Terrible D+ on first semester senior year

Hello everyone! Recently I had just received a D+ in my AP Biology class during my first semester of my senior year. I also ended with a C+ in AP literature, C+ in precalc, and 2 A’s and a B+. Weighted, my GPA turned out as a 3.22, but horrifically a 2.89 UW. While these grades definitely look bad, I do have an excuse as I had moved schools 3 weeks before school started, first into an apartment, then a month and a half later into a house. This had hindered my studying time as I was adjusting, helping move, making friends, etc. To add onto that, I found the class itself to be extremely hard, regardless of the studying I did when I had the time. I have already taken 3 years of lab science, so this isn’t the problem, but I’m just worried about the D+ I got and I’m positive I can perform a lot better second semester since I’m all settled. Questions I have is, should I write about this to the colleges I applied to right now? Do I wait til I get admitted somewhere to write? Should I take a summer course this summer to make it up? Thanks!

ACT: 25
Overall GPA (without senior yr): 3.79

Where I applied: UC Merced, UC Riverside, UC Irvine, UCLA, UCSD, CSUN, CSUP, CPP, CSUF, CSULB

Yes.

UC: http://admission.universityofcalifornia.edu/how-to-apply/after-you-apply/index.html

CSU: contact the admissions offices of the campuses you applied to.

Otherwise, if you get an admission offer, you will find conditions like not earning any D or F grades in senior year courses, so that if the first time they see the D grade is on your final transcript in the summer, your admission will likely be rescinded. They also expect your GPA not to drop too far (many UCs specifically list 3.0 in your senior year courses, but check the actual admission offers).