EXAMINING MARINE ALGAL CELLS

Duration 3 class periods (2 for collection and activity, 1 for observatory extension).

Theme Marine algal cells are easily viewed using a compound microscope and show similar characteristics to terrestrial plant cells.

Objectives Students will: • Examine the organelles of marine green algal cells. • Gain experience using microscopes and proper microscope technique. • Use the Ocean Networks Canada Data Plotting Utility to investigate the relationship between primary production (estimated using chlorophyll-a) and solar radiation.

Vocabulary • Eukaryote: Any organism whose cells contain a nucleus and other structures (organelles) enclosed within membranes. • Cell membrane: A selectively permeable, biological membrane that separates the interior of a cell from the outside environment. • Nucleus: A membrane-enclosed organelle found in eukaryotic cells containing most of the cell’s genetic material. • Cytoplasm: The gel-like substance enclosed within the cell membrane. Also includes the cell’s organelles. • Cell wall: A tough, flexible layer located outside the cell membrane that provides support and protection to the cell as well as acting as a filtering mechanism. • Vacuole: A membrane-bound organelle resembling an enclosed compartment. Responsible for maintaining turgor pressure (osmotic water flow into plant cells). • Chloroplast: The organelle responsible for conducting photosynthesis. Contains chlorophyll. • Multinucleate: A cell with more than one nucleus. • Uninucleate: A cell with only one nucleus.

PLOs Addressed (Activity + Extensions)

Grade(s) Curriculum Prescribed Learning Outcomes Organizer

8, 9, 10 Processes of Science A1 Demonstrate safe procedures. A3 Represent and interpret information in graphic form. A4 (Grade 8 A5) Demonstrate scientific literacy. A5 (Grade 8 A6) Demonstrate ethical, responsible, cooperative behaviour. A6 (Grade 8 A7) Describe the relationship between scientific principles and technology. A7 (Grade 8 A8) Demonstrate competence in the use of technologies specific to investigative procedures and research.

8 Life Science: B1 Demonstrate knowledge of the characteristics of living things. Cells and Systems B2 Relate the main features and properties of cells to their functions.

8 Physical Science: C2 Explain the properties of visible light. Optics

10 Life Science: B1 Explain the interaction of abiotic and biotic factors within an Sustainability of ecosystem. Ecosystems B3 Explain various ways in which natural populations are altered or kept in equilibrium.

Background Cells are the smallest units of life, containing the basic components necessary for all life functions. All organisms are composed of cells but there is a great diversity in cellular structure. Despite differences between plant, animal, and bacterial cells, there are some common characteristics. All eukaryotic cells contain a cell membrane, a nucleus, and cytoplasm.

Figure 1. Simplified animal cell.

Among the green algae there are few cellular differences to land plants. The green algae are evolutionarily important as they are the descendants of the organisms that gave rise to terrestrial plants. Both plants and the green algae share common characteristics. They all have cell walls, a large vacuole, and the presence of chloroplasts. In this activity students will be able to identify these characteristics using a microscope.

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Figure 2. Simplified plant cell.

The green algae differ from land plants in that they have a thin cell wall with no secondary thickening (i.e., woody tissues). Marine algal cells can be either multinucleate or uninucleate. These features will be evident when viewing the green algae under a compound microscope.

Materials • 1 x bucket • Live marine green algal specimens (e.g., Ulva sp., Cladophora sp., Codium fragile, Acrosiphonia sp.), enough for a class (e.g., 1 specimen per 3–4 students) • Class set of compound microscopes (each capable of 10X and 40X magnification) • 1 x ruler

Activity 1 1. Travel with students to a local dock or rocky intertidal zone. 2. Collect local species of green algae. 3. Bring samples back to the classroom in a bucket of seawater. 4. Optional: Read the poem, The Microscope, by Maxine Kumin (see Extensions section). 5. Using the information in the “Background” and “Vocabulary” sections, introduce cells to the students and draw labeled diagrams of simplified animal and plant cells. 6. Make water mount slides of sections of marine green algae samples. 7. View green algal cells under 10X and then 40X magnification. 8. Draw and label cell structure. 9. Estimate size of cells using a ruler and the field of view of the microscope:

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10. Compare and contrast the differences in cell structure between the different marine algal species collected.

