The relationship of three Brachionus calyciflorus morphotypes （two short-spined, single-spined and spineless ones） was studied in the laboratory. Newly hatched females of each morphotype were cultured individually i...The relationship of three Brachionus calyciflorus morphotypes （two short-spined, single-spined and spineless ones） was studied in the laboratory. Newly hatched females of each morphotype were cultured individually in an inorganic or Asplanchna-conditioned mediums, and the morphotype of their offspring were checked at 200 x magnification. Females of each morphotype, cultured in the inorganic medium, could produce offspring of these three morphotypes in a single generation. Females of all three morphotyes could respond to specific Asplanchna-substances when they were cultured in Asplanchna-conditioned medium. Moreover, we observed that these three morphotype females could coexist in the medium and had three types of egg-bearing females. Based on the above observations we suggest that B. calyciflorus was a morphotype complex and has three basic morphotypes.展开更多
[ Objective] The paper was to study the 24 and 48 h acute toxicity of common pyrethroid insecticides of eypermethrin and deltamethrin on Brachionus calyciflorus. [ Method ] With Guangzhou strain of B. colyciflorus as ...[ Objective] The paper was to study the 24 and 48 h acute toxicity of common pyrethroid insecticides of eypermethrin and deltamethrin on Brachionus calyciflorus. [ Method ] With Guangzhou strain of B. colyciflorus as test animal, the standard toxicity test method was used to carry out acute toxicity test, and LC50 of cypermethrin and deltamethrin on rotifer was determined using probit method. [ Result ] LC50 of cypermethrin on rotifer was 3 376.87 and 5.87 μg/L at 24 and 48 h, respectively, and those of deltamethrin on rotifer was 594.56 and 74.17 μg/L, respectively. [Condusion] Acute toxicity of cypermethrin and dehamethrin on rotifer at 24 and 48 h was different, LC50 of cypermethrin and deltamethrin on rotifer at 48 h was more sensitive to monitor the chemical pollutants in water body than LC50 at 24 h.展开更多
The effect of temperature on the life history characteristics of amictic females (AF), unfertilized mictic females (UMF) and fertilized mictic females (FMF) in Brachionus calyciflorus was studied with replicated indiv...The effect of temperature on the life history characteristics of amictic females (AF), unfertilized mictic females (UMF) and fertilized mictic females (FMF) in Brachionus calyciflorus was studied with replicated individual cultures at 20℃,25℃ and 30℃, and with algae Scenedesmus obliquus for their food. There were highly significant effects of both temperature and female type, independently and interactively, on the duration of juvenile and post-reproduction periods, and the number of eggs produced by the rotifer per life cycle. Among all the temperature-female type combinations, all the juvenile periods of FMF, and the post-reproduction periods of UMF and FMF at 20℃, were the longest, and the number of eggs produced by an UMF at 30℃ was the highest. There were highly significant effects of both temperature and female type on the duration of the reproduction period, but no clear correlation was observed between temperature and female type. The reproduction period of AF was longer than that of UMF and FMF. Only temperature influenced significantly the mean life-span of the three types of females. The duration of juvenile, reproduction and post-reproduction periods as well as the life-span of the three types of females were all reduced very significantly with rise of temperature, but the rates of reduction varied with female type. Among the three types of females, the number of eggs produced per life cycle by an UMF was the highest, and that of a FMF was the lowest. A significant relationship between the number of eggs produced per life cycle and temperature was observed only in the UMF.展开更多
Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few s...Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV - B radiation on five species of microalgae, i. e. , Chlorella sp. , Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV - B radiation when fed with five species of microalgae respectively （ P 〈 0.05 ） which indicates UV - B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp. , then C. muelleri, L galbana, N. clostertum and T. chuii in turn if without UV - B radiation. Under the highest dose of UV - B radiation treatment （2.70 kJ/m^2）, the rotifer preferred to feed C. muelleri, then Chlorella sp. , N. clostertum, L galbana and T. chuii in turn. Chlorella sp. , L galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV - B radiation will lead to the change in the structure of phytoplankton community.展开更多
Effect of UV-B radiation on ingesting and nutritional selecting behavior of the roifer Brachionus urceus on 5 species of microlgae were studied under controlled laboratory conditions. Restdts showed that enhanced UV-B...Effect of UV-B radiation on ingesting and nutritional selecting behavior of the roifer Brachionus urceus on 5 species of microlgae were studied under controlled laboratory conditions. Restdts showed that enhanced UV-B radiation significantly inhibited ingesting of the rotifer B. urceus when it was fed with 5 species of micro-algae （p〈0.05）. The ingesting selectivity rate varied with the UV-B radiation enhancement when it was fed with 5 species micro-algal mixture. Results indicated that the enhanced UV-B radiation could affect ingesting and nutritional selectivity of B. urceus.展开更多
