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Presentation on theme: "Exit Choose to view chapter section with a click on the section heading. ►The Nature of LifeThe Nature of Life ►How Matter and Energy Enter Living SystemsHow."— Presentation transcript:

1 Exit Choose to view chapter section with a click on the section heading. ►The Nature of LifeThe Nature of Life ►How Matter and Energy Enter Living SystemsHow Matter and Energy Enter Living Systems ►The Ocean’s Primary ProductivityThe Ocean’s Primary Productivity ►Energy Flow Through the BiosphereEnergy Flow Through the Biosphere Chapter Topic Menu

2 MenuPreviousNext The Nature of Life Chapter 4 Pages 4-2 to 4-6

3 MenuPreviousNext The Nature of Life Theoretical physicist Stephen Hawking: “The laws of science do not distinguish between the past and the future. In order to survive, human beings have to consume food which is an ordered form of energy, and convert it into heat, which is a disordered form of energy… The progress of the human race in understanding the universe has established a small corner of order in an increasingly disordered universe.”  This principle of physics called entropy, or randomness, appears to be the driving force of all life in our universe. The Nature of Life Chapter 4 Pages 4-2 to 4-6

4 MenuPreviousNext The Nature of Life nDefining life appears simple if you compare a fish and a rock. From a scientific point of view, it’s not quite so cut-and-dried. Often life and nonlife share the same elements; matter, carbon atoms and energy reactions. nEnergy reactions found in living systems also exist outside of life. For example: fire results when a reaction releases chemical energy within substances. Living systems use energy similarly – by releasing chemical energy for life processes. nAll life uses energy. Therefore it is possible to define “life” based on the characteristics living systems have apart from nonliving systems with respect to energy use. The Nature of Life Chapter 4 Pages 4-2 to 4-6

5 MenuPreviousNext Matter and Energy nLife requires matter and energy to exist. All living organisms are composed of about 13 of 118 known elements from the periodic table.  Carbon, hydrogen, oxygen, and nitrogen account for 99% of the mass. Ten other elements account for the remaining 1%. These elements, in combinations, account for all biological chemicals. The Nature of Life Chapter 4 Pages 4-3 to 4-5

6 MenuPreviousNext Matter and Energy Elements Essential for Life The Nature of Life Chapter 4 Pages 4-3 to 4-5

7 MenuPreviousNext Matter and Energy nElements, in various combinations, account for all biological chemicals.  These range from very simple sugars to DNA – the most complex known molecule.  Scientists recognize more than 1.6 million different species. Some biologists estimate that as many as 30 million may exist.  All organisms organize matter into biological chemicals and into cells. A cell is the smallest whole structure that can be defined as a living system. Some organisms consist of single cells; others consist of billions of codependent cells. Non- living things consists of matter, but don’t consist of cells. The Nature of Life Chapter 4 Pages 4-3 to 4-5

8 MenuPreviousNext Matter and Energy nThe first way fire differs from life: Fire consists of matter (gases), but it doesn’t consist of cells. It lacks any other structure that organizes matter in the way that living systems do. The Nature of Life Chapter 4 Pages 4-3 to 4-5

9 MenuPreviousNext Matter and Energy nEnergy is defined as the capacity to do work; it’s necessary for life because living systems use it to accomplish the processes of life: reproduction, growth, movement, eating, etc. nOrganisms need energy to break down complex molecules into simple molecules, and to build distinct complex molecules from simple molecules. The Nature of Life Chapter 4 Pages 4-3 to 4-5

10 MenuPreviousNext Matter and Energy nThe first law of thermodynamics states that energy cannot be created or destroyed only transferred from one state to another. nAlthough organisms require energy, they cannot create it; all living systems acquire energy from outside sources. The Nature of Life Chapter 4 Pages 4-3 to 4-5

11 MenuPreviousNext Matter and Energy What’s a “machine?” The Nature of Life Chapter 4 Pages 4-3 to 4-5

12 MenuPreviousNext Matter and Energy nA machine is a combination of matter capable of using energy to perform useful work.  Arguably living systems are machines. They’re combinations of matter capable of using energy to perform useful work.  What separates living systems from other machines is that they’re the only machines known that were not created by human beings.  Machines are also incapable of reproducing themselves (at least so far).  Organisms use energy for the useful work of the processes of life, including creating organization. The Nature of Life Chapter 4 Pages 4-3 to 4-5

