By C. KohnAgricultural Sciences,Waterford WI

*Water Pollution

*Aquatic Ecosystems

*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.

beavercountyconservationdistrict.org

*Surface Water Ecosystems

*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: http://www.marine.usf.edu/pjocean/packets/f00/nwq1.pdf

*How Aquatic Ecosystems Work

*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: http://www.marine.usf.edu/pjocean/packets/f00/nwq1.pdf

tutorvista.com

*Aquatic Ecosystem Health*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.

svsu.edu

*Water Pollution

*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.

azine.noaa.gov

*Biomagnification

* 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.

web.bryant.edu

*Biomagnification

*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.

*Biomagnification

*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).

mhhe.com

*Biomagnification

*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.

*Biomagnification*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.

*Biomagnification

*Many pollutants that biomagnify interrupt the ability of an organism’s 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).

raptoreducationgroup.blogspot.com

*Mutagenic Pollutants

*Other pollutants can be mutagenic and interfere with a living organism’s DNA.

*DNA is basically the instruction manual for a living organism’s 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 5th leg on this frog).

cgee.hamline.edu

*PCBs

*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.

*PCB’s were manufactured from 1929 until they were banned in 1979.

*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.

chem.unep.ch

*PCBs

*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!

*PCBs

*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, PCB’s are a major concern even today.

* E.g. as recently as October 19th, 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.

*Eutrophication

*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.

*Eutrophication

*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.

*Eutrophication

*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 fertilizer’s 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

*Eutrophication

*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 can’t photosynthesize, they can’t produce oxygen, and oxygen levels begin to drop.

*Eutrophication

*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.

*Eutrophication

*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.