Well, reputed journals would have an average turn-around time for review. In case of most Springer Journals, they claim that their "Reviewers are given a tight deadline to review the manuscript. In most cases, the decision is made in less than three months." I think you've waited long enough. Perhaps, following up with the publisher for the status of your paper via e-mail/enquiry would be a prudent step given the time interval.

As a journal editor myself, I would suggest you contact the editor-- bc often we don't know if a paper has been languishing for 8 months... so here you are waiting and they have no idea. I always respond when it is a personal email to me rather than one of the hundreds of articles I have to sift through every week.