08 - Marine plants = base if of the food chain tertiary...

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1 The Ocean Forest: Plankton, Algae, and Plants The Ocean Forest: Plankton, Algae, and Plants primary producers primary consumers secondary consumers tertiary consumer Marine plants = base if of the food chain Marine “plants” • autotrophic photosynthesizers – phytoplankton (drifters) • picoplankton / nanoplankton •d ia toms • dinoflagellates • coccolithophores – algae; aka: “seaweed” (attached) • red algae •b rown a lgae • green algae – seagrass Energy from the sun trapped by chlorophyll in “primary producers” (bacteria, algae, plants) and changed into chemical energy. Chemical energy used to build carbohydrates (food) either used by the primary producers or eaten by other organisms. 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/m 2 /yr). Primary production Phytoplankton • picoplankton / nanoplankton – discovered in the 1980’s – cyanobacteria – very small size (0.2-2 μ m or 4 to 40 millionths of an inch!) => ~100 million in every L of seawater – up to 80% of all photosynthetic activity in sea! •d ia toms • coccolithophores • dinoflagellates Prochlorococcus, a cyanobacterium. Along with Synechococcus , this extraordinary tiny creature (discovered in 1980s) dominates the photosynthetic
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2 How do we know? Plankton nets (first used on RV Meteor in 1920s!) No wonder we didn’t know about pico/nano sizes… Other methods measure: -tota lC - amount of carbohydrates produced in given volume - chlorophyll concentrations Fig. 14-2a, p. 383 “Official” vs “micro” food chain • The “official” food chain of larger planktonic organisms (green on left) contrasts with the “black market economy” of the microbial loop (red on right). • Larger planktonic organisms are unable to separate the astonishingly small cyanobacteria and microscopic consumers from the water and so cannot utilize them as food. Fig. 14-4, p. 385 Microbial loop vs “Official” food chain Fishes Microciliates microflagellates Zooplankton Decomposition, wastes Copepod Phytoplankton Cyanobacteria Wastes, decomposition Diatom Dinoflagellate ProchlorococcusSynechococcus Dissolved organic material; inorganic nutrients Diatoms • majority of phytoplankton “primary productivity” • unicellular “algae”- can be round, elongate, branched, triangular, etc. •S iO 2 “shell” (like glass) • reproduce by dividing in half (get smaller) • thought to be ~50,000 species (~12,000 described species) • occur in fresh and salt water
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3 The transparent frustrule of the diatom Coscinodiscus as shown with a light micrograph. - many small perforations that
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08 - Marine plants = base if of the food chain tertiary...

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