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APES: Chapter 7 & 8 Reading Guides
Terms in this set (41)
1. Why should we care about coral reefs? What challenges do they currently face?
Coral reefs provide a number of important ecological and economic services valued conservatively at $375 billion a year. The services include the following:
-Removing some of the carbon dioxide from the atmosphere as part of the carbon cycle (when coral polyps form limestone shells)
-Acting as natural barriers that help protect 15% of the world's coastlines from erosion by battering waves and storms and allow the ocean to replenish nearby beaches with sand
-Supporting at least one-fourth of all identified marine species and 65% of marine fish species even though such reefs occupy less than 1% of the ocean floor
-Producing roughly 10% of the global fish catch and 25% of the catch in developing countries
-Providing fish and shellfish, jobs, and building materials for some of the world's poorest countries
-Supporting fishing and tourism industries worth billions of dollars each year
-Giving us an underwater world to study and enjoy
Unfortunately, more than one-fourth of the world's coral reefs have been lost to coastal development, pollution, overfishing, warmer ocean temperatures, and other stresses that are increasing. One problem is coral bleaching, which occurs when a coral becomes stressed and expels most of its colorful algae. This occurs because of stresses such as increased water temperature and runoff of silt that covers the coral and prevents photosynthesis.
2. Identify and describe the 5 groups or types of aquatic life.
-Phytoplankton, or plant plankton: free-floating microscopic cyanobacteria and many types of algae that are the producers supporting most aquatic food chains and food webs
-Zooplankton, or animal plankton: a mixture of (1) nonphotsynthetic primary consumers (herbivores) that feed on phytoplankton and (2) secondary consumers that feed on other zooplankton. They range from single-celled protozoa to large invertebrates such as jellyfish
-Nekton: strongly swimming consumer such as fish, turtles, and whales.
-Benthos: bottom-dwellers such as (1) barnacles and oysters that anchor themselves to one spot, (2) worms that burrow into the sand or mud, and (3) lobsters and crabs that walk about on the bottom. Some of these species get food by filtering it from water.
-Decomposers: mostly bacteria that break down the organic compounds in the dead bodies and wastes of aquatic organisms into simple nutrient compounds for use by producers
3. Compare and contrast a Mangrove Forest, an estuary and a wetland.
A mangrove forests (or swamps) are swamps found on the coastlines in warm, tropical climates. They are dominated by mangrove trees; any of about 55 species of trees and shrubs can live partly submerged in the salty environment of coastal swamps. An estuary is a partially enclosed coastal area at the mouth of a river where its fresh water, carrying fertile silt and runoff from the land, mixes with salty seawater. A wetland is a land covered all or part of the time with salt water or fresh water, excluding streams, lakes, and the open ocean. Temperature a salinity levels vary widely in estuaries and coastal wetlands because of the daily rhythms of the tides, seasonal variations in the flow of fresh water into the estuary, and unpredictable flows of fresh water from coastal land and rivers after heavy rains and of salt water from the ocean as a result of storms, hurricanes, and typhoons. Estuaries and coastal wetlands are some of the earth's most productive ecosystems, and provide other important ecological and economic services.
4. What are the limiting factors in aquatic environments?
Important environmental factors determining the types and numbers of organisms found in the layers are:
-Access to sunlight for photosynthesis
-Dissolved oxygen content
-Availability of nutrients (carbon and phosphorus for producers)
5. List several of the ecological and economic services provided by aquatic ecosystems.
-Waste treatment and dilution
-Reduced storm impact (mangrove, barrier islands, coastal wetlands)
-Habitats and nursery areas for marine and terrestrial species
-Genetic resources and biodiversity
-Animal and pet feed (fish meal)
-Harbors and transportation routes
-Coastal habitats for humans
-Offshore oil and natural gas
6. What are some of the challenges for organisms in the rocky seashore/ tide pool areas?
Organism living in this stressful zone must be able to avoid being (1) swept away or crushed by waves, (2) immersed during high tides, and (3) left high and dry (and much hotter) at low tides. They must also cope with changing levels of salinity when heavy rains dilute salt water. To deal with such stresses, most intertidal organisms hold on to something, dig in, or hide in protective shells.
