Name: Section: Due Date: Lab 10A-1 Primary Productivity (Phytoplankton) Lab Before Coming to Lab: Read Chapter 13 (387-424) in Thurman & Trujillo, 11 th ed. The purpose of this lab is to familiarize you with the spatial distribution of phytoplankton using satellite images and to examine its causes. In other words, you will learn where the tiny algae at the bottom of the ocean food chain like to live and explain why they like to live there. About Phytoplankton 1. 2. 3. Names of Group Members: Phytoplankton are tiny (one-celled) algae, plant-like organisms that use sunlight as an energy source to make their own food in a process called photosynthesis ( making with light ). To carry out photosynthesis, they need large amounts of water and the gas carbon dioxide, both abundant in the ocean, to make carbohydrates (the food molecules). Sunlight + Water + Carbon Dioxide Carbohydrates + Oxygen ("Sugars") They also need small amounts of nutrients, molecules that they use to build their bodies or molecular tools that are needed to carry out photosynthesis, but are not used up in the process. (A hammer is a tool that can be used in the process of building a chair, but the hammer is not part of the chair as the end of the process. It can be re-used again and again to build more chairs.) Examples of nutrients include nitrates, phosphates, and silica. Primary productivity is the rate at which food molecules (carbon compounds that chemically store the energy captured from sunlight) are created. The more phytoplankton that are present, the higher the primary productivity will be. Sunlight and nutrients are the hardest things for phytoplankton to obtain, so wherever there are both sunlight and nutrients, phytoplankton will be abundant. Animals will be attracted there too, because phytoplankton are at the bottom of the ocean food chain. In other words, animals in the ocean eat phytoplankton (e.g., zooplankton) or they eat other animals which eat phytoplankton. The phytoplankton make their own food, so we call them primary producers: they make ( produce ) organic material Think of nutrients as fertilizing the phytoplankton. Nutrients are not food or eaten by phytoplankton. (Phytoplankton make their own food.) As you will observe under the microscope, phytoplankton have no tentacles, arms, or other structures with which to grab the extremely tiny nutrients. Instead they rely upon chance: the nutrients drift into their bodies through the holes in their shells or cell walls from inorganic material (carbon dioxide, water). This is the first or primary step in the food chain. Animals are secondary, tertiary, etc. producers depending upon their level in the food chain. They make the organic material of their bodies from organic material that they eat.
Lab 10A-2 Sunlight is, of course, most abundant at the top of the ocean. As sunlight goes downward through ocean water, it is absorbed by the water, warming the surface of the ocean but leaving the deep ocean cold and dark. Anything that helps phytoplankton float like unusually cold and salty water (high density water) at the surface of the ocean and upwelling (water moving upward from the deep to replace surface water pushed away by winds) leads to the growth of more phytoplankton. In fact, many phytoplankton are more dense than water (because of their hard calcium carbonate or silica shells), so they sink. They rely upon waves or other mixing mechanisms to bring them back up towards the sunlight at the surface. Their bodies are shaped so that they fall slowly, allowing them to wait for that lucky wave. There is at least one advantage to falling, though: their bodies are exposed to more nutrients. Nutrients enter the ocean when they are washed off the land by rain runoff. (The nutrients in soil allow plants to grow.) Thus, phytoplankton like to live near the coast, and nutrients are hard to find out in the middle of ocean. As dead organisms and wastes sink towards the bottom of the ocean, they are slowly decomposed by bacteria or dissolved by ocean water, releasing nutrients back into the water in the deep ocean. However, many nutrients are released too deep, where phytoplankton cannot live because of a lack of sunlight. Anything that brings these nutrients up to surface will lead to the growth of lots of phytoplankton. Upwelling (water moving upward from the deep to replace surface water pushed away by winds) is the most effective means of bringing up nutrients, but upwelling only happens in special places