1. Phytoplankton and Seaweeds: Salad Bar of
the Sea
- Photosynthesis and Food Webs
- Large Marine Plants - Seaweeds
- Small Marine Plants - Phytoplankton
Reading:
4th Ed., Ch 14 Secs 2-5, 7-8, 10-12, 15-16, 19-23
5th Ed., Ch 13 Secs 3-6, Ch 14 Secs 2, 4-6, 9, 11-12, 14-18
Graphic: Kelp, one of the largest marine plants. National Ocean Service Photo
Gallery.
2. Flows of Energy
Energy flows from the sun to organisms and is ultimately lost
Producers - build organic material from sunlight (photosynthesis)
Consumers - use organic material for energy (respiration)
Graphic: Garrison, 4th Ed., Fig. 14.1, pg 348, 5th Ed. Fig. 13.2, pg 306.
3. Cycles of Matter
Matter cycles between producers and consumers
Products of photosynthesis are used for respiration
Products of respiration are used for photosynthesis
Graphic: Garrison, 4th Ed., Fig. 14.2, pg 349.
4. Photosynthesis
Photosynthesis binds energy into large organic molecules:
sunlight
6 CO2 + 6 H2O -->
C6H12O6 + 6 O2
carbon water
glucose
oxygen
dioxide
(carbohydrate)
- Done by plants during sunlit hours
- The basis for most life on Earth
Graphics: Top: Marsh plant, South Carolina. NOAA National Estuarine Reserve
Collection. Bottom: Red algae. National Museum of Natural History and the
Smithsonian Institution.
5. Respiration
Respiration converts organic matter to energy:
C6H12O6 + 6 O2
--> 6
CO2 + 6 H2O + chemical energy
glucose oxygen
carbon dioxide water
- Energy used for metabolism, movement, maintaining body heat
- Done by both plants and animals
Graphic: Top: Emperor penguins , M. Van Woert, photographer. Bottom: Moonrise on
Hobart Bay, Cmdr. J. Bortnaik, photographer. Courtesy of NOAA.
6. Terrestrial (Land) and Marine Plants*
Both need sunlight, CO2, nutrients and water, but...
- Land plants access water and nutrients via roots (favors large plants)
- Most ocean plants need to float to remain within the sunlit zone (favors very
small plants)
Graphic: Pinet, Fig. 14.9.
7. Comparison of Marine and Land Plants
Property
Land Plants
Marine Plants
Obtaining nutrients
roots
exchange across cell walls
Obtaining sunlight
expansive leaves float in euphotic zone
Structural support
trunks, stems little
or none required
Size
usually large
usually small
Graphics: (left) Coastal forest, courtesy of NOAA, (right) C.Wighamii, National
Ocean Service Photo Gallery.
8. Marine Food Webs
Graphic: Garrison, 4th Ed., Fig. 14.4, pg 351, 5th Ed., Fig. 13.6, pg 310.
9. Trophic Transfers
Only about 10% of food is stored in consumers as flesh
- each trophic step is about 10% of the mass of the step below
- large organisms are less common than small organisms
- most marine communities depend on plants for their “base”
Graphic: Garrison, 4th Ed., Fig. 14.3, pg 350, 5th Ed., Fig. 13.5, pg 309.
10. Marine Plants – Limited by Light
The vertical distribution of marine plants is controlled by the availability of
light
Below the euphotic zone, there is not enough light for photosynthesis
The depth of the euphotic zone depends on water clarity (the amount of suspended
material in the water)
Graphic: Garrison, Fig 13.11, 4th Ed., pg 334, 5th Ed., pg 316.
11. Marine Plants – Limited by Nutrients
The horizontal distribution of marine plants is controlled by the availability
of nutrients (i.e., fertilizer)
Nutrients are in short supply in much of the euphotic zone except where
upwelling or vertical wind mixing brings nutrients to the surface
Graphics: Garrison (top) 4th Ed., Fig. 9.15a, pg 221, 5th Ed., Fig. 9.16a, pg
213, (bottom) 4th Ed., Fig. 9.14a, pg 220, 5th Ed., Fig. 9.15a, pg 212.
12. Where are the Plants?
Most ocean areas are biological “deserts” with low productivity
Exceptions: coastal and equatorial upwelling zones, zones of vigorous wind
mixing
Image provided by the SeaWiFS project, NASA/Goddard Space Flight Center and
Orbimage.