The effects of four microalgae, Chlorella vulgaris, Platymonas helgolandicavar, Isochrysis galbana, and Nitzschia closterium on the grazing and filtering rates of the marine rotifer, Brachionus plicatilis, were evalua...The effects of four microalgae, Chlorella vulgaris, Platymonas helgolandicavar, Isochrysis galbana, and Nitzschia closterium on the grazing and filtering rates of the marine rotifer, Brachionus plicatilis, were evaluated under laboratory conditions. The grazing rates in separate cultures of the four microalga were as follows： C. vulgaris 〉 P. helgolandicavar 〉 L galbana 〉 N. closterium. However, the filtering rates occurred in the following order： P. helgolandicavar 〉 N. closterium 〉 C. vulgaris 〉 L galbana. A mixed diets experiment revealed that P. helgolandicavar was the preferred diet of B. plicatilis. In addition, the grazing rate of B. plicatilis increased gradually as the density of the microalgae increased, until concentrations of 2.5×10^6 cells mL^-1 for C. vulgaris and 1.5×10^6 cells mL^-1 for I. galbana were obtained. Furthermore, the filtering rate increased slightly when the density of the microalgae was low, after which it declined as the microalgal density increased. The grazing rates of B. plicatilis were as follows during the different growth phases： stationary phase 〉 exponential phase 〉 lag phase 〉 decline phase. Additionally, the filtering rates during the growth phases were： exponential phase 〉 lag phase 〉 stationary phase 〉 decline phase. The results of this study provide foundational information that can be used to explore the optimal culture conditions for rotifers and to promote the development of aquaculture.展开更多
Due to industrial activities,heavy metal concentrations in aquatic systems of Mexico,are on the rise.Zooplankton,particularly rotifers,being sensitive and common components of freshwater,are widely used in ecotoxicolo...Due to industrial activities,heavy metal concentrations in aquatic systems of Mexico,are on the rise.Zooplankton,particularly rotifers,being sensitive and common components of freshwater,are widely used in ecotoxicological tests for establishing water quality criteria.Depending on the route of exposure(i.e.via medium or algal food),the toxicity of heavy metals varies.In the present study we evaluated the effect of cadmium and mercury exposed through medium and via algal food for the rotifer B.rubens.For both the heavy metals,we exposed rotifers via medium containing Chlorella at 0.5×10^(6)cells/ml or fed daily on previously exposed(1,2 and 4 h)alga to the toxicants(using 5 times the value of LC_(50)for B.rubens).For cadmium toxicity through medium,we used 3 toxicant levels(0.1,0.2 and 0.4 mg/L)and for mercury,we used 0.005,0.010 and 0.015 mg/L.Based on the LC_(50),B.rubens was 24 times more sensitive to mercury(0.035±0.002 mg/L)than cadmium.At a concentration of 0.4 mg/L,cadmium through the medium caused increased lag phase of B.rubens.When grown on Chlorella exposed for different durations to cadmium,the rotifer density decreased with the increasing duration of algal exposure to the heavy metal.When mercury was used in the medium or via algal food,the trends in the population growth of B.rubens were similar to those for cadmium.An increase in heavy metal concentration in the medium resulted in a decrease of the rate of population increase per day(r).The r varied from 0.33(in control)to 0.02 d^(-1)(in heavy metal treatment)depending on the mode of exposure though medium or via algal food.展开更多
The toxicity of seven major HAB （harmful algal bloom） species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense （AT-6, non-PSP producer）, Alexandrium lusitanicum, A...The toxicity of seven major HAB （harmful algal bloom） species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense （AT-6, non-PSP producer）, Alexandrium lusitanicum, Alexandrum tamarense （ATHK） and Heterosigma akashiwo were studied against rotifer Brachionus plicatilis under laboratory conditions. The results show that P donghaiense, P. globosa, P. micans, A. tamarense （AT-6）, or A. lusitanicum could maintain the individual survival and reproduction, as well as the population increase of the rotifer, but the individual reproduction would decrease when exposed to these five algae at higher densities for nine days; H. akashiwo could decrease the individual survival and reproduction, as well as population increase of the rotifer, which is similar to that of the starvation group, indicating that starvation might be its one lethal factor except for the algal toxins; A. tamarense （ATHK） has strong lethal effect on the rotifer with 48h LCs0 at 800 cells/mL. The experiment on ingestion ability indicated by gut pigment change shows that P. donghaiense, P. globosa, P micans, A. tamarense （AT-6） and A. lusitanicum can be taken by the rotifers as food, but A. tamarense （ATHK） or H. akashiwo can be ingested by the rotifers. The results indicate that all the indexes of individual survival and reproduction, population increase, gut pigment change of the rotifers are good and convenient to be used to reflect the toxicities of HAB species. Therefore, rotifer is suggested as one of the toxicity testing organisms in detecting the toxicity of harmful algae.展开更多
In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif feren...In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life history parameters of rotifers(B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom(S keletonema costatum) and four dinofl agellates( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi cum). Compared with the control treatment(CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production(CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span(CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate(CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., fi nite rate of increase(CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase(CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton, resulting in an increase in algal numbers.展开更多
Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However, the cost of sex...Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However, the cost of sex may make the inferior competitor more vulnerable. To investigate the effect of sexual reproduction on the inferior competitor, we experimentally paired the competition of one Brachionus angularis clone against three Brachionus ealyciflorus clones. One of the B. calyciflorus clones showed a low propensity for sexual reproduction, while the other two showed high propensities. The results show that all B. calyciflorus clones were excluded in the competition for resources at low food level. The increased food level promoted the competition persistence, but the clones did not show a clear pattern. Both the cumulative population density and resting egg production increased with the food level. The cumulative population density decreased with the mixis investment, while the resting egg production increased with the mixis investment. A trade-off between the population growth and sexual reproduction was observed in this research. The results indicate that although higher mixis investment resulted in a lower population density, it would not determinately accelerate the exclusion process of the inferior competitor. On the contrary, higher mixis investment promoted resting egg production before being excluded and thus promised a long- term benefit. In conclusion, our results suggest that mixis investment, to some extent, favored the excluded inferior competitor under fierce competition or some other adverse conditions.展开更多
The interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal blooms(HAB) species were investigated experimentally by single culture method. B. plicatilis population and the growth of ...The interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal blooms(HAB) species were investigated experimentally by single culture method. B. plicatilis population and the growth of the two algae were compared at different algal cell densities. The results demonstrated that the B. plicatilis obtained sufficient nutrition from Prorocentrum donghaiense to support net population increase. With exposure to 2.5×104 cells mL-1 of P. donghaiense,the number of B. plicatilis increased faster than it did when exposed to other four algal densities(5,10,15 and 20 ×104 cells mL-1),and the increase rate of B. plicatilis population(r) at this algal density was 0.104 ± 0.015 r d-1. Cell densities of P. donghaiense decreased due to the grazing of B. plicatilis. In contrast,Heterosigma akashiwo had an adverse effect on B. plicatilis population and its growth was largely unaffected by rotifer grazing. In this case,B. plicatilis population decreased and H. akashiwo grew at a rate similar to that of the control.展开更多
The impacts of Prorocentrum donghaiense Lu and Alexandrium catenella Balech, causative species of the large-scale HAB in the East China Sea, were studied under laboratory conditions. According to bloom densities, the ...The impacts of Prorocentrum donghaiense Lu and Alexandrium catenella Balech, causative species of the large-scale HAB in the East China Sea, were studied under laboratory conditions. According to bloom densities, the effects of monocuhure and mixture of the two species were examined on the egg-hatching success ofArgopecten irradiarts Lamarck, and the population growth of Brachionus plicatilis MUller and Moina mongolica Daday. The results showed that monocuhure of A. catenella had a significant inhibition on the egg hatching success of A. irradians, and the population growth of B. plicatilis and M. mongolica. The median effective densities （ED50） inhibiting the egg hatching success of A. irradhms for 24 h and the population growth of B. plicatilis and M. mongolica for 96 h were 800, 630, and 2 400 cells/cm^3 , respectively. Monoculture of P. dongha/ense has no such inhibitory effect on the egg hatching success of A. irradians; P. donghaiense at lower suitable densities could sustain the population growth of B. plicatilis （ 1 × 10^4 ～ 3 ×10^4 cells/cm^3 ） and M. mongolica （2 × 10^4～5 ×10^4 cells/cm^3 ） ; P. donghaiense at higher densities had significantly adverse effect on the population growth of B. plicatilis （4 × 10^4 ～ 10×10^4 cells/cm^3 ） and M. mongolica （ 10 ×10^4 cells/cm^3）. When the two algae were mixed according to bloom densities, P. donghaiense at suitable densities to some extent could decrease the toxicity of A. catenella to B. plicatilis and M. mongolica. The results indicated that the large-scale HAB in the East China Sea could have adverse effect on zooplankton, and might further influence the marine ecosystem, especially when there was also Alexandrium bloom.展开更多
