Doctor Cardy was a scientist working for Lex Luthor.
After capturing Aquaman, Luthor thought the best place to hide him was the aquatic park where Cardy was chief oceanographer. But the longer the King of Atlantis was held captive, the more strange fish attacks occurred. Luthor and Cardy discovered the link, and Luthor ordered Aquaman to be moved further inland.
Entering Aquaman's cell, Cardy stumbled upon a stowaway: Lois Lane. He had his security detail take both. Luthor was not pleased—holding Lois Lane in captivity was a sure way of getting Superman involved. Luthor ordered them both killed; disregarding Cardy's request no further study the creature.
At a dump site, he had his men take out the captives. Aquaman managed to communicate with nearby seagulls, who managed to distract Cardy and his men and free him and Lois. As they fled, Cardy had to inform Luthor.