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Primary Producers

Kelp forests are one of the ocean’s most productive habitats.

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Key Ideas

l Energy flows through living systems, but matter is recycled.

l Primary producers (autotrophs) synthesize glucose byphotosynthesis or chemosynthesis.

l Heterotrophs cannot synthesize glucose; they must consumeautotrophs or other heterotrophs for food.

l Feeding relationships resemble webs.

l Phytoplankton are some of the world’s most importantproducers; zooplankton are the most abundant consumers in theocean.

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Capture and Flow of Energy

Most of the energy used by marine organisms to makefood comes from the sun.

Photosynthesis is the process used by mostproducers to convert the sun’s energy to food energy.

Chemosynthesis is the production of food in theabsence of light using chemical energy.

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Flow of Energy Through Living Systems

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Cycling of Matter Through Living Systems

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Terms used to describe feeding relationships:

Autotrophs – organisms that make their own food, also calledproducers.

Heterotrophs - organisms that must consume other organisms forenergy

Trophic pyramid - a model that describes who eats whom

Primary consumers - organisms that eat producers

Secondary Consumers - organisms that eat primary consumers

Top consumers - the top of the trophic pyramid

Feeding Relationships

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Feeding Relationships

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Primary Productivity

Synthesis of organic material from inorganic substances isprimary productivity.

Primary productivity is measured in grams of carbonbound into organic material per square meter of oceansurface per year, or, more simply:

gC/m2/yr

Recent studies suggest that total ocean productivity isbetween75 gC/ m2/yr and 150 gC/ m2/yr.

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Primary Productivity

Oceanic productivityis measured ingC/ m2/yr.

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Factors That Limit Productivity

lWaterlCarbon dioxidelInorganic nutrientslSunlight

Since water and carbon dioxide are in goodsupply in the ocean, the factors that usually limitmarine primary productivity are inorganicnutrients and sunlight.

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Phytoplankton are drifting autotrophs of many species. They are collectedand studied using plankton nets.

Phytoplankton

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Types of Phytoplankton

Diatoms - the dominant and most productive ofthe plankton; tests of silica

Dinoflagellates and silicoflagellates- useflagella to move

Coccolithophores - tests of calcium carbonate

Nanoplankton and picoplankton -encompasses most other types of plankton; verysmall.

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The euphotic zoneis the site ofphotosyntheticproduction.

The Euphotic Zone

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Productivity Versus Respiration

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Compensation Depth

The balance between respiration and photosynthesis at different depths.The compensation depth is the “break even” depth.

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Productivity indifferent

regions duringthe year.

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Mid-Latitude Productivity

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Tropical Productivity

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Global Distribution of PlanktonProductivity

The distribution of phytoplankton corresponds to the distribution ofmacronutrients. The productivity of plankton varies between theseasons.

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Productivity Versus Standing Crop

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Productivity of Oceanic Environments

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Some oceanic autotrophs are attached (plankton are drifters).Attached autotrophs are forms of protists commonly called algae orseaweed. Seaweeds can be classified based on the type of pigmentsthey have.

Chlorophytes are green due to the presence of chlorophyll and thelack of accessory pigments.

Phaeophytes are brown; they contain chlorophyll and a secondarypigment.

Rhodophytes get their red color from accessory pigments.

Larger Marine Producers

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Marine Angiosperms

Angiosperms are advanced vascular plants thatreproduce with flowers and seed. Most angiosperms arefound on land but a few species are found in oceanenvironments.

Sea grasses are found on the coasts and are veryproductive compared to phytoplankton.

Mangroves are found in tropical lagoons, bays andestuaries.