Transcript I. Marine Microbes B. Marine Bacteria 1. Autotrophic a. Photosynthetic i. Cyanobacteria • Nitrogen fixation - IMPORTANT • Contain chlorophyll + phycocyanin & phycoerythrin • Occur in a variety of habitats - Polar bear hair - Endolithic.

I.
Marine Microbes
B.
Marine Bacteria
1.
Autotrophic
a.
Photosynthetic
i.
Cyanobacteria
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Nitrogen fixation - IMPORTANT
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Contain chlorophyll + phycocyanin & phycoerythrin
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Occur in a variety of habitats
- Polar bear hair
- Endolithic (inside calcareous rocks, coral skeletons)
- Epiphytic (on algae or plants)
- Endophytic (inside algal or plant cells)
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Some form filaments or mats (aids N fixation)
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Some similarities to eukaryotic algae:
- Contain chlorophyll a
- Produce gaseous O2
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May have been first photosynthetic organisms on earth
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Fossil stromatolites from 3 billion years ago
- Calcareous mounds: sediment + cyanobacteria
Stromatolites
Fig. 6-10
http://www.fossilmall.com/Science/About_Stromatolite.htm
I.
Marine Microbes
B.
Marine Bacteria
1.
Autotrophic
b.
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
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Carry out primary production without sunlight
Fig. 6-11
I.
Marine Microbes
B.
Marine Bacteria
2.
Heterotrophic
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Most are decomposers (break down organic material)
Important in nutrient cycling (microbial loop)
May be symbiotic
Fig. 6-14
I.
Marine Microbes
B.
Marine Bacteria
2.
Heterotrophic
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•
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Most are decomposers (break down organic material)
Important in nutrient cycling (microbial loop)
May be symbiotic
Fig. 6-14
I.
Marine Microbes
C.
Archaea
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Resemble bacteria superficially but may be
more closely related to eukaryotes than bacteria
Includes extremophiles and mesophiles; may
comprise up to 40% of microbial biomass in
open ocean
Biochemically distinct from Eubacteria and
Eukarya
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Structure of membranes, cell walls, etc.
Bacteriorhodopsins to capture light
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Pigments similar to eukaryotic rhodopsins
San Francisco Bay salt ponds
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I.
Marine Microbes
D.
Eukarya
2.
Stramenopiles (Heterokonts)
a.
Diatoms
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Unicellular; some may form chains, which then
may form mats
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Important open-water primary producers,
especially in temperate and polar regions
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Prefer well-mixed, nutrient-rich conditions (Why?)
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Explosive population growth --> Bloom
- May deplete nutrients locally
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Important food source for planktonic grazers
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Sediments beneath areas where diatoms are
abundant may contain many tests
- Diatomaceous oozes (>30% diatom tests)
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Life cycle includes sexual & asexual reproduction
Fig. 6-20
I.
Marine Microbes
D.
Eukarya
2.
Haptophytes
a.
Coccolithophores
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Very small (typically less than 20 μm)
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Usually in warm water at relatively low light
intensities
- Most abundant at depths of ca. 100 m in clear,
tropical, oceanic water
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Blooms may cover extensive areas
Ex – Bloom covering 1000 x 500 km of sea
surface in North Atlantic (area ~Great Britain)
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Coccoliths may be important components of
sediments
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
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a.
b.
Membranous sacs (alveoli) beneath cell membranes
Dinoflagellates
Ciliates
Fig. 6-25
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
a.
Ceratium furca
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Dinoflagellates
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Important open-water primary producers, especially in
tropical regions
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More tolerant of low nutrients and low light than diatoms
- Advantage under post-diatom-bloom conditions
- Often abundant in summer/autumn following spring
and summer diatom blooms
- Motility allows individuals to maintain position in water
column under low-turbulence conditions
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Motility also allows individuals to spend daylight hours in
surface waters and night hours in deeper waters (Why?)
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Most abundant phytoplankton in stratified, nutrient-poor
tropical and subtropical waters
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Blooms can produce harmful algal blooms (HABs),
aka red tides or brown tides
http://www.whoi.edu/redtide/
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I.
Marine Microbes
D.
Eukarya
3.
Alveolates
a.
Dinoflagellates
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Red tides typically visible @ densities >2-8 x 106 cells l-1
- Cell densities may exceed 108 cells l-1
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Nutrient depletion + viral effects (if any)  bloom
breakdown
- Bacteria decompose senescing cells  O2 depletion
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Red tides may not be toxic; HABs are
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Toxin (Saxitoxin) may be
1) Released into water
2) Transmitted directly to higher organisms, esp.
suspension feeders (e.g. clams, mussels, scallops,
oysters), which may be eaten by larger animals
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Consuming tainted fish or bivalves can 
Paralytic Shellfish Poisoning (PSP)
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
b.
Ciliates
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Present in all parts of ocean
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May be extremely abundant in some areas
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Cilia may be used for both locomotion and feeding
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Typically prey on small phytoplankton,
zooplankton, bacteria
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Tintinnids
- Vase-shaped, proteinaceous external shells
- Relatively small (20-640 μm); may be important
because of wide distribution
- May consume up to 60% of primary production in
some coastal waters
I.
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
- Especially abundant in surface waters b/w 40oN and 40oS
- Tests may form foraminiferan oozes, esp. in shallow waters
beneath tropics
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Benthic forms (calcareous or agglutinated)
- Calcareous tests can be important sources of beach sand
Homotrema rubrum
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Fig. 6-29
http://www.ucl.ac.uk/GeolSci/micropal/foram.html
Globigerinoides ruber
III. Marine Microbes
D.
Eukarya
5.
Amoeboid Protozoans
b.
Radiolarians
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Common in all oceanic regions, especially in cold
waters, including deep sea
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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 branched pseudopodia
(axopodia) through pores in test
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Trap bacteria, protists, detritus, other small
organisms including diatoms (Why diatoms?)
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May form gelatinous colonies up to 1 m across
Fig. 6-30