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1A-1 Topic 01A: Introduction to Oceanography Online Lecture: Basic Concepts of Oceanography 1A-2 Oceanography: A Science of Maps ○ In science, diagrams & pictures are important. Look for the fish! In oceanography, we look at a LOT of maps & pictures. ○ When looking at a map, the FIRST thing to do is to determine its point-of-view . – bird’s-eye-view (view from above, plan view, map view) – side-view (cross-section, profile) Side-View Bird's-Eye-View Land Ocean Land 1A-3 Label your map of the world ○ Please familiarize yourself with: – 7 continents Direction? – 5 oceans – position of the Equator & Poles – the 4 directions (north, east, south, west) Common Misconceptions about Plankton “Plankton” means 1A-4 “wanderers” ○ Plankton – ocean algae (“plants”) & animals that: – try to float – drift with waves & currents ● some can swim, but are not “good” swimmers ○ most of the biomass in the ocean consists of tiny pelagic organisms (pelagic = planktonic) ○ many animals grab / strain / filter the tiny plankton from the water (this is called “suspension” or “filter” feeding) – not all plankton are small e.g., jellyfish Phytoplankton There are 2 major kinds of plankton…. 1A-5 Dinoflagellate Diatoms Coccolithophore 1A-6 Phytoplankton ○ tiny (single-celled) ○ algae (like plants) ○ make their own food using a process called photosynthesis: light + carbon dioxide + water → carbohydrates + oxygen “food” = carbohydrates = sugars = glucose ○ to carry out photosynthesis, they need – sunlight – nutrients There is plenty of CO2 and water in the ocean. Mr. Ray (the science teacher) in Finding Nemo: “Seaweed is cool, seaweed is fun, seaweed makes its food from the rays of the Sun.” Nutrients could call them “minerals,” but not “vitamins.” ○ chemicals / molecules in ocean water ○ washed off the land into the ocean when it rains They are NOT soil (sediments). ○ are needed to make the molecular “tools” that carry out photosynthesis (to make “food”) – like a hammer is used to build a house, or a spatula is used to make a hamburger ○ are needed to make shells, typically made of: – calcium carbonate “Got milk?” – silica “glass” ○ Nutrients are fertilizers, not food. 1A-7 Why Photoplankton Are Important 1A-8 Small Organisms, Big Impact food for the animals we eat make over 50% of the oxygen we breathe reduce the greenhouse effect remains become “fossil fuels” (e.g., oil) Zooplankton 1A-9 Copepods “Arrow Worm” krill Jellyfish Slug Simplified Food Chain 1 phytoplankton 2 “Trophic Levels” (Steps in the Food Chain) 3 4 zooplankton small fish Simplified Ocean Food Chain animals undergo respiration, the opposite of photosynthesis 1A-10 big fish Earth About how much of the Earth is covered by the ocean? about 70% Irony of the name “Earth.” 1A-11 Size of the Ocean & Shape of the Ocean Floor ○ What is the average depth of the ocean? ○ Most of the ocean bottom is pretty flat : 1A-12 2.5 miles (4 km) – continental shelves: flat areas near the continents – abyssal plains: deep, flat areas (2-3 miles deep) – continental slope: steep area connecting the continental shelves & plains Land, Continent Continental Slope Mid-Ocean Abyssal Ridge Plain Continental Shelf Trench Continental Shelf Continental Slope Abyssal Plain Mid-Ocean Abyssal Ridge Plain The Mid-Ocean Ridge Underwater Chain of Volcanic Mountains 1A-13 I often abbreviated it “MOR” Trenches Close to Land! Continents or Island Chains Mariana Trench: Deepest Place in the World 1A-14 Most in the Pacific Ocean Volcanoes: Located Next to Trenches 1A-15 Ring of Fire Volcanic Mountains & Island are common next to trenches Earthquakes: happen next to trenches and the Mid-Ocean Ridge 1A-16 “10. The Abyss” Sediments & the Sea Floor 1A-17 Rocks Washed or Blown Off the Land Sediments Composed of Shells May also include mucus; 1A-18 fecal pellets; and the dead, decaying parts of organisms. 2 major categories of sediments: rocks & shells 2 major kinds of biological sediments: calcium carbonate & silica 1A-19 Winds ○ Warm air rises ( low density ) and cold air sinks ( high density) ○ Air gets pushed away from the cold place, and moves in to replace the rising warm air “Convection Cell” Winds cause waves and currents. High Altitude Winds Surface Winds Warm Cold Ocean Current Clouds and rain occur where air rises. Skies are clear where air sinks. 1A-20 Ocean Currents ○ like a river in the ocean, water is flowing from place to place ○ affect the climate: a warm current makes the climate… – warmer – more humid (& more rain), because more water evaporates from the ocean ○ can bring up or push down nutrients, affecting the amount of life in the ocean Evaporate ≠ Rise The Water Cycle 1A-21 Most of our drinking water comes from ocean! Bacteria 1A-22 ○ single-celled organisms that do not have a “nucleus” to store & protect their DNA ○ “recyclers”: breakdown (“decompose”) dead, decaying material, releasing nutrients back into the environment – Why is releasing nutrients important? Algae (like phytoplankton) need nutrients to build their shells and carry out photosynthesis (make their own food) → fertilizing the next generation of algae for animals to eat… Humans and the Ocean I 1A-23 ○ We will look at a variety of issues, including overfishing, coastal development, common ocean pollutants, etc… Humans and the Ocean ○ Humans sometimes add nutrients to the ocean (e.g., sewage, fertilizers) – can cause the growth of “good” ocean life, but also diseasing-causing bacteria and toxic algae Most nutrients enter the ocean naturally (are washed off the land), not owing to human activities. 1A-24 1A-25 But Wait, There’s More! ○ Nature of Science: Hypotheses, Theories, & Observations ○ Water Chemistry (the Chemistry of Life): What’s so special about water molecules? ○ Waves, Beaches, and Tides ○ Coral Reefs, Kelp Forests, & Deep-Sea Life ○ Tsunami, Hurricanes, & El Niño ○ Plate Tectonics (e.g., Earthquakes and Volcanoes) ○ Global Warming, the Greenhouse effect, & Pollution “25. Darla!,” End of “26. Goodbye Dory”