Photosynthesis (Primary Production)

1
Photosynthesis (Primary Production)

• Requirements for photosynthesis
• sunlight (and chlorophyll to capture energy)
• nutrients (nitrogen, phosphorus..), space
• CO2 H2O C6H12O6 O2 H2O

photosynthesis
respiration
sugars, fixed carbon
2
Spatial Distribution

• Fig. 2.1 A spatial classification of marine
  organisms.

3
sperm whale 1150m giant squid 1500m
octopus, 5000m
deepest fish, 8370m
Trieste, 1960, 10,912m (Marianas Trench, 10,923m)
4
Light in the ocean
Water not very transparent to light Photic zone
where enough light penetrates for
photosynthesis Range few meters in coastal
zone, to 200 m in clear, tropical ocean Affected
by transparency of water angle of sunlight
hitting the water atmospheric absorption of
light
5
Primary Production in the Sea
Factors that Affect Primary Production

• Light in Water.

• Fig. 1.21 Fate of sunlight as it enters sea
  water. The violet and red ends of the visible
  spectrum are absorbed first.

6
Primary Production in the Sea

• Measurement of Primary Production

Fig. 3.20 The results of a hypothetical light-
and dark-bottle experiment.
7
Primary Production in the Sea

• Fig. 3.22 This phytoplankton bloom along the
  California coast, was imaged by SeaWiFS on 10-11
  August, 2003 for true color (left) and for
  chlorophyll a concentrations.

8
Primary Production in the Sea

• Factors that Affect Primary Production
• Nutrient Regeneration. Marine producers rely on a
  number of mechanisms of nutrient regeneration,
  such as turbulent mixing, convective mixing, and
  upwelling.

9
Primary Production in the Sea

• Nutrient regeneration

Fig. 3.35 Seasonal growth and decline of
thermoclines in tropical (top), temperate
(center), and polar (bottom) ocean waters.
10
Primary Production in the Sea

• Factors that Affect Primary Production
• Nutrient Regeneration.

Fig. 3.36 Coastal upwelling in the Northern
Hemisphere.
11
Productivity in the oceans
12
Primary Production in the Sea

• Factors that Affect Primary Production
• Grazing. Small herbivorous grazers routinely
  occur at such high concentrations that
  phytoplankton communities may be destroyed over a
  period of just a few weeks.

13
Primary Production in the Sea
Factors that Affect Primary Production

• Grazing.

• Fig. 3.24 Generalized population changes of a
  prey species and its predator, oscillating
  between unlimited (solid) and limited (dashed)
  phases of population growth.

14
Contribution to Primary Production in Ocean

• One-celled plankton contribute 90-95 of primary
  productivity in the ocean
• Macroalgae (large, attached algae in the coastal
  zone) contribute 5-10

15
marine snow particulate organic matter that
originates in the ocean
Formed by collisions of debris and large
particles, or decaying material, with bacteria
and protists attached. Sinks to bottom,
carrying nutrients away from surface.
e.g., dead pelagic tunicate covered with bacteria
and protists http//life.bio.sunysb.edu/marinebio/
plankton.html
16
Vertical migration of zooplankton
Definition Migration pattern over 24 hrs,
typically upwards at dusk and downwards at
dawn,poorly understood, Why migrate? Several
hypotheses Avoid visual predators during
daylight at greater depths and return to shallow
zones with abundant food during night Save
energy during non-feeding daylight time in
deeper, colder water Exploit different currents
at different depths and remain in same general
area, or ascend to fresh, ungrazed food
resources the next day Range up to 200 m
(copepods) to 800 m (krill) speed 10 200
m/hour http//www.jochemnet.de/fiu/OCB3043_25.html
17
Vertical migration of zooplankton

• Consequences
• faster transport of organic matter into deep
  water
• animals capture prey at shallower depths and
  transport it downwards
• either as their body mass or fecal products both
  are faster than sedimentation
• Not all individuals migrate the same range at
  the same time
• population will lose some and gain others,
  enhances genetic mixing
• Samples from same depths taken during day and
  night will differ in
• species composition and total biomass
• http//www.jochemnet.de/fiu/OCB3043_25.html

18
Vertical migration of zooplankton
Deep Scattering Layers False echosound
signals by larger zooplankton (krill, shrimp)
and fish, but sometimes also copepods, makes
ocean seem to have a false bottom Military
interest in this DSL (submarines can hide under
the layer) http//www.jochemnet.de/fiu/OCB3043_25
.html
19
sexual reproduction
Fig. 2.3 The basic components of sexual
reproduction. The chromosome arrangement of each
cell is shown to the right.
20
Sexual vs Asexual Reproduction

• Asexual reproduction no genetic recombination
  cloning, budding, fission
• Sexual reproduction reduction division to
  produce gametes (half of parent DNA), combine to
  form a genetically mixed zygote different from
  either parent

21
(No Transcript)
22
(No Transcript)
23
(No Transcript)