The purpose of this study was to clarify the distribution of oceanic Halobates in the area of the Kuroshio flowing near the southern shore in the direction of 100° - 120°, and also to compare the population ...The purpose of this study was to clarify the distribution of oceanic Halobates in the area of the Kuroshio flowing near the southern shore in the direction of 100° - 120°, and also to compare the population density of Halobates between the area within or outside the area of the Kuroshio and also among seasons. This study was carried out during 8 cruises by R/V TANSEIMARU. The Kuroshio area south of the southern Japan coast (30°00'N - 35°00'N, 130°25'E - 141°04'E) was dominated by H. sericeus, and the averaged population-density of this species was significantly higher inside the Kuroshio than outside this current. On the Kuroshio, H. sericeus was dominant with the population density of 16,396.4 km-2 ± 66,138.4 [26] (Mean ± SD [n]), whereas the density of H. germanus was 8,581.9 km-2 ± 24,443.2 [26]. The two oceanic sea skaters, H. sericeusand H. germanus showed significant seasonal variation in the population density, with significantly higher density in October than other months, whereas there was no such significant October peak in the cosmopolitan oceanic sea skater, H. micans. The results of this study may suggest that H. sericeus could use the Kuroshio as a transportation tool to distribute a wide latitude area of from 10°N to 40°N in the western tropical, subtropical and temperate area in the Pacific Ocean.展开更多
This study aims, first, to examine the limit for tolerance to lower salinity by an oceanic sea skater, Halobates micans, and , second, to make it clear whether exclusively fresh water Halobatinae species, Metrocoris h...This study aims, first, to examine the limit for tolerance to lower salinity by an oceanic sea skater, Halobates micans, and , second, to make it clear whether exclusively fresh water Halobatinae species, Metrocoris histrio has salinity tolerance. Adults of H. micans were collected using Neuston Net from the starboard side of R/V MIRAI on a fixed station at 8°S, 80°E, whereas those of M. histrio were collected from a small pond filled with a spring fresh water in Kochi (33°N, 133°E), Japan. Time in survival was measured in starved condition under several salinity conditions: 0‰, 2‰, 4‰, 6‰, 8‰, 9‰ and 10‰ for H. micans;0‰, 5‰, 10‰, 12.5‰, 15‰ for M. histrio. Half of adults were in coma due to lower salinity under 10‰ and time in survival was less than 10 hours under less than 4‰ for H. micans. Time in survival was half at 5‰ of 80 hours on average at 0‰ as a control and less than 10 hours at 10‰ or higher salinity for M. histrio. Relatively flexible osmo-regulation ability by H. micans would be related to wide variety of salinity condition of surface oceanic water, whereas very limited tolerance even to lower salinity of 5‰ may be permitted by the no chances to be exposed to brackish water in natural habitats of M. histrio. This study showed that salinity tolerance of Halobatinae species would reflect, directly, the salinity condition of their habitats.展开更多
The tolerance to temperature increase was tested for Halobates individuals collected during two cruises in the western tropical Pacific Ocean （MR-06-05-Leg 3, December 21, 2006-January 12, 2007, 0°N-8°N; KH...The tolerance to temperature increase was tested for Halobates individuals collected during two cruises in the western tropical Pacific Ocean （MR-06-05-Leg 3, December 21, 2006-January 12, 2007, 0°N-8°N; KH-06-02-Leg 5, August 18-31, 2006, 12°N-17°N）. High temperature coma experiments were conducted on adults and 5th instar larvae. On average, H. sericeus （distributed in the wide latitude zone of 5°N-40°N）, H. germanus （distributed in the moderate latitude zone of 0°N-35°N） and H. micans （distributed mainly in the lower latitudes around the equator） were on average paralyzed at 35.6℃（SD： 0.89）, 32.9℃ （SD： 2.17） and 31.6℃ （SD： 2.60）, respectively （P = 0.035）. According to the current dynamics during the cruise, the colony ofH. sericeus at one station （5°N 137°E） may have been transferred from the northern area of 14°N by three currents （North Equatorial Current, Mindanao Current and North Equatorial Counter Current） to the area of 5°N 138°E. Extremely high heat resistance was shown by the adults of H. germanus in the sea area around the equator. Dynamic current and air movements in this area around the equator, that is a ＂warm seawater pool＂, could be hypothesized to be related to the high resistance to heat shown in this study.展开更多
