What is blackice-icecap user console on port 8081 on my MacBook air?

The "blackice-icecap user console" is a piece of administration software for a firewall system. However, it is very unlikely that you have that system running on your MacBook Air.

In essence your port list just writes the name of the software that has registered the port with IANA - i.e. they're saying that "our software uses this port". However, other software can also use the port number - and this is what happened for you.

You can run the following commands in the Terminal to find out, which program has opened the ports:

lsof -n -i4TCP:8080
lsof -n -i4TCP:8081

You'll find both the command name and the process ID (PID) of the program that opened the ports.

Whether or not you should be concerned about it depends on what that program is. If it is something you installed yourself, is aware of, and you're using - then that's OK. If it is something that is running without your knowledge, or you're no longer using, you will probably want to look further into it.