Don't get too excited about an increase in poor quality activity.
An upsurge in poll votes, likes, sharing, has little long-term impact upon the community. Spikes are fun, but it's poor quality activity.
It doesn't lead to the sorts of activity that leads to sustained growth, activity, or sense of community.
Some believe that members begin their journey through the community via these simple activity channels. Yet there is no evidence of this, and plenty against it.
Ultimatey, it's the activity through which you get to know other members that matters. It's the discussions, the exchange of views, the participation in events, blog posts, and similar content which counts. It's this that develops a stronger sense of community. Without this, people simply stop coming back.
Whilst an upsurge in activity may look good for your figures, in the long-run it's relatively meaningless. Focus and direct members towards the meaningful activity.