Maternal eff ects are one of the most interesting topics in evolutionary ecology as they can aff ect the rate of evolution and population dynamics by phenotypic manipulation of off spring related to fi tness. At prese...Maternal eff ects are one of the most interesting topics in evolutionary ecology as they can aff ect the rate of evolution and population dynamics by phenotypic manipulation of off spring related to fi tness. At present, studies examining the interaction between maternal environment eff ects and maternal age (birth order) eff ects are scarce. We designed an experiment to reveal whether environmentally induced maternal manipulation works equally on off spring across birth orders in rotifer Brachionus calycifl orus. In the experiment, newborn amictic mothers (F0) were cultured parallelly in low (LD) and high (HD) population density. Off spring (F1) of young (YF0) and old (OF0) mothers in both LD and HD groups were cultured under a crowded condition and the mixis ratios of both F1 and F2 were examined. Results show that F1 from HD-YF0 had a signifi cantly higher mixis ratio and those amictic ones produced daughters (F2 ) with higher mixis ratio in response to crowding than those from HD-OF0. In contrast, no such diff erences among F1 siblings were found in the LD-F0 group. Therefore, the eff ect of maternal age on the sexual propensity of the off spring can be aff ected independently by the maternal population density.展开更多
Large numbers of rotifer eggs from sediment resting egg banks may hatch simultaneously under appropriate conditions; therefore, natural populations are likely to be multiclonal in a growing season. A recent field inve...Large numbers of rotifer eggs from sediment resting egg banks may hatch simultaneously under appropriate conditions; therefore, natural populations are likely to be multiclonal in a growing season. A recent field investigation showed that subordinate and ephemeral clones were able to establish populations in an environment with several strongly dominant clone populations. However, it was not clear how the subordinate populations maintained their growth under these conditions where the crowding signal would induce high levels of sexual reproduction in the dominant clone populations. In the present study, we conducted a continuous passage to 60 generations for new populations at three different temperatures （15~C, 25~C, and 35~C）. These populations emerged from resting eggs produced by a clone population. At the first, 30th, and 60th generations, the populations were sampled and fitness was assayed using the life-table method. We found a significant short-term fitness advantage for populations newly emerged from resting eggs produced by a clone population of the rotifer Brachionus calycifiorus, followed by a significant decrease in relative fitness with long-term continuous passage. Our results suggested that the early short- term fitness advantage was important for later-hatched and subordinate clone populations in an environment with multiple sympatric clones. The early short-term fitness might also promote the coexistence of sympatric clones because it could help to offset the cost of early sexual reproduction.展开更多
The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985-1998. Several clone...The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985-1998. Several clones derived from each batch of resting eggs were cultured under the same conditions for 21 days. The percentage of clones appearing resting eggs and the average yield of resting eggs produced from each clone were recorded and statistically analyzed to find the differences between the mixis potential of those resting egg batches. Results showed that different batches of resting eggs had different mictic levels among their descendent clones; but no regular relationship was found between the mixis potential of resting eggs and their collection times/preservation periods. Several internal and external factors that might affect the mixis potential of resting eggs were discussed.展开更多
The effect of UV-B radiation enhancement at experimental doses of 0.00,0.24,0.48,0.72,0.96,and 1.20 kJ/m 2 on the population dynamics of the rotifer Brachionus urceus feeding on the alga Chlorella sp.was studied under...The effect of UV-B radiation enhancement at experimental doses of 0.00,0.24,0.48,0.72,0.96,and 1.20 kJ/m 2 on the population dynamics of the rotifer Brachionus urceus feeding on the alga Chlorella sp.was studied under controlled laboratory conditions using clonal culture and life-table techniques.The results show that UV-B radiation treatment significantly shortened the survival time of the rotifer （P 0.05）： The longest survival time （336 h） occurred in the control （0.00 kJ/m 2 ） while the shortest （222 h） occurred when exposed to the highest UV-B radiation treatment （1.20 kJ/m 2 ）.The fecundity of the rotifer B.urceus was enhanced by the lower UV-B radiation treatment （0.24 and 0.48 kJ/m 2 ） but inhibited by the higher treatments （0.96 and 1.20 kJ/m 2 ）.Life expectancy also was obviously affected by UV-B radiation （P 0.05）.The highest life expectancy occurred in the control （0.00 kJ/m 2 ）,and it became shorter with increasing doses of UV-B radiation.The resutls in the present study indicate that the life expectancy of the rotifer B.urceus can be used as an indicator for UV-B radiation enhancement.展开更多
文摘The relationship of three Brachionus calyciflorus morphotypes （two short-spined, single-spined and spineless ones） was studied in the laboratory. Newly hatched females of each morphotype were cultured individually in an inorganic or Asplanchna-conditioned mediums, and the morphotype of their offspring were checked at 200 x magnification. Females of each morphotype, cultured in the inorganic medium, could produce offspring of these three morphotypes in a single generation. Females of all three morphotyes could respond to specific Asplanchna-substances when they were cultured in Asplanchna-conditioned medium. Moreover, we observed that these three morphotype females could coexist in the medium and had three types of egg-bearing females. Based on the above observations we suggest that B. calyciflorus was a morphotype complex and has three basic morphotypes.