13 MenuPreviousNext Matter and Energy nThe second way fire differs from living things: A fire results from the release of energy, but it is not performing useful work in the sense that it doesn’t regulate energy use or matter acquisition to meet its needs. It simply burns the available fuel.  A living system uses energy for the processes of life, including creating the organization that fire lacks. The Nature of Life Chapter 4 Pages 4-3 to 4-5

14 MenuPreviousNext Entropy nThe second law of thermodynamics states that disorder increases with the passage of time.  It is the law that random processes lead to chaos and simplicity, not order and sophistication. In other words, it says that the universe is “wearing out,” or moving toward a state of disorganization.  This explains why energy is useful—it flows from areas of high concentration to low concentration; and it is this flow that living systems can harness to perform useful work. The Nature of Life Chapter 4 Pages 4-5 to 4-6

15 MenuPreviousNext Entropy nWhenever you use energy, taking it from one form to another to perform work, some energy is lost as heat (another form of energy).  Eventually all energy and matter will be distributed evenly throughout the universe, but the distribution process isn’t uniform as it progresses.  There are areas with high order and others with low order. The Nature of Life Chapter 4 Pages 4-5 to 4-6

16 MenuPreviousNext Entropy nEntropy is the measure of how much unavailable energy exists in a system due to even distribution. High entropy = low organization and low energy potential. nLiving systems use energy to create order and to gather and store potential energy. The increased order is local and temporary, and requires more energy to create than it retains. Here, matter exists in a low-entropy (organized) state. nExample: About 85% of the energy required to organize protein into complex muscle tissue is ultimately lost as heat in creating the tissue. The Nature of Life Chapter 4 Pages 4-5 to 4-6

17 MenuPreviousNext How Matter and Energy Enter Living Systems Chapter 4 Pages 4-7 to 4-12

18 MenuPreviousNext Autotrophy and Heterotrophy nAll living things obtain the matter and energy they need from external sources.  Terrestrial organisms and most marine organisms get their energy directly or indirectly from the sun.  Energy in the form of sunlight combines with inorganic compounds to become energy-rich organic compounds. These compounds provide energy when living systems break them down during respiration. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-7

19 MenuPreviousNext Autotrophy and Heterotrophy nAutotrophy is the process of self-feeding – the ability to create their own carbohydrates. Plants are autotrophs.  Autotrophs can feed themselves by converting the energy from sunlight and inorganic compounds into carbohydrates. nOrganisms, like humans, that cannot produce their own carbohydrates must consume other organisms to get it, and are called heterotrophs.  All heterotrophs rely on photosynthesizing plants, bacteria and other microorganisms for life either directly or indirectly by consuming other organisms. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-7

20 MenuPreviousNext nOrganisms that use oxygen engage in cellular respiration, a process that releases energy from carbohydrates to perform the functions of life. (Note that this differs from respiration as commonly used to mean breathing). nThe chemical process is represented by the formula:  Sugar (glucose, a simple carbohydrate) plus oxygen converts to carbon dioxide, water and energy.  This conversion of the food you eat into energy your body uses is why you need oxygen to live, and why you exhale carbon dioxide. Cellular Respiration How Matter and Energy Enter Living Systems Chapter 4 Pages 4-7 to 4-8

21 MenuPreviousNext Photosynthesis nPrimary producers are organisms that combine energy from sunlight with inorganic materials to form energy-rich organic compounds. nThey are the conduit through which the biosphere gets almost all its energy. nPrimary producers harness only about one two-thousandth of the light reaching Earth, yet this powers life. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

22 MenuPreviousNext Photosynthesis nOrganisms with chlorophyll account for the vast majority of primary producers (plants, certain bacteria and other microorganisms).  It allows these organisms to capture sunlight energy to produce carbohydrates from inorganic material. nCarbohydrates are high-energy compounds living systems use as food.  Simple carbohydrates are sugars (saccharides) like glucose.  Complex carbohydrates are long sugar chains called polysaccharides, commonly called starches. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

23 MenuPreviousNext Photosynthesis nThe process of using light energy to create carbohydrates from inorganic compounds is called photosynthesis.  Carbohydrates consist of carbon, hydrogen and oxygen.  During photosynthesis, organisms use light energy to disassemble carbon dioxide and water molecules, rebuilding them into carbohydrates.  Because the carbon dioxide and water have more oxygen than is needed to make carbohydrate, the process also releases oxygen needed for respiration. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

