APES Unit 8 Comprehensive Review

What is an excellent example of a river that has a large number of pollutants from the land?

Mississippi River (1/3 of the topsoil in the United States has been lost to the Gulf of Mexico)

What are areas of low oxygen called?

hypoxic dead zones

What are places that directly discharge pollution?

point sources of pollution

What are some examples of point sources?

factories, sewage, power plants, coal mines, and oil well discharge.

When does nonpoint source pollution occur?

Nonpoint sources of pollution are poorly defined and scattered. It occurs when pollutants run off from agricultural fields, urban areas, roadways, and other impervious surfaces such as parking lots where pollutants tend to collect. This makes them difficult to monitor and identify.

What are some examples of nonpoint sources of pollution?

storm-water drainage and atmospheric deposition

What is bioaccumulation?

a problem where small, seemingly harmless amounts of something received over long periods of time eventually reach toxic levels because the body has no way to metabolize these compounds

When does bioaccumulation occur?

when small amounts of a substance are consumed by small organisms such as phytoplankton.

How do phytoplankton facilitate bioaccumulation?

Well, to obtain their nutrition, phytoplankton must filter large quantities of water. As they filter water, they obtain nutrients such as nitrogen and phosphorus. If the water also contains human-made chemicals such as DDT or polychlorinated biphenyls (PCBs), these chemicals will also be taken up by the phytoplankton.

Once the phytoplankton take up the chemicals, what happens?

Since they cannot metabolize the chemicals, the phytoplankton will have increasing levels of them retained in their structure, especially in any storage cells such as fat cells. This bioaccumulation then leads to biomagnification in the food chain as other organisms such as zooplankton and small fish feed on vast quantities of phytoplankton.

What happens when bioaccumulation becomes compounded through a food chain?

it is called biomagnification.

When does bioaccumulation most often occur?

with heavy metal pollution, such as mercury or lead

What would happen if mercury was released into a waterway in low doses?

even still, the plankton will absorb the low dose and will be unable to process the mercury.

What is an example of biomagnification in action?

When the plankton are eaten by a larger fish that requires many plankton to survive, the larger fish will have the mercury from all the plankton in its body. Then, an even larger fish may eat the smaller fish. This larger fish will need many smaller fish to survive, so it will have all of the mercury that was in the smaller fish, resulting in even higher levels of contamination. This process repeats up the food chain until apex predators have very high levels of contaminants in their bodies.

What happens if substances are not persistent?

they biodegrade (become broken down by natural factors) and do not accumulate nor magnify.

What are the four negative effects of bioaccumulation?

disruption of physiological processes; impairment of organ function; damage to the nervous system; and increased risk of chronic diseases

What are the four negative effects of biomagnification?

health risks including cancer, kidney diseases, liver failure, birth defects, respiratory disorders, and heart diseases; ecosystem disruption affecting reproduction and development in animals; and predator impact

Why is mercury deleterious in aquatic ecosystems?

Mercury bioaccumulates in fish, especially predatory species like tuna and swordfish. As larger fish consume smaller ones, mercury levels increase, which can pose health risks to humans who consume these fish.

What determines the amount and type of living organisms living in that ecosystem?

the amount and type of nutrients available to aquatic ecosystems

What ecosystems are low in nutrients, usually clear and deep, with stable algae populations, and high in dissolved oxygen?

oligotrophic ecosystems

What ecosystems are high in nutrients, turbid and shallow, with high algae populations, and low in dissolved oxygen?

eutrophic ecosystems

What ecosystem falls somewhere in between oligotrophic waterways and eutrophic waterways?

mesotrophic ecosystems

What is the aging progression of a waterway?

It starts with oligotrophic, moves to mesotrophic, and ends with eutrophic. Lakes and ponds may actually fill in during the process, resulting in a terrestrial ecosystem such as a marsh, pond, swamp, and eventually a forest climax community. (oligotrophic → eutrophic → swamp → dry land)

What two elements are limiting in aquatic ecosystems, and why are they important?

nitrogen and phosphorus are limiting in aquatic ecosystems, and the amount of them in the water limits how much phytoplankton can grow.

How do ponds become green from cultural eutrophication?

The ponds are green because fertilizers from the lawns and/or agricultural areas have run off into the pond, increasing the amount of nitrogen and phosphorus in the water, and causing an explosion in the algal and cyanobacteria populations. When the algal and cyanobacteria populations experience explosive growth in these waters, they frequently cover the surface of the pond. This allows them to get the sunlight they need, but they also block sunlight from reaching the bottom of the waterway, pond, or lake. This causes photosynthetic organisms attached to the bottom to die because they can no longer photosynthesize. Once these plants die, they are decomposed by decomposers that use oxygen to function. This causes more organisms in the water to die, which increases the amount of decomposition and oxygen usage, which further reduces the amount of oxygen available in the water. This positive feedback loop continues until there is no more oxygen in the water, and the area becomes a dead zone.

