Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University Volume 6 Issue 2
1966-12-20 発行

Observations on the tubicolous amphipod, Corophium acherusicum Costa, in Fukuyama Harbor Area

Onbe, Takashi
Observations were made on the population of a marine tubicolous amphipod, Corophium acherusicum COSTA, which was found in greatest abundance in Fukuyama Harbor, Inland Sea of Japan. The results obtained are summarized as follows :

1) Abundance in population density, as expressed in terms of the number of individuals per unit weight of dried mud-tubes of C. acherusicum, fluctuates seasonally, showing a single prominent peak in June.
2) There is a remarkable seasonal variation in size of both male and female, being larger in colder season than in summer season. This fact suggests the presence of large-sized over-wintering generations and small-sized summer generations. In general, the females are larger in size than the males.
3) Breeding continues throughout the year. But, there is an indication that the breeding seems most active in March-mid-July and next, October- November. Both in the coldest and the warmest seasons breeding activity may be suppressed.
4) The relationship between the number of eggs incubated in brood pouch (N) and the standard length of mother animal (L, mm) can be expressed as N = 0.28L2. 98.
5) The females are commoner than the males. The average sex-ratio is 1.6 (females) : 1 (male).
6) Importance of the amphipod as the member of fouling community and the prey for some littoral young fishes is described.