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Chapter 13 Life in the Ocean. Biodiversity. Earth contains over 100 million different species. All species are made up of the same major elements. 2. Elements.
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Biodiversity • Earth contains over 100 million different species. All species are made up of the same major elements. 2
Elements • All of Earth's organisms are composed of about 23 of the 107 known chemical elements. Four elements-carbon, hydrogen, oxygen, and nitrogen-make up 99% of the mass of all living things. 3
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.
Produces Sunlight Glucose (C6H12O6) Chlorophyll 6 Oxygen (O2) + + 6 Water (H2O) 6 Carbon dioxide (CO2) Stepped Art Fig. 13-2, p. 349
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).
Photosynthesizers: Green plants and algae, and specialized bacteria Respirers: Animals and decomposers and plants at night Light energy Energy of movement, waste heat, entropy Chemical energy (carbohydrates, etc.) Sun Producers Consumers To space Stepped Art Fig. 13-3, p. 350
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.
Glucose (C6H12O6) + 6 Oxygen (O2) + 24 sulfur (S) 18 Water (H2O) + 24 Hydrogen sulfide (H2S) 6 Carbon dioxide (CO2) + Stepped Art Fig. 13-4, p. 350
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.
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.
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
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.
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 killer whale. The arrows show the direction of energy flow; the numbers on each area represent the trophic level at which the organism is feeding.
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 (DNA) • Phosphorus and silicon – found in rigid parts of organisms (Phosphate=Backbone of DNA) • Iron and trace metals - used for electron transport
The Carbon Cycle Is Earth’s Largest 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.
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.
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.
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 • acid-base balance • salinity • hydrostatic pressure • dissolved nutrients
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 • metabolic wastes • defense of territory
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).
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)!
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.
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.
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.
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.
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
Systems of Classification May Be Artificial or Natural The study of biological classification is called taxonomy. (left) 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.
Systems of Classification May Be Artificial or Natural A family tree showing the relationship of kingdoms presumable 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.
