New agricultural technologies are often justified morally in terms of their expected benefits, e.g., feeding the world's hungry. Such justifications stand or fall, not only on whether such benefits are indeed forthcoming, but on whether or not they are outweighed by attendant dangers. The practical details of easch case are, therefore, all-important. In this paper agriculture and aquaculture are examined from the perspective of ecosystem integrity, and with further reference to the uncertain effects of anthropogenic changes in the earth's atmosphere. (...) The principle of integrity provides a strong justification for a cautious approach to new technologies, and particularly so in the case of transgenics. (shrink)