Intensive Pyropia aquaculture in the coast of southwestern Yellow Sea and its subsequent waste, including disposed Ulva prolifera, was speculated to be one of the major sources for the large-scale green tide proceedin...Intensive Pyropia aquaculture in the coast of southwestern Yellow Sea and its subsequent waste, including disposed Ulva prolifera, was speculated to be one of the major sources for the large-scale green tide proceeding in the Yellow Sea since 2007. It was, however, unclear how the detached U. prolifera responded and resumed growing after they detached from its original habitat. In this study, we investigated the growth and photosynthetic response of the detached U. prolifera to various temperature, salinity and irradiance in the laboratory. The photosynthetic rate of the detached U. prolifera was significantly higher at moderate temperature levels(14–27℃)and high salinity(26–32), with optimum at 23℃ and 32. Both low(14℃) and highest temperature(40℃), as well as low salinity(8) had adverse effects on the photosynthesis. Compared with the other Ulva species, U. prolifera showed higher saturated irradiance and no significant photoinhibition at high irradiance, indicating the great tolerance of U. prolifera to the high irradiance. The dense branch and complex structure of floating mats could help protect the thalli and reduce photoinhibition in field. Furthermore, temperature exerted a stronger influence on the growth rate of the detached U. prolifera compared to salinity. Overall, the high growth rate of this detached U. prolifera(10.6%–16.7% d^–1) at a wide range of temperature(5–32℃) and salinity(14–32) implied its blooming tendency with fluctuated salinity and temperature during floating. The environmental parameters in the southwestern Yellow Sea at the beginning of green tide were coincident with the optimal conditions for the detached U. prolifera.展开更多
The cytological characteristics of major green-tide-forming green algae <i>Ulva prolifera</i> collected from Yellow Sea were studied th<span style="white-space:normal;"><span style="...The cytological characteristics of major green-tide-forming green algae <i>Ulva prolifera</i> collected from Yellow Sea were studied th<span style="white-space:normal;"><span style="font-family:;" "="">r</span></span><span style="white-space:normal;"><span style="font-family:;" "="">ough cutting segments, long time low temperature or dark treatments. After </span></span><span style="white-space:normal;"><span style="font-family:;" "="">being </span></span><span style="white-space:normal;"><span style="font-family:;" "="">dried in the shade and preserved at -</span></span><span style="white-space:normal;"><span style="font-family:;" "="">20<span style="white-space:nowrap;">°</span></span></span><span style="white-space:normal;"><span style="font-family:;" "="">C for 30 days, the <i>U.</i> <i>prolifera</i> was cultured at 4<span style="white-space:nowrap;">°</span>C in sterilized seawater under 40 μmol photons m<sup>-2</sup>·s<sup>-1</sup> light intensity for 120 days, results indicated that the plastid of <i>U. prolifera</i> continuously shrank with the extension of treatment, and most cells turned white and died, only a small amount of cells still contained a few of visible inclusions at the 120d of treatment. Then those samples were transferred to 20<span style="white-space:nowrap;">°</span>C and 40 μmol photons m<sup>-2</sup>·s<sup>-1</sup> condition for recovery cultivation, after about 10 days, some recovery cells were observed in the thallus, and those cells developed to young thallus gradually and released germ cells almost in the same time. After about 60 days of recovery cultivation, the newly-grown green thallus broke through the original dead thallus, and the germ cells also grew to new individual thallus. Before dark treatment, the <i>U.</i> <i>prolifera</i> cells were filled with plastid, contained visible starch grain and discernible cell outlines, while after 120 days of dark treatment, the plastid shrank and degraded together with the disappearance of cell inclusions, and the cell outlines also blurred, then those samples were transferred to optimal culture conditions at 20<span style="white-space:nowrap;">°</span>C in 40 μmol photons m<sup>-2</sup>·s<sup>-1</sup> light intensity, and 15 days later, newly-grown cells appeared on the almost dead thallus, these cells divided continuously and grew to young thallus, and those newly-grown thallus also generated active germ cells, which developed to new thallus that cytologically identical to the original thallus. Observation of chopped tissue of <i>U.