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Chapter 13 Life in the Ocean

Oceanography An Invitation to Marine Science, 7th Tom Garrison. Chapter 13 Life in the Ocean. Chapter 13 Study Plan. Life on Earth Is Notable for Unity and Diversity The Flow of Energy through Living Things Allows Them to Maintain Complex Organization

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Chapter 13 Life in the Ocean

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  1. Oceanography An Invitation to Marine Science, 7th Tom Garrison Chapter 13 Life in the Ocean

  2. Chapter 13 Study Plan • Life on Earth Is Notable for Unity and Diversity • The Flow of Energy through Living Things Allows Them to Maintain Complex Organization • Primary Productivity Is the Synthesis of Organic Materials • Living Organisms Are Built from a Few Elements • Elements Cycle between Living Organisms and Their Surroundings • Marine Life Success Depends upon Physical and Biological Environmental Factors • The Marine Environment Is Classified in Distinct Zones • The Concept of Evolution Helps Explain Life in the Ocean • Oceanic Life Is Classified by Evolutionary Heritage

  3. Chapter 13 Main Concepts • All of Earth’s life-forms are related. All have apparently evolved from a single ancient instant of origin. • All life activity is involved, directly or indirectly, in energy transformation and transfer. Photosynthesis appears to be the dominant method of binding energy into carbohydrates on this planet (at least at Earth’s surface). • Primary productivity involves the synthesis of organic materials from inorganic substances by photosynthesis or chemosynthesis. Primary productivity is expressed in grams of carbon bound into organic material per square meter of ocean surface area per year (gC/m2/yr). • The atoms and small molecules that make up the biochemicals, and thus the bodies, of organisms move between the living and nonliving realms in biogeochemical cycles. An organism’s success can be limited by inappropriate amounts of these materials. • Evolution happens. Organisms change as time passes, adapting by natural selection to their environments. • Oceanic life is classified by evolutionary heritage and its location in the environment.

  4. Energy Can Be Stored through Photosynthesis • Most of the energy used by marine organisms to make food comes from the sun. • Photosynthesis is the process used by most producers to convert the sun’s energy to food energy. • Chemosynthesis is the production of food from inorganic molecules in the environment.

  5. Energy Can Be Stored through Photosynthesis In photosynthesis, energy from sunlight is used to bond six separate carbon atoms (derived from carbon dioxide) into a single energy-rich, six-carbon molecule (the sugar glucose). The pigment chlorophyll absorbs and briefly stores the light energy needed to drive the reactions. Water is broken down in the process and oxygen is released.

  6. Energy Can Be Stored through Photosynthesis The flow of energy through living systems. At each step, energy is degraded (that is, transformed into a less useful form).

  7. Sun Light energy Photosynthesizers: Green plants and algae, and specialized bacteria Chemical energy (carbohydrates, etc.) Respirers: Animals and decomposers and plants at night Energy of movement, waste heat, entropy Producers Consumers To space Stepped Art Fig. 13-3, p. 347

  8. Energy Can Also Be Stored through Chemosynthesis A form of chemosynthesis. In this example, 6 molecules of oxygen and 24 molecules of hydrogen sulfide to form glucose. (other products include 24 sulfur atoms and 18 water molecules.) The energy to bond carbon atoms into glucose comes from breaking the chemical bonds holding the sulfur and hydrogen atoms together in hydrogen sulfide.

  9. Primary Productivity Is the Synthesis of Organic Materials Oceanic productivity – the incorporation of carbon atoms into carbohydrates – is measured in grams of carbon bound into carbohydrates per square meter of ocean surface area per year gC/m2/yr.

  10. Global Primary Productivity Oceanic productivity can be observed from space. NASA’s SeaWiFS satellite, launched in 1997, can detect the amount of chlorophyll in ocean surface water. Chlorophyll content allows an estimate of productivity. Red, yellow, and green areas indicate high primary productivity; blue areas indicate low. This image was derived from measurements made from September 1997 through August 1998.