where the winds blow in the right directions like the Equator, along west coasts at mid- and low latitudes, and in the middle of the Southern (Antarctic) Ocean. In most parts of the ocean, nutrients are brought up by waves and other mixing mechanisms that stir up the nutrients from below. Waves can only bring up nutrients if the surface water is not too warm. Cold, nutrient-rich water from below cannot float in warm surface water its density is too high so it will sink back down rather than mix with the surface water. Surface Water Warm Cold Sediments are not nutrients. Sediments are much larger than the phytoplankton themselves! There are many different kinds of phytoplankton. Some have calcium carbonate shells (e.g., coccolithophores, foraminifera), some have silica shells (e.g., diatoms, radiolarians), and some have no hard shells at all and can swim (e.g., dinoflagellates). Silica dissolves more rapidly in warm water than cold water, so silica-shelled phytoplankton tend to prefer living in colder surface water. Calcium-carbonate dissolves more rapidly in cold, carbon-dioxide-rich water (more acidic), so calcium-carbonate-shelled phytoplankton tend to prefer living in warmer surface water. That being said, there are many examples of calcium-carbonate-shelled phytoplankton and zooplankton who live in cold water and silica-shelled phytoplankton and zooplankton who live in warm water, so this is not an absolute rule. Gap Upwelling Upwelling Surface Water California Land
Lab 10A-3 Activity #1: Productivity in the Coastal Ocean Stamps Write your name in this box. Examine the satellite image showing primary productivity (amount of phytoplankton) in the Caribbean Sea just north of South America in the productivity folder. We can estimate the number of phytoplankton in a satellite image from the color of the water: the Color Red & Yellow Light Blue & Light Green Dark Blue & Dark Purple Black Productivity High Moderate Small No Signal greener the water, the more phytoplankton are present. A color contour map is then made to make the pattern clearer. The black arrow shows an ocean current. Note the location of the Orinoco River. (Sail away, sail away, sail away, ). 1. Using a blue pencil, sketch the ocean current into the map and label it ocean current. Using a green pencil, color in the locations in the southern Caribbean Sea where productivity is high. 2. Why is the productivity high at these locations in the southern Caribbean Sea? Caribbean Sea Orinoco River
Lab 10A-4 Examine the satellite image showing productivity near New York City. Long Island Sound 3. (a) Why is the productivity naturally so much higher in Long Island Sound than elsewhere along the coast? In other words, why is productivity higher in estuaries than along the coast? Long Island Long Island Sound is an estuary, a place where the ocean is partially surrounded by land. (b) There are currents along the coast here, not just in the Caribbean. Why doesn t the region of high productivity extend out of Long Island Sound and away from the coast as it does in the previous satellite image of the Caribbean?
Lab 10A-5 Activity #2: Productivity and Water Temperature Examine the satellite image showing primary productivity near the east coast of the United States in the productivity folder. The Gulf Stream is the meandering black arrow in the image. (Remember, the image shows the productivity, not the water temperature.) 4. Does the Gulf Stream carry warm or cold water north along the coast of the United States? 5. Based on your answer to the question above, is the water north of the Gulf Stream probably warmer or colder than the water in the Gulf Stream? 6. Color the Gulf Stream in the map on the right with a red pencil. Label the temperature of the water. In other words, write warm in red and cold in blue in appropriate places on the map. (Remember, the image shows the productivity, not the water temperature.) Circle the water where life is more abundant with a green circle. 7. Where is productivity highest, in the Gulf Stream or north of the Gulf Stream? In other words, is productivity higher in the warm water or the cold water? Gulf Stream Why is productivity higher in this place? In other words, how does living in warm or cold water benefit phytoplankton and help them thrive? Give 2 reasons. (a) (b)
