IMO tools such as the "Like" button have also contributed to less interaction, people don't have to type anything, just point & click, and voila, they have contributed with a Like.
That is very true. I've been running a couple websites for about 18 years now, not aquarium related, fly fishing related (rod building & fly tying sites) and one thing I have found to be true from personal experience over the years is that there are two things that can not only cut down on the interaction of a forum style website, but can actually kill it. That's a like button (cuts down on interaction) and a facebook group. Facebook groups that are under the same name as a forum style website really start to kill off the forum website.
On the rod building site I run it was active for about 10 years with 50+ post per day, then we started the same group on facebook which was just meant to be in addition to the forum site. Well with in 1 year we went from 50+ post per day on the forum to about 1-2 post per week in a good week. Everyone uses the facebook group rather than the forum. That's why on the flytyingforum that I admin I refuse to start a facebook group or even put a "like" button on the site.