Transcript Feb 5 - University of San Diego

I.
Zonation
C.
Depth Zones
2.
Benthic
c.
d.
Sublittoral (Mean low water to edge of continental shelf)
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Region of sea floor underlying neritic zone (8%)
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Character of zone changes with depth and distance
offshore: concentrations of benthic algae decrease,
hard substrate replaced by soft substrate
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Highly productive; supports higher densities of
organisms than deeper zones
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Vast majority of large benthic species live in this zone
Bathyal (200–4000 m)
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Essentially no primary production
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Organismal densities decrease with increasing depth
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Within this zone, physical parameters change
dramatically: light availability, temperature, [O2]
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Covers 16% of sea floor
I.
Zonation
C.
Depth Zones
2.
Benthic
c.
d.
Abyssal (4000-6000 m)
•
Largest ecological region on earth
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Covers 75% of sea floor (>50% of earth’s surface)
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Light virtually absent, pressure high, cold, food scarce
and somewhat unpredictable in space & time
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Organisms difficult to study and poorly known,
compared to shallow-living relatives
Hadal (6000–11,000 m)
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Oceanic trenches
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Trenches may accumulate organic detritus (food) that
may form basis of trench food webs
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Organisms difficult to study and not well known
II.
Ocean Circulation
A.
Surface Currents
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Driven by winds
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Surface currents deflected to right/left of wind direction
by Coriolis Effect
Anticyclonic gyres in major basins
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Clockwise in N. Hemisphere
Counterclockwise in S. Hemisphere
Fig. 4-14
Fig. 4-15
II.
Ocean Circulation
A.
Surface Currents
•
Driven by winds
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•
Anticyclonic gyres in major basins
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•
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Clockwise in N. Hemisphere
Counterclockwise in S. Hemisphere
Currents transport heat from equator to poles
•
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Surface currents deflected to right/left of wind direction
by Coriolis Effect
Why is Antarctica covered with ice today?
Surface temperatures higher on western
margins of ocean basins vs. eastern margins
II.
Ocean Circulation
B.
Vertical Circulation
•
Thermohaline circulation
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Driven by unstable water column with denser water at
surface
Drives Great Ocean Conveyor
Fig. 4-16
II.
Ocean Circulation
B.
Vertical Circulation
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Thermohaline circulation
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•
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Driven by unstable water column with denser water at
surface
Drives Great Ocean Conveyor
Upwelling and Downwelling
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Driven by wind
Fig. 4-22
III.
Marine Microbes
A.
Marine Viruses
•
B.
Not alive in traditional sense
Marine Bacteria
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C.
Organized by nutritional mode and taxon
Archaea
•
D.
“Extremophiles”
Eukarya
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•
•
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Fungi
Stramenopiles
Haptophytes
Alveolates
Choanoflagellates
Amoeboid Protozoans
Fig. 6-1
III. Marine Microbes
A.
Marine Viruses
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Virion outside of host cell
10x as abundant as marine bacteria
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Up to 1010 virions per liter
DNA or RNA encapsulated in protein capsid
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DNA viruses
Helical tail
Two basic life cycles: lytic, lysogenic
Ecologically important
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•
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Facilitate breakdown of microbial blooms
Alter food/nutrient availability
Cause diseases in marine animals
Fig. 6-3
Fig. 6-2
III. Marine Microbes
A.
Marine Viruses
•
•
Virion outside of host cell
10x as abundant as marine bacteria
•
•
Up to 1010 virions per liter
DNA or RNA encapsulated in protein capsid
•
•
•
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DNA viruses
Helical tail
Two basic life cycles: lytic, lysogenic
Ecologically important
•
•
•
Facilitate breakdown of microbial blooms
Alter food/nutrient availability
Cause diseases in marine animals
Fig. 6-4
III. Marine Microbes
A.
Marine Viruses
•
•
Virion outside of host cell
10x as abundant as marine bacteria
•
•
Up to 1010 virions per liter
DNA or RNA encapsulated in protein capsid
•
•
•
•
DNA viruses
Helical tail
Two basic life cycles: lytic, lysogenic
Ecologically important
•
•
•
Facilitate breakdown of microbial blooms
Alter food/nutrient availability
Cause diseases in marine animals
III. Marine Microbes
B.
Marine Bacteria
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Many shapes - spheres, coils, rods, rings
Very small cells (usually less than 1 μm across)
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May be very large (by bacterial standards)
Coccus
Bacillus
Spirillum
Fig. 6-5
III.
Marine Microbes
B.
Marine Bacteria
1.
Autotrophic
a.
b.
2.
Photosynthetic
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Energy from sunlight
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Contain chlorophyll or other photosynthetic pigments
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Important primary producers in open ocean
i.
Cyanobacteria (aerobic) – Some perform nitrogen
fixation
ii.
Purple and green photosynthetic bacteria (anaerobic)
Chemosynthetic
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Obtain energy from chemical compounds
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Ex: Hydrogen, hydrogen sulfide, ammonium ion
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Often anaerobic, may be symbiotic
Heterotrophic
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Most are decomposers (break down organic material)
Important in nutrient cycling
May be symbiotic
Fig. 6-8
III.
Marine Microbes
B.
Marine Bacteria
1.
Autotrophic
a.
b.
2.
Photosynthetic
•
Energy from sunlight
•
Contain chlorophyll or other photosynthetic pigments
•
Important primary producers in open ocean
i.
Cyanobacteria (aerobic) – Some perform nitrogen
fixation
ii.
