The clarity of lake water is affected by the amount of phytoplankton (marine plants), soil, clay, and other solids suspended in the lake. Suppose the concentration of carbon dioxide in the atmosphere changed from 340 ppm to 380 ppm from 1980 to 2005. What effect would this have on the occurrence of the full body plate trait? Explain your answer. Hint: Think about how carbon dioxide is related to photosynthesis.

Carbon dioxide and oxygen are differentially exchanged between the atmosphere and the oceans in the carbon cycle. An increase in atmospheric carbon dioxide also raises the carbon dioxide absorbed by the oceans. This increases the pH of the ocean waters which consequently affects the growth of phytoplankton. Low pH affects negatively the growth of phytoplankton. The clarity of the waters would, therefore, increase with pH due to low plankton growth.