. Which of these choices would help explain why the Zebra mussel population was 0 in 1991, while the population of native Unionid mussels was over 3000 organisms per square meter?
a
The scientists had a hard time spotting the mussels that year.
b
The climate was too cold for the Zebra mussels to reproduce that year.
c
The Zebra mussels had not yet been introduced to the area.
d
The water was moving too fast for the Zebra mussels to survive that year.
2. Over the 18 years of data depicted here, which mussel species was generally more successful?
Unionid Mussels
Zebra Mussels