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Chapter 7 Aquatic Ecosystems. Aquatic Ecosystems. Types of organisms determined by salinity Divided into freshwater & marine. Characteristics of Aquatic Ecosystems. Factors such as temp., sunlight, O 2 , & nutrients determine which organisms live in which area of the water.
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Aquatic Ecosystems • Types of organisms determined by salinity • Divided into freshwater & marine
Characteristics of Aquatic Ecosystems • Factors such as temp., sunlight, O2, & nutrients determine which organisms live in which area of the water. • Organisms grouped by location & adaptations • 3 groups of aquatic organisms: • Plankton-mostly microscopic animals (zooplankton) or plants (phytoplankton) that float freely • Nekton-swim actively • Benthos -bottom-dwelling organisms, often attached to hard surfaces. ***Decomposers are also aquatic organisms.
Watersheds • A watershed is an area of land that feeds all the water running under it and draining off of it into a body of water. • Topography determines where and how water flows. • Waterways within the watershed all feed into that main body of water, which could be a river, lake, or stream. • The beginnings of a water source are called headwaters. • The spot where headwaters progressively join other water sources is called the confluence, and the endpoint of the waterways that open into the main body of water is called the mouth.
Lentic vs. Lotic • A Lotic Ecosystem has flowing waters. Examples include: creeks, streams, runs, rivers, springs, brooks and channels. • A Lentic Ecosystem has still waters. Examples include: ponds, basin marshes, ditches, reservoirs, seeps, lakes, and vernal / ephemeral pools.
Strahler Stream Order Strahler method In the Strahler method, all links without any tributaries are assigned an order of 1 and are referred to as first order. The stream order increases when streams of the same order intersect. Therefore, the intersection of two first-order links will create a second-order link, the intersection of two second-order links will create a third-order link, and so on.
Rivers • Usually cold & full of O2 & runs swiftly through a shallow riverbed • As a river flows down a mountain, it may broaden, become warmer, wider, slower, & decrease in O2. • A river changes with the land & the climate through which it flows.
Rivers in Danger • Industries use river water in manufacturing processes & as receptacles for wastes. • People have used rivers to dispose of their sewage and garbage. • This has polluted rivers with toxins, which have killed river organisms & made river fish inedible. • Runoff puts pesticides & other poisons into rivers & coats riverbeds with toxic sediments.
Dissolved Oxygen Rapidly moving water, such as in a mountain stream or large river, tends to contain a lot of dissolved oxygen, whereas stagnant water contains less. Bacteria in water can consume oxygen as organic matter decays. Thus, excess organic material in lakes and rivers can cause eutrophic conditions, which is an oxygen-deficient situation that can cause a water body "to die." Anoxic waters are areas depleted of dissolved oxygen and are a more severe condition of hypoxia. The dissolved oxygen concentration is less than 0.5 milligrams per liter.
Hypoxic Zones Dead zone" is a more common term for hypoxia, which refers to a reduced level of oxygen in the water. Hypoxic zones are areas in the ocean of such low oxygen concentration that animal life suffocates and dies, and as a result are sometimes called "dead zones.“ D.O. = <2 milligrams per liter
Learning Targets • I can describe the factors that determine where an organism lives in an aquatic ecosystem. • I can describe the littoral zone and the benthic zone that make up a lake or pond. • I can describe two environmental functions of wetlands. • I can describe one threat against river ecosystems.
Lakes & Ponds • Form naturally where groundwater reaches the Earth’s surface • Types of organisms depend on the amount of sunlight • Create artificial lakes by damming flowing rivers & streams to use them for power, irrigation, water storage, & recreation
Life in a Lake • Animals have adaptations that help them obtain what they need to survive. • For example, water beetles use the hairs under their bodies to trap surface air so that they can breathe during their dives for food. • In regions where lakes partially freeze in the winter, amphibians burrow into the littoral mud to avoid freezing temperatures.
How Nutrients Affect Lakes • Eutrophication-increase in the amount of nutrients in an aquatic ecosystem • Increase in plants/algae growth=increase in bacteria that feed on decaying organisms • These bacteria use the O2 dissolved in the lake’s waters. Eventually the reduced amount of O2 kills oxygen loving organisms. • A lake that has large amounts of plant growth due to nutrients is known as a eutrophic lake. • Lakes naturally become eutrophic over a long period of time. • Can be accelerated by runoff that can carry sewage, fertilizers, or animal wastes from land into bodies of water
Freshwater Wetlands • Areas of land that are covered with fresh water part of the year • 2 types of freshwater wetlands: • Marshes • Swamps • Most located in the SE US • largest is Florida Everglades
Human Impact on Wetlands • Once considered wastelands that are breeding grounds for insects • Many have been drained, filled, & cleared for farms or development • Laws & the federal government protect many wetlands. • Most states now prohibit the destruction of wetlands.
Marshes • Low, flat lands that have little water movement • Different types of marshes are classified by salinity. • Brackish marshes have slightly salty water • Salt marshes contain saltier water. • Benthic zones are nutrient rich & contain plants, many decomposers, & scavengers • Attract migratory birds
Swamps • Occur on flat, poorly drained land, often near streams & are dominated by woody shrubs or water loving trees. • Freshwater swamps are the ideal habitat for amphibians because of the continuous moisture. • Birds are attracted to hollow trees near or over the water. • Reptiles are the predators of the swamp, eating almost any organism that crosses their path.