</i> <i>prolifera</i> cultivated at 20<span style="white-space:nowrap;">°</span>C, 40</span></span><span style="white-space:normal;"><span style="font-family:;" "=""> </span></span><span style="white-space:normal;"><span style="font-family:;" "="">μmol m</span></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">-</span></sup></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">2</span></sup></span><span style="white-space:normal;"><span style="font-family:;" "="">·s</span></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">-</span></sup></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">1</span></sup></span><span style="white-space:normal;"><span style="font-family:;" "=""> showed that the morphological upper part cells turned to germ cells first, those germ cells including gametophyte and sporophyte, which released later and grew to new individual thallus. These findings provided cytological evidences for how <i>U. prolifera</i> live through stress conditions such as low temperature, darkness, and also useful for understanding the mechanism of the occurrence of green tide.</span></span>展开更多
黄海绿潮已成为中国近海一种新的自然灾害,对经济、环境等方面均有影响,研究黄海绿潮的生消过程及其影响因素,对进一步了解浒苔暴发机制、开展绿潮灾害防治工作有重要意义。基于拉格朗日运输模型(Larval TRANSport Lagrangian model, LT...黄海绿潮已成为中国近海一种新的自然灾害,对经济、环境等方面均有影响,研究黄海绿潮的生消过程及其影响因素,对进一步了解浒苔暴发机制、开展绿潮灾害防治工作有重要意义。基于拉格朗日运输模型(Larval TRANSport Lagrangian model, LTRANS),构建了可以模拟浒苔生长消亡的物理-生态耦合模型(Larval TRANSport Lagrangian model-Green Tide, LTRANS-GT),模拟了黄海浒苔漂移扩散和生长消亡过程,讨论了绿潮生物量季节变化特征及海表面温度、光照及氮磷营养盐在不同生消阶段所起到的作用。结果表明,在生长阶段,绿潮所在海域的海表面温度及光照处于适宜浒苔生长范围内,而氮磷营养盐浓度年际间差别较大。在消衰阶段,绿潮所在海域光照与生长阶段相比无明显差异,温度相较于生长阶段有着很明显的升高,且在浒苔消亡阶段末期平均温度均超过了26℃,温度的升高降低了浒苔的生长率,同时增加了浒苔的死亡率,此时氮磷营养盐均也处于较低水平。由敏感性试验结果发现,在生长阶段,海表面风场及表层流场的差异造成浒苔分布区域不同,带来的浒苔周围海域营养盐浓度差异是绿潮生长阶段年际差异的主导因素;在消衰阶段,温度的大幅上升及营养盐浓度的下降共同影响了绿潮消亡。展开更多
基金The Special Funds for Basic Ocean Science Research of FIO under contract Nos 2012T08,2014G33 and 2008T30the National Natural Science Foundation of China-Shandong Joint Funded Project“Marine Ecology and Environmental Sciences”under contract No.U1406403+1 种基金the National Natural Science Foundation of China under contract Nos 41206162 and 41206161the National Basic Research Program(973 Program)of China under contract No.2010CB428703
文摘Intensive Pyropia aquaculture in the coast of southwestern Yellow Sea and its subsequent waste, including disposed Ulva prolifera, was speculated to be one of the major sources for the large-scale green tide proceeding in the Yellow Sea since 2007. It was, however, unclear how the detached U. prolifera responded and resumed growing after they detached from its original habitat. In this study, we investigated the growth and photosynthetic response of the detached U. prolifera to various temperature, salinity and irradiance in the laboratory. The photosynthetic rate of the detached U. prolifera was significantly higher at moderate temperature levels(14–27℃)and high salinity(26–32), with optimum at 23℃ and 32. Both low(14℃) and highest temperature(40℃), as well as low salinity(8) had adverse effects on the photosynthesis. Compared with the other Ulva species, U. prolifera showed higher saturated irradiance and no significant photoinhibition at high irradiance, indicating the great tolerance of U. prolifera to the high irradiance. The dense branch and complex structure of floating mats could help protect the thalli and reduce photoinhibition in field. Furthermore, temperature exerted a stronger influence on the growth rate of the detached U. prolifera compared to salinity. Overall, the high growth rate of this detached U. prolifera(10.6%–16.7% d^–1) at a wide range of temperature(5–32℃) and salinity(14–32) implied its blooming tendency with fluctuated salinity and temperature during floating. The environmental parameters in the southwestern Yellow Sea at the beginning of green tide were coincident with the optimal conditions for the detached U. prolifera.
