Topic 22 Plankton

GEOL 2503Introduction to Oceanography

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Characteristics

• Floating organisms that drift with currents (although some forms are weak swimmers)

• Generally microscopic although some forms larger

• Largest biomass on the planet

A micrometer (m) is one millionth of a meter, one thousandth of a millimeter

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Reason for small size

• Related to buoyancy. The smaller an organism the greater the surface area relative to weight

• Surface area often increased by development of pores or spines

• Flotation sometimes improved by secretion of low density oil

• Rely on turbulence to stay afloat

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Bacterioplankton

• Kingdom Monera, smallest living organisms. Difficult to capture even with finest net

• Most abundant organisms (planet & ocean)• Live at all ocean depths as free-living

decomposers

Phytoplankton

• Floating plants• 99.9% of the food source in the oceans• Mainly protista living in epipelagic zone• Diatoms—siliceous plants• Dinoflagellates—microscopic with flagella

for minor locomotion• Cocolithophores—calcareous plants

Plankton are an energy source for marine ecosystemsMany plankton are primary producers. Over 90% of marine primary production (energy produced) is from phytoplankton! The rest is from marine plants and other sources.

This map shows productivity in the Oceans. Red and yellow are most productive, followed by green and blue. Black is least productive.

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Coccolithophore:calcareous phytoplankton

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Diatoms

• Single celled photosynthetic Protista which secrete small shell of SiO2

• Reproduce by cell division until organism becomes too small; then develop auxospore

• May discolor water during large blooms

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Marine diatoms as seen through a microscope.Image ID: corp2365, NOAA At The Ends of the Earth Collection Photographer: Dr. Neil Sullivan, University of Southern Calif.

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Centric diatoms

Chain diatoms

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Diatoms and other phytoplankton can divide many times per day producing large blooms that are sometimes visible from space.

Blooms

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Dinoflagellates

• Single celled Protista (most but not all photosynthetic)

• Naked cell or covering of cellulose• Two whip-like flagella allow motility• Some forms bioluminescent• Blooms responsible for toxic red tides

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19Sargassum--brown algae

Zooplankton

• Floating animals (consumers)• Most abundant in epipelagic zone but also

occur in mesopelagic zone• Foraminifera—single celled, calcareous• Radiolaria—single celled, siliceous• Krill—shrimp-like, food for baleen whales• Jellyfish—multicellular, colonial

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Foraminifera & Radiolaria

• Microscopic Protista which feed on phytoplankton

• Foraminifera secrete shell of CaCO3

• Radiolaria secrete shell of SiO2

Foraminifera—calcareous zooplankton

Foraminifer

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Radiolaria—siliceous zooplankton

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A living radiolaria

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Medusa jellyfish

Moon Jelly

Gelatinous zooplankton common in temperate and tropical waters, stinging cells are not toxic and don’t sting like other jellyfish, 95% water but serve as food for many animals including turtles , feed by producing a sticky mucus that traps other plankton

Image ID: reef2547, NOAA's Coral Kingdom Collection Photographer: Florida Keys National Marine Sanctuary StaffCredit: Florida Keys National Marine Sanctuary (moon jelly) 28

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Siphonophore

30Comb jelly

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• Simple crustacean with jointed exoskeleton• Use enlarged first antenna to swim• Among the most common animals on Earth (most abundant of

the net zooplankton)

Image ID: fish3229, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC

Copepod

Not as abundant as copepods they aggregate into huge, dense schools, prefer colder polar waters, feed on diatoms and solid wastes of other zooplankton, important food for whales, tread water to stay afloat. Image ID: sanc0126, NOAA's Sanctuaries Collection

Location: Gulf of the Farallones National Marine SanctuaryPhotographer: Jamie Hall

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Krill

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Pteropods (mollusks)

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Holoplankton

• Regular old plankton• Spend their entire life cycle as plankton• Examples include: dinoflagellates, diatoms,

foraminifera, krill

Meroplankton

• Planktonic larval stages of animals which are not planktonic as adults

• Larvae of snails, fish, barnacles, coral, etc.• Egg cases

Crab Larva

• Some invertebrates have a whole series of different larval stages

• Charleston Bump Expedition. Zooplankton. Crab larva.

Image ID: expl0215, Voyage To Inner Space - Exploring the Seas With NOAA CollectLocation: Southeast of Charleston, South CarolinaPhoto Date: 2003 August 10Photographer: Jerry MclellandCredit: Charleston Bump Expedition 2003. NOAA Office of Ocean Exploration; Dr. George Sedberry, South Carolina DNR, Principal Investigator 36

Brittle star larva Skate egg case

Octopus Larva

Temporary members of the plankton, octopus and squid become nektonic (free swimming) and benthic (crawling). Giant squid are the largest invertebrates in the ocean

Zooplankton. Octopus larva. Image ID: fish3612, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC38

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Barnacle Larva

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Fish Larvae

Coastal waters are rich in meroplankton (temporary members of the plankton)Nearly all marine fish have planktonic larvaeFish larvae may change from herbivores to carnivores as they grow

Image ID: fish3363, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC