Transcript Feb 7 - University of San Diego

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 (inside calcareous rocks, coral skeletons)
- Epiphytic (on algae or plants)
- Endophytic (inside algal or plant cells)
•
Some form filaments or mats (aids N fixation)
•
Some similarities to eukaryotic algae:
- Contain chlorophyll a
- Produce gaseous O2
•
May have been first photosynthetic organisms on earth
•
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
•
Obtain energy from chemical compounds
•
Ex: Hydrogen, hydrogen sulfide, ammonium ion
•
Often anaerobic, may be symbiotic
•
Carry out primary production without sunlight
Fig. 6-11
I.
Marine Microbes
B.
Marine Bacteria
2.
Heterotrophic
•
•
•
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
•
•
•
Most are decomposers (break down organic material)
Important in nutrient cycling (microbial loop)
May be symbiotic
Fig. 6-14
I.
Marine Microbes
C.
Archaea
•
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
•
•
•
•
Structure of membranes, cell walls, etc.
Bacteriorhodopsins to capture light
•
Pigments similar to eukaryotic rhodopsins
San Francisco Bay salt ponds
wikimedia.com
environmentalgraffiti.com
I.
Marine Microbes
D.
Eukarya
2.
Stramenopiles (Heterokonts)
a.
Diatoms
•
Unicellular; some may form chains, which then
may form mats
•
Important open-water primary producers,
especially in temperate and polar regions
•
Prefer well-mixed, nutrient-rich conditions (Why?)
•
Explosive population growth --> Bloom
- May deplete nutrients locally
•
Important food source for planktonic grazers
•
Sediments beneath areas where diatoms are
abundant may contain many tests
- Diatomaceous oozes (>30% diatom tests)
•
Life cycle includes sexual & asexual reproduction
Fig. 6-20
I.
Marine Microbes
D.
Eukarya
2.
Haptophytes
a.
Coccolithophores
•
Very small (typically less than 20 μm)
•
Usually in warm water at relatively low light
intensities
- Most abundant at depths of ca. 100 m in clear,
tropical, oceanic water
•
Blooms may cover extensive areas
Ex – Bloom covering 1000 x 500 km of sea
surface in North Atlantic (area ~Great Britain)
•
Coccoliths may be important components of
sediments
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
•
a.
b.
Membranous sacs (alveoli) beneath cell membranes
Dinoflagellates
Ciliates
Fig. 6-25
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
a.
Ceratium furca
blogs.scotland.gov.uk
Dinoflagellates
•
Important open-water primary producers, especially in
tropical regions
•
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
•
Motility also allows individuals to spend daylight hours in
surface waters and night hours in deeper waters (Why?)
•
Most abundant phytoplankton in stratified, nutrient-poor
tropical and subtropical waters
•
Blooms can produce harmful algal blooms (HABs),
aka red tides or brown tides
http://www.whoi.edu/redtide/
1.bp.blogspot.com
Blue Surf - YouTube
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
a.
Dinoflagellates
•
Red tides typically visible @ densities >2-8 x 106 cells l-1
- Cell densities may exceed 108 cells l-1
•
Nutrient depletion + viral effects (if any)  bloom
breakdown
- Bacteria decompose senescing cells  O2 depletion
•
Red tides may not be toxic; HABs are
•
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
•
Consuming tainted fish or bivalves can 
Paralytic Shellfish Poisoning (PSP)
I.
Marine Microbes
D.
Eukarya
3.
Alveolates
b.
Ciliates
•
Present in all parts of ocean
•
May be extremely abundant in some areas
•
Cilia may be used for both locomotion and feeding
•
Typically prey on small phytoplankton,
zooplankton, bacteria
•
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
•
Test (shell) made of calcium carbonate (CaCO3) or
agglutinated sediment particles
- Fossil tests used to age geological deposits
•
May have multiple chambers
- Tests increase in size as organism grows
•
Feed by extending pseudopodia through pores in test
- Trap bacteria and other small organisms/detritus
- Some have bacterial symbionts
•
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
•
Benthic forms (calcareous or agglutinated)
- Calcareous tests can be important sources of beach sand
Homotrema rubrum
www.bios.edu
www.travelimg.org
Fig. 6-29
http://www.ucl.ac.uk/GeolSci/micropal/foram.html
Globigerinoides ruber
III. Marine Microbes
D.
Eukarya
5.
Amoeboid Protozoans
b.
Radiolarians
•
Common in all oceanic regions, especially in cold
waters, including deep sea
•
Test made of silica (SiO2)
•
Tests may form radiolarian oozes, esp. in deep
water in temperate and polar regions
•
Feed by extending branched pseudopodia
(axopodia) through pores in test
•
Trap bacteria, protists, detritus, other small
organisms including diatoms (Why diatoms?)
•
May form gelatinous colonies up to 1 m across
Fig. 6-30