Homebrewing - Beer, Mead, Wine, Cider

I don't have experience with mead/melomel. But it looks like you have too little headspace? For beer I would leave 1/3 of the vessel for headspace so the foam doesn't go through the water lock. I think the seperation is normal

The process is normal - fermentation creates carbon dioxide that rises up as bubbles once it reaches a concentration high enough to no longer dissolve in the liquid around it. Bubbles then stick to whatever they find around that can act as a nucleation site - in your case, the bits of pear - and transport the thing to the top.

The concern here is that once you get very high krausen, you'll potentially block off your airlock with bits of fruit and cause a small geyser as the pressure builds up and your cork pops off. Do try and monitor it to make sure that does not happen. You could replace the airlock with a blow-off tube that has a bigger diameter - just seal one end to the bottle (you'd normally use a rubber bung of adequate diameter and run the tubing through it) and put the other end in a jar of water. This way, you also have an airlock but any misbehaving bits of fruit can just end up in the jar via tube.

Welcome to mead brewing! Melomels are a great first brew!

Without knowing the recipe you used it’s hard to provide a ton of specific help but something’s to consider:

• the separation comes from the CO2 pushing the fruit bits up… you can do some punching down with a sanitized stirring tool (spoon, chopstick, whatever works) to let some of that gas out
• this becomes extra important if you brew your next melomel in a bucket - punching down keeps your fruit moist and prevents mold growth
• watch for blow off - some yeast goes hard for fruit and may cause a ton of expulsion of gas which can get in your airlock. If that happens either clean it out or swap to a blow off tube rig

Otherwise, good job and have fun watching your yeast chomp that sugar.