  11. Food Webs Disperse Energy through Communities • What terms are used to describe feeding relationships? • Autotrophs – organisms that make their own food, also calledproducers. • Heterotrophs – organisms that must consume other organisms for energy • Trophic pyramid – a model that describes who eats whom • Primary consumers – these organisms eat producers • Secondary Consumers – these organisms eat primary consumers • Top consumers – the top of the tropic pyramid

  12. Food Webs Disperse Energy through Communities A generalized trophic pyramid. How many kilograms of primary producers are necessary to maintain 1 kilogram of tuna, a top carnivore? What is required for an average tuna sandwich? Using the trophic pyramid model shown here, you can see that 1 kilogram of tuna (enough to make ten 1/4-pound tuna sandwiches) at the fifth trophic level (the fifth feeding step of the pyramid) is supported by 10 kilograms of mid-sized fish at the fourth, which in turn is supported by 100 kilograms of small fish at the third, who have fed on 1,000 kilograms of zooplankton (primary consumers) at the second, which have eaten 10,000 kilograms of phytoplankton (small autotrophs, primary producers) at the first. The quarter-pound tuna sandwich has a long and energetic history.

  13. Food Webs Disperse Energy through Communities Diatoms, and other primary producers, convert the energy from the sun into food used by the rest of the oceanic community. (left) A simplified food web, illustrating the major trophic relationships leading to an adult blue whale. The arrows show the direction of energy flow; the numbers on each area represent the trophic level at which the organism is feeding.

  14. Elements Cycle between Living Organisms and Their Surroundings • What are some atoms and molecules that cycle in biogeochemical cycles? • Carbon - present in all organic molecules • Nitrogen - found in proteins and nucleic acids • Phosphorus and silicon – found in rigid parts of organisms • Iron and trace metals - used for electron transport

  15. The Carbon Cycle Is Earth’s Largest Cycle The Carbon Cycle. Carbon dioxide dissolved in seawater is the source of the carbon atoms assembled into food (initially glucose) by photosynthesizers and most chemosynthetic organisms. When this food is metabolized, the carbon dioxide is returned to the environment. Some carbon dioxide is converted into bicarbonate ions and incorporated into the shells of marine organisms. When these organisms die, their shells can sink to the bottom and be compressed to form limestone. Tectonic forces may eventually bring the limestone to the surface, where erosion will return the carbon to the ocean.

  16. Nitrogen Must Be “Fixed” to Be Available to Organisms The Nitrogen Cycle. The atmosphere’s vast reserve of nitrogen cannot be assimilated by living organisms until it is “fixed” by bacteria and cyanobacteria, usually in the form of ammonium and nitrite ions. Nitrogen is an essential element in the construction of proteins, nucleic acids, and a few other critical biochemicals. Upwelling and runoff from the land bring useful nitrogen into the photic zone, where producers can incorporate it into essential molecules.

  17. Phosphorus and Silicon Cycle in Three Distinct Loops The Phosphorus Cycle. Phosphorus is an essential part of the energy-transporting compounds used by all of Earth’s life-forms. Much of the phosphorus-containing materials in the ocean falls to the seabed, is covered with sediment, is subducted by tectonic forces, and millions of years later returns to the surface through volcanic eruptions.

  18. Physical and Biological Factors Affect the Functions of an Organism • A limiting factor is a factor found in the environment that can be harmful if present in quantities that are too large or too small. • Any factor required for life can become a limiting factor. • Any aspect of the physical environment that affects living organisms is a physical factor. • What are the most important physical factors for marine organisms? • Light, dissolved gases, temperature, salinity • Acid-base balance, hydrostatic pressure, nutrients

  19. Physical and Biological Factors Affect the Functions of an Organism • Biological factors also affect living organisms in the ocean. • Some biologic factors that affect ocean organisms: • Feeding relationships • Crowding (competition for space) • Metabolic wastes • Defense of territory

  20. Photosynthesis Depends on Light Most of the biological productivity of the ocean occurs in an area near the surface called the euphotic zone. Below the euphotic zone lies the disphotic zone. Below the disphotic zone lies the dark aphotic zone, the vast bulk of the ocean where sunlight never reaches. (left) The relationship among the euphotic, disphotic, and aphotic zones. (The euphotic zone statistic is for mid-latitude waters averaged through a year).

  21. Temperature Influences Metabolic Rate Temperatures of marine waters capable of supporting life. Some isolated areas of the ocean, notable within and beneath hydrothermal vents, may support specialized living organisms at temperatures of up to 400°C (750°F)!

  22. Substances Move through Cells by Diffusion, Osmosis, and Active Transport Organisms in the ocean rely on these processes for many life functions. • Diffusion is mixing due to random molecular movements. • Osmosis is diffusion of water through a membrane • Active transport is the transport of a substance against a concentration gradient. Active transport requires energy input. (left) The effects of osmosis in different environments. (a) An isotonic solution contains the same concentration of dissolved solids (green) and water molecules (blue) as a cell. Cells placed in isotonic solutions do not change size since there is no net movement of water. (b) A hypertonic solution contains a higher concentration of dissolved solids than a cell does. A cell placed in a hypotonic solution will shrink as water moves out of the cell to the surrounding solution by osmosis. (c) A hypotonic solution contains a lower dissolved solids concentration than a cell does. A cell placed in a hypotonic solution will swell and rupture as water moves by osmosis from the environment into the cell.

