Salinity Lab Report

Topics: Photosynthesis, Oxygen, Water Pages: 3 (926 words) Published: May 6, 2013
The Effect Salinity Has on Primary Productivity

Research Question: How does the amount of salinity in the water affect gross primary productivity? Hypothesis: The higher the salinity content in the water the lower the gross primary productivity values. Variables: Control- The group with zero salt added.

Dependent- Dissolved oxygen reading.
Independent- The salt concentration in the water.
Introduction: On the surface waters of lakes and oceans, plants are mainly unicellular algae, and most consumers are microscopic crustaceans and protozoans. Both the producers and consumers are very small, and they are easily contained in a liter of water. If you put these organisms in a bottle and turn on the lights, you get photosynthesis. If you turn off the lights, you turn off the primary production. Darkness has no effect on respiration. This is because cellular respiration is actually the reverse process of photosynthesis. Oxygen is a necessity of life requirements for basically all living organisms.* In this lab we are testing how different levels of salinity in the water indirectly affects the gross primary productivity in aquatic plants. To measure this you would use the light and dark bottle method. Only respiration (R) can occur in the bottle stored in the dark. The decrease in dissolved oxygen in the dark bottle over time is a measure of the rate of respiration. Both photosynthesis and respiration can occur in the bottle exposed to light, however the difference between the amount of oxygen produced through photosynthesis and that consumed through respiration is the net primary productivity (NPP). The difference in dissolved oxygen over time between the bottles stored in the light and in the dark is a measure of the total amount of oxygen produced by photosynthesis. The total amount of oxygen produced is called the gross primary productivity (GPP). The equation for this method is as followed: GPP= NPP + R

NPP= light bottle – initial DO
R= initial DO- dark...
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