Periwinkle Snails Prefer to Feed on the Green Alga Enteromorpha

Multiple Choice

Periwinkle snails prefer to feed on the green alga Enteromorpha . In tide pools, Enteromorpha , which other alga species, while in areas exposed at low tide, the red alga Chondrus outcompetes Enteromorpha . How did these feeding and competing interactions affect the algal populations?

A) Periwinkles decreased species richness in both tide pools and exposed areas.
B) Periwinkles eliminated all of the less dominant algal species.
C) Periwinkles eliminated the dominant algae entirely.
D) Periwinkles decreased species richness when Enteromorpha is dominant, but increased species richness when Enteromorpha is competitively inferior.
E) Periwinkles increased species richness when Enteromorpha is dominant, but decreased species richness when Enteromorpha is competitively inferior.