- 著者
- Kazuki Yoshida Tatsuma Sato Kaoru Narita Takeshi Tomiyama
- 出版者
- 日本プランクトン学会、日本ベントス学会
- 雑誌
- Plankton and Benthos Research (ISSN:18808247)
- 巻号頁・発行日
- vol.12, no.1, pp.53-60, 2017-02-28 (Released:2017-02-28)
- 参考文献数
- 25
- 被引用文献数
- 2
The moonsnail Laguncula pulchella (Naticidae, formerly known as Euspira fortunei) is an invasive species that has had a negative impact on the Manila clam (Ruditapes philippinarum) population in northern Japan. In southern Japan, few records of L. pulchella exist; furthermore, the knowledge concerning the ecology of this organism is currently limited. Unexpectedly, we found many L. pulchella individuals in the Misuji River estuary, located in Hiroshima in southern Japan, during May 2015. We conducted a field survey on the density and body size of L. pulchella at a tidal flat in the Misuji River estuary (Site H) and compared those to L. pulchella in Matsukawaura Lagoon, located in Fukushima in northern Japan (Site F). The adult population of L. pulchella in a clam fishing ground (40,500 m2) at Site H was estimated to be 2,048 individuals in 2015. Densities of both surfaced individuals and egg collars of L. pulchella were lower at Site H than at Site F. Sizes of L. pulchella individuals and their egg collars as well as the somatic weight of the individuals at Site H were significantly smaller than those at Site F. These results suggest that the biological characteristics of L. pulchella largely differ between the two sites.
- 著者
- KOICHI SASAKI MAKOTO KUDO TAKESHI TOMIYAMA KINUKO ITO MICHIO OMORI
- 出版者
- The Japanese Society of Fisheries Science
- 雑誌
- Fisheries science (ISSN:09199268)
- 巻号頁・発行日
- vol.68, no.1, pp.104-116, 2002 (Released:2009-03-31)
- 参考文献数
- 13
- 被引用文献数
- 19
The predation pressure on the siphons of the bivalve Nuttallia olivacea by the juvenile stone flounder Platichthys bicoloratus in the Natori River estuary, Miyagi, was estimated from both sides of the predator-prey relationship to analyze the specific relationship in which predators remove a part of the prey. Feeding experiments determined the feeding rate required to achieve the growth of juvenile stone flounders in the field. A juvenile cropped siphon tips at a mean of 56 per day from March to early July. The siphon tips that a juvenile consumed in a season amounted to 6375 pieces (6.2 g). In terms of predation, the duration since the last cropping in the field from the regeneration of cropped siphons was analyzed. The mean cropping rate of 0.211 times a day per clam in an area of intensive predation indicated that a clam was cropped 25.8 times (22.1 mg) in a season by fishes. The mean cropping rate by juvenile stone flounders was estimated to be 0.160 times a day. Of the 25.8 croppings, 19.5 (16.9 of the 22.1 mg) could be attributed to juvenile stone flounders. The results proved that a juvenile stone flounder preyed on approximately 370 clams in a season.