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BIO308: Marine Biology

Unit 2: Marine Food Webs   In this unit, you will begin your introduction to marine life by looking at how organisms are connected through trophic levels, or food chains.  This unit will address what types of organisms are primary producers, consumers, and detritivores (deposit feeders) and will examine their interactions.  Although some animal species will be specifically named in this section, for the moment focus on the relationships among them rather than on their names or taxonomic affiliations; species will be described in more detail in Unit 3.

Unit 2 Time Advisory
It should take you approximately 5 hours to complete this unit and all of its linked materials.

☐    Subunit 2.1: 1 hour

☐    Subunit 2.2: 1 hour

☐    Subunit 2.3: 1 hour

☐    Subunit 2.4: 1 hour

☐    Subunit 2.5: 1 hour

Unit2 Learning Outcomes
Upon successful completion of this unit, the student will be able to:

  • Explainfood webs (structure, roles of species) and describe the flow of energy within them (including assimilation efficiency up the food chain).
  • Identify primary producers, consumers, and detritivores.
  • Answer questions about the anatomy and function of macroalgae.
  • Answer questions about phytoplankton, including their vital role in primary production, and identify limiting factors for them.
  • Answer questions about locations of animals in areas of the marine environment (plankton, benthos, etc.) and identify organisms’ locations as a product of their life-cycle stage (e.g. belonging to the meroplankton vs. holoplankton).

  • Lecture: MIT: Professor Penny Chisholm’s “Regulation of Productivity” Link: MIT: Professor Penny Chisholm’s “Regulation of Productivity” (Adobe Flash, iTunes U, and MP3)
     
    Instructions: Watch Lecture 19 (“Regulation of Productivity”) in its entirety (47:20 minutes).  This lecture will cover Unit 2 (and will serve as a refresher for material in Unit 1).  Because the first part of the lecture focuses on terrestrial ecosystems, begin watching 14 minutes into the video lecture.  MIT Opencourseware gives you the option of watching this video from its site or downloading it via iTunes; do whichever you prefer.  Approximately two or three minutes of lecture (in the section on diatoms) have no video, as images were removed due to copyright concerns, but the rest of the video is intact.
     
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2.1 Primary Producers   2.1.1 Algae   Note: The appropriate taxonomic classification of marine algae (seaweeds and kelp) is a much-debated topic, and not all “seaweeds” are classified in the same general taxa—or even in the same phylum.  It is generally agreed, however, that algae are not true plants, as they lack vasculature and root systems and reproduce not by flowering but via spores.  For these reasons, even though they are large, multicellular organisms, they are sometimes placed in the kingdom Protista.

  • Reading: National University of Ireland, Galway: Michael Guiry’s Seaweed Site: “What Are Algae?”, “What Are Seaweeds?”, “Green Seaweed,” “Brown Seaweed,” and “Red Seaweed;” Proquest and CSA’s Discovery Guides: Katina Bucher Norris’s “Dimethylsulfide Emission: Climate Control by Marine Algae?” Links: National University of Ireland, Galway: Michael Guiry’s Seaweed Site: “What Are Algae?” (HTML), “What Are Seaweeds?” (HTML), “Green Seaweed” (HTML), “Brown Seaweed” (HTML), and “Red Seaweed” (HTML); Proquest and CSA’s Discovery Guides: Katina Bucher Norris’s “Dimethylsulfide Emission: Climate Control by Marine Algae?” (HTML)
     
    Instructions: From Michael Guiry’s Seaweed Site, read the entirety of every section except “Green Seaweed”; for this section, read only the subsection “Characteristics.”  Do not concern yourself with the details of the chemical composition of the algal types.  In “Dimethylsulfide Emission,” read the Introduction, The Production of DMS, and DMS Effects on Grazing; this will introduce you to some of the chemicals that are produced and/or released by many marine algae and microalgae, which both affect larger biogeochemical cycles and function as inducible chemical defenses.
     
