Chronically ill marine biologist here to say you absolutely would still have job opportunities available to you despite chronic illness. (I am actually trying to get a fibro diagnosis as we speak - my rheumatologist is unfortunately if it’s doesn’t show in a blood test it’s not real type).

Post undergrad I tech’d a few labs as a field/lab tech. Those jobs were physically demanding, but if I had been less physically able I would have been able to get reasonable accommodations for the most part (such as more breaks, taking a break from the more physical aspects like pulling the trawl/carrying heavy objects etc.). The more professional the lab (as in more PIs, post-docs etc) usually better treatment of techs from my experience, oh and usually the more women at the lab.

In grad school I also helped run a multi-acre aquaculture demo facility w/ the lab manager since we could not bring undergrads in to help during COVID.

It’s absolutely possible to succeed in marine bio with a chronic illness. I will say some aquariums can be a bit…corporate but I have never had any positive experience with the aquarist career path or aquarium world so I will digress from that. I work in aquaculture now, and mostly on policy related things so stuck doing desk work.

My only other comment is I do think working at sea can be pretty physically demanding. I never did it bc I knew my chronic illnesses would make it a highly uncomfortable experience (certainly not physically impossible for me, but day trips on boats were a much preferable situation for me) but also depends so heavily on what you are doing and who you are working for. Fed and state govt have many more worker protections in place and easier to get accommodations if needed. University labs, and other entities less so (from my experience) and there can be more pressure to exert yourself more to get work done.