Answer the following questions to turn in: • Describe the lifestyle of organisms that are plankton, nekton, and benthos. List one example of each. • Define eutrophication. • List 2 reasons wetlands are important.
Learning Targets • I can explain why an estuary is a very productive ecosystem. • I can compare salt marshes and mangrove swamps. • I can describe two threats to coral reefs. • I can describe two threats to ocean organisms.
Marine Ecosystems • Organisms coastal areas adapt to changes in water level & salinity. • Organisms in the open ocean adapt to changes in temp. & the amount of sunlight & nutrients available.
Coastal Wetlands • Coastal areas covered by salt water all/part time • Provide habitat & nesting areas for fish/wildlife • Absorb excess rain (protects from flooding) • Filter out pollutants & sediments • Recreational areas (boating, fishing, & hunting)
Estuaries • Area where fresh water (rivers/rain) mixes with salt water (ocean) • Currents form & cause mineral/nutrient rich mud to fall to the bottom making in available to producers. • Very productive
Threats to Estuaries • Were used as places to dump waste. • Those filled with waste could then be used as building sites. • The pollutants that damage estuaries include sewage, pesticides, fertilizers, & toxic chemicals. • Most of these pollutants break down over time, but estuaries cannot cope with the amounts produced by dense human populations.
Salt Marshes • Maritime habitats characterized by grasses, & other plants that have adapted to continual, periodic flooding • Absorb pollutants to help protect inland areas
Mangrove Swamps • Have mangrove trees • Protect coastline from erosion & reduce the damage from storms • Habitat • Have been filled with waste & destroyed in many parts of the world
Rocky & Sandy Shores • Rocky shores • more plants & animals than sandy shores • Sandy shores • dry out when the tide goes out & many organisms that live between sand grains eat the plankton left stranded on the sand • A Barrier island is a long ridge of sand or narrow island that lies parallel to the shore & helps protect the mainland. • What are some examples of Barrier Islands in Glynn County?
Coral Reefs • Limestone ridges found in tropical climates & composed of coral fragments that are deposited around organic remains • Thousands of plants/animals live in the crevices of coral reefs (DIVERSITY!!!) • Predators that use stinging tentacles to capture small animals that float/swim close to the reef
Disappearing Coral Reefs • Productive ecosystems • Very fragile • Sensitive to changes in temperature • If water is too muddy, polluted, or too high in nutrients, the algae that live within the corals will either die or grow out control. If the algae grows out of control, it may kill the corals. • Oil spills, sewage, pesticides, & silt runoff have also been linked to coral-reef destruction. • Not able to repair itself after chunks of coral are destroyed • Overfishing can devastate fish populations, upsetting the balance of the reef’s ecosystem. • Grows very slowly
Oceans • Sunlight that is usable by plants for photosynthesis penetrates about 100m into the ocean. • Most ocean life is concentrated in the shallow coastal waters.
Plants and Animals of the Oceans • The types of organisms that may be found in the layers of the ocean at various depths is dependent on available sunlight. • In open ocean, phytoplankton grow only where there is enough light/nutrients • least productive of all ecosystems • The depths of the ocean are very dark, so most food at the ocean floor consists of dead organisms that fall from the surface. • Decomposers, filter feeders, & the organisms that eat them live in the deep areas of the ocean.
Threats to Oceans • Pollution • Runoff from fertilized fields & industrial waste & sewage being discharged into rivers • Overfishing & certain fishing methods are destroying some fish populations. • Marine mammals can get caught & drown in the nets. • Some ships discard fishing lines (Illegal!) into the ocean where they can strangle/kill marine organisms.
Arctic and Antarctic Ecosystems • The Arctic • rich in nutrients from the surrounding landmasses • supports large populations of plankton • The arctic ecosystems at the North and South Poles depend on marine ecosystems because nearly all the food comes from the ocean. • The Antarctic • Only continent never colonized by humans • Used mainly for research • Plankton form the basis of food web
Ticket out the Door • How are salt marshes different than mangrove swamps? • List two things that could damage coral reefs. • What are the primary producers of the open ocean? • Name two threats oceans face.
Answer the following questions: • Where are swamps usually found? • You are likely to find cattails, reeds, and other plants in the ____ zone of a lake. • The 2 main types of freshwater wetlands are ___ & ___. • In estuaries, fresh & salt water mix, forming a _______ ______. • Where is most marine life found? (Choose one: Deep ocean? Shallow, coastal waters?, Vents? Marshes?)
Farm-Raised Salmon Activity Procedure Section: • Use the front page of the packet to answer this. • Come up with at least THREE questions you have. • List at least THREE places/resources you could use.
Farm-Raised Salmon Activity Analysis Section: • EXPLAIN at least THREE advantages & at least THREE disadvantages. • “Refute” means to show it isn’t correct. You should have information to refute at least TWO things in the article. Write the correct information down that you found and cite your sources. • EXPLAIN at least three pieces of information you found that gives the fish farmers’ point of view.
