Blooms of the scyphozoan jellyfish <i><span style="font-family:Verdana;">Aurelia aurita</span></i><span style="font-family:Verdana;"> are greatly regulated by the surv...Blooms of the scyphozoan jellyfish <i><span style="font-family:Verdana;">Aurelia aurita</span></i><span style="font-family:Verdana;"> are greatly regulated by the survival rate of planktonic ephyrae. The ecophysiology of ephyrae is poorly studied compared with polyps and medusae. As extremely strong starvation resistance and recovery capability of </span><i><span style="font-family:Verdana;">A. aurita</span></i><span style="font-family:Verdana;"> ephyrae may due to its low metabolic rate as well as starvation may reduce the swimming ability of ephyrae which may lead to the higher predation loss, the effects of temperature and starvation on their respiration and pulsation rates were examined. In this study, ephyrae under different starvation conditions were measured by a fluorescence-based DO meter after 72 h incubation. And the pulsation rates were measured at every 10-d interval in 1-liter plastic bottle by a hand-held counter. The results showed that the mean respiration rates of newly released ephyrae were 0.24, 0.24 and 0.19 μl O</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> ephyra</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> d</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> at 15°C, 12°C and 9°C, respectively, and the rates tended to decrease with increasing starvation duration. Carbon weight-specific respiration rates did not change significantly with starvation duration. The dry weight-specific respiration rates of newly released </span><i><span style="font-family:Verdana;">A. aurita</span></i><span style="font-family:Verdana;"> ephyrae (</span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;">, 11.7</span><span style="font-size:10pt;font-family:Verdana;">-</span><span style="font-size:10pt;font-family:;" "=""><span style="font-family:Verdana;">14.6 μl O</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> mg DW</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> d</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">) were nearly one order of magnitude lower than the rates for planktonic larvae of other taxa (e.g., molluscs, crustaceans and fish). The maximum pulsation rate taken by </span><i><span style="font-family:Verdana;">A. aurita</span></i><span style="font-family:Verdana;"> ephyrae was 49.2 beats min</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">, which represents the maximum swimming velocity to be 8.87 cm·min</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">. The pulsation rates were not affected by temperature over the range between 9°C and 15°C. However, they were influenced by starvation duration. Starvation-derived decrease in pulsation together with associated body shrinkage may lead to lower encounter rate of prey and lower escaping ability from predators, which may lead to higher predation loss in the field.</span></span>展开更多
Algal biotechnology has advanced greatly in the past three decades.Many microalgae are now cultivated to produce bioactive substances.Odontella aurita is a marine diatom industrially cultured in outdoor open ponds and...Algal biotechnology has advanced greatly in the past three decades.Many microalgae are now cultivated to produce bioactive substances.Odontella aurita is a marine diatom industrially cultured in outdoor open ponds and used for human nutrition.For the first time,we have systematically investigated the effects of culture conditions in cylindrical glass columns and flat-plate photobioreactors,including nutrients(nitrogen,phosphorus,silicon,and sulfur),light intensity and light path,on O.aurita cell growth and biochemical composition(protein,carbohydrate,β-1,3-glucan,lipids,and ash).The optimal medium for photoautotrophic cultivation of O.aurita contained 17.65 mmol/L nitrogen,1.09 mmol/L phosphorus,0.42 mmol/L silicon,and 24.51 mmol/L sulfur,yielding a maximum biomass production of 6.1–6.8 g/L and6.7–7.8 g/L under low and high light,respectively.Scale-up experiments were conducted with flat-plate photobioreactors using different light-paths,indicating that a short light path was more suitable for biomass production of O.aurita.Analyses of biochemical composition showed that protein content decreased while carbohydrate(mainly composed ofβ-1,3-glucan)increased remarkably to about 50%of dry weight during the entire culture period.The highest lipid content(19.7%of dry weight)was obtained under 0.11 mmol/L silicon and high light conditions at harvest time.Fatty acid profiles revealed that 80%were C14,C16,and C20,while arachidonic acid and eicosapentaenoic acid(EPA)accounted for 1.6%–5.6%and 9%–20%of total fatty acids,respectively.High biomass production and characteristic biochemical composition profiles make O.aurita a promising microalga for the production of bioactive components,such as EPA andβ-1,3-glucan.展开更多
