Lab Design
BIOL3790 Teaching Internship
Kyle Robertson
Consequences of Water Quality
Objectives
In this lab, students will use instruments to evaluate the health of the abiotic components of three locations on the Georgia Southern Campus: Lake Wells, the Creek behind the Newton Building, and the Creek between Centennial Place and Watson Commons. After testing the water, they will collect water to use for germinating radish seeds. From this, students will gain an understanding of how water quality can affect plant life first hand.
Materials
· Lab manual
· Fluorescent Lights
· Thermometer
· Dissolved oxygen meter
· pH meter
· Conductivity meter
· 6 50-ml beakers
· 4 50-ml graduated cylinders
· Pipets
· Nitrate test kit $22.90
· Phosphate test kit $12.56
· 24 Petri dishes $23.35
· 24 Filter paper $14.66
· 24 Radish Seed Packets $30.71
· Parafilm $23.28
$127.46 out of a $200 budget used
Each student will use his or her own petri dish, radish seed packet, filter paper, and parafilm.
Content
This lab will be a follow up/continuation to the aquatic ecology lab and occur three weeks after in the semester. Students will be applying the concepts of biotic and abiotic factors on a larger scale, such as water quality, chemical and nutrient excess/shortage, plant growth, and consequences of ecosystem imbalances. This lab will use somewhat of the same materials used for allelopathy, which will provide familiarity to the students, but at the same time expand upon what they already know about radish seeds.
Introduction
The introduction will consist of a quick review and discussion with the students about how the biotic and abiotic factors affected the health, organisms, and ecology of Lake Wells. This will be led by the teaching assistant first summarizing what the class did, and then calling upon students to answer what was learned and how do they think the Lake Wells results compares with other water sources on the campus. The lecture will than focus on the possible pollution of the water quality of the campus water sources and how the effects could alter the ecology around the water sources. The lecture will then provide examples of how pollution, both direct and indirect, has affected ecological communities in our world.
The lab procedure will then be discussed, was well as a quick summary and reminders of the instruments being dealt with.
Procedures
After the lecture, the lab class will then proceed with the first portion of the lab, which will last for 45 minutes. Each bench group will be assigned one instrument, save the thermometer and pH meter, which will both be assigned to one group. Taking up water in beakers and measuring the water within requires two measurements, which are to be averaged to achieve a better result. The exception is for the nitrate and phosphate tests, which only need to be done once per water source.
The first water source that will be tested will be the DI water in the classroom. This will provide an easy example for the students to get reacquainted with the instruments. Once all recordings have been made, 20 mL will be drawn into a 50 mL graduated cylinder and set aside for the second part of the lab. The students will then be lead by teaching assistant outside to Lake Wells with the thermometers, pH meters, dissolved oxygen meters, conductivity meters, and the nitrate and phosphate test kits. Since three weeks has passed since first testing the water, students will again test the water to continue monitoring its water quality. Once recordings have been made, a student will draw 20 mL of Lake Wells water into the graduated cylinder for use in the second portion of the lab. Recordings are expected to be done within 10 minutes, since all students already have had previous experience with the instruments being used.
All students then move to the second water source, which is the small creek that flows between Lakeside Café and Newton building. Students will again perform the same tests in the same manner, with each bench group measuring only with their assigned instrument. From this water source, another 20 mL of water will be drawn and eventually taken back to the classroom.
Once finished at the second water source, students then move to the third and final water source, the small creek by the sidewalk between Centennial Place and Watson Commons. The same measurements are made, and another 20 mL of water will be drawn. Once all groups are finished, the teaching assistant will lead the class back inside for the second part of the lab.
Once inside, the teaching assistant will explain how the second part is to be done, and as he or she is doing so, one Petri dish, 2 filter papers, a strip of Parafilm and one radish seed packet can be handed out to each student. This portion of the lab will take 30 minutes. The 24 students will then be divided into 4 groups of 6 students. Each group will apply 3 mL of a different water source, i.e. group 1 will use Lake Wells water, group 2 will use Newton building creek water. The fourth group will use DI water to create the control scenario. Students will follow the steps below.
1. Open the Petri dish and place both filter papers into the bottom half of the dish.
2. Open the radish seed packet and empty onto filter paper, spreading the seeds evenly around the Petri dish.
3. Obtain a pipet and draw a 3 mL treatment of water from their assigned water source graduated cylinder. Drop the water around the Petri dish, dropping mostly in the middle of the dish.
4. Replace the lid of the dish. Remove the paper on the Parafilm and stretch each portion of the film around the edge of the Petri dish to seal it together.
5. Label the top of the dish with your name, water source, instructor’s name, lab section, and date.
6. Place your dish under the fluorescent lights in the back of the room. Dishes will incubate at 25 °C, just like the allelopathy lab to produce a somewhat comparable result.
7. After one week, open your dish and measure the number of seeds that have germinated, and measure the length of the root and shoot in millimeters. Average the lengths of seedlings.
Data Collection and Analysis
After a week has passed from this lab, the next time the lab meets the measurements of abiotic factors for each of the water sources and the lengths of seedlings for each water source treatment will be collected on the board. The teaching assistant will then lead the class in analyzing the results, and then discussing the potential pollutants that could be in the water that may have inhibited the growth of the radish seeds. The expected outcome is to have the DI water grow the radish seeds the best. The Lake Wells and Watson Commons water treatments result in a normal growth of the radish seeds, and the Newton Building water treatment is expected to have inhibited growth of the radish seeds.
Review and Discussion
As they finish up and seal their plates during the first week of the lab, the teaching assistant should take this opportunity to walk around the room and gain a consensus from the students about what their predictions are. Then before the class lets out, the students should write down their predictions, so as to be discussed during the next week. The class will then let out after all students have cleaned their workstations, put away all instruments, and placed their sealed Petri dishes under the fluorescent lights.
During the beginning of the next week’s lab, the Petri dishes will be opened and the contents measured. Data will be collected on the board, showing the measured abiotic factors, the average class seedling length and germinated seeds by water source. A discussion will then be lead by the teaching assistant, on how the water quality can affect the growth and development of local plants. The discussion will involve asking students what they thought, connecting specific factors to inhibition effects, why do they think the Newton building creek has a higher inhibition effect (such as its proximity to Lakeside Café and the resulting higher probability of littering and runoff), and what can be done to alleviate the problem. The discussion will then lead into what could happen on a grander scale. Questions to be asked could include, “What effect could the runoff of the entire United States have on our agricultural economy? How could it effect our drinking water and thus how will it effect us?” These questions will apply a larger picture to the experiment and have students thinking outside the small box of the classroom.
Assessment
For this lab, students will be evaluated based on their completed workbook of measurements, their predictions, and their participation in the discussion. This lab is also an excellent opportunity to provide bonus points to those that go above and beyond during the discussion, such as participating and giving the most thought to the experiment.
Resources
Tremblay, M. N. 2009. Environmental Biology Laboratory: Manual + Workbook. Caché House, Inc., Eden Prairie, MN.
