Thanks to Shaun P who pointed out this post (in Spanish) by WIllem B on the Almerimar Vivelo Facebook page earlier today....

Here is a Google translation of the post that I have corrected a bit:

Attention to all: Last week I drove my car from Almerimar to El Ejido, passing many roundabouts. Halfway there I was stopped by the Civil Guard in an unmarked car. I did not use my indicator lights when leaving the roundabout. Virtually NO ONE does that. The fine was € 200.-, which is extremely high. So, everyone: be careful and use your indicator lights when you leave a roundabout!