Chapter 5 Marine Microbes

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

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

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)

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

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)

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!

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

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

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/

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

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

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)

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

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

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

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

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

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

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

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

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