Use the following information to answer the next 3 questions.
To measure primary production of algae in a stream, you place two sealed chambers in the stream, each enclosing the sediments as well as the water above them. One chamber is covered with black tape (blocking all light) while the other is transparent to light.
You measure dissolved oxygen (DO) before and after a 24-hour incubation. DO in the light chamber increased by 1.5 g/m2 while DO in the dark chamber decreased by 2.0 g/m2.
(Hint: You have all the information you need to answer the following 3 questions—you do not need initial and final DO values. Think carefully about what is actually being measured in each of the two chambers!)
Top of Form
Q2.30. What is the estimated ecosystem respiration (Re) for the stream?
g O2 m-2 day-1
Top of Form
Q2.31. What is the stream’s estimated NEP (net ecosystem production)?
g O2 m-2 day-1
Bottom of Form
Top of Form
Q2.32. Based on these data, what is the stream’s estimated gross primary production (GPP)?
g O2 m-2 day-1
Bottom of Form
Top of Form
Q2.33. With the current configuration of Earth’s continents, global atmospheric CO2 peaks in late April. Imagine that all of Earth’s land mass was instead bunched tightly together around the South Pole. Assume that seasonal patterns of growth and respiration are otherwise the same, with summer occurring June-August in the Northern Hemisphere and December-February in the Southern Hemisphere.
How will this new configuration affect seasonal swings in average global CO2?
Seasonal swings would be larger, but CO2 would still peak in late April.Seasonal swings would be a little smaller, but CO2 would now peak in late August.Seasonal swings would be larger, but CO2 would now peak in late August.Seasonal swings would be much smaller, perhaps even undetectable.
Q2.34. Changes in O2 levels in light and dark bottles can be used to measure ocean net ecosystem production (NEP) and gross primary production (GPP) but not net primary production (NPP). Why is this?
NPP cannot me estimated without measuring changes in CO2 levels.The bottles include both primary producers and heterotophic consumers.Dark bottles measure changes caused by autotrophic respiration only.Light bottles measure changes caused by heterotrophic respiration only.