文摘The cytological characteristics of major green-tide-forming green algae <i>Ulva prolifera</i> collected from Yellow Sea were studied th<span style="white-space:normal;"><span style="font-family:;" "="">r</span></span><span style="white-space:normal;"><span style="font-family:;" "="">ough cutting segments, long time low temperature or dark treatments. After </span></span><span style="white-space:normal;"><span style="font-family:;" "="">being </span></span><span style="white-space:normal;"><span style="font-family:;" "="">dried in the shade and preserved at -</span></span><span style="white-space:normal;"><span style="font-family:;" "="">20<span style="white-space:nowrap;">°</span></span></span><span style="white-space:normal;"><span style="font-family:;" "="">C for 30 days, the <i>U.</i> <i>prolifera</i> was cultured at 4<span style="white-space:nowrap;">°</span>C in sterilized seawater under 40 μmol photons m<sup>-2</sup>·s<sup>-1</sup> light intensity for 120 days, results indicated that the plastid of <i>U. prolifera</i> continuously shrank with the extension of treatment, and most cells turned white and died, only a small amount of cells still contained a few of visible inclusions at the 120d of treatment. Then those samples were transferred to 20<span style="white-space:nowrap;">°</span>C and 40 μmol photons m<sup>-2</sup>·s<sup>-1</sup> condition for recovery cultivation, after about 10 days, some recovery cells were observed in the thallus, and those cells developed to young thallus gradually and released germ cells almost in the same time. After about 60 days of recovery cultivation, the newly-grown green thallus broke through the original dead thallus, and the germ cells also grew to new individual thallus. Before dark treatment, the <i>U.</i> <i>prolifera</i> cells were filled with plastid, contained visible starch grain and discernible cell outlines, while after 120 days of dark treatment, the plastid shrank and degraded together with the disappearance of cell inclusions, and the cell outlines also blurred, then those samples were transferred to optimal culture conditions at 20<span style="white-space:nowrap;">°</span>C in 40 μmol photons m<sup>-2</sup>·s<sup>-1</sup> light intensity, and 15 days later, newly-grown cells appeared on the almost dead thallus, these cells divided continuously and grew to young thallus, and those newly-grown thallus also generated active germ cells, which developed to new thallus that cytologically identical to the original thallus. Observation of chopped tissue of <i>U.</i> <i>prolifera</i> cultivated at 20<span style="white-space:nowrap;">°</span>C, 40</span></span><span style="white-space:normal;"><span style="font-family:;" "=""> </span></span><span style="white-space:normal;"><span style="font-family:;" "="">μmol m</span></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">-</span></sup></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">2</span></sup></span><span style="white-space:normal;"><span style="font-family:;" "="">·s</span></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">-</span></sup></span><span style="white-space:normal;"><sup><span style="font-family:;" "="">1</span></sup></span><span style="white-space:normal;"><span style="font-family:;" "=""> showed that the morphological upper part cells turned to germ cells first, those germ cells including gametophyte and sporophyte, which released later and grew to new individual thallus. These findings provided cytological evidences for how <i>U. prolifera</i> live through stress conditions such as low temperature, darkness, and also useful for understanding the mechanism of the occurrence of green tide.</span></span>
文摘黄海绿潮已成为中国近海一种新的自然灾害,对经济、环境等方面均有影响,研究黄海绿潮的生消过程及其影响因素,对进一步了解浒苔暴发机制、开展绿潮灾害防治工作有重要意义。基于拉格朗日运输模型(Larval TRANSport Lagrangian model, LTRANS),构建了可以模拟浒苔生长消亡的物理-生态耦合模型(Larval TRANSport Lagrangian model-Green Tide, LTRANS-GT),模拟了黄海浒苔漂移扩散和生长消亡过程,讨论了绿潮生物量季节变化特征及海表面温度、光照及氮磷营养盐在不同生消阶段所起到的作用。结果表明,在生长阶段,绿潮所在海域的海表面温度及光照处于适宜浒苔生长范围内,而氮磷营养盐浓度年际间差别较大。在消衰阶段,绿潮所在海域光照与生长阶段相比无明显差异,温度相较于生长阶段有着很明显的升高,且在浒苔消亡阶段末期平均温度均超过了26℃,温度的升高降低了浒苔的生长率,同时增加了浒苔的死亡率,此时氮磷营养盐均也处于较低水平。由敏感性试验结果发现,在生长阶段,海表面风场及表层流场的差异造成浒苔分布区域不同,带来的浒苔周围海域营养盐浓度差异是绿潮生长阶段年际差异的主导因素;在消衰阶段,温度的大幅上升及营养盐浓度的下降共同影响了绿潮消亡。