A third vacancy on the New Haven Board of Alders looms, as Ward 16 Alder Migdalia Castro announced at Thursday’s Board meeting that she is resigning in order to take a job in City Hall.

Castro, who currently represents the Fair Haven neighborhood, will direct the Department of Elderly Services, replacing Patria Wallace come Feb. 1. Castro is also the third city alder appointed by Mayor Toni Harp to a post in her administration.

Ward 7 Alder Doug Hausladen ’04 was named this week the new director of the Department of Transportation, Traffic and Parking. Ward 3 Alder Jackie James resigned before the start of the term in January in order to become the deputy community services administrator. All three will require special elections this winter or spring to fill the vacancies.

“We’re going to continue working together with the elderly, with the traffic and parking, with all the ones that are moving in different directions,” Castro said. “I’m very excited.” She declined specific comment on the nature of her upcoming work, saying she was waiting to speak with Harp tomorrow.

Castro thanked Board president Jorge Perez in particular, saying he was a mentor for her in city politics.

Hausladen also delivered a farewell message to his colleagues, saying he looks forward to continued service in a new capacity. Both he and Castro received hearty rounds of applause.

Thursday’s Board meeting also saw the election, or re-election, of alders as representatives to city commissions. Ward 1 Alder Sarah Eidelson ’12, who was not present, was re-elected representative to the Development Commission. Ward 25 Alder Adam Marchand was unanimously elected the Board’s representative to the City Plan Commission over Ward 19 Alder Mike Stratton, who was not present.