productivity lab Essay

Submitted By victoriapierce23
Words: 825
Pages: 4

Victoria Pierce
Mr. Hussey
IB Environmental Systems SL
30 October 2014
Gross and Net Aquatic Primary Productivity in a Pond Ecosystem
Two pairs of hip waders
One horizontal niskin bottle
Three Nalgene bottles
Six voa vials
Aluminum foil
Meter stick
Light chamber
1. Take a sample of water from the bottom, middle, and top levels of depth of the pond: lower the Niskin Bottle to the bottom of the pond to collect water, and then place sample into a Nalgene bottle. Record the measurement of depth of the pond. Repeat this process at half the depth of the pond, using the measurement of the total depth to judge where to make collection, and transfer to a second Nalgene Bottle. For the surface water, collect sample directly with the third Nalgene Bottle. Label each sample.
2. Conduct an Oxygen test on the samples, using electronic probes or chemical test kits. Record in data table.
3. Transfer the samples into Voa Vials, two per depth.
4. Seal the vials tightly.
5. Cover one bottle of each pair with aluminum foil to block all light. In the uncovered bottle, photosynthesis as well as respiration of plants, animals, and bacteria present will occur. In the covered bottle, only respiration of the organisms will occur. Label each vial accordingly.
6. Place all samples in the light chamber and leave undisturbed for one week.
7. Remove vials and quickly run the Oxygen test on all samples to determine oxygen content. Record in data table.
8. Calculate the total oxygen produced. Calculations for respiration, gross primary productivity, and net primary productivity are as follows:
1. Net primary Productivity=light final- light initial
2. Respiration= dark final – dark initial
3. Gross Primary Productivity= net primary productivity + respiration (absolute value)

Aspect 1:
D.O Surface
D.O Middle

Day 1 (11/3/140
5.69 mg/L
5.69 mg/L
5.16 mg/L
5.16 mg/L
5.07 mg/L
Day 7 (11/11/14)
5.08 mg/L
4.87 mg/L
5.52 mg/L
4.85 mg/L
5.75 mg/L
5.01 mg/L

Aspect 2:
Net primary productivity= final (light) – initial (light)
Respiration= dark (final) – dark (initial)
Gross= net primary productivity + respiration (absolute value)
Aspect 3:

.61 mg/L
.68 mg/L
.82 mg/L
.31 mg/L
.06 mg/L
1.43 mg/L
.67 mg/L

Victoria Pierce
Mr. Hussey
IB Environmental Systems SL
20 November 2014

Gross and Net Aquatic Primary Productivity in a Pond Ecosystem

Aspect 1: Discussing and Reviewing
The independent variable in the lab was depth. First we had two students use sampling equipment to take water from the top, middle, and bottom of the red bank regional pond. After we got the water we went back to class and measured the temperature, and the dependent variable in the lab which was primary productivity. The controlling variables in the lab were temperature, light source, time, water, sampling equipment. The samples were put under a light source for seven days and after we took them out and measured temperature