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Chapter 5 Marine Microbes
Intro to MicrobesAustralian Institute for Marine Science Video
Viruses
Prokaryotes Bacteria and Archaea
Eukaryotes Unicellular algae/plant-like protists – diatoms,
dinoflagellates, silicoflagellates, coccolithophoridsProtozoans/animal-like protists – forams, radiolarians,
and ciliates
Fungi
VirusesNon-cellular infectious agents that have two
basic characteristics:Not capable of reproduction without a host
cellStructure:
Nucleic acid core- can be DNA or RNACapsid (Protein coat)
Nature.com
VirusesViruses 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)
ProkaryotesArchea 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
ProkaryotesArchea –
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)
BacteriaDomain 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!
ProkaryotesMetabolic diversity:
Photosynthetic – derive energy from light
Chemosynthetic – derive energy from chemical compounds
Heterotrophic – derive energy from organic matter by respiration
CyanobacteriaChlorophyll-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
CyanobacteriaRed 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!
http://www.whoi.edu/redtide/
www.wikipedia.com
DiatomsPhotosynthetic Yellow-brown from photosynthetic pigments,
chlorophyll-a and chl-c and carotenoidsShell of silica called a frustule Most important primary producer on Earth Mostly solitary and unicellular, but some
colonial
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
Diatoms
DinoflagellatesMost species live in marine environmentMostly photosynthetic, some can ingest particlesEach species has unique shape reinforced by
plates of celluloseTwo flagella in grooves on body for motionAlso reproduce by cellular divisionSome are bioluminescent (read “Bay of Fire” on
pg. 96)
DinoflagellatesSymbiodinium 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)
Auburn.ceduNoaa.gov
Algal BloomsDiatoms 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
DinoflagellatesA 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
Other ProtistsA few more species of phytosynthetic plankton:
SilicoflagellatesStar-shaped internal skeleton of silicaTwo flagella of varying lengths
CoccolithophoresOrnate shells of calcium carbonate
ProtozoaForaminiferans (forams)
Exclusively found in marine communityFound on sandy or rocky bottoms Shells of calcium carbonateCan be important contributors of calcareous
material on coral reefs or sandy beachesPseudopods (false feet) extend through pores in
the shell where they are used to capture minute food particles such as phytoplankton
ProtozoaRadiolarians
Planktonic, mostly microscopic, although a few can reach large sizes
Shell of silicaLike forams, they use pseudopods that extend
through pores in the shell where they are used to capture minute food particles such as phytoplankton
CiliatesCilia present for
locomotionMost live as solitary
cellsSome build shells made
of organic debrisMay live on hard
substrateSome are planktonic
FungiEukaryotic and mostly multicellular
Heterotrophic
Most of the 1500 species of marine fungi are microscopic
Biotec.or.th
FungiLike 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