Ecological Role of Protists

Casey Sullivan, Aliah Marzolf, Natalie Minor, Stefani Williams, Max Rossa

● Protozoa○ Use phagocytosis to ingest prey

● Algal○ Use photosynthesis to produce energy○ Can be mixotrophic

● Fungi○ Use phagocytosis to ingest bacteria

and absorb nutrients from environment

Groups of Protists

● Phagotrophic○ Mouth-like structures○ Pseudopodia

● Heterotrophic dinoflagellates○ Novel predator-prey relationships○ Prey on phytoplankton, copepod eggs,

etc.○ Act as prey for some metazoa○ Some predators are prey for other

heterotrophic dinoflagellates

Protozoa

● Photosynthetic● Some mixotrophic (dinoflagellates

and chrysomonads)○ mixotrophic: balances photosynthesis

and phagocytosis○ Use both photosynthesis and

phagocytosis○ In marine and freshwater environments

● Grouped into divisions based on pigments

Algal

● Phagotrophic● Slime Molds

○ Amoeboid Movement○ Ingest bacteria○ Live in decayed wood○ Often brightly colored

Fungal

Gymnodinium breve*Red tide is a microscopic protist

that secretes a potent neurotoxin which contaminates oceans and especially coastal environments.

*These toxins are deadly to aquatic life, as filter feeding organisms consume these toxins, causing it to become concentrated in the vital organs, causing death

*These protists also cause irritation in humans, but exposure is not life-threatening. However, any fish or shellfish contaminated with Red Tide can be very harmful if consumed.

RED TIDE

http://serc.carleton.edu/images/microbelife/topics/red_tide_genera.v3.jpg

*E.coli is a bacteria that can cause extreme illness, and is one that is being found in lakes and creeks. Protists can be used to help fight off the E.coli bacteria by eating it.

*One strain of this bacteria produces a toxin called Shinga that can cause illness in people

*This strain of E.coli does very well because the Shinga toxin fights off aquatic protists that would otherwise eat the bacteria and help keep it in control

Protists and Dangerous Bacteria

• Jeong, H. J. (1999). The ecological roles of heterotrophic dinoflagellates in marine

planktonic community. The Journal of Eukaryotic Microbiology, 46(4), 390-396.

• Mauro, Stephen A.; Opalko, Hannah; Lindsay, Kyle; Colon, Michael P. & Koudelka, Gerald

B. (2013). The microcosm mediates the persistence of Shiga toxin producing E. coli (STEC)

in freshwater ecosystems. Applied and Environmental Microbiology, 79, gdg doi: 10.1128

• Sanders, R. W. (1991). Mixotrophic protists in marine and freshwater ecosystems. The

Journal of Eukaryotic Microbiology, 38(1), 76-81.

• http://biology.clc.uc.edu/courses/bio106/protista.htm

• http://www.atlanticbreezes.com/aquatic/aquatichealth/redtides.htm

• http://triemerlab.plantbiology.msu.edu/Euglena/Index.htm

References