| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Outline of Final Research Achievements |
To assess impacts of global warming on sex determination in marine fish, we selected cobaltcap silverside as an indicator species and screened wild populations for the presence of sex-reversals. Relatively low numbers of sex-reversals (~20%) from both sexes were detected in each area/year, except the population of Tokyo Bay in 2016 (40%~ XX-males observed). To assess the relationship between high temperature and observed XX-males, we conducted otolith increment analysis using fish from 2014-2016 in Tokyo Bay and estimated the hatching date/period and the temperature each individual experienced shortly after hatching from thermal records for the region. The results showed that fish were born later and experienced higher temperatures during the first weeks of life in 2016 than in other years and suggested that exposure to relatively low and high water temperatures had induced development of XY-females and XX-males, respectively, and thus TSD is occurring in wild cobaltcap silverside.
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