Ok so Im having trouble performing the test. Basically, I’m testing the intraspecific interaction between two algae species. I have data for algae count for species 1, species 2, species 1 (mixed with 2) and Species 2 (mixed with 1) I got the density per ml each week. Ive been counting every week for a total of 3 weeks. How would I be able to do the t-test?

I was thinking of doing a t-test of species 1 count alone vs. species 1 count when mixed with 2. Then do a separate t-test of species 2 alone vs. species 2 when mixed with 1. If either gives a p < 0.05, it suggests the count is significant different when mixed than when alone.

Any other tips?