  23. Substances Move through Cells by Diffusion, Osmosis, and Active Transport A summary of the three main ways by which substances move into and out of cells. (a) In diffusion, molecules introduced into a container (left) become evenly distributed after a period of time (right). (b) In osmosis, the diffusion of water may cause a cell to swell. The blue dots represent water molecules, the black dots represent dissolved particles, and the arrows indicate the direction of water movement into the original cell. Under different conditions, water may move out of the cell, causing it to shrink. (c) Active transport enables a cell to accumulate molecules even when there are move inside the cell than outside. Cells may expel other molecules by the same process.

  24. Water Dye cube Day 1 Day 2 Day 5 Day 20 Stepped Art Fig. 13-16, p. 361

  25. The Marine Environment Is Classified into Distinct Zones Scientists divide the marine environment into zones, areas with homogeneous physical features. Zones are classified by location and the behavior of the organisms found there.

  26. Evolution Appears to Operate by Natural Selection • Earth’s organisms have changed, or evolved, over the course of 4 billion years. • Evolution occurs through the process of natural selection. • The environment favors individuals that are well adapted. Their favorable traits are retained because they contribute to the organism’s reproductive success.

  27. Systems of Classification May Be Artificial or Natural • What were the contributions of Carolus Linnaeus? • He was one of the first to use a system of natural classification • He developed a classification system based on hierarchy • He developed a system of scientific names for organisms

  28. Systems of Classification May Be Artificial or Natural The study of biological classification is called taxonomy. (right) Carolus Linnaeus - the father of modern taxonomy - in Laplander costume. (He went on a scientific expedition to Lapland in 1732). Linnaeus invented three supreme categories, or kingdoms: animal, vegetable, and mineral. Today’s biologists leave the mineral kingdom to the geologists and have expanded Linnaeus’s two living kingdoms to six. Linnaeus’s great contribution was a system of classification based on hierarchy, a grouping of objects by degrees of complexity, grade, or class.

  29. Systems of Classification May Be Artificial or Natural A family tree showing the relationship of kingdoms presumably evolved from a distant common ancestor. The Bacteria and Archaea contain single-celled organisms without nuclei or organelles; collectively, they are called prokaryotes. The fungi, protists, animals, and plants contain organisms with cells having nuclei and organelles; collectively, they are called eukaryotes.

  30. Systems of Classification May Be Artificial or Natural The modern system of biological classification, using the Rex sole, a type of flatfish (Glyptocephalus zachirus) as an example. Note the boxes-within-boxes approach, a hierarchy. Ellipses (…) indicate groups not shown for clarity.

  31. Chapter 13 in Perspective In this chapter you learned that the atoms in living things are no different from the atoms in nonliving things; in fact, they move between the living and nonliving realms in large biogeochemical cycles. Also, the energy that powers living things is the same energy found in inanimate objects. So how is it possible to distinguish between life and non-life? The discussion of life in this chapter highlights the highly organized nature of living material and the complex ways that living things manipulate matter and energy. Life runs on food, and some of the world’s most important producers of food are found in the ocean. Understanding the term primary producers is central to this chapter: Primary indicates that food webs start with those organisms; producer emphasizes that the organisms make glucose, an all-important food molecule. Primary producers are organisms that synthesize energy-rich organic compounds (food) from inorganic substances. If someone asks you, “What is produced in primary productivity?” a safe answer is, “The carbohydrate glucose.” Marine life depends on the ocean’s chemical composition and physical characteristics for life support. The aspects of the physical environment that affect living organisms are called physical factors, examples of which are water’s transparency, temperature, dissolved nutrients, salinity, dissolved gases, acid–base balance, and hydrostatic pressure. Life and the ocean have evolved together – change in one is met by change in the other. The evolution of life on Earth and the scheme of natural classification we use to organize it are closely related. Our categorizations of living things are based on their presumed ancestry and history. In the next chapter you will learn about the primary producers themselves and meet the ocean’s largest community, the drifters of the plankton. Primary productivity will be revisited – you will discover how researchers measure productivity and what some of the physical and biological factors are that limit it. We will see how advanced marine plants fit into the overall productivity picture and begin thinking about animals.

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