While it is hard to pinpoint the exact time that aquaponics was first used, there are several early examples of its use. The Aztecs developed a system known as chinampas in the twelfth- and thirteenth centuries, where plants were raised on stationary, or sometimes movable, artificial islands in shallow lakes, and waste materials dredged from canals were used to irrigate the plants. However, as early as 5 AD, the ancient Chinese developed similar early systems using plants, ducks, finfish and catfish together to raise their fish and plants harmoniously. While many different systems are on the market today, the development of the modern aquaponic system is often attributed to the various works of the New Alchemy Institute, of Dr. Mark McMurtry et al. at North Carolina State University, and of Dr. James Rakocy and his colleagues at the University of the Virgin Islands.