Species at the bottom of the food chain (like zooplankton & aquatic insects) will eat large amounts of this phytoplankton. * Small fish will eat large amounts of these zooplankton & macroinvertebrates (insects), and these small fish will be eaten by larger game fish.

9 * Biomagnification increases with every step in the food chain. * Macroinvertebrates & zooplankton will eat many, many phytoplankton. * Many of these insects, which have eaten many, many phytoplankton, will be eaten by small fish. * All of the pollutants absorbed by the phytoplankton were trapped in the tissue of the insects and are now in the bodies of the fish. * All of the pollutants trapped in these fish will become trapped in the bodies of larger fish and other large predators (including mammals, birds, and humans).

10 * Three characteristics are necessary in order for a pollutant to biomagnify: * 1. The pollutant must be long-lived – if the pollutant breaks down too quickly, it would pass out of the tissue of living organisms * 2. The pollutant must be concentrated in organisms at the base of the food chain – usually biomagnification starts with a photosynthetic organism or an animal that is widely consumed by other animals. * 3. The pollutant must be fat-soluble – this allows it to be stored in the tissue of living organisms. * Water soluble substances are passed out of animal bodies when they urinate. * Only fat soluble substances can be stored in the body and accumulate.

11 * Each time a toxin goes up a level in the food chain, it becomes more and more concentrated in the tissues of living organisms. * Because humans are at the top of the food chain and live long lives, we are most susceptible to fat-soluble toxins. * These are toxins that are able to be stored for long periods of time in body fat and tissue.

12 * Many pollutants that biomagnify interrupt the ability of an organisms body to function. * Lead, mercury, and heavy metals all can biomagnify and can cause nervous problems, infertility, and birth defects. * Hunters should never use lead-based ammunition, and lead sinkers should never be used by fishermen because of these concerns. * This may not seem like a big deal because the amount of lead lost by these objects may seem small and insignificant. * However, even a small amount of lead will bioaccumulate over time (such as in this bald eagle dying of lead poisoning).

13 * Other pollutants can be mutagenic and interfere with a living organisms DNA. * DNA is basically the instruction manual for a living organisms cells. * When a mutagenic pollutant is present, it can interfere with the instructions given by DNA, causing birth defects, cancer, and other adverse health effects. * If the instructions for your cells to operate are changed, your cells will not function normally. * This is exactly how a mutagen and can cause tumors, infertility, developmental problems, and other serious issues in both humans and animals (such as the 5 th leg on this frog).

14 * PCBs are a good example of a mutagenic pollutant. * They were used because they were not flammable, were very chemically stable, did not melt easily, and were great insulators for electrical wiring. * They were widely used in paints, plastics, rubber products, dyes, and many other industrial applications. * PCBs were manufactured from 1929 until they were banned in * Despite being banned in 1979, PCBs still enter the environment due to improper disposal of old equipment, leaking hazardous waste sites, and the burning of wastes. * Once released, PCBs break down very slowly and are easily carried all around the world by rain, snow, and water.

15 * If ingested in high enough levels, PCBs can cause cancer, weaken the immune system, reduce birth weights, lower fertility, and cause neurological problems. * PCB levels in top predators such as bald eagles, lake trout and humans can be millions of times those found in surface water. * Every time a large predator consumes their prey, they increase the concentration of toxins in their bodily tissue if they are in an area affected by biomagnification. * As a student in Wisconsin, you too are a large predator in an area such as this!

16 * Because PCBs can be stored in body fat, they stay can build to harmful levels over time. * This can have a major impact on children because they are still developing. * This is why children and pregnant women are advised to minimize their consumption of large fish. * 30 years after they were banned, PCBs are a major concern even today. * E.g. as recently as October 19 th, 2009 dredging of the Fox River in Green Bay was halted to prevent the spread of PCBs. * However, if the Fox River cannot be dredged so that ships can easily pass through, it may seriously affect the 650 jobs and $75 million that shipping on this river contributes to Green Bay. * The impacts of water pollution are economic as well as environmental and health-related.

17 * A substance does not have to be toxic or mutagenic to be a pollutant. * Fertilizers are a major source of water pollution and are not nearly as toxic or mutagenic as some more commonly known pollutants. * Agricultural fertilizers are a concern because they can cause an ecological problem that other pollutants cannot – eutrophication * Eutrophication is the process in which the levels of water nutrients become too high, eventually causing dissolved oxygen levels in the water to become too low.

18 * The process of eutrophication involves a complex series of steps. * In a way, eutrophication is sort of like a set of falling dominoes. * When dominoes fall, it is because of a chain reaction, with one domino causing the fall of another. * Similarly, high levels of nutrients cause oxygen levels to become too low due to a serious of steps and interactions. * These steps can seem unrelated but can ultimately cause the destruction of an aquatic ecosystem.

19 * Step 1: The levels of nutrients become too high. * This could occur for a number of reasons but is most commonly caused by runoff. * For example, if fertilizer is spread on a field, rain water may carry soil and the fertilizers nutrients into a nearby body of water. * This will raise the levels of nitrogen and phosphorus. * These nutrients stimulate plant growth. * Excessive nutrient levels can come from a variety of sources including… * Over-fertilized fields * Poorly built feedlots * Over-fertilized yards and lawns * Overwhelmed sewage treatment plants

20 * Step 2: The nutrients from the fertilizer cause plants and algae to grow rapidly and excessively. * Fertilizers work in water just like they do in land. * Step 3: The rapid growth of algae enables a thick mat of algae to form on the surface of the water. * Light cannot penetrate this mat of algae. * Because there is no light, plants cannot photosynthesize under the water. * Because plants cant photosynthesize, they cant produce oxygen, and oxygen levels begin to drop.

21 * Step 4: Plants without light begin to die. Algae, with its short lifespan, also begins to die. * As these organisms die, they decompose. * The process of decomposition requires oxygen * As decomposition increases, oxygen levels continue to decrease. * With two factors reducing oxygen (low light and high decomposition), dissolved oxygen levels in the water begin to drop to dangerously low levels. * Step 5: Low levels of oxygen reduce many kinds of desirable organisms, including game fish and the macroinvertebrates (insects) they prey upon. * The balance of the food web is upset by the loss of these species.

22 * The aquatic ecosystem becomes less and less suitable for native species. * To make matters worse, the risk of invasive species (including carp and invasive species of cattails) increases as native species decrease. * The invasive species are often more competitive in low-oxygen conditions and out-compete the native species. * As plant matter accumulates (due to the explosive growth caused by high nutrient levels), these aquatic ecosystems become shallower over time. * This too reduces the ability of that habitat to sustain native species.


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