Microscope slides well centers and coverslips

Transcription

1 Pond Biovolume Lab Name: Per: Date: Background Microorganisms thrive in every ecosystem on Earth. They range in complexity from simple to multi-cellular organisms. Microorganisms require food, water, air, ways to dispose of waste and an environment to thrive in. There is an abundance and variety of microscopic life found in pond water, even frozen pond water and geysers. A healthy pond may have from 500 to 1,000 different species of microscopic organisms. These organisms are essential to the balance of the pond ecosystem. Pond water is an excellent place to investigate single cells that behave as independent organisms. These organisms seem relatively unchanged from ancient times. Yet, the environment of a pond is ever-changing and no two ponds are ever exactly alike. Some major types of organisms found in ponds are algae, amoebas, and paramecium. Generally, if you are interested in aspects of population structure, it is not practical to sample every individual of that population. In addition, various attributes of the members of the population, such as size and age must be estimated by sampling. Time often require that we estimate these values, since complete censuses of populations require considerable time and effort. A random sample allows us to obtain a practical amount of information and yet still make conclusions about the entire population in an objective manner. Since we cannot actively select individuals to sample, as that might bias our experiment, we must instead randomly select individuals or plots to include. Materials Pond water Compound microscope Eyedropper Microscope slides well centers and coverslips Pond organisms lab Procedures 1. Collect a few drops of water from your water sample using an eyedropper. 2. Place a drop of pond water in the well of a microscope slide. 3. Cover the slide with a cover slip by lowering the cover slip at an angle over the water drop in a manner that spreads out the water drop, but does not trap air bubbles. 4. Observe the drop of pond water under scanning power to scan and find the organisms. Low power is useful once you have found something to determine details. 5. Draw pictures of each organism observed within your sample in the space provided in the data portion of this lab. Complete this for two samples. 6. Use the Powerpoint and ID sheet attached to identify the organisms observed. 7. Write the name of the organism in the space provided, if the organism can be identified. 8. Determine its volume (here you apply the rules of measurement learned in the microscope lab). Record and place it in Table Determine its trophic level and record in Table 1. If the organisms are moving too fast and therefore difficult to observe; add one drop of Protoslo or Detain to a drop of culture on the slide. If this is unavailable place 2or 3 strands of cotton on the slide first then the drop of pond water. These procedures will slow the organisms. YOU MUST BE PATIENT FINDING THEM, IT IS WORTH WHILE 4Micro_pond_biovol.doc 10/6/09 page 1

2 Data: Organisms in pond water Sample #: Magnification: Field of view diameter: µm Scale: 1 square = µm Number of producers: Number of consumers: Volume calculations: Sample #: Magnification: Field of view diameter: µm Scale: 1 square = µm Number of producers: Number of consumers: Volume calculations: 4Micro_pond_biovol.doc 10/6/09 page 2

3 Table 1: Volume calculations: Sample #: Trophic level Producer Consumer Number Volume of organism (µm 3 ) Total volume (µm 3 ) Table 2: Volume calculations: Sample #: Trophic level Producer Consumer Number Volume of organism (µm 3 ) Total volume (µm 3 ) Table 3: Summary Data Table Trophic level Number of organisms Total volume at trophic level (mm 3 ) Producers Consumers 4Micro_pond_biovol.doc 10/6/09 page 3

4 Table 4: Class Data Table Analysis 1. Using the class data, construct both a numbers pyramid and a biovolume pyramid. Be sure to scale your pyramids. 2. How does the class data compare with to the 10% rule as discussed in ecology? Explain. 4Micro_pond_biovol.doc 10/6/09 page 4

5 4Micro_pond_biovol.doc 10/6/09 page 5