Ecologist here also, even after the ice has melted there is still an ecosystem there, it will just be different to the one we have now. A lot of research is going on to understand how a "new" Arctic might look. Particularly for algae, we are unsure if the ice loss will lead to more of them (since more sunlight gets to the water) or less. This is because as light hits water it will warm it up and cause what we call stratification (warmer water is lighter than cold water so forms 2 separate layers) and reduces the amount of nutrients which can come up from the deep water which algae need to grow. There is also research going on looking back into the past when temperatures have also been warmer and trying to understand what conditions were like and organisms that lived at that time were. We can use this to try and guess what might happen in the future!