7. Be familiar with the types of organisms found in the different coastal ecosystems.
Steep rocky shores: sea urchin, sea star, anemone, hermit crab, shore crab, sculpin, nudibranch, Monterey flatworm, kelp, sea lettuce, mussel, periwinkle and barnacles
Sloping barrier beaches or sandy shores: blue crabs, silversides, peanut worms, dwarf olive, clam, beach flea, tiger beetle, sandpiper, white sand macoma, sand dollar, moon snail, mole shrimp, and ghost shrimp
8. Find or create a diagram showing the biological zones found in the open ocean. Then describe each.
Based primarily on the penetration of sunshine, the open sea is divided into three vertical zones:
-Euphotic zone: the lighted upper zone where (1) photosynthesis occurs mostly by phytoplankton, (2) nutrient levels are low (except around upwellings) and (3) levels of dissolved oxygen are high. Large, fast-swimming predatory fish such as swordfish, sharks and Bluefin tuna populate this zone.
-Bathyal zone: dimly lit middle zone that does not contain photosynthesizing producers because of a lack of sunlight. Various types of zooplankton and smaller fish, many of which migrate to feed on the surface at night, populate this zone.
-Abyssal zone: dark lower zone that is (1) very cold, (2) has little dissolved oxygen, and (3) has enough nutrients on the ocean floor to support about 98% of the 250,000 identified species living in the ocean.
9. How are humans impacting coastal ecosystems? (statistics)
Some major impacts of human activities on marine systems:
-Salt marshes, mangrove forests, and sea grass meadows-the seas three great marine nurseries-are being lost and degraded at a high rate to make way for real estate developments, marinas, golf courses, and shrimp farms
-It is estimated that half the world's coastal wetlands and 53% of those in the lower 48 U.S. states (91% in California) have disappeared since 1800, mostly by being filled in for agriculture and coastal development. According to scientists, by 2080 half of the worlds remaining coastal wetlands is likely to be lost to agriculture, urban development, and rising sea levels from climate change.
-At least 35% of the world original mangrove forests have disappeared since 1980, mostly because of clearing for coastal development, rice fields, and agriculture shrimp farms.% of mangrove forest loss> those for tropical rain forests and coastal reefs. Much of the remaining mangrove forests are threatened. The clearing of mangroves also causes erosion that kills coral reefs by smothering the corals in plumes of soil.
-According to a WWF study, almost 70% of the world's beaches are eroding rapidly because of coastal developments and a rising sea level (caused mostly by global warming)
-Ocean bottom habitats are being degraded and destroyed by dredging operations and trawler boats, which drag huge nets weighed down with chains over ocean bottoms to harvest bottom fish and shellfish.
-According to a 2000 report from the Global Coral Reef Monitoring Network, about 27% of the world's coastal reefs have been severely damaged (up from 10% in 1992), 11% have been destroyed, and another 70% could be gone by 2050. In addition to the biodiversity losses, such a collapse would sharply reduce fish harvest and greatly increase storm damage on the coasts of tropical and warm temperate areas.
10. Create a diagram showing the biological zones found in a freshwater lake. Find or create a diagram to show where they are and then describe each.
-Littoral zone: consists of the shallow sunlit waters near the shore to the depth at which rooted plants stop growing. It has a high biological diversity.
-Limnetic zone: the open, sunlit water surface layer away from the shore that extends to the depth penetrated by sunlight. As the main photosynthetic body of the lake, it produces the food and oxygen that support most of the lake's consumers.
-Profundal zone: the deep, open water where it is too dark for photosynthesis. Without sunlight and plants, oxygen levels are low. Fish adapted to its cooler and darker water are found in this zone.
-Benthic zone: at the bottom of the lake. It is inhabited mostly by organisms that tolerate cool temperatures and low oxygen levels.
11. Describe what thermal stratification is.
Thermal stratification is the scientific term that describes the layering of bodies of water based on their temperature. As water heats and cools, it expands and contracts, changing in density. Still bodies of water including ponds and lakes separate into horizontal layers that have distinctly different temperatures. Each layer of water is stacked above or below the others with the warmest water on top and the coldest on the bottom.
