[2] Returning to Ireland in 1939 from Sweden, de Valéra became an assistant in the department of natural history at University College Galway (UCG).
Being the only botanist on the staff, de Valéra taught all of the botanical courses, with the work load doubling when the lectures were offered in Irish.
During World War II de Valéra was involved in a survey of marine algae as potential sources of agar on behalf of the Industrial Research Council from 1943 to 1946.
Much of this fieldwork was carried own along the west coast of Ireland, and it led to her writing the foreword of Notes on some common Irish seaweeds in 1950.
The work she conducted on Pterocladia and Gelidium during this time was the basis of her doctoral thesis, being awarded her PhD by NUI in 1945.
[1] The Máirín de Valéra Carron Field Research Facility, established first in 1975, is named in her memory.