24 MenuPreviousNext Photosynthesis nNote that photosynthesis is a complimentary process to respiration. The formula representing photosynthesis is: nDuring photosynthesis autotrophs use carbon dioxide, water and sun energy to create high-energy carbohydrates. nDuring respiration, they consume oxygen and release low energy carbon dioxide. nThrough photosynthesis and respiration, carbon, oxygen and water recycle continuously from inorganic to organic form and back. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

25 MenuPreviousNext Photosynthesis nRespiration as described above is aerobic respiration, meaning respiration that uses oxygen.  Some organisms exist in environments without oxygen through anaerobic respiration.  Anaerobic respiration is the process of releasing energy for the processes of life through chemical reactions that do not require oxygen.  Anaerobic respiration is not as efficient as aerobic respiration. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

26 MenuPreviousNext Photosynthesis Energy Transfer How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

27 MenuPreviousNext Photosynthesis Energy Cycle How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

28 MenuPreviousNext Photosynthesis Energy Cycle How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

29 MenuPreviousNext Photosynthesis nWithout primary production – the photosynthesis in plants, bacteria, and other microorganisms all over the world – you would not have the oxygen you need for respiration.  You would also not have the carbohydrates you need for energy.  Humans and all heterotrophs reply on photosynthesizing plants, bacteria and other microorganisms for life.  This is why the health of natural environments is a crucial issue. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-9 to 4-11

30 MenuPreviousNext Chemosynthesis nNot all the energy used by living systems use comes directly or indirectly from the sun; there is another process called chemosynthesis.  Chemosynthesis is the process of using chemicals to create energy-rich organic compounds.  This is similar to photosynthesis because it produces carbohydrates. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-11 to 4-12

31 MenuPreviousNext Chemosynthesis nChemosynthetic organisms are also primary producers.  Both chemosynthesis and photosynthesis are forms of fixation. Fixation is the process of converting or fixing an inorganic compound into a useable organic compound.  Chemosynthesis and photosynthesis both fix carbon into carbohydrates. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-11 to 4-12

32 MenuPreviousNext Chemosynthesis nInstead of light energy, chemosynthesis uses chemical energy within inorganic compounds.  It’s not as efficient as photosynthesis, and produces waste products other than oxygen.  Although the existence of chemosynthesis has been known for some time, hydrothermal vent communities weren’t discovered until 1977 by Woods Hole Oceanographic Institute scientists, diving in the submersible Alvin.  These communities live well below the reach of sunlight and rely on chemical energy from the minerals in the hot spring water. nThere are also “cold seep” chemosynthetic communities, where primitive single cell organisms use methane that seeps from the sea bottom. How Matter and Energy Enter Living Systems Chapter 4 Pages 4-11 to 4-12

33 MenuPreviousNext The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-22

34 MenuPreviousNext Marine Biomass nThe main “products” of primary production are carbohydrates.  Carbohydrates are the primary units of useable energy in living systems, plus a source of carbon used in an organism’s tissues. nScientists measure primary productivity in terms of the carbon fixed (bound) into organic material.  This is expressed as grams of carbon per square meter of surface area per year (gC/m 2 /yr).  Current estimates are that the oceans’ primary average productivity ranges from 75 to 150 gC/m 2 /yr.  The estimates for land and marine primary productivity put land’s slightly higher at 50 to 70 billion metric tons of carbon annually versus 35 to 50 billion. The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-15

35 MenuPreviousNext Marine Biomass nBiomass is the mass of living tissue, while the biomass at a given time is called the standing crop (both express both terms in mass).  Marine and terrestrial systems differ with respect to the biomass of the primary producers.  The standing crop in the ocean is one to two billion metric tons, versus on land, where it’s 600 to 1,000 billion metric tons. Phytoplankton accounts for between 92% and 96% of the ocean’s primary productivity. The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-15

36 MenuPreviousNext Marine Biomass nWhile there is a huge difference in average standing crop between the ocean and land, their respective productivity is nearly equal.  This occurs because marine ecosystems cycle energy and nutrients much faster than on land.  The rate of photosynthesis-respiration cycle is called turnover, and the marine turnover is much shorter than terrestrial.  The shorter the turnover time, the faster the standing crop passes energy into the ecosystem. The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-15