文摘The purpose of this study was to clarify the distribution of oceanic Halobates in the area of the Kuroshio flowing near the southern shore in the direction of 100° - 120°, and also to compare the population density of Halobates between the area within or outside the area of the Kuroshio and also among seasons. This study was carried out during 8 cruises by R/V TANSEIMARU. The Kuroshio area south of the southern Japan coast (30°00'N - 35°00'N, 130°25'E - 141°04'E) was dominated by H. sericeus, and the averaged population-density of this species was significantly higher inside the Kuroshio than outside this current. On the Kuroshio, H. sericeus was dominant with the population density of 16,396.4 km-2 ± 66,138.4 [26] (Mean ± SD [n]), whereas the density of H. germanus was 8,581.9 km-2 ± 24,443.2 [26]. The two oceanic sea skaters, H. sericeusand H. germanus showed significant seasonal variation in the population density, with significantly higher density in October than other months, whereas there was no such significant October peak in the cosmopolitan oceanic sea skater, H. micans. The results of this study may suggest that H. sericeus could use the Kuroshio as a transportation tool to distribute a wide latitude area of from 10°N to 40°N in the western tropical, subtropical and temperate area in the Pacific Ocean.
文摘This study aims, first, to examine the limit for tolerance to lower salinity by an oceanic sea skater, Halobates micans, and , second, to make it clear whether exclusively fresh water Halobatinae species, Metrocoris histrio has salinity tolerance. Adults of H. micans were collected using Neuston Net from the starboard side of R/V MIRAI on a fixed station at 8°S, 80°E, whereas those of M. histrio were collected from a small pond filled with a spring fresh water in Kochi (33°N, 133°E), Japan. Time in survival was measured in starved condition under several salinity conditions: 0‰, 2‰, 4‰, 6‰, 8‰, 9‰ and 10‰ for H. micans;0‰, 5‰, 10‰, 12.5‰, 15‰ for M. histrio. Half of adults were in coma due to lower salinity under 10‰ and time in survival was less than 10 hours under less than 4‰ for H. micans. Time in survival was half at 5‰ of 80 hours on average at 0‰ as a control and less than 10 hours at 10‰ or higher salinity for M. histrio. Relatively flexible osmo-regulation ability by H. micans would be related to wide variety of salinity condition of surface oceanic water, whereas very limited tolerance even to lower salinity of 5‰ may be permitted by the no chances to be exposed to brackish water in natural habitats of M. histrio. This study showed that salinity tolerance of Halobatinae species would reflect, directly, the salinity condition of their habitats.
文摘The tolerance to temperature increase was tested for Halobates individuals collected during two cruises in the western tropical Pacific Ocean （MR-06-05-Leg 3, December 21, 2006-January 12, 2007, 0°N-8°N; KH-06-02-Leg 5, August 18-31, 2006, 12°N-17°N）. High temperature coma experiments were conducted on adults and 5th instar larvae. On average, H. sericeus （distributed in the wide latitude zone of 5°N-40°N）, H. germanus （distributed in the moderate latitude zone of 0°N-35°N） and H. micans （distributed mainly in the lower latitudes around the equator） were on average paralyzed at 35.6℃（SD： 0.89）, 32.9℃ （SD： 2.17） and 31.6℃ （SD： 2.60）, respectively （P = 0.035）. According to the current dynamics during the cruise, the colony ofH. sericeus at one station （5°N 137°E） may have been transferred from the northern area of 14°N by three currents （North Equatorial Current, Mindanao Current and North Equatorial Counter Current） to the area of 5°N 138°E. Extremely high heat resistance was shown by the adults of H. germanus in the sea area around the equator. Dynamic current and air movements in this area around the equator, that is a ＂warm seawater pool＂, could be hypothesized to be related to the high resistance to heat shown in this study.
