Campbell Biology 11th Edition by Lisa Urry,Michael Cain,Steven Wasserman,Peter Minorsky,Jane Reece

Exercise 14

Interpreting a Scatter Plot with a Regression Line
How Does the Carbonate Ion Concentration of Seawater Affect the Calcification Rate of a Coral Reef Scientists predict that acidification of the ocean due to higher levels of atmospheric CO₂ will lower the concentration of dissolved carbonate ions, which living corals use to build calcium carbonate reef structures. In this exercise, you will analyze data from a controlled experiment that examined the effect of carbonate ion concentration ([
]) on calcium carbonate deposition, a process called calcification.
How the Experiment Was Done For several years, scientists conducted research on ocean acidification using a large coral reef aquarium at Biosphere 2 in Arizona. They measured the rate of calcification by the reef organisms and examined how the calcification rate changed with differing amounts of dissolved carbonate ions in the seawater.
Data from the Experiment The black data points in the graph form a scatter plot. The red line, known as a linear regression line, is the best-fitting straight line for these points.
(a) If the seawater carbonate ion concentration iS₂70 mol/kg, what is the approximate rate of calcification, and approximately how many days would it take 1 square meter of reef to accumulate 30 mmol of calcium carbonate (CaCO 3 )
(b) If the seawater carbonate ion concentration iS₂50 mol/kg, what is the approximate rate of calcification, and approximately how many days would it take 1 square meter of reef to accumulate 30 mmol of calcium carbonate
(c) If carbonate ion concentration decreases, how does the calcification rate change, and how does that affect the time it takes coral to grow