13. Seaweeds - Large Marine Plants
- Multicellular
- Lack vascular systems
- Most attach to a substrate
- Account for 2-5% of marine primary productivity
- Economically important
Graphic: Kelp forest, Channel Islands National Marine Sanctuary Collection.
Courtesy of NOAA.
14. Algae and Color
Marine plants have many pigments to take advantage of the penetration of
different colors of light in the ocean
- primary = chlorophyll (green)
- accessory = brown, red, tan etc
Green algae (chlorophytes) 0-10 m
Brown algae (phaeophytes) 0-35 m
Red algae (rhodophytes) to 250 m
Graphic: (top) Garrison, 4th Ed., Fig. 13. 11b, pg 334, 5th Ed., Fig. 13.11b, pg
316, (center) Brown algae, A.Shepard (OAR/NURP), (bottom), Red algae, National
Estuarine Research Reserve Collection.
15. Phytoplankton - Small Marine Plants
- Small and free-floating
- Energy obtained via photosynthesis
- Very abundant, 90-96% of total ocean primary productivity
Small size allows:
- diffusion of nutrients into cells and transfer of wastes out
- efficient use of cellular material
Graphic: Phytoplankter. Courtesy of NASA Goddard Space Flight Center.
16. Diatoms - Phytoplankters Living in Glass Houses
- Dominant type of phytoplankton
- Forms silica "shells"
- Store energy as oils (floatation)
- Free floating (no locomotion)
- Can live singly or form long chains
Graphic: Diatom morphology, courtesy of the SeaWiFS project, NASA/GSFC and
ORBIMAGE.
17. Coccoliths
Single-celled plants covered with calcium carbonate disks
Turn seawater "milky" during blooms
Shells can form thick sedimentary deposits
Graphics: Coccoliths, courtesy of the SeaWiFS project, NASA/GSFC and ORBIMAGE.
18. Dinoflagellates
Single-celled plants that use flagella (whiplike appendedges) to adjust position
and orientation
Many species are toxic and can cause harmful algal blooms
Graphics: (top) Dinoflagellate. Courtesy NASA Goddard Space Flight Center,
(center) Garrison, 4th Ed., pg 361, 5th Ed., pg 339, (bottom) courtesy of the
SeaWiFS project and NASA/GSFC.
19. Primary Productivity
Primary productivity = synthesis of organic matter from inorganic substances
Expressed in grams of carbon per unit area per unit time (grams/meter2/day or
grams/meter2/year)
Graphic: Garrison, 4th Ed., Fig. 14.5a, pg 352, 5th Ed., Fig. 13.3a, pg 307.
20. Variations in Primary Productivity
Primary productivity is regionally variable
Some of the most productive ecosytems on Earth are marine
Graphic: After Garrison, 4th Ed. Fig. 14.5c, pg 352, 5th Ed. Fig. 13.3c, pg 307.
21. Seasonal Patterns of Primary Productivity
Tropical regions have nearly constant production levels
Mid-latitudes (temperate regions) have Fall and Spring blooms
Polar regions have short summer growing seasons
Graphic: (left) Garrison 4th Ed., Fig 14.17, 5th Ed., Fig. 14.10 pg 345, (right)
plant pigment concentration in the ocean, provided by the SeaWiFS Project,
NASA/Goddard Space Flight Center and ORBIMAGE.
22. The Spring Bloom
The shift from winter to spring is marked with an explosion in the abundance of
marine phytoplankton
Conditions needed:
- abundant light, nutrients
- warm, calm conditions
- low grazing rates by animals
Graphics: Ocean color (top) Feb 2001, (bottom) May 2001. Images courtesy of
SeaWiFS and Orbimage. (animation)
23. Preview of Next Lecture
Spineless Wonders
Reading:
4th Ed., Ch 15 Secs 2-6, 8-13
5th Ed., Ch 15 Secs 2-8, 10-14
Graphics: (top) "Mystery Squid", NOAA and Science, (middle) Lima sea star,
K.Evans, photographer. Courtesy of National MarineSanctuaries Photo Gallery.
(bottom) Red shrimp. National Ocean Service Photo Gallery.