Catalysis of the reaction: (9Z,12Z)-octadecadienoyl-containing glycerolipid + 2 Fe(II)- + 2 H+ + O2 = a (9Z)-octadec-9-en-12-ynoyl-containing glycerolipid + 2 Fe(III)- + 2 H2O.
delta12-fatty acid dehydrogenase activity