37 MenuPreviousNext Marine Biomass Productivity Terrestrial and Marine The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-15

38 MenuPreviousNext Marine Biomass nGross primary productivity is the measure of how much energy primary producers capture for creating carbohydrates.  The primary producers use some of the energy for life processes and convert the rest into biomass (tissue and other organic material).  Gross productivity minus what’s used by the primary producers themselves is called net primary productivity. The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-15

39 MenuPreviousNext Marine Biomass Comparison of net primary productivity in marine and land-based ecosystems. The Ocean’s Primary Productivity Chapter 4 Pages 4-13 to 4-15

40 MenuPreviousNext Plankton nPlankton are organisms that:  Drift or swim weakly in the ocean; they are at the mercy of currents, tides and other water motion.  Don’t represent any specific kind of organism, but a group of organisms with a common lifestyle and habitat.  It’s important to know that plankton are not a species, but include many species from virtually every major group of organisms found in the sea. Capturing Plankton With Nets. The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

41 MenuPreviousNext Plankton nPlankton includes autotrophs and heterotrophs, as well as predators and grazers. nMost plankton are very small, but some may grow several meters long. Microscopic Photo of Plankton The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

42 MenuPreviousNext Plankton nSome organisms start life as planktonic larvae, and then leave the plankton community as they grow large enough to swim as nektonic organisms or attach themselves to the bottom as benthic organisms. nPhytoplankton are the primary producers (autotrophs). nZooplankton are primary and secondary consumers that feed on phytoplankton and other heterotrophic plankton. nPhytoplankton are the most important primary producers in the sea, responsible for between 92 and 96 percent of the oceans’ primary productivity. nMarine plants, kelp and other multicellular photosynthesizing organisms account for only two to five percent, with the remainder from deep ocean chemosynthesis (which may be much higher than current estimates). The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

43 MenuPreviousNext Plankton - Diatoms nDiatoms are the most dominant and productive of the phytoplankton.  Diatoms are photosynthetic organisms characterized by a rigid cell wall made of silica.  This cell wall, called a frustule, admits light much like glass, an ideal cell material for a photosynthesizer.  Diatoms are the most efficient photosynthesizers known (they can convert more than half the light energy they absorb into carbohydrate chemical energy).  There are thousands of known species, including bottom dwelling (benthic) species as well as plankton (pelagic) species. The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

44 MenuPreviousNext Plankton - Diatoms The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

45 MenuPreviousNext Plankton - Dinoflagellates nDinoflagellates are the second most abundant phytoplankton. nDinoflagellates are (in most species) characterized by one or two whip-like flagella, which they move to change orientation or to swim vertically in the water.  Most, but not all species of dinoflagellates are autotrophs.  Besides planktonic species, other dinoflagellate species live within coral polyps, and are the most significant primary producers in the coral reef community.  Because they can reproduce rapidly, dinoflagellates are the principal organisms responsible for plankton blooms. The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

46 MenuPreviousNext Plankton - Coccolithophores nCoccolithophores are single celled autotrophs characterized by shells of calcium carbonate (the shells are called coccoliths).  Coccolithophores live in brightly lit, shallow water.  It’s hypothesized their translucent coccoliths protect them by screening the light.  Areas with high coccolithophore concentrations may appear milky or chalky. The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

47 MenuPreviousNext Plankton - Picoplankton nMicrobial plankton ecology:  Each liter of seawater contains billions of marine bacteria, archae and viruses. Although microscopic, the total mass of the bacteria alone is thought to exceed the combined mass of zooplankton and fishes.  Tropical regions were once thought to be unproductive. Picoplankton – extremely tiny plankton between.2 and 2 micrometers – may account for 79% of the photosynthesis in tropical waters and other marine habitats. The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

48 MenuPreviousNext Plankton - Picoplankton nMicrobial plankton ecology.  Many picoplankton are cyanobacteria, which are bacteria with chlorophyll. These are the most common bacteria in the ocean.  Picoplankton productivity is unproductive in the sense that they’re too small for consumption by larger consumers. Heterotrophic bacteria consume them and return the nutrients to inorganic form, so picoplankton don’t contribute much to food webs. However, they play a significant role in producing oxygen, taking up carbon dioxide and producing nitrogen compounds. The Ocean’s Primary Productivity Chapter 4 Pages 4-15 to 4-18

