Chapter 6 Marine Microbes

Key Concepts Microbial life in the sea is extremely diverse, including members of all three domains of life as well as viruses.

Marine Viruses Significance: Marine food webs Population biology Diseases of marine organisms

Marine Bacteria General characteristics simple, prokaryotic, few genes reproduce by binary fission many shapes and sizes

Nutritional Types Cyanobacteria (blue-green bacteria) photosynthetic found in high dissolved oxygen, and produce free oxygen

Nutritional Types Chemosynthetic bacteria Use energy from chemical reactions Less efficient than photosynthesis Found around hydrothermal vents

Nutritional Types (Heterotrophic Bacteria) Decomposers Marine snow

Symbiotic Bacteria Chemosynthetic bacteria live within tube worms and clams Some deep-sea or nocturnal animals host helpful bioluminescent bacteria

Archaea General characteristics Small Prokaryotic Extreme environmental conditions

Archaea Nutritional Types Photosynthesizers, chemosynthesizers and heterotrophs Most are methanogens Halobacteria thrive at high salinities

Archaea Hyperthermophiles Survive at temperatures exceeding 100o C Potential for biomedical and industrial application

Fungi Decomposers, prey, pathogens and symbionts

Fungi General features Heterotrohic decomposers

Figure 6-14 (a) ARENICOLOUS MARINE FUNGUS.

Fungi Salinity is toxic to fungi, devote energy to removing sodium Most live on wood from land Some live on grass in salt marshes Others live on algae, mangroves or sand

Maritime Lichens Lichens: mutualistic associations between a fungus and an alga

Diatoms 2 basic diatom shapes: Radially symmetrical valves (generally planktonic) Bilaterally symmetrical valves (generally benthic)

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Diatoms Diatomaceous sediments Sink and collect on the seafloor Mined for use as filtering material, a mild abrasive, and for soundproofing and insulation products Accumulate in siliceous oozes accounting for most of the worlds petroleum reserves

Alveolates Dinoflagellates Globular, unicellular (sometimes colonial) with 2 flagella Most are planktonic, some are benthic and others parasitic Can be bioluminescent – Bioluminescent Bay, Puerto Rico

Figure 6-25 DINOFLAGELLATES.

Alveolates (Dinoflagellates) Ecological roles of dinoflagellates Major component of phytoplankton Some are parasites of copepods (crustaceans) Zooxanthellae: symbionts of jellyfish, corals and molluscs

Alveolates (Dinoflagellates) Harmful Algal Blooms (HABs) Photosynthetic dinoflagellates undergo a population explosion Colors the water red, orange or brown Dinoflagellates that cause HABs produce toxins Paralytic shellfish poisoning (PSP) occurs in humans Toxins cannot be destroyed by cooking Oxygen content of the water may be reduced to deadly levels as bacteria decompose animals killed by dinoflagellate toxins