What is the entire process of explosive algae growth to dead zone called?

cultural eutrophication

What are the main culprits in supplying nitrogen and phosphorus?

fertilizer and animal waste runoff from yards and agricultural lands

What describes the ability of a living organism to deal with the biotic and abiotic factors they encounter in an ecosystem?

ecological tolerance

What is the level at which the organisms grow or survive the best called?

the optimum level for each resource

What is a s

What organism do corals have a symbiotic relationship with?

a type of algae known as zoox

What do corals do when they are stressed?

What do coral do when

What do coral do when they are stressed?

algae will leave the coral tissue

What do coral do when they are bleached?

without algae, coral loses its major source of food, turns white, is more susceptible to disease, and will ultimately die

What are the most common causes of coral bleaching?

changes in ocean temperature; sediment runoff; pollution; over/underexposure to sunlight/ and extremely low tides (can bleach corals)

How does sediment runoff negatively impact coral reefs?

When soil erodes from land due to activities like deforestation or construction, it is carried into the ocean where it can smother coral reefs, blocking sunlight from reaching the corals. When this happens, the algae in the coral tissues cannot photosynthesize and grow. As a result, corals bleach and become more susceptible to disease.

How does pollution negatively impact coral reefs?

The same runoff that carries sediments into the ocean can also carry pollution from land-based sources into the ocean. These pollutants can stress corals, disrupt delicate coral reef ecosystems, and, ultimately, cause coral bleaching.

How does overexposure to sunlight negatively impact coral reefs?

The algae in corals have a sunlight tolerance - they do not want too much or too little. If the level of sunlight is beyond the optimum range, corals can bleach. Typically, corals bleach when sunlight in shallow waters is too intense, but if the symbiotic algae in corals do not receive enough sunlight, they can struggle to photosynthesize enough to support themselves and their coral symbiont.

How are destructive fishing practices negative to the health of coral reefs?

Practices such as dynamite fishing, where explosives are used to stun or kill fish, can have devastating impacts on coral ecosystems. The explosions not only kill marine life directly but also destroy the physical structure of the reefs, leaving behind rubble instead of vibrant, healthy coral habitats.

How can fishing gear also negatively impact coral reefs?

Throwing an anchor overboard to fish at a coral reef can harm the reef if the anchor hits it. Lost fishing traps, known as ghost traps, fishing line, lost nets, and other abandoned fishing gear can physically damage coral reefs and entangle marine life.

What happens when an oil spill occurs?

organisms in the water are exposed to harmful hydrocarbons found in oil.

How do oil spills harm animals?

These hydrocarbons can be toxic to marine life, leading to illness and even death of various species. Oil that floats to the surface of the water forms a thick layer that sticks to the bodies of water birds and mammals. This coating disrupts the insulating properties of feathers and fur, making it difficult for the animals to regulate their body temperature. As a result, many birds and marine mammals suffer from hypothermia.

How does oil negatively impact bottom-dwelling organisms?

heavier components of oil sink to the bottom and impact bottom-dwelling organisms that are crucial to the marine food chain. The presence of oil on the ocean floor can smother these organisms, disrupting the balance of the ecosystem and leading to a cascading effect on the entire marine environment.

What happened in the Exxon Valdez oil spill?

It occurred on March 24,1989, in Prince William Sound, Alaska, when the oil tanker struck a reef, running aground. Approximately 11 million gallons of oil (260,000 barrels) spilled into the ocean.

What were the ecological impacts of the Exxon Valdez oil spill?

The spill covered about 1300 miles of coastline, resulting in the deaths of hundreds of thousands of seabirds, otters, seals, and whales. Nearly 30 years later, pockets of oil remain in some locations.

What were the economic impacts of the Exxon Valdez spill?

Exxon paid about $2 billion in cleanup costs and another $1.8 billion for habitat restoration and personal damages.

What happened in the BP Deepwater Horizon oil spill?

It occurred on April 20,2010, off the coast of Louisiana in the Gulf of Mexico when an oil rig suffered a series of explosions. For 87 days, oil flowed into the ocean before the well was finally capped. Approximately 210 million gallons of oil were released into the ocean, resulting in the largest marine oil spill in history.

What were the ecological impacts of the BP Deepwater Horizon?

The spill covered about 1300 miles of coastline, resulting in the deaths of hundreds of thousands of seabirds, otters, seals, and whales.

What were the economic impacts of the BP Deepwater Horizon disaster?

