Productivity is a major factor affecting food web and ecosystem dynamics in natural systems (Slobodkin, 1960, 1962; Odum, 1969; Fretwell, 1977, 1987; Oksanen et al., 1981, this volume). Productivity can influence aspects of food weds like food chain length, stability, interaction strength, and species diversity (Rosenzweig, 1971; Oksanen et al., 1981; DeAngelis et al., 1989a, 1989b; DeAngelis, 1992; Moore et al., 1993; and Abrams and Roth, 1994a, 1994b). Among these, food chain length has been the most discussed. Food chain length has been suggested to lengthen with productivity because trophic transfers from resources to consumers entail losses to heat and waste. Therefore more trophic levels (longer food chains) should be supported if the web receives more energy or limiting materials or if trophic transfers are more efficient. These classical trophic transfer arguments posed by Elton (1927) and developed by Hutchinson (1959) and Slobodkin (1960) are basic to productivity-based food chain models (Oksanen et al., 1981; Fretwell, 1987). The actual support for the argument that energetic constraints limit food chain length in natural systems is, however, open to debate (Pimm and Kitching, 1987; Oksanen, 1988; Lawton, 1989; Pimm, 1991; Persson et al. , 1992; Hairston and Hairston, 1993; Wootton and Power, 1993).