© 2011 pearson education, inc. chapter 13 biological productivity

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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