User:Siena Eve Romano/Notebook/Biology 210 at AU

Lab 2: “Identifying Algae and Protists” 1/22/2015 Italic text Purpose: The purpose of this experiment was to study the protists that were living in the Hay Infusion Culture as well as identify those protists/algae using a dichotomous key based on their observed characteristics. After setting up a Hay Infusion the experiment intended to better understand the species of organisms living in a particular niche on the American University campus and how they interact with their environment. The hypothesis for this experiment is that if samples are taken from different sections of the Hay Infusion with different environmental properties, then the organisms that live in each will have different characteristics as well based on which section they are obtained from.

Materials and Methods: One week prior to the experiment a Hay Infusion Culture was set up by filling a 50 mL conical tube with a soil and ground vegetation sample from the groups designated 20 meter by 20 meter transect. Then 12 grams of the soil/ground vegetation was placed in a plastic jar with 500 mLs of deerpark water. After 0.1 gm of dried milk was added to the jar and a lid was secured, the jar’s contents were mixed thoroughly. The lid was removed and the jar was left in lab for a week. Upon returning to lab initial observations of the culture were made followed by samples being taken for microscopic observation. One sample was taken from the niche at the top of the liquid while the second was taken from the bottom where the soil/ground vegetation settled. Then a wet mount from the two different niches was made and studied under a microscope during which the sizes of the protists/algae were measured/recorded with the ocular micrometer. Lastly, the protists/algae present were determined using a dichotomous key.

Data and Observations:

Initial Observations of Hay Infusion Culture: extremely foul smell, solid contents (especially soil) settled to the bottom, some water evaporated, no observable indication of life on top of the liquid

Sample from Top of Hay Infusion Culture: Top of culture was mainly opaque liquid and free of observable particles, Very little abiotic particles to naked eye and when under the microscope, No other observable protists, At first less # of algae (only 2) but over time more emerged (4), Algae were moving around rapidly (motile), Unicellular, Algae were small with a circular shape (12 um, 13 um, 15 um, 20 um), Identified as Chlamydomonas based on size and shape

The photo above is of a drawing of the algae observed under the microscope, which was identified as Chlamydomonas.

The photo above is an image of an actual Chlamydomonas under a microscope taken from http://en.wikipedia.org/wiki/Chlamydomonas#mediaviewer/File:Chlamydomonas_EPA.jpg

Sample from Bottom of Hay Infusion Culture: Bottom of culture had settled soil and vegetation, Dirt clumps and other abiotic particles in sample observable to naked eye & under microscope, 4 protists were observed, Protists were moving around rapidly (motile), Protists were larger with an oval shape (~50 um), Observed tiny circular organelles inside cell, Identified as Colpidium, a protozoa,

The photo above is an image of the ocular view of the microscope when steadying the bottom of the Hay Infusion Culture in which one can see the protozoa and other abiotic materials

The photo above is of a drawing of the protist observed under the microscope along with some of its organelles, which was identified as Colpidium.

Conclusions and Future directions: The experimental results supported the hypothesis because organisms differed based on the section/environment of the hay infusion culture from which they were obtained. However, there was only one identifiable organism in each of the two sample sections of the hay infusion culture. The Chlamydomonas was at the top of the culture likely because algae need to be closer to the sunlight to undergo photosynthesis effectively via their light-absorbing chloroplasts. However, the protozoa, Colpidium were living at the bottom of the culture. This is likely because organisms that are closer to the bottom of the culture are closer to the plants and therefore consume nutrients from breaking down the plants as they are catabolic. Also, it is likely the protozoa were closer to the plants in order to meet their oxygen needs as plants release oxygen during photosynthesis. According to Freeman on page 2, organisms such as Chlamydomonas must meet all the needs of life. Chlamydomonas contains all its genetic information in its single cell and acquires the energy it needs to function from photosynthesis. Furthermore, there is diversity in the species such as the size of the organism that allows for its continual evolution. If the Hay Infusion Culture grew for another two months I predict the plant materials would decompose so maybe there would be less observable protozoa because they need to feed off the plant nutrients (selective pressure) and more species of algae or fungi protists instead. Another selective pressure reducing the number of protozoa would be a decline in oxygen as plants die. However, in order to continue this study of protists in their environment, the Hay Infusion Culture could be left for months and samples could be taken each week to record any difference in the species of organisms.