The local fishing and tourism industry was deeply affected, especially since the spill affected the beaches during the busy tourism season on the Gulf Coast. BP paid over $65 billion for the disaster, including $5.5 billion to the US government in a civil suit, $4 billion in the criminal suit, cleanup costs, fines, and compensation for damages.

What are places in water where there is no oxygen, making it difficult or impossible for life to survive?

dead zones

When can dissolved oxygen be reduced?

when sediments, especially clay, are present in runoff or if fertilizers are present in runoff, which can catalyze cultural eutrophication, which reduces the amount of oxygen in the water

Where is there a huge, recurring dead zone today?

in the Gulf of Mexico - this dead zone is the result of enormous amounts of nutrients and other contaminants washing into the Gulf from the Mississippi River

What happens when pollutants enter an aquatic ecosystem?

they are high near the source, and they gradually decrease in concentration the farther you get from the source. Hence, eutrophication and biological oxygen demand, or BOD, are highest near the source and dissolved oxygen is lowest near the source.

What do you get when you graph low DO and high BOD near the source of the pollutant and low BOD and high DO the farther you get from the source?

Oxygen Sag Curve

Why are heavy metals dangerous?

They can enter waterways, ending up in groundwater, making it unusable for human consumption or irrigation. They can also bioaccumulate and biomagnify in the food chain, coming back to haunt us in our food.

How can mercury enter waterways?

as runoff from industrial and mining operations as well as from the use of metal-containing fossil fuels, such as coal

What happens when mercury enters water?

bacteria in the water convert it to highly toxic methylmercury.

What was the Minamata case study?

basically, a fertilizer manufacturing company released lots of mercury into the waterways near the fishing village of Minamata, and the methyl mercury bioaccumulated in fish and other marine life, which was then consumed by the residents of Minamata, most of whom went on to develop Minamata Disease. Affected individuals developed skeletomuscular deformities, lost the ability to control their motor functions, in addition to vision, hearing, and speech loss. Over 1700 individuals afflicted died.

Why is lead dangerous?

Lead from pre-1986 gasoline, incinerators, and paints can contaminate waterways. Lead is very toxic to humans in small quantities, so it is highly regulated and no longer allowed in gasoline or paint. It can bioaccumulate in the food chain, leading to chronic and acute toxicity, which may cause neurological damage, liver and lung diseases, kidney damage, and even cancer.

Why is acid mine drainage dangerous?

It usually contains acidic water with heavy metals and sulfates, and acid mine drainage from coal and other mines can also pollute waterways, making them too acidic for organisms to survive and making the water supply unfit for humans to drink.

How does acid mine drainage occur?

through the oxidation of sulfide minerals like pyrite (iron sulfide) when exposed to water and air. The process generates sulfuric acid and dissolved iron, which can lead to the formation of red, orange, or yellow sediments, in streams.

Why is litter dangerous?

litter that reaches aquatic ecosystems poses serious threats to wildlife and the environment. Additionally, it can also introduce toxic substances into the food chain.

What is an example of why litter is dangerous?

Marine animals such as turtles and seabirds may mistake plastic bags for food, leading to intestinal blockages and eventual death. Similarly, small aquatic organisms can get entangled in discarded fishing nets, leading to injuries or drowning.

How can litter introduce toxic substances into the food chain?

Chemicals from plastic debris can leach into the water, affecting the health of fish and other marine animals. This contamination can impact the aquatic life directly exposed to the litter and organisms higher up in the food chain, including humans who consume seafood.

What six human activities erode topsoil along our rivers?

industrialized agriculture, deforestation, channelized waterways, overgrazed rangelands, construction sites, strip-mine areas, etc.

What happens when sediment enters waterways?

it increases the turbidity, which means the water is cloudier

What happens with increased turbidity?

light cannot penetrate as deep in the water

What happens if light cannot penetrate as far?

the depth at which photosynthesis can occur decreases, reducing the amount of photosynthesis in the water

Why is sediment pollution negative?

it can smother organisms and deposit toxins, making food fish hazardous to humans. Sediments can also clog waterways, which can interfere with transportation and commerce.

What are areas where water covers the soil all or part of the time?

wetlands

What is the difference between submerged aquatic vegetation and emergent aquatic vegetation?

SAV grows entirely underwater, whereas emergent emerges from under the water.

What are some types of wetlands?

marshes (salt, brackish, intermediate, and fresh), swamps, bogs, and mangroves.

What are dominated by soft-stemmed grasses and are typically shallow?

salt marshes. They occur on quiet coastlines around the globe, from sub-arctic zones to warm, temperate zones.

