We report the first record of the invasive freshwater jellyfish Craspedacusta sowerbii Lankester in Kralklzl Dam Lake, Southeastern Anatolia, Turkey. The medusa was found only in August, 2008 when average surface wate...We report the first record of the invasive freshwater jellyfish Craspedacusta sowerbii Lankester in Kralklzl Dam Lake, Southeastern Anatolia, Turkey. The medusa was found only in August, 2008 when average surface water temperatures were 26.9℃.展开更多
To explore the life cycle of Craspedacusta, the authors collected male and female specimens of the Craspedacusta sowerbyi xinyangensis in a small fire-fighting pond in Ningbo, Zhejiang Province in July, 2005 and 2006....To explore the life cycle of Craspedacusta, the authors collected male and female specimens of the Craspedacusta sowerbyi xinyangensis in a small fire-fighting pond in Ningbo, Zhejiang Province in July, 2005 and 2006. The development of C. sowerbyi xinyangensis was studied from zygote to medusa by means of light microscopy and digital camera. The zygotes of C. sowerbyi xinyangensis are globular and smooth （90- 105 μm diameter） and have an equal, total cleavage to the two-cell stage 15 min after fertilization. The embryos enter the four-cell stage after another 15 min and become multicellular embryos after 3h 15min. At this stage the embryos have a diameter similar to fertilized eggs but have uneven surfaces that are distinct from the smooth surfaces of the uncleaved zygotes. Solid gastrulae are formed 7 h after fertilization. These are spherical planulae with short surface cilia that begin to swim in slow clockwise circles. After 12 h, they lose their cilia, cease swimming and become elongated planulae with one end larger than the other. Rod-like planulae, similar in thickness at both ends, are formed after an additional 7 h. After 4 days, the planulae develop into tiny polyps having two germ layers and a gastrovascular cavity. The polyp mouth is 50 - 62 μm in diameter, lacking tentacles but having nematocysts around the mouth. Planulae become mature polyps after 10 days （15 days after fertilization）. Medusa buds （45 - 88 μm diameter） are formed by polyp budding, which soon become free-living medusae with 8 tentacles （380 - 620 μm diameters） . Sometimes, the movement of frustules, which are formed by the polyps and similar to planulae in morphology can also be observed [ Current Zoology 55 （3） ： 227 - 234, 2009].展开更多
The effects of osmotic pressure, temperature and stocking density on medusae survival of Craspedacusta sowerbii were examined. The medusae were shown to be sensitive to the variations of osmotic pressure. And the surv...The effects of osmotic pressure, temperature and stocking density on medusae survival of Craspedacusta sowerbii were examined. The medusae were shown to be sensitive to the variations of osmotic pressure. And the survival time was 〈90 h at 34 mOsm/L and it declined rapidly with rising osmotic pressure. The peak survival time of 〉200 h was recorded at 0.2 mOsm/L. Comparing with 27℃ and 32 ℃ treatments, 23 ℃ treatment yielded lower activities at a range of 8-13/min. However, there was a longer survival time. A non-linear relationship existed between survival time and stocking density. Lower density resulted in larger body size. And sexual reproduction resumed after breeding for 〉22 days. Newly-formed polyps and medusae appeared subsequently but only in the higher-density groups of 10, 14 and 18 ind./L. It suggested that the number of newly-formed polyps and medusae was highly dependent on stocking density. That is, a higher stocking density produced more organisms. However, newly-formed medusae died within one month and none grew a diameter of 〉5 mm.展开更多
文摘We report the first record of the invasive freshwater jellyfish Craspedacusta sowerbii Lankester in Kralklzl Dam Lake, Southeastern Anatolia, Turkey. The medusa was found only in August, 2008 when average surface water temperatures were 26.9℃.
基金funded by Program for Changjiang Scholar and Innovative Research Teamin University(IRT0734)The Natural Science Foundation of Zhejiang Province(No.Y307063)Zhejiang Education Bureau(No.20061639)
文摘To explore the life cycle of Craspedacusta, the authors collected male and female specimens of the Craspedacusta sowerbyi xinyangensis in a small fire-fighting pond in Ningbo, Zhejiang Province in July, 2005 and 2006. The development of C. sowerbyi xinyangensis was studied from zygote to medusa by means of light microscopy and digital camera. The zygotes of C. sowerbyi xinyangensis are globular and smooth （90- 105 μm diameter） and have an equal, total cleavage to the two-cell stage 15 min after fertilization. The embryos enter the four-cell stage after another 15 min and become multicellular embryos after 3h 15min. At this stage the embryos have a diameter similar to fertilized eggs but have uneven surfaces that are distinct from the smooth surfaces of the uncleaved zygotes. Solid gastrulae are formed 7 h after fertilization. These are spherical planulae with short surface cilia that begin to swim in slow clockwise circles. After 12 h, they lose their cilia, cease swimming and become elongated planulae with one end larger than the other. Rod-like planulae, similar in thickness at both ends, are formed after an additional 7 h. After 4 days, the planulae develop into tiny polyps having two germ layers and a gastrovascular cavity. The polyp mouth is 50 - 62 μm in diameter, lacking tentacles but having nematocysts around the mouth. Planulae become mature polyps after 10 days （15 days after fertilization）. Medusa buds （45 - 88 μm diameter） are formed by polyp budding, which soon become free-living medusae with 8 tentacles （380 - 620 μm diameters） . Sometimes, the movement of frustules, which are formed by the polyps and similar to planulae in morphology can also be observed [ Current Zoology 55 （3） ： 227 - 234, 2009].
基金supported by grants from the Yunnan Province Science and Technology Programa major program,a innovation plan of science and technology+4 种基金a seed industry programthe Basic Research Programme of Yunnan Province(2012FB183)the Yunnan Biodiversity Protection Programa major program of the Chinese Academy of Sciences(Y206B51181)the Yunnan Province Science and Technology Program(2012CA014)
文摘The effects of osmotic pressure, temperature and stocking density on medusae survival of Craspedacusta sowerbii were examined. The medusae were shown to be sensitive to the variations of osmotic pressure. And the survival time was 〈90 h at 34 mOsm/L and it declined rapidly with rising osmotic pressure. The peak survival time of 〉200 h was recorded at 0.2 mOsm/L. Comparing with 27℃ and 32 ℃ treatments, 23 ℃ treatment yielded lower activities at a range of 8-13/min. However, there was a longer survival time. A non-linear relationship existed between survival time and stocking density. Lower density resulted in larger body size. And sexual reproduction resumed after breeding for 〉22 days. Newly-formed polyps and medusae appeared subsequently but only in the higher-density groups of 10, 14 and 18 ind./L. It suggested that the number of newly-formed polyps and medusae was highly dependent on stocking density. That is, a higher stocking density produced more organisms. However, newly-formed medusae died within one month and none grew a diameter of 〉5 mm.