The increasing amounts of artificial marine substrates, in many parts of the world have been proposed as a potential driver of Aurelia spp. blooms, on account of providing extra habitats for the settlement and the pro...The increasing amounts of artificial marine substrates, in many parts of the world have been proposed as a potential driver of Aurelia spp. blooms, on account of providing extra habitats for the settlement and the proliferation of the benthic stage(polyps). Previous experiments have mainly focused on the substrate choices of Aurelia spp. planulae. However, substrate preferences for the proliferation and immigration of polyps have not been reported. We monitored the propagation and immigration of Aurelia aurita(s. l.) polyps on two natural and nine artificial substrates at constant temperature(20±0.5°C) and salinity(30±0.5) in beakers and a glass aquarium in the laboratory, respectively. The results showed that, among artificial substrates, the highest number for polyp proliferation and immigration was found on nets, rigid polyvinyl chloride plates(RPVC), and wood. The lowest density of polyps was present on iron plates. Among natural substrates, the asexual reproduction rate of polyps on Patinopecten yessoensis(Jay, 1857) shells was significantly higher than Azumapecten farreri(Jones & Preston, 1904). On the account of the distinction in the roughness, chemical properties and biofilms of these material surfaces, bare artificial or natural substrates discriminatively affect the proliferation and the immigration of Aurelia spp. polyps at laboratory. These observations suggest that, even in the natural environment, different materials and texture may influence the composition and the abundance of the fouling communities and the assemblages of polyps and, indirectly, have effects on the amounts of released medusae.展开更多
Objective:To estimate the biological and population parameters required for proposing a preparation to sustain and manage this valuable fish resource.Methods:Aging was done by scales reading,and growth was estimated b...Objective:To estimate the biological and population parameters required for proposing a preparation to sustain and manage this valuable fish resource.Methods:Aging was done by scales reading,and growth was estimated by using the back-calculation method.The values of growth parameters L_(∞),k and t_(o)were calculated by von Bertalanffy model.Results:The results of growth parameters L_(∞),k and t_(o)were 28.36 cm,0.184 per year and-0.8437 per year,respectively.Mortality coefficient,survival and exploitation rates estimated to perceive yield per recruit and biomass per recruit.Conclusions:Biological reference points and virtual population analysis were prepared to plan appropriate managements forSardinella aurita fisheries.展开更多
文摘Blooms of the scyphozoan jellyfish <i><span style="font-family:Verdana;">Aurelia aurita</span></i><span style="font-family:Verdana;"> are greatly regulated by the survival rate of planktonic ephyrae. The ecophysiology of ephyrae is poorly studied compared with polyps and medusae. As extremely strong starvation resistance and recovery capability of </span><i><span style="font-family:Verdana;">A. aurita</span></i><span style="font-family:Verdana;"> ephyrae may due to its low metabolic rate as well as starvation may reduce the swimming ability of ephyrae which may lead to the higher predation loss, the effects of temperature and starvation on their respiration and pulsation rates were examined. In this study, ephyrae under different starvation conditions were measured by a fluorescence-based DO meter after 72 h incubation. And the pulsation rates were measured at every 10-d interval in 1-liter plastic bottle by a hand-held counter. The results showed that the mean respiration rates of newly released ephyrae were 0.24, 0.24 and 0.19 μl O</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> ephyra</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> d</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> at 15°C, 12°C and 9°C, respectively, and the rates tended to decrease with increasing starvation duration. Carbon weight-specific respiration rates did not change significantly with starvation duration. The dry weight-specific respiration rates of newly released </span><i><span style="font-family:Verdana;">A. aurita</span></i><span style="font-family:Verdana;"> ephyrae (</span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;">, 11.7</span><span style="font-size:10pt;font-family:Verdana;">-</span><span style="font-size:10pt;font-family:;" "=""><span style="font-family:Verdana;">14.6 μl O</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> mg DW</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> d</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">) were nearly one order of magnitude lower than the rates for planktonic larvae of other taxa (e.g., molluscs, crustaceans and fish). The maximum pulsation rate taken by </span><i><span style="font-family:Verdana;">A. aurita</span></i><span style="font-family:Verdana;"> ephyrae was 49.2 beats min</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">, which represents the maximum swimming velocity to be 8.87 cm·min</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">. The pulsation rates were not affected by temperature over the range between 9°C and 15°C. However, they were influenced by starvation duration. Starvation-derived decrease in pulsation together with associated body shrinkage may lead to lower encounter rate of prey and lower escaping ability from predators, which may lead to higher predation loss in the field.</span></span>
