© 2011 pearson education, inc. chapter 13 biological productivity
TRANSCRIPT
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CHAPTER 13Biological Productivity
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Primary Productivity• Photosynthesis uses solar radiation.
• Chemosynthesis uses chemical reactions.
• 99.9% of the ocean’s biomass relies directly or indirectly on photosynthesis for food.
• Ocean productivity equal to Land
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Photosynthetic Marine Organisms
• Macroscopic (large) algae
• Microscopic (small) algae
• Photosynthetic bacteria
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Microscopic Algae
• Produce food for 99% of marine animals• Most planktonic• Golden algae
– Diatoms – tests made of silica– Coccolithophores – plates of calcium carbonate
• Dinoflagellates
– Red tide (harmful algal bloom)
– Toxins
– Fish kills
– Human illness
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Microscopic Algae
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Photosynthetic Bacteria
• Extremely small
• May be responsible for half of total photosynthetic biomass in oceans
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Macroscopic Algae
“Seaweeds”•Brown algae
•Green algae
•Red algae
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Energy Flow in Marine Systems
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Factors Affecting Primary Productivity
• Nutrient availability – Nitrate, phosphorous, iron, silica– Upwelling and river runoff
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Factors Affecting Primary Productivity
• Solar radiation – Uppermost surface seawater and shallow
seafloor– Compensation depth – net photosynthesis
becomes zero– Euphotic zone—from surface to about
100 meters (330 feet)
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Color in the OceanSecchi Disk – measures water transparency
•Green Photoplankton
•Blue-no or zooplankton
•Red-dinoflagellates/red tide
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Measurement of Primary Productivity
• Directly – Nets
• Measure radioactive carbon in seawater
• Monitor ocean color with satellites – Green pigment
chlorophyll
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Upwelling and Nutrient Supply
• Cooler, deeper seawater is nutrient-rich.
• Areas of coastal upwelling are sites of high productivity.
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Upwelling and Nutrient Supply
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Comparison of Global Productivities
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Polar Ocean Productivity
• Winter darkness• Summer sunlight• Phytoplankton
(diatoms) bloom• Zooplankton (mainly
small crustaceans) productivity follows
• Example: Arctic Ocean’s Barents Sea
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Polar Ocean Productivity
• No thermocline
• Plankton remain at surface
• Blue whales migrate to feed on maximum zooplankton productivity.
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Productivity in Tropical Oceans
• Permanent thermocline is barrier to vertical mixing
• Low rate of primary productivity – lack of nutrients
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Productivity in Tropical Oceans
• High primary productivity in areas of– Equatorial upwelling
– Coastal upwelling
– Coral reefs• Recycle nutrients within the ecosystem
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Temperate Ocean Productivity• Productivity limited by
– Available sunlight– Available nutrients
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Comparison of Global Productivities
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Energy Flow in Marine Systems
• Producers – photosynthesis or chemosynthesis– Autotrophic
• Consumers– Eat other organisms– Heterotrophic
• Decomposers – break down dead organisms or waste
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Energy Flow in Marine Systems
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Trophic Levels
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Adaptations to Avoid PredationSymbiotic Relationships
• Mutualism – both organisms benefit
• Parasitism-parasite benefits at expense of host
• Commensalism –benefits one without harming host
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Mutualism
• Both organisms benefit
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Parasites
• Benefits at expense of host
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Parasites
• Benefits at expense of host
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Commensalism
• Benefits one without harming host