Life near the surface

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Marine life 3 categories:

1. Benthos: bottom dwellers; sponges, crabs

2. Nekton: strong swimmers- whales, fish, squid

3. Plankton: animal/plants that drift in water. The have little control over their movement.

Includes: diatoms, dinoflagellates, larvae, jellyfish, bacteria.

What physical factors are plankton subject to?

1. Waves

2. Tides

3. Currents

Plankton classified by:

• Size

• Habitat

• Taxonomy

Size:• Picoplankton (.2-2 µm) bacterioplankton• Nanoplankton (2 - 20 µm) protozoans• Microplankton (20-200 µm) diatoms, eggs,

larvae• Macroplankton (200-2,000 µm) some eggs,

juvenile fish• Megaplankton (> 2,000 µm) includes

jellyfish, ctenophores, Mola mola

Plankton• Holoplankton

Portuguese Man-O-War

Plankton• Meroplankton

Holoplankton orMeroplankton?

TaxonomyZooplankton Phytoplankton

Phytoplankton- restricted to the euphotic zone where light is available for photosynthesis.

Blooms:• High nutrients• Upwelling• Seasonal conditions

Primary Producers

Common NameBlue-green algae (cyanobacteria)Red algaeBrown algaeGreen algaeCoccolithophoridsDinoflagellatesDiatomsSeagrass

• Crustaceans: Copepods KrillCladoceraMysidsOstracods

• Jellies• Coelenterates (True jellies, Man-of-wars, By-the-

wind-sailors) • Ctenophores (comb jellies)• Urochordates (salps and larvacea)• Worms (Arrow worms, polychaetes)• Pteropods (planktonic snails)

Some important types of zooplankton

Importance of krill in Antarctic food web

ChaetognathCopepod

Crab larvae

jellies

Fish larvae

Queen Trigger fish Egg to Juv.

Oikopleura

Jelly-like house

Marine snow

tunicate

Marine Snow

Marine Snow

Base of Florida Escarpment covered with marine snow. Octocorals attach to steep sides and under ledges to avoid burial.

A major component of marine snow is fecal pellets

Marine Snow

Ocean Productivity

Importance of Phytoplankton

Phytoplankton population decline causes zooplankton and apex predators to decline .

Phytoplankton is the base of the food chain.

Regional productivity

• Photosynthetic productivity varies due to:

– Amount of sunlight – Availability of nutrients

• Thermocline (a layer of rapidly changing temperature) limits nutrient supply

• Examine three open ocean regions:1. Polar oceans (>60° latitude)2. Tropical oceans (<30° latitude)3. Temperate oceans (30-60° latitude)

Productivity in tropical, temperate, and polar oceans

Zooplankton

Productivity polar oceans

Productivity in tropical oceans

Productivity in temperate oceans

Solar Energy

Microbial Loop

CO2

nutrients

Phytoplankton

Herbivores

Planktivores

Piscivores

DOC

Bacteria Nanoplankton(protozoans)

Diurnal vertical migration

Organisms within the deep scattering layer undertake a daily migration to hide in deep, darker waters during daytime

Plankton PatchinessPlankton Patchiness

• Zooplankton not distributed uniformly or randomly

• Aggregated into patches of variable size

Causes of PatchinessCauses of Patchiness• Aggregations around phytoplankton

- If phytoplankton occurs in patches, grazers will be drawn to food- Similar process that led to phytoplankton patches will form zooplankton patches

• Grazing “holes”• Physical process

- Langmuir Cells- Internal waves

Accumulation of Plankton Accumulation of Plankton in Langmuir Cellsin Langmuir Cells

• Buoyant particles and upward-swimming zooplankton will accumulate over downwelling zones

Langmuir Cells

Internal Waves• Underwater

waves propagated along the thermocline

• Generated by overflow over rough topography

• Much greater amplitude than surface waves

Satellite image of internal wave

Deep sea scattering layer:Deep sea scattering layer:Composite echogram of hydroacoustic data showing a distinct krill scattering layer.Black line represents surface tracking of a blue whale feeding

patchiness

Planktivory

Sponges

Filter feeding in Aurelia (Moon Jelly)

Jellyfish

Corals

HermatypicAhermatypic

Bivalves

                                 

                                                         

lancet

Christmas tree worms

Filter feeding in Krill

the six thoracopods form a very effective "feeding basket"

Barnacle feeding

Modified legs

Predator

Filter feeder

Oikopleura

tunicate

Gill Rakers

Includes: manta rays, basking shark, whale shark, megamouth, paddlefish, gizzard shad, menhaden, and bighead carp.  

Flamingo

Manta Ray

Paddle fish

Basking Shark Gill Arches

Basking Shark Gill Arches

• Gill rakers shed during cold months.• May be hibernation

Continuous ram feeding

Intermittent ram feeders

Sling jaw Wrasse

http://www.youtube.com/watch?v=pDU4CQWXaNY

Inquiry

1. Why is the open ocean a biological desert?2. Where are the most productive regions

located?3. Describe productivity in temperate, polar and

tropical water.4. Why does the zooplankton lag behind the

phytoplankton?5. If you want to catch microplankton, what size

mesh net do you need?6. Why does eutrophication sometimes result in

mass fish kills?

Inquiry

7. Where do plankton aggregate?8. What is the difference between

holoplankton and meroplankton?9. What is marine snow composed

of?10. What is the connection between

the deep sea scattering layer and DVM?

11.Why aren’t phytoplankton found in neuston?

Inquiry

12. Describe key characteristics of nocturnal and diurnal planktivorous fish.

13. What types tools do animals use to catch plankton.