The aquatic basis of ancient civilisations: the case of Synodontis schall and the Nile Valley

This chapter focuses on the role of aquatic resources in the ancient economies of the Nile Valley. We suggest that these resources have been overlooked in traditional interpretations because of a reliance on wall paintings and carvings in tombs, assumptions about the dominance of cereal crops, and a dearth of well-excavated faunal assemblages from settlement sites. We focus on the faunal material from Tell el- Amarna and in particular the fish remains, which are dominated by the catfish, Synodontis schall. We show that, in conjunction with the study of modern control samples, we can obtain reliable estimates of age-at-death and size from growth increments in the pectoral spines, and thus analyse the age and size distribution of fish caught and their growth rates. As might be expected, the modern schall populations show evidence for more intensive fishing pressure than the ancient populations. Unexpectedly, however, the Roman material suggests that schall were exploited more intensively than in the preceding Dynastic period, and that they suffered lower growth rates. We argue that the slower growth rates are the result of climatic deterioration in the 6th century AD, and that the increased pressure on schall may reflect a decline in food supplies from other sources and a need for greater reliance on the fish resources of the river

Fabrication of domain reversed gratings for SHG in LiNbO/sub 3/ by electron beam bombardment

A novel technique for the lithographic definition and the fabrication of domain reversed regions in LiNbO/sub 3/ is reported, with application to periodic structures for second harmonic generation (SHG). For the first time, to the authors' knowledge, domain reversal has been achieved on the negative c-face of the crystal. Such a structure should be useful for quasi-phase-matched SHG of infrared laser radiation