Aquatic Protists Lifestyles of the unicellular and bizarre.

Definition – what is a protist? Kingdom Protista – a catch-all kingdom composed of anything that … –Is eukaryotic –Is unicellular, OR… –If multicellular, cells display no great amount of specialization (there are no organs or systems)

3 Basic Types of Protists Animal – like –Heterotrophic –Usually motile; sometimes sessile –Include amoebas, paramecia, etc. Plant – like –Autotrophic –Planktonic; (Exception: Euglenas, which are motile) –Include algaes, diatoms, euglenas, volvox Fungus – like –Heterotrophic –Parasitic OR Decomposers –Include the water molds

Protozoa

Algae

Water Molds

Protist? Why or why not?

Why care about something you can’t see? Protists form the bottom of every aquatic food chain. Protists are EXCELLENT indicators of an aquatic system’s health. Certain aquatic protists cause disease (Cholera, Malaria, Dysentery) They are EXTREMELY FASCINATING!

Setting up your Slides Here is refresher for the preparation of wet mount slides: 1. Be sure to stir the pond water sample to insure uniform distribution of the organisms present in the water. 2. Take a clean microscope slide and place two to three drops of the stirred sample in the center of the slide. 3. Take a clean coverslip and place it at the edge of the water drop at a 450 angle to permit water and material to spread evenly beneath the tilted coverslip. 4. Slowly lower the coverslip until there is a film of water with organism and NO air bubbles under the coverslip 5. View the slide using the techniques learned in laboratory 1 6. When using the reference microscope be sure to notice the magnification

So what to look for? Use a microscope. Obtain water from the “scummiest” parts of your sample. (No clear water!) Move your slide around. Spend a minimum of two minutes on each slide. When you come across what you think might be a protist, draw what you see USING PENCILS (no pens!) Use to attempt to identify what you have.

So what does this tell me? Health of aquatic ecosystems and indicator organisms Category Indicator Explanation Natural unpolluted lake - High species diversity; the algal community often is diverse with several groups present. A balanced ratio of diatoms and green algae is commonly observed.

Toxic waste contamination No Algae. Although some algae species are very resistant to toxic waste products, most are not and thus very few algae will be present in the contaminated ecosystem

Sewage discharge Cyanobacteria Organic pollution (sewage discharge) in a lake or stream causes blooms of cyanobacteria that form thick algal mats.

Nitrogen rich pollution (fertilizer) Euglena Nitrogen rich contamination increases the ratio of euglenophytes (Euglena) above normal levels. Very little diversity is observed in this type of aquatic ecosystem.

Protists: Get into them!