| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥2,400,000 (Direct Cost: ¥2,400,000)
|
|---|
| Research Abstract |
The increasing atmospheric concentration of carbon dioxide (CO_2) has been acidifying the whole neritic ocean, thereby driving all marine organisms to live in increasingly acidic environments. In the present study, we evaluated the long-term effects of increased seawater CO_2 on the marine shrimp Palaemon pacificus. Shrimps were reared in seawater equilibrated with air containing 1,000 ppmv and 1,900 ppmv (parts per million by volume) CO_2, the atmospheric CO_2 concentration predicted to occur around the year 2100 and 2300, for 30 and 15 weeks, respectively, to investigate effects on survival, growth, feeding, moulting and reproduction. Survival was significantly suppressed in both CO_2 groups compared to the respective controls (the final survival of the 1,000 ppmv group 55%, control 95% ; 1,900 ppmv 65%, control 95%). Growth of the 1,900 ppmv shrimps was significantly depressed compared to the control although feeding was unaffected. In contrast, both growth and feeding were unaffected by the 30-week exposure to 1,000 ppmv, while moulting became significantly more frequent than in the control after 18 weeks. In addition, only one of the five females in the 1,000 ppmv group bore eggs once, compared with 1 to 3 times of egg production in all control females (n=6). The present results demonstrate that the predicted future seawater CO_2 conditions would possibly reduce shrimp population through negatively affecting mortality, growth, and reproduction. If other crustaceans are similarly affected, the future marine ecosystem may be drastically altered through changing the essential constituents of the marine food web.
|
