User:Eliza B/Notebook/Biology 210 at AU

1/25 EB Lab 2: Discovering Protist Habitats Introduction Despite common opinion, ecosystems can be as large or as small as the environment allows. Though a 20 by 20 meter transect is an ecosystem in its own right, there are much smaller, more specified ecosystems and niches throughout the entire area. Even the niche from the surface of our Hay Infusion differs from the niche on the bottom. The purpose of this week’s lab was both to understand these nuances of ecosystem dynamics and to determine which protists resided in our whole transect’s ecosystem. Without a firm understanding of the microscopic ecosystem of our area, we cannot accurately study the transect as a whole.

Materials and Methods

The core goal of this lab was to identify different protists that lived in the Hay Infusion made from a sample of our transect’s dirt. We first practiced identifying protists using a dichotomous key. Once we felt comfortable finding and identifying protists, we moved on to studying protists from our Hay infusion. We took samples using a transfer pipette from both the surface and the bottom of the Hay Infusion, and placed them in separate flat disk containers. We took a sample from approximately 1cm from the bottom in the middle of the jar, and one sample right below the growths on the surface. We tried to take samples from the growths themselves, but they were too large to be transferred by the pipette. With two lids of water representing the two different niches, we then made three wet mounts of each niche. Each member of our group took one wet mount from the top and one from the bottom to observe. We tried to find three specimens from the top and three from the bottom using the dichotomous key to identify any cells we found. For each specimen, we recorded its appearance, size, and scientific name.

Data and Observations

The Hay Infusion smelled like musty dirt and rotting sewage. A film had grown on the surface, with most of the dirt and plant matter settling to the bottom. A picture of the jar is below.

Our group found six different protists in the Hay Infusion. However, possibly because we were unable to pipette water from the surface due to the film growth and instead had to draw from directly under the film, there was far more diversity in the bottom niche than on the top. We found four different protists from the bottom, but were only able to identify two different protists from the top, both paramecia. Below is a table detailing our findings and drawings of each protist.

Perhaps the reason so few organisms lived in the surface niche was because of the film of life that grew on the top of the water. Sunlight and other resources might have been monopolized by the growth on top, leaving less for other organisms that might usually thrive in a surface level niche. Organisms on the bottom might prefer different conditions and require different resources than those on top, explaining why such diversity appeared there. For example, there was more plant matter on the surface of the culture than on the bottom. Therefore, heterotrophic cells, like paramecia, would be more likely to thrive on the surface, where food is readily available, than on the bottom. This is shown by our results. We found only heterotrophic species on the surface, whereas 3 out of the four bottom protists were autotrophs. Though many protists are single-celled and relatively simple, they fit all the requirements for life. Take Gonium, for instance. Though it simple and non-motile, it fits all five of Freeman’s needs for life: made of cells, uses energy, processes information, replicates, and is a product of evolution. Gonium colonies typically contain 16 or less cells. They are cells because they are surrounded by a phospholipid bilayer. They use energy through photosynthesis, which is easy to ascertain by observing their green color. They can reproduce through either sexual or asexual reproduction, which shows that they are a product of evolution. Farther back in their evolutionary line, cells only reproduced through asexual reproduction (Clamydomonas is an example). Gonium, however, is an intermediary step between asexual and sexual reproduction, capable of both. Finally, they can process information, shown by the fact that they have and use DNA.

Conclusion and Further Direction

Our Hay Infusion fostered a plethora of different protist species in the one week it had to grow. From photosynthesizing, single celled organisms to large colonies of cells, to motile heterotrophic cells, protists of all natures flourished in the culture. If left to grow even longer, the culture certainly would have gained even more life. However, the diversity of this life is questionable. In the beginning stages of growth, many different species could thrive in the culture, since space would appear unlimited. As the cells continued to grow and reproduce, however, competition for resources would increase. Perhaps, if left for several months, only the best-suited protists would remain in the culture, having defeated other protists in the fight for resources. On the other hand, a longer time lapse would allow more cells to enter the culture through the air. As different students entered and exited the classroom, different particles could be deposited into the culture. This would lead to greater diversity. Without experimenting, it is impossible to know how the Hay Infusion would change through time. Future labs should test the hypothesis that extended time would lead to either an increase or decrease in diversity in the culture.

1/22/14 EB

Lab 1: Observing a Transect

Intro

Observation, simple as it may sound, is key to understanding science. No theories, hypotheses, or even scientific questions can emerge without this first vital step of the scientific method. This lab’s core goal was to collect observations about a specific transect on AU’s campus, namely the Wildlife Habitat transect, located between Cassel Hall and Hughes Hall. My group observed, drew, sampled, and analyzed the 20 by 20 meter plot in order to grasp how organisms within an ecosystem interact and develop. The data collected from this initial observation will be used throughout this semester’s study of campus ecosystems.

Materials and Methods

For this lab, the most important material was simply sensory information. Aside from the tube used to collect a dirt sample, all data was collected from observing, listening, and smelling a given transect. We first drew a map of the plot, including both the area within the transect and a few meters outside our area to show the boundaries. We then scrutinized each part of the transect, listing each biotic and abiotic element we found. Finally, we collected a sample of dirt representative of that area in a tube to use for Hay Infusions. The second part of lab was preparing the Hay Infusions for next class. We added .1 grams of powdered milk and 10 grams of dirt to a large jar filled with 50mLs of water in order to create an ecosystem where protists could thrive. After shaking the mixture to ensure the milk and dirt were properly mixed, we left the jars, lids off, for a week to allow the ecosystem time to grow.

Data Collected

Below is both a drawing and digital picture of my group’s transect, the wildlife habitat ecosystem, or transect 2.

Our transect was located on the North side of campus, on a slight slope. Aside from the slight downward tilt, the transect was mostly flat, with few bumps or small hills. The soil appeared hard and dry, but was surprising moist and loose once we began collecting samples. We found that our transect contained diverse biotic elements, but relatively uniform abiotic elements. The abiotic factors we documented were a piece of crumpled tissue paper, a few large boulders on the periphery of the transect, a row of smaller rocks dividing the transect, and lots of dirt and mulch throughout. Most of the transect, in fact, was covered in brittle dirt or scattered with wood chip mulch. When we came to biotic factors, we found more diversity. For plants, there were four trees, two of them big, one medium, and one small, that created the boundaries for our transect. There were several clumps of shrubs, some in the south with numerous purple leaves and some towards the north along the rocks that were stick-like and bare of leaves. Small clumps of monkey grass grew right next to the rocks as well, and fallen leaves scattered the ground. Since we were out late at night, there were few bird species, but observing the transect during the day revealed numerous sparrows. Though not seen, our group heard and felt at least one rat scurrying in the transect. We saw no bugs in the transect, but their absence could be due to the cold winter weather.

Conclusions and Future Directions

Since this lab did not attempt to test any hypothesis, there are no conclusions regarding any outcomes of our observations. However, the data we collected showed that the our transect contained a diverse assortment of plants, a small number of animals, and a few different abiotic components. The area was relatively litter-free, containing only one piece of trash. This cleanliness combined with the surprisingly moist soil allowed the transect to live up to its name of ‘wildlife habitat.’ The soil sample we collected should be an accurate representation of the transect as a whole, though the cold of winter, which left most of the plants in the transect deadened, might have affected the overall protist population of the region. Future tests should gather samples from numerous different seasons to determine the affect of cold weather on protist life.