基金Supported by the National High Technology Research and Development Program of China(863 Program)(Nos.2009AA06440,2013AA065805)the National Basic Research Program of China(973 Program)(No.2011CB2009001)the National Natural Science Foundation of China(No.31170337)
文摘Algal biotechnology has advanced greatly in the past three decades.Many microalgae are now cultivated to produce bioactive substances.Odontella aurita is a marine diatom industrially cultured in outdoor open ponds and used for human nutrition.For the first time,we have systematically investigated the effects of culture conditions in cylindrical glass columns and flat-plate photobioreactors,including nutrients(nitrogen,phosphorus,silicon,and sulfur),light intensity and light path,on O.aurita cell growth and biochemical composition(protein,carbohydrate,β-1,3-glucan,lipids,and ash).The optimal medium for photoautotrophic cultivation of O.aurita contained 17.65 mmol/L nitrogen,1.09 mmol/L phosphorus,0.42 mmol/L silicon,and 24.51 mmol/L sulfur,yielding a maximum biomass production of 6.1–6.8 g/L and6.7–7.8 g/L under low and high light,respectively.Scale-up experiments were conducted with flat-plate photobioreactors using different light-paths,indicating that a short light path was more suitable for biomass production of O.aurita.Analyses of biochemical composition showed that protein content decreased while carbohydrate(mainly composed ofβ-1,3-glucan)increased remarkably to about 50%of dry weight during the entire culture period.The highest lipid content(19.7%of dry weight)was obtained under 0.11 mmol/L silicon and high light conditions at harvest time.Fatty acid profiles revealed that 80%were C14,C16,and C20,while arachidonic acid and eicosapentaenoic acid(EPA)accounted for 1.6%–5.6%and 9%–20%of total fatty acids,respectively.High biomass production and characteristic biochemical composition profiles make O.aurita a promising microalga for the production of bioactive components,such as EPA andβ-1,3-glucan.
基金Supported by the State Key Program of National Natural Science of China(No.41230963)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA11020305)+1 种基金the Shandong Joint Fund for Marine Ecology and Environmental Sciences(No.U1406403)the National Natural Science Foundation of China(No.41506144)
文摘The increasing amounts of artificial marine substrates, in many parts of the world have been proposed as a potential driver of Aurelia spp. blooms, on account of providing extra habitats for the settlement and the proliferation of the benthic stage(polyps). Previous experiments have mainly focused on the substrate choices of Aurelia spp. planulae. However, substrate preferences for the proliferation and immigration of polyps have not been reported. We monitored the propagation and immigration of Aurelia aurita(s. l.) polyps on two natural and nine artificial substrates at constant temperature(20±0.5°C) and salinity(30±0.5) in beakers and a glass aquarium in the laboratory, respectively. The results showed that, among artificial substrates, the highest number for polyp proliferation and immigration was found on nets, rigid polyvinyl chloride plates(RPVC), and wood. The lowest density of polyps was present on iron plates. Among natural substrates, the asexual reproduction rate of polyps on Patinopecten yessoensis(Jay, 1857) shells was significantly higher than Azumapecten farreri(Jones & Preston, 1904). On the account of the distinction in the roughness, chemical properties and biofilms of these material surfaces, bare artificial or natural substrates discriminatively affect the proliferation and the immigration of Aurelia spp. polyps at laboratory. These observations suggest that, even in the natural environment, different materials and texture may influence the composition and the abundance of the fouling communities and the assemblages of polyps and, indirectly, have effects on the amounts of released medusae.
基金supported by General Authority for Fish Resources Development(GAFRD),Egypt.
文摘Objective:To estimate the biological and population parameters required for proposing a preparation to sustain and manage this valuable fish resource.Methods:Aging was done by scales reading,and growth was estimated by using the back-calculation method.The values of growth parameters L_(∞),k and t_(o)were calculated by von Bertalanffy model.Results:The results of growth parameters L_(∞),k and t_(o)were 28.36 cm,0.184 per year and-0.8437 per year,respectively.Mortality coefficient,survival and exploitation rates estimated to perceive yield per recruit and biomass per recruit.Conclusions:Biological reference points and virtual population analysis were prepared to plan appropriate managements forSardinella aurita fisheries.