Purple and green photosynthetic bacteria (anaerobic)
Chemosynthetic
•
Obtain energy from chemical compounds
•
Ex: Hydrogen, hydrogen sulfide, ammonium ion
•
Often anaerobic, may be symbiotic
Heterotrophic
•
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Most are decomposers (break down organic material)
Important in nutrient cycling
May be symbiotic
Fig. 6-11
III.
Marine Microbes
B.
Marine Bacteria
1.
Autotrophic
a.
b.
2.
Photosynthetic
•
Energy from sunlight
•
Contain chlorophyll or other photosynthetic pigments
•
Important primary producers in open ocean
i.
Cyanobacteria (aerobic) – Some perform nitrogen
fixation
ii.
Purple and green photosynthetic bacteria (anaerobic)
Chemosynthetic
•
Obtain energy from chemical compounds
•
Ex: Hydrogen, hydrogen sulfide, ammonium ion
•
Often anaerobic, may be symbiotic
Heterotrophic
•
•
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Most are decomposers (break down organic material)
Important in nutrient cycling
May be symbiotic
Fig. 6-14
III.
Marine Microbes
C.
Archaea
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Resemble bacteria superficially but may be more closely
related to eukaryotes than bacteria
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Very small cells (0.1 – 15 μm)
Heterotrophs or autotrophs (photo- or chemosynthetic)
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Many methanogens
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Some fix nitrogen
Important decomposers
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Abundant in sediments
Extremophiles
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Deep sea (barophiles)
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Hydrothermal vents (thermophiles)
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Salt ponds/lakes (halophiles)
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Antarctic (psychrophiles)
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Acid/Alkaline lakes (acidophiles)
III. Marine Microbes
D.
Eukarya
1.
Fungi
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Unicellular or multicellular (produce hyphae)
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Body = mycelium
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Mostly microscopic
Cell walls made of chitin
Heterotrophic
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Important decomposers, esp. of wood
Some pathogenic forms
Host to algae in lichens
Fig. 6-17
III. Marine Microbes
D.
Eukarya
2.
Stramenopiles (Heterokonts)
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Diverse group
Bear two different flagella at some point in life cycle
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One complex with mastigionemes
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Photosynthetic and nonphotosynthetic forms
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Photosynthetic = Ochrophytes
a. Diatoms
b. Silicoflagellates
Fig. 6-18
III. Marine Microbes
D.
Eukarya
2.
Stramenopiles (Heterokonts)
a.
Diatoms
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Unicellular; may form chains
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Cell enclosed by silica frustules (test)
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Shape: centric or pennate
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Test usually perforated and ornamented with
spines or ribs (Why?)
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Perforations allow gases, nutrients, waste
products to pass through test to cell
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Important open-water primary producers,
especially in temperate and polar regions
Fig. 6-19
Centric
Pennate
Fig. 6-20
III. Marine Microbes
D.
Eukarya
2.
Stramenopiles (Heterokonts)
b.
Silicoflagellates
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Silica test, usually with spines
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One or two flagella
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Especially abundant in
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cold water
Fig. 6-21
III. Marine Microbes
D.
Eukarya
2.
Haptophytes
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a.
Two similar simple flagella
Coccolithophores
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Covered by calcium carbonate coccoliths
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Abundant and important in tropics
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Coccoliths may be important in sediments
Fig. 6-23
Fig. 6-24
III. Marine Microbes
D.
Eukarya
3.
Alveolates
•
a.
b.
Membranous sacs (alveoli) beneath cell membranes
Dinoflagellates
Ciliates
Fig. 6-25
III. Marine Microbes
D.
Eukarya
3.
Alveolates
a.
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Fig. 6-26
Dinoflagellates
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Motile forms possess two flagella
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Some lack flagella
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May be autotrophic, heterotrophic (~50%),
mixotrophic
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Some symbiotic (e.g. zooxanthellae)
Two basic forms
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Thecate – Covered with theca made of cellulose
plates, sometimes with spines (Why?)
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Athecate – Less common
III. Marine Microbes
D.
Eukarya
3.
Alveolates
b.
Ciliates
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Important small heterotrophs
Fig. 6-27
III. Marine Microbes
D.
Eukarya
4.
Choanoflagellates
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Solitary or colonial free-living heterotrophs
Best-known from surface waters
Important grazers on bacteria
Closest living relatives of metazoans
Fig. 6-28
III.
Marine Microbes
D.
Eukarya
5.
Amoeboid Protozoans
a.
Foraminiferans
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Test (shell) made of calcium carbonate (CaCO3) or
agglutinated sediment particles
- Fossil tests used to age geological deposits
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May have multiple chambers
- Tests increase in size as organism grows
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Feed by extending pseudopodia through pores in test
- Trap bacteria and other small organisms/detritus
- Some have bacterial symbionts
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Pelagic forms (calcareous)
- Often have spines
- Tests may form foraminiferan oozes, esp. in shallow
water beneath tropics
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Benthic forms (calcareous or agglutinated)
- Calcareous tests can be important sources of sand
for beaches
http://earthguide.ucsd.edu/earthguide/imagelibrary/orbulinauniversa.html
http://www.ucl.ac.uk/GeolSci/micropal/foram.html
III. Marine Microbes
D.
Eukarya
5.
Amoeboid Protozoans
b.
Radiolarians
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Test made of silica (SiO2)
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Tests may form radiolarian oozes, esp. in deep
water in temperate and polar regions
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Feed by extending pseudopodia through pores in
test
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Trap diatoms and other small organisms/detritus
(Why diatoms?)
Fig. 6-30