12. Describe what a fall overturn and spring overturn are.
In general fall and spring overturns are the sinking of surface water and rise of bottom water in a lake or sea that results from changes in temperature that commonly occur in spring and fall. Fall overturn is a physical phenomenon that may take place in a body of water during early autumn. The sequence of events leading to fall overturn include: (1) The cooling of surface waters; (2) A density change in surface waters producing convection currents from top to bottom; (3) The circulation of the total water volume by wind action; and (4) Eventual vertical temperature equality. The overturn results in a uniformity of the physical and chemical properties of the entire water body. Spring overturn is a physical phenomenon that may take place in a lake or similar body of water during the early spring, most frequently in lakes located in temperate zones where the winter temperatures are low enough to result in freezing of the lake surface. The sequence of events leading to spring overturn include: (1) the melting of ice cover; (2) the warming of surface waters; (3) density changes in surface waters producing convection currents from top to bottom; (4) circulation of the total water volume by wind action; and (5) vertical temperature equality. The overturn results in a uniformity of the physical and chemical properties of the entire water mass.
13. What are the different life zones of a river or stream?
-Source zone: in this first and narrow zone, head water or mountain highland streams of cold, clear water rush over waterfalls and rapids. As this turbulent water flows and tumbles downward, it dissolves large amounts of oxygen from the air so photosynthesis is a less important source of oxygen than it is in ponds and lakes. Plants such as algae and mosses are attached to rocks and the zone is populated by cold-water fish (trout) which need lots of dissolved oxygen. Many fish and other animals have compact and flattened bodies that allow them to live under stones.
-Transition zone: the headwater streams merge to form wider, deeper streams that flow down gentler slopes with fewer obstacles. The warmer water and other conditions in this zone support more producers (phytoplankton) and a variety of cool-water and warm-water fish species (black bass) with slightly lower oxygen requirements.
-Floodplain zone: streams join into wider and deeper rivers that meander across broad, flat valleys. Water in this zone usually has higher temperatures and less dissolved oxygen than water in the first two zones. These slow-moving rivers sometimes support fairly large populations of producers such as algae and cyanobacteria and rooted aquatic plants along the shores. Because of increased erosion and runoff over a larger area, water in this zone often is muddy and contains high concentrations of suspended particulate matter (silt). The main channels of these slow-moving, wide, and murky rivers support distinctive varieties of fish (carp and catfish), whereas their backwaters support species similar to those present in lakes. At its mouth, a river may divide into many channels as it flows through coastal wetlands and estuaries, where the river mixes with ocean water.
Species that normally live and thrive in a particular ecosystem
Non native species:
Species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans
Members of two or more species trying to use the same limited resources in an ecosystem
Two or more organisms of a single species trying to use the same limited resources in an ecosystem
Species that play roles affecting many other organisms in an ecosystem
They are patches of suitable habitat type surrounded by large areas of unsuitable habitat and they occur when humans clear an area for development, they remove, alter, or destroy the resources organisms need to survive.
Situation in which one species limits access of another species to a resource, regardless of whether the resource is abundant or scarce
Situation in which two competing species have equal access to a specific resource but differ in how quickly or efficiently they exploit it
Species that serve as early warnings that a community or ecosystem is being degraded
Breakup of a habitat into smaller pieces, usually as a result of human activities.
Interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host
Type of species interaction in which both participating species generally benefit
Interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree
1. Why are flying foxes considered a keystone species? And what is the significance of a keystone species?
According to ecologists, flying foxes are keystone species in tropical forest ecosystems. They are important for the plant species they pollinate, the plant seeds they disperse in their droppings (which help maintain forest biodiversity and regenerate deforested areas), and the many other species that depend on them. The significance of a keystone species is that it is a species that play roles affecting many other organisms in an ecosystem.
2. Describe what stratification is (example: a tropical rain forest is stratified)
Stratification is a system or formation of layers, classes, or categories.
3. Where is the majority of biodiversity found? (think latitude and depth)
Studies indicate that the most species rich environments are tropical rain forest, coral reefs, the deep sea, and large tropical lakes. During field investigations, ecologists have found that three major factors that affect species diversity:
-Latitude (distance from the equator) in terrestrial communities-most groups of plants and animals, species diversity on continents decreases steadily with distance from the equator to either pole (highest species diversity in tropical areas, and lowest in polar areas)
-Depth in aquatic systems. In marine communities, species diversity increases from the surface to a depth of 2,000 meters and then begins to decline with depth until the deep sea bottom is reached, where species diversity is very high.
-Pollution in aquatic systems. A decrease in species diversity and species abundance in aquatic systems as pollution increases and kills off or impairs the reproduction of various aquatic species.