49 MenuPreviousNext Limits on Marine Primary Productivity nLimiting factors are physiological or biological necessities that restrict survival. Too much or too little of a limiting factor will reduce population. nMost autotrophs require water, carbon dioxide, inorganic nutrients and sunlight. nIn the ocean, water and carbon dioxide are almost never limiting factors - inorganic nutrients such as nitrogen and phosphorous compounds can be.  Sunlight is often a limiting factor in the sea due to season, depth or water clarity.  Several factors can limit the availability of inorganic nutrients. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

50 MenuPreviousNext Limits on Marine Primary Productivity nPlankton blooms can deplete the nutrients by rapid consumption, whereby depriving other species. nIn extreme cases, plankton blooms can consume all the oxygen and release by-products that are toxic in such amounts that fish and other organisms cannot survive (HABs – Harmful Algal Blooms, sometimes called “red tide”).  Plankton blooms occur naturally, but they may also be caused when pollution eliminates a limiting factor.  Nutrient-rich pollution removes nutrients as a limiting factor, allowing the plankton to overpopulate. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

51 MenuPreviousNext Limits on Marine Primary Productivity nDepth can limit nutrients by allowing dead organisms, which normally provide nutrients, to sink below the depths that sunlight can reach.  a. This creates a limiting factor until water motion brings the nutrients back to shallower water. nWater temperature can interfere with normal mixing when different temperature waters resist mixing because of their different densities.  This phenomenon traps nutrients in colder, deeper water, and is why tropical waters tend to have low productivity.  In the tropics, there’s ample sunlight and carbon dioxide, but the warm upper water layer traps nutrients in the cold layers that are too deep for photosynthesizing autotrophs.  In the Artic and Antarctic, there’s little temperature difference between shallower and deeper water, allowing nutrients to cycle to shallower water more easily.  Coastal areas tend to have more primary productivity because more nutrients from rain run-off and because shallow water keeps them from sinking below the productive zone. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

52 MenuPreviousNext Limits on Marine Primary Productivity nBesides depth, location can affect productivity.  Coral reefs are an important exception to the low productivity of tropical waters. Unlike most marine ecosystems, which rely on phytoplankton as their primary autotrophs, coral reefs rely on dinoflagellate autotrophs that live within coral tissue. The coral reef recycles its nutrients efficiently, with very little loss to the open sea, but make up less than one percent of the ocean’s surface area. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

53 MenuPreviousNext Limits on Marine Primary Productivity nBesides depth, location can affect productivity.  Exceptions to the relatively low productivity typical of tropical waters are regions extending westward from northern South America and northern Africa.  These high productivity regions are explained by upwelling.  Some of the highest productivity takes place in the Antarctic Convergence Zone, where it can reach 200 gC/m 2 /yr. Long summer days combined with water upwelling of nutrients cause explosive productivity. The short summer season makes this high productivity short-lived. The Arctic area doesn’t have comparable productivity intervals due to differing oceanographic conditions. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

54 MenuPreviousNext Limits on Marine Primary Productivity nBesides depth, location can affect productivity.  Productivity in temperate regions fluctuates with season. During the summer, a warm water upper layer traps nutrients in deeper water, but this layer disappears in the winter. Water motion from winter storms allows deep water nutrients to return to shallower water. During the spring, longer daylight hours combine with these nutrients for explosive phytoplankton growth.  Because of nutrient availability, the greatest total primary productivity occurs in near-shore temperate regions and southern subpolar waters.  Typical productivity in the temperate zone is 120 gC/m 2 /yr. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

55 MenuPreviousNext Limits on Marine Primary Productivity nThe amount of daylight affects photosynthesis and, therefore, primary productivity. nLight diminishes with depth, so depth also affects photosynthesis and primary productivity. nWater absorbs light selectively (something discussed in-depth later). nSuspended particles and the sun angle can also limit how much light penetrates water. nEven in very clear water, little photosynthesis takes place below 100 meters (328 feet). nPhotoinhibitation takes place when too much light overwhelms an autotroph, so some autotrophs cannot photosynthesize if the water is too shallow. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

56 MenuPreviousNext Limits on Marine Primary Productivity nDifferent phytoplankton species have different optimal depths.  As light conditions change, the advantage shifts from species to species. nAutotrophs produce carbohydrates and oxygen during photosynthesis, but they also respire (use the carbohydrates, as well as some oxygen, for respiration). nThe less light there is, the less photosynthesis and carbohydrate production, so as you go deeper the less carbohydrates autotrophs produce. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