基金Supported by Natural Science Foundation of Education Department of Anhui Province(KJ2010B269,KJ2008A138,KJ2010A328)Municipal Research Project of Lu'an City Directly Commissioned to West Anhui University(2009LW026)~~
文摘[ Objective] The paper was to study the 24 and 48 h acute toxicity of common pyrethroid insecticides of eypermethrin and deltamethrin on Brachionus calyciflorus. [ Method ] With Guangzhou strain of B. colyciflorus as test animal, the standard toxicity test method was used to carry out acute toxicity test, and LC50 of cypermethrin and deltamethrin on rotifer was determined using probit method. [ Result ] LC50 of cypermethrin on rotifer was 3 376.87 and 5.87 μg/L at 24 and 48 h, respectively, and those of deltamethrin on rotifer was 594.56 and 74.17 μg/L, respectively. [Condusion] Acute toxicity of cypermethrin and dehamethrin on rotifer at 24 and 48 h was different, LC50 of cypermethrin and deltamethrin on rotifer at 48 h was more sensitive to monitor the chemical pollutants in water body than LC50 at 24 h.
基金NSFC (No .3 9870 15 8) ,NaturalScienceFoundationofAnhuiProvince (No .10 0 3 3 0 No .0 42 416)andtheExcellentYouthFoundation (No .0 40 43 0 5 0 )
文摘The effect of temperature on the life history characteristics of amictic females (AF), unfertilized mictic females (UMF) and fertilized mictic females (FMF) in Brachionus calyciflorus was studied with replicated individual cultures at 20℃,25℃ and 30℃, and with algae Scenedesmus obliquus for their food. There were highly significant effects of both temperature and female type, independently and interactively, on the duration of juvenile and post-reproduction periods, and the number of eggs produced by the rotifer per life cycle. Among all the temperature-female type combinations, all the juvenile periods of FMF, and the post-reproduction periods of UMF and FMF at 20℃, were the longest, and the number of eggs produced by an UMF at 30℃ was the highest. There were highly significant effects of both temperature and female type on the duration of the reproduction period, but no clear correlation was observed between temperature and female type. The reproduction period of AF was longer than that of UMF and FMF. Only temperature influenced significantly the mean life-span of the three types of females. The duration of juvenile, reproduction and post-reproduction periods as well as the life-span of the three types of females were all reduced very significantly with rise of temperature, but the rates of reduction varied with female type. Among the three types of females, the number of eggs produced per life cycle by an UMF was the highest, and that of a FMF was the lowest. A significant relationship between the number of eggs produced per life cycle and temperature was observed only in the UMF.
基金This work was supported by the National Natural Science Foundation of China under contract Nos 30270258 and 40506028 the National High Technology Research and Development Program of China under contract No. 2002AA648010+2 种基金 the China Postdoctoral Science Foundation under contract No. 2005037237 the Shandong Scientific Research Encouragement Foundation for Talent Youths under contract No. 03BS120the Doctor Scientific Research Foundation of Dongying Vocational College under contract No. B J0602.
文摘Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV - B radiation on five species of microalgae, i. e. , Chlorella sp. , Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV - B radiation when fed with five species of microalgae respectively （ P 〈 0.05 ） which indicates UV - B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp. , then C. muelleri, L galbana, N. clostertum and T. chuii in turn if without UV - B radiation. Under the highest dose of UV - B radiation treatment （2.70 kJ/m^2）, the rotifer preferred to feed C. muelleri, then Chlorella sp. , N. clostertum, L galbana and T. chuii in turn. Chlorella sp. , L galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV - B radiation will lead to the change in the structure of phytoplankton community.
