Biological data analysis of settlement success in coral

I have no idea how to run any statistical tests on the following data. This is the experiment I ran:
I exposed corals to a chemical in lab. Every day, I collected the coral larvae from the coral every day for 3 weeks. My advisor had me then pool the larvae from the same treatments, and score them for settlement success a week later. How would I compare whether or not the corals that were exposed to the chemical had reduced settlement? I'm not quite sure how to do this, since I have data collected over 3 weeks and the sample sizes have a wide range. This is an example of the data:

Treatment: Percent Settlement: Days the coral was exposed:
A 40% 1 day
B 60% 2 days...etc.

Any ideas? Thank you!