Gamma-ray spectra of some primary producers (single-cell plants), filter-feeding herbivores, and carnivores, assigned to trophic levels I, II, and III–V, respectively, were prepared from marine samples taken in the Pacific off Oregon during 1961–1962. These organisms had been exposed in their natural environment to both fission produ cts from fallout and neutron-induced radionuclides from reactors on the Columbia River....