Questions: • Identify the structures that differentiate a marine algal cell from an animal cell. o Marine algal cells (like plants) have a cell wall (animal cells only have a cell membrane), chloroplasts (for photosynthesis), and a large vacuole (animal cells have one or more smaller vacuoles). • Identify the structures that differentiate a marine algal cell from a terrestrial plant cell. o Marine green algal cells have thinner cell walls than terrestrial plants and are more commonly multinucleate than terrestrial plant cells. • Why do different species have different arrangements of organelles? o E.g., Cladophora sp. has a spiral network of chloroplasts due to the genus’ peculiar growth pattern influenced by turgor pressure in the cells. • Why are the cells so small? Why aren’t they larger? o As a cell grows, its surface area/volume ratio decreases (i.e. the surface area does not increase as much as the volume). At some point in a cell’s growth this ratio becomes so small that its surface area is too small to allow the passage of enough raw materials to sustain activities within the entire volume. At this point the cell cannot get larger. • Discuss the limitations of techniques and instruments (e.g., compound microscopes) to the study of cell structure. o See below. • Examine scanning electron microscope images of cells (you can find good examples here) and discuss the advantages (and disadvantages) to this type of microscopy. o A good overview of the advantages and disadvantages of optical and electron microscopes can be found here.

Fieldtrip Safety • While students are collecting algae on the beach or dock they should be wearing lifejackets at all times. Docks can be slippery and the students will be reaching over the dock to collect samples. • At a beach, the intertidal zone can be a dangerous area, especially before and after storms. Students and teachers should watch for rogue waves that may catch students off guard. Always have at least one student on guard to watch for unexpected waves or swells.

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Activity 2 5. Open the Ocean Networks Canada Data Plotting Utility by entering the following into your browser address bar: http://dmas.uvic.ca/PlottingUtility 6. Towards the top of the screen, underneath the gray menu options, find the section titled, Time Period Selection. In the Date From (UTC) box, enter 01-Jan-2014; in the Date To (UTC) box, enter 18-Jul-2014. 7. Click the Plot button under Refresh Plot(s). You’ll now see this date range listed in the Time Range History box on the right. 8. Next, select the Cambridge Bay Community Observatory in the left-had sidebar by clicking the “+” next to each of following in sequence: Arctic > Cambridge Bay. 9. Next, click the “+” next to Cambridge Bay to expand the menu, click the “+” next to Underwater Network, then the “+” next to Water Quality Monitor. 10. From the list of parameters measured by the water quality monitor, click on Chlorophyll. A graph should now display on screen for the date range you selected in Step 2. 11. Next, in the sidebar, under Cambridge Bay, click the “+” next to Shore Station, then the “+” next to Meteorological Station A, followed by the “+” next to Meteorological Station. 12. From the list parameters measured by the meteorological station, click on Solar Radiation. A second graph should now display on screen. 13. Overlay the plots by right-clicking on one of the plotted parameters in the sidebar (e.g. Solar Radiation) and selecting Add to Plot 1 Right Y Axis, where Plot 1 is Chlorophyll and Plot 2 is Solar Radiation. You should now see a graph that looks like the one below (Chlorophyll in blue, Solar Radiation in red):

Questions: 1. How does chlorophyll vary with solar radiation during the time period we’ve chosen? Why does this relationship exist? • Chlorophyll concentration generally increases as solar radiation increases. • Early in the year, sunlight (solar radiation) is a limiting factor on algal growth and chlorophyll concentrations are low. As we move from winter into spring and then summer, sunlight increases and is no longer limiting algal growth. As growth of algae increases, so too does chlorophyll concentration.

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2. What other abiotic factor(s) might influence the growth of marine algae and therefore the production of chlorophyll? • Nutrient availability (e.g., nitrate and phosphate), temperature, and salinity are other possible factors affecting marine algal growth. 3. What change in chlorophyll concentration would you expect during the winter months? You can test your prediction by entering different dates in the Date From (UTC) and Date To (UTC) boxes. Alternatively, you can show all the data available for the chosen sensors: Immediately to right of the Date From (UTC) box is the Time Presets section; choose All Available from the drop-down menu, then click the Plot button next to it. • Chlorophyll concentrations decrease in the winter due to lower solar radiation— reduced dramatically due to ice cover and Cambridge Bay’s northern latitude. • To visually inspect the differences in algal growth between seasons, students can investigate video footage from Ocean Networks Canada’s SeaTube Pro: o Open SeaTube Pro by entering the following into your browser address bar: http://dmas.uvic.ca/SeaTube o In the sidebar on the left, select the Cambridge Bay Community Observatory under Location by clicking the “+” next to each of following in sequence: Arctic > Cambridge Bay. o Next, click the “+” next to Underwater Network. Choose the date of interest by clicking the “+” next to 2014, then choose a month and day within the range used to plot the graphs (January 1–July 18, 2014): click on a month to select it, followed by a day, and then a time—a camera recording for this time period made from the observatory will then be displayed. By looking at recordings from different months and days, you should be able to see differences in algal growth at different times. For example:

