1. Chapter 5 Marine Microbes

2. Intro to Microbes Australian Institute for Marine Science Video
Viruses
Prokaryotes
Bacteria and Archaea
Eukaryotes
Unicellular algae/plant-like protists – diatoms, dinoflagellates, silicoflagellates, coccolithophorids
Protozoans/animal-like protists – forams, radiolarians, and ciliates
Fungi

4. Viruses
Non-cellular infectious agents that have two basic characteristics:
Not capable of reproduction without a host cell
Structure:
Nucleic acid core- can be DNA or RNA
Capsid (Protein coat)
Nature.com

5. Viruses Viruses in the Marine Community:
They are common in marine waters
They can infect bacteria, plankton, fish, sea turtles and marine mammals
Lysis (bursting) of viral infected cells spills contents and releases large amounts of organic matter that can be utilized by other organisms (dissolved organic matter or DOM)

6. Prokaryotes Archea and Bacteria
Characteristics of Archean and Bacterial Cells:
Prokaryotic- no nucleus
Single chromosome (normally circular)- some also with plasmids
Most with cell wall
Great metabolic diversity

7. Prokaryotes
Archea –
Ancient organisms – fossils found that date back 3.8 billion years
Extremophiles – Found in extreme environments like hydrothermal vents and salt flats (two very extreme environments)
Variety of metabolic types
Widely distributed in the marine community
They can tolerate wide ranges in temperature, salinity and even desiccation (drying out)

8. Bacteria Domain Bacteria Prokaryotes
Many shapes – spheres, spirals, rods, rings
Cell walls
Ensure the recycling of nutrients in detritis (VERY important!)
Most abundant form of life on earth!

9. Prokaryotes Metabolic diversity:
Photosynthetic – derive energy from light
Chemosynthetic – derive energy from chemical compounds
Heterotrophic – derive energy from organic matter by respiration

10. Cyanobacteria
Chlorophyll-a, phycocyanin (bluish pigment), phycoerythrin (redish pigment) – color depends on the amount of pigment of each color
Epiphytes (on seagrasses and seaweeds) and Endophytes (in algae)
Stromatolites – calcareous mounds formed by cyanobacteria

11. Cyanobacteria
Red tides – planktonic species multiply rapidly and contain red pigment. Can be devistating to ecosystems.
Endolithic species burrow into rocks and coral or form thick, dark crusts on wave-splashed rocky coasts
Prochlorococcus – most abundant marine organism!

12. Diatoms Photosynthetic
Yellow-brown from photosynthetic pigments, chlorophyll-a and chl-c and carotenoids
Shell of silica called a frustule
Most important primary producer on Earth
Mostly solitary and unicellular, but some colonial

13. Diatoms Around half of the 12,000 known species are marine
Most planktonic
Store excess energy as an oil which also aids in buoyancy
Tiny pores in shell used for gas/nutrient exchange
Some produce a toxin, known as domoic acid, that can accumulate in the tissues or organisms that eat diatoms such as shellfish and small fish
Larger organisms that eat these shellfish or small fish can become ill or die from this accumulated toxin

14. Diatoms

15. Dinoflagellates Most species live in marine environment
Mostly photosynthetic, some can ingest particles
Each species has unique shape reinforced by plates of cellulose
Two flagella in grooves on body for motion
Also reproduce by cellular division
Some are bioluminescent (read “Bay of Fire” on pg. 96)

16. Dinoflagellates Symbiodinium sp.
live in a symbiotic relationship with corals, sea anemones and other organisms (many of these host organisms have little or no growth without their symbiotic partner)
Noaa.gov
Auburn.cedu

17. Algal Blooms
Diatoms and dinoflagellates can go through periods of rapid growth known as “blooms”
This is a result of high levels of nutrients in the water
These blooms can be harmful to marine organisms and even people at times
Noaa.gov

18. Dinoflagellates
A few species lack chloroplasts and live as parasites in marine organisms
Some species can reproduce in larger numbers and produce “Red Tide” (read pg. 338)
Pfiesteria produces very serious toxins that can cause massive fish kills, harm shellfish and impair the nervous system in humans.
Pfiesteria was discovered near the Outer Banks in North Carolina
Whoi.edu

19. Other Protists A few more species of phytosynthetic plankton:
Silicoflagellates
Star-shaped internal skeleton of silica
Two flagella of varying lengths
Coccolithophores
Ornate shells of calcium carbonate

20. Protozoa Foraminiferans (forams) Exclusively found in marine community
Found on sandy or rocky bottoms
Shells of calcium carbonate
Can be important contributors of calcareous material on coral reefs or sandy beaches
Pseudopods (false feet) extend through pores in the shell where they are used to capture minute food particles such as phytoplankton

22. Protozoa Radiolarians
Planktonic, mostly microscopic, although a few can reach large sizes
Shell of silica
Like forams, they use pseudopods that extend through pores in the shell where they are used to capture minute food particles such as phytoplankton

24. Ciliates Cilia present for locomotion Most live as solitary cells
Some build shells made of organic debris
May live on hard substrate
Some are planktonic

25. Fungi Eukaryotic and mostly multicellular Heterotrophic
Most of the 1500 species of marine fungi are microscopic
Biotec.or.th

26. Fungi
Like bacteria, many fungus break down dead organic matter into detritus
Some fungus live in symbiosis with cyanobacteria, these are known as lichens
Marine lichens often live in wave-splashed areas of rocky shorelines and other hard substrate