Plankton

1
Plankton
Marine life is classified into three groups
Plankton, Nekton, and Benthos
Benthos
2
Plankton

• Plankton refers to the drifting organisms within
  the pelagic zone
• Phytoplankton are autotrophic, photosynthetic
  algae, which form the base of the marine food web
• Zooplankton are heterotrophic the primary (and
  in some cases secondary and tertiary) consumers
  of the marine food web

3
Plankton form the base of the marine food web
4
Bottom of the Food Chain
5
How are plankton classified?

• By Metabolism (autotrophic vs. heterotrophic)
• By Life History (meroplankton vs. holoplankton)
• By Taxonomy (Crustaceous vs. Gelatinous
  zooplankton, for example)

http//www.whoi.edu/annualreport02/highlights/glob
ec_en3.html
6
Phytoplankton

• Phytoplankton are responsible for 40 of all the
  worlds photosynthetic food on Earth (and 95 of
  all the oceans!)
• Provide one half of all the oxygen we breathe!
• Collectively, the production of organic compounds
  from CO2 is referred to as primary productivity

7
Phytoplankton

• Phytoplankton require nutrients, especially
  nitrogen and phosphorus (macronutrients) but also
  iron (micronutrients)
• For this reason, phytoplankton appear in
  abundance (blooms) in regions of upwelling,
  where cold, nutrient-rich water reaches the
  photic zone

8
(No Transcript)
9
Global Primary Productivity
http//www.nasa.gov/centers/goddard/images/content
/95573main_plankton_satellite.jpg
10
Localized Primary Productivity

• In tropical regions, there is plenty of sunlight
  but productivity is limited by nutrients trapped
  beneath the thermocline
• In polar regions, there are plenty of nutrients,
  but sunlight (and sinking out of the photic zone
  via mixing) limits productivity
• In temperate regions, the combination of sunlight
  and nutrients is just right, but only seasonally!

11
Tropical Productivity Profile
12
Primary Productivity in Temperate Regions

• Localized primary productivity occurs seasonally,
  accompanied by physical changes to the water
  column
• In temperate regions, primary productivity is
  limited by light (winter) and by nutrients
  (summer)
• Peak productivity occurs during spring, in an
  abundance of phytoplankton known as a spring
  bloom

13
(No Transcript)
14
Primary Productivity in Temperate Regions

• During winter, nutrients are at their highest,
  but light is at its lowest
• In spring, solar energy reaching the photic zone
  increases and nutrients are still abundant
• In summer, strong warming of the water creates a
  seasonal thermocline which restricts nutrients
  from reaching the photic zone
• In fall, storms enhance mixing, and a second
  seasonal bloom results

15
(No Transcript)
16
Compensation Depth

• Net primary productivity is the amount of carbon
  dioxide removed via photosynthesis minus the
  amount of carbon dioxide released by respiration
• Compensation depth refers to the depth in the
  water column at which the rate of photosynthesis
  equals the rate of respiration
• Above this depth, phytoplankton survive
• Below this depth, phytoplankton die

17
(No Transcript)
18
Phytoplankton

• Phytoplankton are mostly single-celled algae
  (Kingdom Protista)
• There are 8 major types of phytoplankton, 2 of
  which are most prominent
• Diatoms
• Dinoflagellates

19
Diatoms

• Dominant (gt5,600 species)
• Composed of silica shells
• Important source of nutrition for zooplankton

v
20
Dinoflagellates

• Can be autotrophic or heterotrophic!
• Most are planktonic, but others form symbiotic
  relationships with coral (zooxanthellae) and
  giant clams
• Flagella for movement
• Responsible for red tides
  (harmful algal blooms)

21
Red Tide caused by Dinoflagellate
22
Harmful Algae Blooms (HABs)
Caused by dinoflagellates and other small
flagellates
23
Zooplankton

• Zooplankton are the most numerous primary
  consumers in the ocean
• The most important source of protein in the
  oceans!
• Zooplankton eat bacteria, phytoplankton, and
  other zooplankton!
• Nearly every major animal group is represented in
  the zooplankton

24
Zooplankton

• Zooplankton are classified as either
• Holoplankton
• Meroplankton

• Holoplankton are always plankton they live and
  die in the water column
• Meroplankton are only plankton for part of their
  lives many marine organisms begin their lives as
  small planktonic organisms, but gain the ability
  to swim or metamorphose into a benthic organism

25
Holoplankton
Once a copepod, always a copepod
26
Meroplankton

• Includes larval (very young) fish, crabs, clams,
  squid, lobsters, starfish, etc.

27
(No Transcript)
28
Types of Zooplankton Copepods

• Copepods are the most abundant of all the
  zooplankton (70)
• Holoplanktonic
• Crustaceous
• Herbivorous, Omnivorous, Carnivorous, and
  Parasitic
• Marine and freshwater

29
Copepods

• 14,000 species globally
• You, too, can become a copepodologist!
• Important source of protein for secondary
  consumers!

30
Types of Zooplankton Pteropods
Composed of calcium carbonate, CaCO3
31
Jellyfish and ctenophores are gelatinous
zooplankton!
32
Avoiding Predation

• Translucence and Transparency
• Outward spines for protection
• Swimming behavior and migration

33
The Greatest Migration on Earth
Increasing Depth
34
(No Transcript)
35
Deep-Scattering Layer
36
How to capture zooplankton
37
Quantitative Zooplankton Tows
38
Think Like Plankton

• Life in a pelagic habitat (no solid substrate)
  3-D
• Properties of water

39
Properties of Water

• Water is viscous, ESPECIALLY if you are a very
  small organisms living in it
• Reynolds number
• Re inertial forces

viscous forces
40
Reynolds Number

• For very small organisms, inertia is
  non-existent
• Viscous forces dominate (low Reynolds number)
  for small organisms, such as plankton!
• Inertial forces dominate (high Reynolds number)
  for larger organisms, such as humans, large fish
  or whales

41
Reynolds Number
http//brodylab.eng.uci.edu/jpbrody/reynolds/figu
re3.gif
42
(No Transcript)