Lab 10A-6 Activity #3: California s Coast Examine the image showing primary productivity near the coast of California in the productivity folder. The black arrows show the California Current and associated currents. 8. Using a green pencil, color in the locations along the coast of California where productivity is highest in the map on the right. 9. Sketch the California Current in blue into the map on the right, and label it California Current. Do phytoplankton like to live in the California Current? Why or why not? Discuss the current itself, not other things that happen along the coast of California. 10. The dashed arrow (--->) in the map above represents the coastal winds along the coast of California. Use red arrows to show the direction that it pushes the surface water. (Hint: Don t forget about the Coriolis effect.) How does this cause upwelling? 11. Does upwelling lead to higher productivity or lower productivity along the coast of California? Why? Give at least 2 different reasons. (a) (b)
Lab 10A-7 Activity #4: The Equator Examine the satellite image showing primary productivity near the Galapagos Islands in the productivity folder. The black arrows are the equatorial currents, not the winds or Ekman Transport. 12. Where is productivity higher, near the Equator or far to north and south of the Equator? (Note: The Galapagos Islands lie on the Equator.) There is more life in this location, because it is an upwelling zone. 13. Sketch the trades winds in green onto the map. Then, sketch the direction that the water is pushed by the trade winds in red. (In other words, sketch the Ekman Transport, not the equatorial currents.) Galapagos Islands 14. Why is there upwelling in the place that you identified above (question #12)? Hint: Discuss the directions that the winds push the water (question #13) or think about how the Coriolis effect will affect the equatorial currents shown in the satellite image. 15. Is the productivity higher on the eastern coast or the western coast of the Galapagos Islands? Why is the productivity higher here? Explain your reasoning. 16. Would you expect to find more calcium-carbonate-shelled or silica-shelled phytoplankton and zooplankton in the sediments piling up on the ocean floor on the Equator? Why? Explain your reasoning. Hint: Think about the temperature of the water on and near the Equator, and how upwelling affects the surface water s temperature.
Lab 10A-8 Activity #5: Samples of Phytoplankton & Zooplankton Examine the slides under the microscopes on the counter. 17. Sketch one plankton specimen from each microscope slide (A, B, C, no label) into the spaces below. Sample A: Radiolaria (zooplankton) Sample B: Diatoms (phytoplankton) Sample C: Foraminifera (zooplankton) No Label: Copepod (zooplankton) 18. Write animal or plant-like in each space above. Do you find it surprising that some of them are animals? 19. Write calcium-carbonate shells or silica shells in spaces A, B, and C above. Hint: If you do not know, look up the organisms in your textbook or carefully read the information at the beginning of the lab. 20. What differences do you see between calcium-carbonate shells and silica shells? Describe how they are different. 21. Which of these organisms dissolve more rapidly in warm water? Which of these organisms dissolve more rapidly in cold water?
Lab 10A-9 Activity #6: Blooms & Seasonal Productivity Examine the satellite image showing open ocean productivity in the North Atlantic during different seasons in the productivity folder. Color Red & Yellow Light Blue & Light Green Dark Blue & Dark Purple Black Productivity High Moderate Small No Signal When answering these questions, make sure that you are looking at the right place in the satellite images! Use the map on the right as a guide. Look at the open ocean, not the coastal ocean. Polar Temperate Tropical 22. During which season is productivity highest in the polar open ocean? Why is productivity highest during this season and not the others? 23. (a) During which season is productivity highest in the temperate open ocean? Why is productivity highest during this season and not the others? (b) Why doesn t the bloom in the temperate open ocean happen during the season when life is most abundant at the Poles (your answer to question 22)? (Hint: How are the temperate ocean and polar ocean different during this season?) 24. Is productivity in the tropical open ocean always high or low? Why is productivity always high or always low? In other words, what conditions make the tropics such a good or poor place for phytoplankton? Do not look at the Equator. The Equator is different from the rest of the tropical ocean.