During dry times, are the salinities in marshes higher or lower than during the rainy season?

higher - when runoff from the land dilutes the salts in the water, the salinity is lowered.

What are dominated by salt-tolerant woody-stemmed trees?

mangrove swamps

What are some requirements for mangrove trees?

They must have their roots exposed to air at least once/day. This is why many mangrove trees have raised roots that stick out of the sediment.

Are mangroves only local to certain areas, or do they occur worldwide?

worldwide in tropical and subtropical climates

What are some ecological functions of wetlands?

habitat for coastal species (highly productive and diverse ecosystems and are home to crabs, birds, fish, etc.); slow erosion; reduce flooding; filter water; nurseries; and carbon storage

How is slow erosion an ecological function of a wetland?

slow wave currents are in a wetland, increasing sedimentation in marsh, forming a protective barrier to land erosion

How is reduced flooding an ecological function of a wetland?

absorb and store excess rainwater, reducing severity of floods

How is water filtration an ecological function of a wetland?

Marshes filter water from the land, removing excess nutrients, protecting marine areas from eutrophication

How are nurseries an ecological function of wetlands?

they serve as places for juvenile fish and other organisms to grow

How is carbon storage a positive effect of a wetland?

Wetlands store carbon within their plants and soil, helping to moderate global climate

What are the six threats to wetlands?

HIPPCO - habitat destruction; invasive species; population growth; pollution; climate change; overexploitation

How is habitat destruction a threat to wetlands?

wetlands are often used for drainage for agriculture, which destroys the habitat and disrupts the natural water storage and filtration systems; urban development, resulting in the loss of biodiversity and increased flood risk; and water diversion, which can lead to habitat fragmentation and reduced water quality.

How are invasive species a threat to wetlands?

non-native species can outcompete native flora and fauna; prey on native species; hybridize with native species; and introduce new species, all of which can alter food webs, cause a loss of biodiversity, modify the habitat, reduce genetic diversity, and impact human services from wetlands, like bird-watching, water distribution, navigation, and resource provisioning

How is population growth a threat to wetlands?

because as the population grows, we drain for agriculture; drain for urban development; drain for housing; produce more waste and runoff, which runs into wetlands; exploit resources in wetlands for food; divert water for domestic and agricultural use; build infrastructure such as roads and dams; and increase the speed and severity of climate change

How is pollution a threat to wetlands?

agricultural runoff containing pesticides and fertilizers; industrial discharge, such as heavy metals; urban runoff that can carry oil, heavy metals, and trash into wetlands; sewage overflow during heavy rain events; plastic pollution; and acid rain

How is climate change a threat to wetlands?

changes in precipitation, flooding, or drying out wetlands; increased temperatures causing increased evaporation; increased salinity caused by sea level rise; warmer temperatures can change wetlands from carbon sinks to sources; flooding wetlands due to rising sea levels; species loss as habitats become unsuitable for native residents; increased erosion and sedimentation

How is overexploitation a threat to wetlands?

excessive withdrawal of water for agricultural, industrial, or domestic use; unsustainable fishing and hunting; overharvesting of resources, such as plants, peat, or fish; draining for agriculture, urban development, or housing; pollution from intensive agriculture; tourism pressure; illegal activities such as poaching and unauthorized use

What are hormones?

they regulate metabolism (insulin and thyroid hormones), growth and development (growth hormone), reproduction (testosterone and estrogen), homeostasis, and even our moods (serotonin, dopamine, endorphins).

What is the chemical messenger system in animals called?

it involves a series of feedback loops of hormones released by internal glands such as the hypothalamus, pituitary gland, and pineal gland among several other glands. It is found in all mammals and in birds, fish, etc.

What are chemicals that can interfere with the endocrine system of animals?

endocrine disruptors

How can one be exposed to endocrine disruptors?

through diet, air, skin, and water

What are some common exposure routes to endocrine disruptors?

released treated effluent from sewage treatment plants; leachate from landfills; consuming food and beverages; taking medicine; applying pesticides; using cosmetics; some plastics; gasoline

What chemicals at high exposure levels have been directly tied to endocrine disruptions?

organochlorine compounds, ethane (DDT) and its metabolite DDE, polychlorinated biphenyls (PCBs), dioxins, and some naturally occurring plant estrogens

What are examples of endocrine disruptors according to the NIH?

Bisphenol A (BPA), Dioxins, perchlorate, perfluoroalkyl and polyfluoroalkly substances (PFAs), phthalates, phytoestrogens, polybrominated diphenyl ethers (PBDE), polychlorinated biphenyls (PCB), and triclosan

Which endocrine disruptor is used to make polycarbonate plastics and epoxy resins, which are found in many plastic products including food storage containers?

bisphenol A (BPA)