life near the surface 015a. marine life 3 categories: 1.benthos: bottom dwellers; sponges, crabs...
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Life near the surface
015a
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
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.