Transcript Spatial Distribution

Photosynthesis (Primary Production)
Requirements for photosynthesis:
• sunlight (and chlorophyll to capture energy)
• nutrients (nitrogen, phosphorus..), space
photosynthesis
CO2 + H2O
C6H12O6 + O2 + H2O
respiration
sugars, fixed carbon
Spatial Distribution
•Fig. 2.1 A spatial classification of marine organisms.
sperm whale 1150m
giant squid 1500m
octopus, 5000m
deepest fish, 8370m
Trieste, 1960, 10,912m
(Marianas Trench, 10,923m)
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
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.
Primary Production in the Sea
• Measurement
of Primary
Production
Fig. 3.20 The results of a hypothetical light- and dark-bottle experiment.
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.
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.
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.
Primary Production in the Sea
• Factors that Affect Primary Production
– Nutrient Regeneration.
Fig. 3.36 Coastal
upwelling in the
Northern
Hemisphere.
Productivity in the oceans
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.
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.
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%
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
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
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
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
sexual reproduction
Fig. 2.3 The basic
components of sexual
reproduction. The
chromosome arrangement of
each cell is shown to the
right.
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