Hi! I will just throw my questions out there, because I dont really know how to start haha.

Im a educated zoo keeper from Sweden and my goal is to work scientifically with sharks and other sea creatures in the ocean in the future. But im also up to work as a aquarist or anything that has to do with animals and water. I have a Advanced PADI OW and Advanced Freediver, and planning to go further with both. 

But to get even more attractive on the market, do anyone recommend HSE SCUBA or should I just save money and go on the PADI track? 
We have one place in Sweden that you can get certified with and its called S-30(which is like HSE SCUBA but worse I think), but doesnt even get to the level of European Scientific Diver (ESD) (Is HSE SCUBA ESD or where can I live up to that?)
and its IDSA Level 1. From what I have heard IDSA is useless?
They do tho have a another course too to get a A-40 cert(which is like HSE Surface Supplied I think, or between that and SCUBA?), but its still IDSA.

In the fields I want to work in, does it matter if it is HSE SCUBA(or similar) or A-40 or higher? Is it always better to have the higher one or for an example HSE SCUBA which is made for that kind of field?



Is anything of this worth it? Is IDSA worth in that case or should I travel to another country to another course?

Thanks in advanced!