基金Supported by the National Natural Science Foundation of China (30270258, 40506028)the National High Technology Research and Development Program of China (2002AA648010)+1 种基金the Encouraging Foundation for Outstanding Youth Scientists of Shandong Province (03BS120)China Postdoctoral Sience Foundation(2005037237)
文摘Effect of UV-B radiation on ingesting and nutritional selecting behavior of the roifer Brachionus urceus on 5 species of microlgae were studied under controlled laboratory conditions. Restdts showed that enhanced UV-B radiation significantly inhibited ingesting of the rotifer B. urceus when it was fed with 5 species of micro-algae （p〈0.05）. The ingesting selectivity rate varied with the UV-B radiation enhancement when it was fed with 5 species micro-algal mixture. Results indicated that the enhanced UV-B radiation could affect ingesting and nutritional selectivity of B. urceus.
基金Supported by Natural Science Foundation of China (No 30270258)Program for New Century Excellent Talents in University (NCET-05-0597)
文摘The effects of four microalgae, Chlorella vulgaris, Platymonas helgolandicavar, Isochrysis galbana, and Nitzschia closterium on the grazing and filtering rates of the marine rotifer, Brachionus plicatilis, were evaluated under laboratory conditions. The grazing rates in separate cultures of the four microalga were as follows： C. vulgaris 〉 P. helgolandicavar 〉 L galbana 〉 N. closterium. However, the filtering rates occurred in the following order： P. helgolandicavar 〉 N. closterium 〉 C. vulgaris 〉 L galbana. A mixed diets experiment revealed that P. helgolandicavar was the preferred diet of B. plicatilis. In addition, the grazing rate of B. plicatilis increased gradually as the density of the microalgae increased, until concentrations of 2.5×10^6 cells mL^-1 for C. vulgaris and 1.5×10^6 cells mL^-1 for I. galbana were obtained. Furthermore, the filtering rate increased slightly when the density of the microalgae was low, after which it declined as the microalgal density increased. The grazing rates of B. plicatilis were as follows during the different growth phases： stationary phase 〉 exponential phase 〉 lag phase 〉 decline phase. Additionally, the filtering rates during the growth phases were： exponential phase 〉 lag phase 〉 stationary phase 〉 decline phase. The results of this study provide foundational information that can be used to explore the optimal culture conditions for rotifers and to promote the development of aquaculture.
基金This research was funded by a grant from PAPIIT—IN204101.SSSS and SN also thank National System of Investigators(SNI一18723&20520)
文摘Due to industrial activities,heavy metal concentrations in aquatic systems of Mexico,are on the rise.Zooplankton,particularly rotifers,being sensitive and common components of freshwater,are widely used in ecotoxicological tests for establishing water quality criteria.Depending on the route of exposure(i.e.via medium or algal food),the toxicity of heavy metals varies.In the present study we evaluated the effect of cadmium and mercury exposed through medium and via algal food for the rotifer B.rubens.For both the heavy metals,we exposed rotifers via medium containing Chlorella at 0.5×10^(6)cells/ml or fed daily on previously exposed(1,2 and 4 h)alga to the toxicants(using 5 times the value of LC_(50)for B.rubens).For cadmium toxicity through medium,we used 3 toxicant levels(0.1,0.2 and 0.4 mg/L)and for mercury,we used 0.005,0.010 and 0.015 mg/L.Based on the LC_(50),B.rubens was 24 times more sensitive to mercury(0.035±0.002 mg/L)than cadmium.At a concentration of 0.4 mg/L,cadmium through the medium caused increased lag phase of B.rubens.When grown on Chlorella exposed for different durations to cadmium,the rotifer density decreased with the increasing duration of algal exposure to the heavy metal.When mercury was used in the medium or via algal food,the trends in the population growth of B.rubens were similar to those for cadmium.An increase in heavy metal concentration in the medium resulted in a decrease of the rate of population increase per day(r).The r varied from 0.33(in control)to 0.02 d^(-1)(in heavy metal treatment)depending on the mode of exposure though medium or via algal food.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-208)National Natural Science Foundation of China (No. 40821004, U0733006)National Basic Research Program of China (973 Program, No. 2001CB409700)
文摘The toxicity of seven major HAB （harmful algal bloom） species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense （AT-6, non-PSP producer）, Alexandrium lusitanicum, Alexandrum tamarense （ATHK） and Heterosigma akashiwo were studied against rotifer Brachionus plicatilis under laboratory conditions. The results show that P donghaiense, P. globosa, P. micans, A. tamarense （AT-6）, or A. lusitanicum could maintain the individual survival and reproduction, as well as the population increase of the rotifer, but the individual reproduction would decrease when exposed to these five algae at higher densities for nine days; H. akashiwo could decrease the individual survival and reproduction, as well as population increase of the rotifer, which is similar to that of the starvation group, indicating that starvation might be its one lethal factor except for the algal toxins; A. tamarense （ATHK） has strong lethal effect on the rotifer with 48h LCs0 at 800 cells/mL. The experiment on ingestion ability indicated by gut pigment change shows that P. donghaiense, P. globosa, P micans, A. tamarense （AT-6） and A. lusitanicum can be taken by the rotifers as food, but A. tamarense （ATHK） or H. akashiwo can be ingested by the rotifers. The results indicate that all the indexes of individual survival and reproduction, population increase, gut pigment change of the rotifers are good and convenient to be used to reflect the toxicities of HAB species. Therefore, rotifer is suggested as one of the toxicity testing organisms in detecting the toxicity of harmful algae.
