Chapter 5 Marine Microbes

Intro to MicrobesAustralian Institute for Marine Science Video VirusesProkaryotes

Bacteria and ArchaeaEukaryotes

Unicellular algae/plant-like protists – diatoms, dinoflagellates, silicoflagellates, coccolithophorids

Protozoans/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 BacteriaCharacteristics 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 typesWidely distributed in the marine communityThey can tolerate wide ranges in temperature,

salinity and even desiccation (drying out)

BacteriaDomain BacteriaProkaryotesMany shapes – spheres, spirals, rods, ringsCell wallsEnsure the recycling of nutrients in detritis

(VERY important!)Most abundant form of life on earth!

ProkaryotesMetabolic diversity:Photosynthetic – derive energy from lightChemosynthetic – derive energy from chemical

compoundsHeterotrophic – 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

waterThese 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 organismsSome 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 multicellularHeterotrophicMost of the 1500 species of marine fungi are

microscopic

Biotec.or.th

FungiLike bacteria, many fungus break down dead

organic matter into detritusSome fungus live in symbiosis with

cyanobacteria, these are known as lichensMarine lichens often live in wave-splashed areas

of rocky shorelines and other hard substrate