What is this on the starboard engine of the Dash 8?
It is the engine drain mast. From the Dash 8 Series 400 airport planning document - Chapter 2, Page 40:



Dash 8 engine drain; image from Dash 8 Series 400 airport planning document

Basically, the drain mast houses the drains that allow for the removal of the fluids (oil and fuel) that come out of the engine, due to seepage, leaks etc. For example, this incident report is a case where it was,


  ... observed ... fuel dripping from RH engine drain mast.