基金Supported by the Innovation Research Group Program of National Natural Science Foundation of China(No.41121064)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA01020304)
文摘In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life history parameters of rotifers(B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom(S keletonema costatum) and four dinofl agellates( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi cum). Compared with the control treatment(CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production(CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span(CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate(CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., fi nite rate of increase(CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase(CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton, resulting in an increase in algal numbers.
基金Supported by the National Natural Science Foundation of China(No.30970349)
文摘Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However, the cost of sex may make the inferior competitor more vulnerable. To investigate the effect of sexual reproduction on the inferior competitor, we experimentally paired the competition of one Brachionus angularis clone against three Brachionus ealyciflorus clones. One of the B. calyciflorus clones showed a low propensity for sexual reproduction, while the other two showed high propensities. The results show that all B. calyciflorus clones were excluded in the competition for resources at low food level. The increased food level promoted the competition persistence, but the clones did not show a clear pattern. Both the cumulative population density and resting egg production increased with the food level. The cumulative population density decreased with the mixis investment, while the resting egg production increased with the mixis investment. A trade-off between the population growth and sexual reproduction was observed in this research. The results indicate that although higher mixis investment resulted in a lower population density, it would not determinately accelerate the exclusion process of the inferior competitor. On the contrary, higher mixis investment promoted resting egg production before being excluded and thus promised a long- term benefit. In conclusion, our results suggest that mixis investment, to some extent, favored the excluded inferior competitor under fierce competition or some other adverse conditions.
基金supported by the National Natural Sci-ence Foundation of China under No. 30270258the pro-gram for New Century Excellent Talent in University under No. NCET-05-0597the Natural Science Foundation of Ningbo University under No. RCL2008002 and XK0715048.
文摘The interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal blooms(HAB) species were investigated experimentally by single culture method. B. plicatilis population and the growth of the two algae were compared at different algal cell densities. The results demonstrated that the B. plicatilis obtained sufficient nutrition from Prorocentrum donghaiense to support net population increase. With exposure to 2.5×104 cells mL-1 of P. donghaiense,the number of B. plicatilis increased faster than it did when exposed to other four algal densities(5,10,15 and 20 ×104 cells mL-1),and the increase rate of B. plicatilis population(r) at this algal density was 0.104 ± 0.015 r d-1. Cell densities of P. donghaiense decreased due to the grazing of B. plicatilis. In contrast,Heterosigma akashiwo had an adverse effect on B. plicatilis population and its growth was largely unaffected by rotifer grazing. In this case,B. plicatilis population decreased and H. akashiwo grew at a rate similar to that of the control.
文摘The impacts of Prorocentrum donghaiense Lu and Alexandrium catenella Balech, causative species of the large-scale HAB in the East China Sea, were studied under laboratory conditions. According to bloom densities, the effects of monocuhure and mixture of the two species were examined on the egg-hatching success ofArgopecten irradiarts Lamarck, and the population growth of Brachionus plicatilis MUller and Moina mongolica Daday. The results showed that monocuhure of A. catenella had a significant inhibition on the egg hatching success of A. irradians, and the population growth of B. plicatilis and M. mongolica. The median effective densities （ED50） inhibiting the egg hatching success of A. irradhms for 24 h and the population growth of B. plicatilis and M. mongolica for 96 h were 800, 630, and 2 400 cells/cm^3 , respectively. Monoculture of P. dongha/ense has no such inhibitory effect on the egg hatching success of A. irradians; P. donghaiense at lower suitable densities could sustain the population growth of B. plicatilis （ 1 × 10^4 ～ 3 ×10^4 cells/cm^3 ） and M. mongolica （2 × 10^4～5 ×10^4 cells/cm^3 ） ; P. donghaiense at higher densities had significantly adverse effect on the population growth of B. plicatilis （4 × 10^4 ～ 10×10^4 cells/cm^3 ） and M. mongolica （ 10 ×10^4 cells/cm^3）. When the two algae were mixed according to bloom densities, P. donghaiense at suitable densities to some extent could decrease the toxicity of A. catenella to B. plicatilis and M. mongolica. The results indicated that the large-scale HAB in the East China Sea could have adverse effect on zooplankton, and might further influence the marine ecosystem, especially when there was also Alexandrium bloom.