4. Explain the species equilibrium model or theory of island biogeography.
The species equilibrium model or theory of island biogeography is the number of species found on an island is determined by a balance between two factors: the (1) immigration rate (of species new to the island) from other inhabited areas and (2) extinction rate (of species established on the island). The model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of different species (species diversity).
5. Why are amphibians disappearing and why are they more vulnerable than other species?
Amphibians are disappearing because of:
-Habitat loss and fragmentation, especially because of the draining and filling in of inland wetlands, deforestation, and development
-Prolonged drought-dries up breeding pool and weakens amphibians, making them more susceptible to fatal viruses, bacteria, fungi, and parasites.
-Pollution-all stages of life=sensitive to many pollutants, can cause harm to immune and endocrine systems, make them more vulnerable to bacterial infections and skin fungi, and cause sexual abnormalities.
-Increases in UV radiation- harmful to young embryos
-Increased incidence of parasitism by a flatworm=frog deformities but not necessarily the worldwide decline of amphibians
-Overhunting (frog legs)
-Epidemic diseases (pollution and other factors that weaken the immune systems could cause them to be more susceptible)'
-Immigration or introduction of nonnative predators and competitors (such as fish) and disease organisms
Frogs are especially vulnerable to environmental disruption at various points in their life cycle. As tadpoles they live in water and eat plants, and as adults they live mostly on land and eat insects (which can expose them to pesticides). Their eggs have no protective shells to block UV radiation or pollution. As adults, they take in water and air through their thin, permeable skins that can readily absorb pollutants from water, air, or soil.
6. Examples of ways that organisms compete for resources. (both plants and animals)
-Some plants secrete chemicals that inhibit the growth of seedlings of their own and other species
-Other plant species compete with other members of their species for living space and nutrients by dispersing their seeds to other sites by air (wind), water, and animals.
-Territoriality: patrol or mark an area around their home, nesting or major feeding site and defend it against members of their own species.
-With significant niche overlap, one of the competing species must migrate to another area (if possible), shift its feeding habits or behavior through natural selection and evolution, suffer a sharp population decline, or become extinct in that area.
-Interference competition: in which one species may limit another's access to some resource, regardless of its abundance, using the same types of methods found in intraspecific competition. For example, a territorial hummingbird species may defend patches of spring wildflowers from which it gets nectar by chasing away members of other hummingbird species. In desert and grassland habitats, many plants release chemicals into the soil. These chemicals prevent the growth of competing species or reduce the rates at which their seeds germinate.
-Exploitation competition: in which competing species have roughly equal access to a specific resource but differ in how fast or efficiently they exploit it. The species that can use the resource more quickly gets more of the resource, and hampers the growth, reproduction, or survival of the other species.
7. Why should we care about alligators?
Gator holes can collect fresh water during dry spells, serve as refuges for aquatic life, and supply fresh water and food for many animals. In addition, large alligator nesting mounds providing nesting and feeding sites for herons and egrets. Alligators also eat large numbers of gar ( a predatory fish) and thus helps maintain populations of game fish such as bass and bream. As alligators move from gator holes to nesting mounds, they help keep areas of open water free of invading vegetation. Without these ecosystem services, freshwater ponds and shrubs and trees would fill in coastal wetlands in the alligator's habitat, and dozens of species would disappear. Some ecologists classify the North American alligator as a keystone species because of the important ecological roles in helping maintain the structure and function of its natural ecosystems.
8. What is the competitive exclusion principle?
Competitive exclusion principle is when no two species can occupy exactly the same fundamental niche indefinitely in a habitat where there is not enough of a particular resource to meet the needs of both species.
9. Describe what resource partitioning is.
Resource partitioning is the process of dividing up resources in an ecosystem so species with similar needs (overlapping ecological niches) use the same scarce resources at different times, in different ways, or in different places.
10. How do prey defend themselves? (there are several ways)
-The ability to run, swim, or fly fast
-A highly developed sense of sight or smell that alerts them to the presence of predators
-Protective shells (as on armadillos, which roll themselves up into an armor plated ball, and turtles)
-Thick bark (giant sequoia)
-Spines (porcupines) or thorns (cacti and rosebushes)
-Limbs that break off which gives them time to escape (lizards with their brightly colored tails)
-Camouflage by having certain shapes or colors or the ability to change colors
-Chemical warfare: discourages predators with chemicals that are poisonous, irritating, foul smelling, bad tasting
-Warning coloration: brightly colored advertising that enables experienced predators to recognize and avoid them.
