Chapter 5 Marine Microbes

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! www.wikipedia.com http://www.whoi.edu/redtide/

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