While several studies have documented the large-scale, seasonal movements of horseshoe crabs, little is known about their fine-scale, daily movement patterns. In this study we used a fixed array ultrasonic telemetry s...While several studies have documented the large-scale, seasonal movements of horseshoe crabs, little is known about their fine-scale, daily movement patterns. In this study we used a fixed array ultrasonic telemetry system to track the movements of 12 male and 16 female horseshoe crabs in the Great Bay estuary, New Hampshire. Data were obtained during the mating season, as well as during the remainder of the summer and fall, in the years 2005-2008. During the mating season animals were often, but not always, active during the high tides when they were approaching and leaving the spawning beaches. On average, both males and females approached mating beaches during 33% of the high tides they experienced and they most often made the tran- sition from being inactive to active during the last two hours of an incoming tide. From April-October horseshoe crabs were significantly more active during high tide periods vs low tide periods, with no clear preference for diurnal vs nocturnal activity. After the mating season ended horseshoe crabs continued to move into shallower water at high tide and then return to deeper water at low tide. Observations by SCUBA divers suggest that during these excursions into the mudflats horseshoe crabs were digging pits in the sediment while foraging for food. Thus, the tidal rhythm of activity that has been so well documented during the mating season probably persists into the fall, and primarily involves foraging activities展开更多
After World War Ⅱ,there were two opposing viewpoints on how to establish the world order. The United States continued to advocate the "Open Door"principle while the Soviet Union adhered to the "Sphere ...After World War Ⅱ,there were two opposing viewpoints on how to establish the world order. The United States continued to advocate the "Open Door"principle while the Soviet Union adhered to the "Sphere of Influence" principle. The Cold War arose from the irreconcilable antagonism between the two principles. Though it occurred between the U.S. and the USSR after World War Ⅱ,this antagonism could be traced back to the rivalry of US-Russian, US-Japan,US-Britain over the Far East since the beginning of the 20 th century. The "Open Door"was the diplomatic strictly followed by the US, and it was also the American national characteristics, thinking tradition and life style for a long time. Because of the balane of power in the international reality, the US could not achieve its ambition for establishing an opened world Pax Americana. Thus, it had to give up its original intention of opening the global market, began to recognize the existence of"influence sphere", and began to put itself into the vie with the USSR for sphere of influence. By the 1950s, the American government began to change its "Open Door" policy to Containment policy.展开更多
基金supported by NSF IOB 0517229 and NSF IOS 0920342 grants to WHW Ⅲ and CCC
文摘While several studies have documented the large-scale, seasonal movements of horseshoe crabs, little is known about their fine-scale, daily movement patterns. In this study we used a fixed array ultrasonic telemetry system to track the movements of 12 male and 16 female horseshoe crabs in the Great Bay estuary, New Hampshire. Data were obtained during the mating season, as well as during the remainder of the summer and fall, in the years 2005-2008. During the mating season animals were often, but not always, active during the high tides when they were approaching and leaving the spawning beaches. On average, both males and females approached mating beaches during 33% of the high tides they experienced and they most often made the tran- sition from being inactive to active during the last two hours of an incoming tide. From April-October horseshoe crabs were significantly more active during high tide periods vs low tide periods, with no clear preference for diurnal vs nocturnal activity. After the mating season ended horseshoe crabs continued to move into shallower water at high tide and then return to deeper water at low tide. Observations by SCUBA divers suggest that during these excursions into the mudflats horseshoe crabs were digging pits in the sediment while foraging for food. Thus, the tidal rhythm of activity that has been so well documented during the mating season probably persists into the fall, and primarily involves foraging activities
文摘After World War Ⅱ,there were two opposing viewpoints on how to establish the world order. The United States continued to advocate the "Open Door"principle while the Soviet Union adhered to the "Sphere of Influence" principle. The Cold War arose from the irreconcilable antagonism between the two principles. Though it occurred between the U.S. and the USSR after World War Ⅱ,this antagonism could be traced back to the rivalry of US-Russian, US-Japan,US-Britain over the Far East since the beginning of the 20 th century. The "Open Door"was the diplomatic strictly followed by the US, and it was also the American national characteristics, thinking tradition and life style for a long time. Because of the balane of power in the international reality, the US could not achieve its ambition for establishing an opened world Pax Americana. Thus, it had to give up its original intention of opening the global market, began to recognize the existence of"influence sphere", and began to put itself into the vie with the USSR for sphere of influence. By the 1950s, the American government began to change its "Open Door" policy to Containment policy.