57 MenuPreviousNext Limits on Marine Primary Productivity nAt some point, carbohydrates production exactly equals the amount consumed by the autotrophs for respiration.  This point of zero net primary production is called the compensation depth.  The autotrophs lack sufficient energy to reproduce (in meaningful amounts), so there’s no food source to pass energy up the food web.  This is typically the depth at which about one percent of the surface light penetrates.  The compensation depth varies with water clarity, surface disturbances and the sun angle.  If phytoplankton remain below the compensation depth for more than a few days, they will die as they consume the available carbohydrate faster than they create it. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

58 MenuPreviousNext Limits on Marine Primary Productivity The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

59 MenuPreviousNext Limits on Marine Primary Productivity The compensation depth has no set point. Note that it can be very shallow in turbid coastal waters and very deep in the clear waters of the tropics. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

60 MenuPreviousNext Limits on Marine Primary Productivity nThis is another concern regarding red tide and harmful algae blooms.  Red tide and algae blooms can abruptly block light from penetrating more than a few meters.  If conditions don’t change within a couple of days, the loss of light begins killing deeper phytoplankton.  This causes local primary productivity to fall, removing the food source for the ecosystem. The Ocean’s Primary Productivity Chapter 4 Pages 4-18 to 4-21

61 MenuPreviousNext Energy Flow Through the Biosphere Chapter 4 Pages 4-23 to 4-27

62 MenuPreviousNext Energy Flow Through the Biosphere Chapter 4 Pages 4-23 to 4-24 Trophic Relationships nA trophic pyramid represents how energy transfers from one level of organisms to the next as they consume each other; it’s a hierarchy of what-eats-what. nPrimary producers make up the pyramid base, which, in the ocean, are primarily phytoplankton.  Phytoplankton are marine organisms (usually microscopic or near-microscopic) that photosynthesize.

63 MenuPreviousNext Trophic Relationships nThe first level of heterotrophs—called primary consumers— eats the primary producers.  Because most of the primary producers are plants, most of the primary consumers are herbivores. nMost phytoplankton are so small that the most important primary consumers are the zooplankton.  The zooplankton are marine planktonic animals that eat phytoplankton or other heterotrophic plankton. nSecondary consumers are heterotrophs that eat the primary consumers.  In the ocean, secondary consumers feed primarily on zooplankton. Energy Flow Through the Biosphere Chapter 4 Pages 4-23 to 4-24

64 MenuPreviousNext Trophic Relationships Trophic Pyramid Energy Flow Through the Biosphere Chapter 4 Pages 4-23 to 4-24

65 MenuPreviousNext Trophic Relationships A Simple Three-Level Food Pyramid Energy Flow Through the Biosphere Chapter 4 Pages 4-23 to 4-24

66 MenuPreviousNext Energy Loss Through Trophic Levels nThere are additional levels of consumers above the secondary level, where each level eats the organisms of the level below.  Each level in the pyramid has significantly less biomass than the level below because energy is lost to entropy as it’s used in life processes at each level.  Only about ten percent of the energy transfers from one level to the next, so that each level is only about a tenth the size of the level below.  At each level, 90 percent of the energy is lost to entropy. Energy Flow Through the Biosphere Chapter 4 Pages 4-25

67 MenuPreviousNext Food Webs nA food web represents the flow of energy through consumption in nature. A food web shows that organisms often have choices of prey and eat across the trophic pyramid’s theoretical levels. nThis represents how energy flows through an ecosystem. Energy Flow Through the Biosphere Chapter 4 Pages 4-25 to 4-26

68 MenuPreviousNext Decomposition nDecomposers are organisms that break down organic material into inorganic form. nBy taking out the last remnants of useable energy from the organic matter to sustain themselves, these bacteria and fungi convert dead organisms and other organic waste into the compounds primary producers use. nDecomposition is important because it completes the materials cycle; it renews the inorganic materials (matter) necessary for energy to enter life. nWithin systems, energy flows and matter cycles. nBacteria and archaea, both very simple organisms, are the most important decomposers.  On the average, there are one billion bacteria per liter of seawater. Energy Flow Through the Biosphere Chapter 4 Pages 4-26 to 4-27

69 MenuPreviousNext Decomposition Energy Flow Through the Biosphere Chapter 4 Pages 4-26 to 4-27


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