Basswise in Opeth

From what I've seen, a lot of the basswork on the first 2 albums isn't done with 4 string bass, but I may be wrong.
 
No, that's not true. The bass on both Morningrise and Orchid was played by Johan DeFarfalla (incredible by the way). Mike played all of the bass on My Arms Your Hearse because Mendez did not have enough time to learn the songs as he had just joined the band.

That was what my understanding was. I don't know where the person who has it as their signature got their ideas from.

Just a bit of trivia - while recently trying to look into what Johan was doing these days I stumbled upon a wikipedia page stating that he's a member of the Christian Democrats party...