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January 1, 2014

July 18, 2014

4. Does a relationship exist between chlorophyll and oxygen? Why do you think so? How would you illustrate this using the Data Plotting Utility? • Yes, a relationship exists between chlorophyll and oxygen. Chlorophyll concentrations are an indicator of marine algal growth. As marine algae are photosynthetic organisms, they produce oxygen: therefore, more algal growth (higher chlorophyll concentrations) leads to more oxygen production; low algal

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growth (low chlorophyll concentrations) leads to less oxygen production. Thus, chlorophyll and oxygen are positively correlated. • Use the Data Plotting Utility to produce graphs for chlorophyll and oxygen, as for chlorophyll and solar radiation. For example:

5. How would you investigate the chlorophyll, solar radiation, and oxygen data for today? • Use the Data Plotting Utility to produce graphs for chlorophyll, solar radiation, oxygen, and restrict the date range for today’s date, or use the drop down menu under “Time Presets” and choose “Last 10 Minutes”, “Last 2 Hours”, or “Last 24 hours”. For example:

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Extensions The Microscope (by Maxine Kumin)

Anton Leeuwenhoek was Dutch. He sold pincushions, cloth, and such. The waiting townsfolk fumed and fussed As Anton’s dry goods gathered dust.

He worked, instead of tending store, At grinding special lenses for A microscope. Some of the things He looked at were: mosquitoes’ wings, the hairs of sheep, the legs of lice, the skin of people, dogs, and mice; ox eyes, spiders’ spinning gear, fishes’ scales, a little smear of his own blood, and best of all, the unknown, busy, very small bugs that swim and bump and hop inside a simple water drop.

Impossible! Most Dutchmen said. This Anton’s crazy in the head! We ought to ship him off to Spain! He says he’s seen a housefly’s brain! He says the water that we drink Is full of bugs! He’s mad, we think!

They called him dumkopf, which means dope.

That’s how we got the microscope.

Questions: 1. Why do you think the poem was written in this way? (I.e., why/how does the author use dramatic irony?) 2. How would you explain what you would have seen under the first microscope? 3. What is the author alluding to with things “that swim and bump and hop”?

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Further questions Grade 8 • What characteristics do marine algae share with other living things? • The marine algae you looked at were collected from shallow water. Would you expect to find algae in deep ocean water? Why? • What wavelengths of light are important for photosynthesis in marine algae? How deep do each of these wavelengths penetrate into deep ocean water? Grade 10 • How might changes in abiotic factors (e.g., changes in ocean current patterns, extreme weather, water contamination), impact marine algal populations? How might impacts to these populations affect other living things, including humans?

Additional Activities • Ocean News Teacher’s Guide, “Exploring the Fluid Frontier”, Part A: Pages 8–14 feature activities investigating the properties of visible light, the behavior of light in water, and adaptations of marine organisms to low ambient light levels: http://oceanlink.island.net/ONews/OceanNewsReader/TG1a.pdf • Ocean News Teacher’s Guide, “Exploring the Fluid Frontier”, Part B: Pages 45 and 47– 50 feature activities investigating the use of satellites to monitor ocean chlorophyll concentrations: http://oceanlink.island.net/ONews/OceanNewsReader/TG1b.pdf • Ocean News Teacher’s Guide, “Marine Biodiversity”: Pages 173–175 looks at the use of seaweed and seaweed derivatives by humans: http://oceanlink.island.net/ONews/OceanNewsReader/TG5.pdf

Resources • Druehl, L. (2001). Pacific Seaweeds. Harbour Publishing. • Raven, P., Johnson, G.B., Mason, K.A., Losos, J.B., Singer, S.S. (2014). Biology. McGraw- Hill Education. • This activity is a good refresher on how to wet mount slides and estimate cell size under a microscope: http://www.radford.edu/jkell/CellsizeEx3.pdf • Video resources discussing why plants appear green: o http://youtu.be/aAQYpra4aUs o http://youtu.be/545rqaOJQD8

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