- 著者
- Puneeta Pandey Vijai Dharmamony Yamamoto Jun Sakurai Yasunori
- 出版者
- Inter-Research
- 雑誌
- Marine ecology progress series (ISSN:01718630)
- 巻号頁・発行日
- vol.551, pp.277-281, 2016-06-10
- 被引用文献数
- 5
Batch spawning, intermittent spawning and multiple spawning represent common reproductive strategies among cephalopods. These flexible spawning strategies are also common in fishes, and are thought to be a female trait that is programmed depending on environmental parameters. The ommastrephid squid Todarodes pacificus, being a terminal spawner, is considered to have a single spawning event, extruding one large egg mass and dying soon thereafter. Females that are interrupted by males exhibiting mating behavior, while extruding the egg mass, spawn multiple egg masses over the course of 2-3 d instead of dying soon after spawning the first egg mass. We demonstrate that male mating behavior causes 'forced' intermittent spawning by females (i.e. more than one spawning event). We hypothesize that in T. pacificus, some males use this strategy to mate with females unable to repel advances while spawning, thus providing the male with the opportunity to contribute sperm and enhance gene flow.
- 著者
- Shinomiya Yuichi Chiba Susumu Kanamori Makoto Hashizume Shigeyuki Yoshino Kenji Goshima Seiji
- 出版者
- Inter-Research
- 雑誌
- Marine ecology progress series (ISSN:01718630)
- 巻号頁・発行日
- vol.570, pp.157-171, 2017-04-27
- 被引用文献数
- 14
To understand the effects of patch attributes of seagrass beds on the persistence of an animal population, we examined shifts in patch utilization that occur with the life stages of a decapod crustacean, Hokkai shrimp Pandalus latirostris, inhabiting only eelgrass beds. The abundance of juveniles did not relate to the abundance of prey or patch size, but adult abundance decreased significantly when patches were smaller. Edge effects were suggested for adults. Since patch size and shoot density were inseparable structures at our study site, we conducted an experiment using artificial seagrass units (ASUs) to clarify structures that were effective as shrimp habitat. This experiment showed that while adults recruited mainly to the small patches regardless of shoot density, juveniles, though much smaller in number, recruited to all patch types. Adults frequently emerged from natural patches to bare spaces at night, while juveniles seldom used the bare spaces at all. When we experimentally released shrimps between ASUs at night, adults generally used the bare spaces while juveniles randomly moved to all habitat types. We tethered adults in the interior of seagrass patches and bare spaces during both daytime and nighttime, and found that the predation rate was high only in bare spaces during daytime. We demonstrated that the habitat functions of seagrass patches can vary with the life stages of this decapod crustacean, and suggest that spatial management of various sizes of patches is crucial for population persistence of Hokkai shrimp.