Apologies to you both, Heywood and Shane!!
I have been reading this certificate wrongly. You seem to have worked that out!!
You are right - it is James Dournean who is the father of Marcella Dournean with the mother being Mary, formerly Kavanagh. James Dournean being the father and the fisherman.
The names do have their links as my mother was Dorothy Mary Kavanagh b. 1927, in Birkenhead, her father James Ryan Kavanagh, b. 1902 in Birkenhead, and Marcella as shown above.
Is there any trace of Mary Kavanagh in the censuses of 1891, 1881 in Arklow/Wicklow?
Jim