Lab 10A-10 Activity #7: Measuring Primary Productivity Two methods of measuring productivity are collecting plankton by dragging a net through the ocean and measuring the color of the ocean using satellites (the greener the water, the more phytoplankton are present). 25. In what ways are satellites a better way to measure ocean productivity than nets? In other words, what are the advantages of satellite measurements? What are the disadvantages of net measurements? 26. In what ways are nets a better way to measure ocean productivity than satellites? In other words, what are the advantages of net measurements? What are the disadvantages of satellite measurements? 27. Why do people spend so much time, energy, and money measuring primary productivity? Who uses this information? How does it benefit them? Describe at least 1 way that you or someone else could use information about primary productivity (past, current, or typical conditions) for their own benefit. (Make sure that it is clear how the person uses the information and how they benefit from the information.) In other words, give an example.
Lab 10A-11 Phytoplankton Lab (10A) Review: Hints & Advice Remember: You ALWAYS need to explain why phytoplankton need or are attracted to something. You may be repeating yourself, but since questions are evaluated individually, this is necessary to get full credit plus it is really good practice so that you do not forget to do the same on an exam. Remember: You ALWAYS need to explain why nutrients or sunlight are more abundant in one place or time. For example: What is carrying nutrients to the location? How or why are nutrients trapped in a location? What is causing the nutrients to rise up towards the surface of the ocean? Activity 1 The answers to the questions on page 3 must discuss more than runoff from the land. In both cases, you must discuss and explain WHY nutrients are more abundant at certain places along the coast. The questions on page 3 also involve the role of ocean currents: the last question is asking you to explain why ocean currents affect the distribution of phytoplankton in the first satellite image but not the second. Activity 2 Remember: Red and green areas are places with lots of phytoplankton, and blue areas show where phytoplankton are not abundant. The colors do NOT tell you about the temperature of the water. Instead, you need to use your knowledge of ocean currents and the water temperature that phytoplankton prefer to identify where the warm and cold water are found in the map. Make sure that you explain WHY phytoplankton prefer warm or cold water. You must explain how the water temperature helps them get 2 things that they need, and you should note why the phytoplankton need these things. Activity 3 Make sure that you discuss the California Current itself and not what happens nearby (upwelling and rainwater runoff). In other words, what do you know about the California Current? Why would phytoplankton like these conditions? NOTE: THE DASHED ARROW ( - - - - > ) REPRESENTS THE COASTAL WINDS, not the California Current. Sometimes students describe the conditions under which upwelling happens, but do not explain why it happens. For example, they might say because the currents move apart or because the water is pushed away from the land. When explaining the cause or causes of upwelling, make sure that you finish your explanation by explaining how or why the water rises as well. (Continued on the Next Page)
Lab 10A-12 Activity 4 Draw the direction that the water is pushed by the winds (the Ekman Transport ), NOT the ocean currents shown on the map. Sometimes students describe the conditions under which upwelling happens, but do not explain why it happens. For example, they might say because the currents move apart or because the water is pushed away from the land. When explaining the cause or causes of upwelling, make sure that you finish your explanation by explaining how or why the water rises as well. If you claim that upwelling is happening somewhere, then you must explain how or why upwelling is happening in this location. For more information on water temperature, plankton shells, and seafloor sediments, read the last paragraph in the short reading assignment at the beginning of the lab. Also: When determining the kind of sediment that will be found on the ocean floor, remember: the Equator is a upwelling zone this is the point of activity 4! Activity 5 Notice that the instructions do NOT tell you to write in the material that copepod s shell is made of, because it is not made of calcium carbonate or silica. Instead, copepods like other crustaceans have an exoskeleton made of chitin, a tough substance made from glucose ( sugars ). Be sure to describe differences between organisms that you can SEE not ones that you learned about by reading. For example, answers like calcium carbonate shells dissolve is cold water will not be accepted. Activity 6 There is always plenty of sunlight in the tropical ocean. To answer the last question, make sure that you explain why it is difficult for phytoplankton to get nutrients if the surface water is too warm. Activity 7 Be as specific as possible when answering the last question explain in a way that even someone who is not in the class could understand. This person should be convinced that measuring the abundance of phytoplankton in the ocean is an important thing to do.