-Mimicry, when a nonpoisonous animals looks and acts like a poisonous animal
-Behavioral strategies such as puffing up (blowfish), spreading their wings (peacock), or mimicking a predator.
-Some prey gain protection by living in large groups (schools of fish, herds of antelope, flocks of birds)
11. Examples of symbiotic relationships.
-Parasitism: interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host.
Ex. Tapeworms, disease causing microorganisms live inside their hosts. Ticks, fleas, mosquitoes, mistletoe plants, and fungi attach themselves to the outside of their hosts.
-Mutualism: type of species interaction in which both participating species generally benefit
Ex. The pollination relationship between flowering plants and animals such as insects, birds, and bats is one of the most common forms of mutualism
-Commensalism: interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree
Ex. A redwood sorrel, a small herd, benefits from the shade of redwood trees, raccoon, opossums, and rats obtain food from our trash.
12. Describe the stages of succession and characteristics of each stage.
Ecologists recognize two types of ecological succession, depending on the conditions present at the beginning of the process:
-Primary succession involves the gradual establishment of biotic communities on nearly lifeless ground. Begins with an essentially lifeless area where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic ecosystem. Examples include bare rock exposed by a retreating glacier or severe soil erosion, newly cooled lava, an abandoned highway or parking lot, a newly created shallow pond or reservoir. Before a community of plants, consumers, and decomposers can become established on land, there must be soil, which depending on the climate can take natural processes several hundred to thousand years to produce fertile soil. Soil formation begins with hardy pioneer species (lichens and mosses) attach themselves to inhospitable patches of bare rock. The soil formation process starts by trapping wind-blown soil particles and tiny pieces of detritus, producing tiny bits of organic matter, and secreting mild acids that slowly fragment and break down the rock, in addition to physical weathering. Then when the situation becomes suitable enough early successional plant species (small perennial grasses, herbs) which grow close to the ground, can establish large populations quickly under harsh conditions, and have short lives begin to thrive. Eventually, midsuccessional plant species (herbs, grasses, and low shrubs) begin to grow and then late successional plant species (mostly trees) that can tolerate shade. Unless fire, flooding, severe erosion, tree cutting, climate change, or other natural or human processes disturb the area, what was once bare rock becomes a complex forest community.
-Secondary succession, the more common type, involves the reestablishment of biotic communities in an area where some type of biotic community is already present. Begins in an area where the natural community of organisms has been disturbed, removed, or destroyed but some soil or bottom sediment remains. Candidates include abandoned farmlands, burned or cut forests, heavily polluted streams, and land that has been damned or flooded. Due to the presence of some soil or sediment, new vegetation can usually begin to germinate within a few weeks. Seeds can be present in the soils, or they can be carried from nearby plants by wind or by birds and animals. Changes in vegetation affect food and shelter for various types of animals, and as succession proceeds the number and types of animals and decomposers also change.
13. Describe the intermediate disturbance hypothesis.
The intermediate disturbance hypothesis predicts that the greatest diversity occurs at moderate levels of disturbance. High levels of disturbance will wipe out all species, and low levels of disturbance allow superior competitors to eventually drive other species to extinction. Disturbances can include alterations to the environmental structure, habitat fragmentation, and biotic factors, and can simply be defined as anything that changes the composition of niches. These disturbances increase the availability of resources to new species by eliminating or reducing the populations of potential competitors.
14. How are the terms inertia, constancy and resilience connected with ecological stability?
It is useful to distinguish among three aspects of stability or sustainability in living systems:
-Inertia, or persistence: the ability of a living system to resist being disturbed or altered
-Constancy: the ability of a living system such as a population to keep its numbers within the limits imposed by available resources
-Resilience: the ability of a living system to bounce back after an external disturbance that is not too drastic
15. How could you apply the precautionary principle to natural ecosystems?
The precautionary principle is when there is scientific uncertainty about potentially serious harm from chemicals or technologies, decision makers should act to prevent harm to humans and the environment. This could apply to natural ecosystems because it is supposed to prevent harm to to organisms within an ecosystem despite lack of evidence.
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