霞地区および広島湾沿岸域の出土貝類とその利用

In this paper, I discuss the shellfish collected from the Kasumi campus during a 2010 survey of the Hiroshima Bay area, as well as how their use changed since the Jomon period. Seventy-five archaeological shellfish specimens were collected from sites dating from the Jomon to modern periods, many of which were Yayoi and medieval. The remains of the Jomon and Yayoi periods are located slightly more inland from the current coastline and further upstream, in other words, in the inner part of Hiroshima Bay, and the medieval remains are located near the modern coastline.
From the Kasumi campus specimens, five types of snails and nine types of bivalves were identified. Overall, oysters (Crassostrea gigas) were the most common, followed by clams (Meretrix lusoria), and Japanese littleneck clams (Ruditapes philippinarum), wedge-shaped surf clams (Mactra veneriformis), top shells (Rapana venosa), and others were used to varying degrees during these periods. Oysters were observed during stage I (middle and late Jomon period), and during stages II-Ill (middle and late Jomon period), various species, mainly clams, were found. In the last Jomon period, blood cockle (Tegillarca granosa) was also used a lot, and oysters were commonly used at some sites in the early and late Yayoi periods. Oysters again became the main constituent during stage N (Kofun to the Nara and Heian periods), and during stage V (from the Nara and Heian periods to the middle ages), some clams and Japanese littleneck clams (Ruditapes philippinarum) were found, but oysters remained the main constituent. The presence of Japanese basket clams (Corbicula japonica) at Hiroshima Castle during this period is likely due to its coastal environment in the early modern period.
It is probable that during the late and final Jomon period, oysters, Japanese littleneck clams, and other types of clams were collected from the tidal flats. Muddy mudflats were formed as the sea level decreased, and the marine environment's salt concentration decreased slightly. Most oysters were likely obtained from these mudflats. In the Yayoi period, farming was presumed to have started in the Hiroshima Bay area, causing people to move inland in search of wider flatlands, but as shellfish-gathering activities also continued, many shell mounds formed in these inland areas. After the small sea level regression during the Yayoi period, the sea level rose again, and people's lifestyle changed to mainly gathering hard clams.
In the Nara, Heian, and medieval periods, shell mounds formed near sea areas, and hard clams were used mainly for half-crenated ark (Scapharca kagoshimensis), Japanese littleneck clams, and oysters. Japanese littleneck clams, oysters, and wedge-shaped surf clams are the most commonly used hard clams in the modern period, but with the development of the distribution network, shellfish that live in slightly deeper waters and reefs, such as abalone and horned turbans (Turbo cornutus), were able to be transported to samurai residences. Therefore, in the modern period, their presence does not directly indicate a contemporary marine environment near the archaeological site, but it may indicate that particular shellfish species were selectively collected.
The shellfish analysed from the Kasumi campus and the Hiroshima Bay survey revealed that shellfish remained a consistent part of people's lives, but that different periods preferred different types.