Gary Johnson has added to the capture of David Clarkson from Motherwell by snapping up a new goalkeeper and a promising young defender.

Custodian Dean Gerken arrives from Colchester for an undisclosed fee to add competition for places between the posts.

Johnson has also taken a chance on free Portsmouth man Andre Blackman, 18.

"I think Andre has a super future in the game and I don't feel he is a million miles away right now," the Ashton Gate boss told the Bristol Evening Post.

"I think he had become a little frustrated and impatient that he wasn't as close to the Portsmouth first-team as he would have liked.

"He is a confident lad with excellent athleticism and bags of pace so I have got high hopes for him.

"People at his other clubs have been talking about his potential and this move gives him a chance to show some of it."