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2.1.2 Kelp   - Reading: Wikipedia's "Kelp" Food and Agriculture Organization of the United Nations' Fisheries and Aquaculture Department: Macrocystis' “Morphology and anatomy” and “Life cycle and reproduction” Link: Wikipedia's "Kelp" (HTML); Food and Agriculture Organization of the United Nations' Fisheries and Aquaculture Department: Macrocystis'  “Morphology and anatomy” (HTML) and “Life cycle and reproduction” (HTML)
 
Instructions: Read the Wikipedia article for an overview on kelp and the two FAO sections in their entirety, focusing on morphology and reproduction.
 
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2.1.3 Bacteria   - Reading: University of California Museum of Paleontology’s “Cyanobacteria:” “Introduction” and “Life Link: University of California Museum of Paleontology’s “Cyanobacteria:” “Introduction” (HTML) and “Life History and Ecology” (HTML)
 
Instructions: Read the entire “Introduction.”  In “Life History and Ecology,” read only the subsection “Cyanobacteria Are Photosynthetic.”
 
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2.2 Plankton   2.2.1 Phytoplankton   - Reading: NASA’s “What Are Phytoplankton?” and MarineBio’s “Forests of the Sea: Phytoplankton and Marine Plants” Links: NASA’s “What Are Phytoplankton?” (HTML) and MarineBio’s “Forests of the Sea: Phytoplankton and Marine Plants” (HTML)
 
Instructions: On “What Are Phytoplankton,” read the introduction, and then click on the links on the right to read the sections entitled “Importance of Phytoplankton” and “Studying Phytoplankton.” For the “Forests of the Sea” reading, scroll down the webpage and read only the paragraphs entitled “Phytoplankton,” “Diatoms,” and “Dinoflagellates.”
 
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2.2.2 Zooplankton   - Reading: MarineBio’s “Zooplankton” Link: MarineBio’s “Zooplankton” (HTML)
 
Instructions: Read this page in its entirety, but do not concern yourself with the technical, taxonomic names of various members of the zooplankton.  Instead, notice the incredible diversity of life and life stages of organisms in the plankton, and pay close attention to their adaptations and the factors that influence their community structure and distribution.
 
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2.3 Filter Feeders (Also Called “Suspension Feeders”)   - Reading: The Daily Kos’s “Marine Life Series: Filter Feeders” Parts I and II Link: The Daily Kos’s “Marine Life Series: Filter Feeders” Part I (HTML) and Part II (HTML)
 
Instructions: Read both sections in their entirety.
 
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2.4 Predators   - Reading: Texas A&M; University: Professor Robert Stewart’s Oceanography in the 21st Century: “Marine Food Webs” Link: Texas A&M University: Professor Robert Stewart’s Oceanography in the 21st Century: “Marine Food Webs” (HTML)
 
Instructions: Read the subsections “Small Predators,” “Top Predators,” and “Food Chains and Food Webs.”
 
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2.5 Deposit Feeders   - Assessment: McGraw-Hill: Drs. Peter Castro and Michael Huber’s Marine Biology: “Quiz for Chapter 6: Multicellular Primary Producers” Link: McGraw-Hill: Drs. Peter Castro and Michael Huber’s Marine Biology: “Quiz for Chapter 6: Multicellular Primary Producers” (HTML)
 
Instructions: Answer all questions (1-15) on this multiple choice quiz.  This quiz will assess what you have learned in Unit 2.
 
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  • Reading: EconGuru’s Fundamentals of Ecology: “Ecosystems” and Washington State Department of Ecology: Shellyne Grisham’s “Nearshore Food Web” Link: EconGuru’s Fundamentals of Ecology: “Ecosystems” (HTML) and Washington State Department of Ecology: Shellyne Grisham’s “Nearshore Food Web” (HTML)
     
    Instructions: Scroll down the EconGuru webpage to the text and figure on “An Ocean Detritus Food Web.”  Read this text (one paragraph before and one after the figure), and study the accompanying figure. Arrows in the figure sometimes indicate what is eating what and sometimes relate to cycles of decay.  For a more straightforward figure, go to the Nearshore Food Web figure.
     
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  • Assessment: The Saylor Foundation’s “Your Own Food Web” Link: The Saylor Foundation’s “Your Own Food Web” (PDF)
     
    Instructions: Please complete the entire assessment.  You can check your answers against the answer key here