基金Supported by the National Natural Science Foundation of China(Nos.31470445,30970349)
文摘Maternal eff ects are one of the most interesting topics in evolutionary ecology as they can aff ect the rate of evolution and population dynamics by phenotypic manipulation of off spring related to fi tness. At present, studies examining the interaction between maternal environment eff ects and maternal age (birth order) eff ects are scarce. We designed an experiment to reveal whether environmentally induced maternal manipulation works equally on off spring across birth orders in rotifer Brachionus calycifl orus. In the experiment, newborn amictic mothers (F0) were cultured parallelly in low (LD) and high (HD) population density. Off spring (F1) of young (YF0) and old (OF0) mothers in both LD and HD groups were cultured under a crowded condition and the mixis ratios of both F1 and F2 were examined. Results show that F1 from HD-YF0 had a signifi cantly higher mixis ratio and those amictic ones produced daughters (F2 ) with higher mixis ratio in response to crowding than those from HD-OF0. In contrast, no such diff erences among F1 siblings were found in the LD-F0 group. Therefore, the eff ect of maternal age on the sexual propensity of the off spring can be aff ected independently by the maternal population density.
基金Supported by the National Natural Science Foundation of China(Nos.30970349,41206110)
文摘Large numbers of rotifer eggs from sediment resting egg banks may hatch simultaneously under appropriate conditions; therefore, natural populations are likely to be multiclonal in a growing season. A recent field investigation showed that subordinate and ephemeral clones were able to establish populations in an environment with several strongly dominant clone populations. However, it was not clear how the subordinate populations maintained their growth under these conditions where the crowding signal would induce high levels of sexual reproduction in the dominant clone populations. In the present study, we conducted a continuous passage to 60 generations for new populations at three different temperatures （15~C, 25~C, and 35~C）. These populations emerged from resting eggs produced by a clone population. At the first, 30th, and 60th generations, the populations were sampled and fitness was assayed using the life-table method. We found a significant short-term fitness advantage for populations newly emerged from resting eggs produced by a clone population of the rotifer Brachionus calycifiorus, followed by a significant decrease in relative fitness with long-term continuous passage. Our results suggested that the early short- term fitness advantage was important for later-hatched and subordinate clone populations in an environment with multiple sympatric clones. The early short-term fitness might also promote the coexistence of sympatric clones because it could help to offset the cost of early sexual reproduction.
文摘The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985-1998. Several clones derived from each batch of resting eggs were cultured under the same conditions for 21 days. The percentage of clones appearing resting eggs and the average yield of resting eggs produced from each clone were recorded and statistically analyzed to find the differences between the mixis potential of those resting egg batches. Results showed that different batches of resting eggs had different mictic levels among their descendent clones; but no regular relationship was found between the mixis potential of resting eggs and their collection times/preservation periods. Several internal and external factors that might affect the mixis potential of resting eggs were discussed.
基金The National Natural Science Foundation of China under contract Nos 30270258 and 40506028the National High Technology Research and Development Program of China under contract No. 2002AA648010+2 种基金the China Postdoctoral Science Foundation under contract No. 2005037237the Shandong Scientific Research Encouragement Foundation for Talent Youths under contract No. 03BS120the Doctor Scientific Research Foundation of Dongying Vocational College under contract Nos BJ0602 and KJ0804
文摘The effect of UV-B radiation enhancement at experimental doses of 0.00,0.24,0.48,0.72,0.96,and 1.20 kJ/m 2 on the population dynamics of the rotifer Brachionus urceus feeding on the alga Chlorella sp.was studied under controlled laboratory conditions using clonal culture and life-table techniques.The results show that UV-B radiation treatment significantly shortened the survival time of the rotifer （P 0.05）： The longest survival time （336 h） occurred in the control （0.00 kJ/m 2 ） while the shortest （222 h） occurred when exposed to the highest UV-B radiation treatment （1.20 kJ/m 2 ）.The fecundity of the rotifer B.urceus was enhanced by the lower UV-B radiation treatment （0.24 and 0.48 kJ/m 2 ） but inhibited by the higher treatments （0.96 and 1.20 kJ/m 2 ）.Life expectancy also was obviously affected by UV-B radiation （P 0.05）.The highest life expectancy occurred in the control （0.00 kJ/m 2 ）,and it became shorter with increasing doses of UV-B radiation.The resutls in the present study indicate that the life expectancy of the rotifer B.urceus can be used as an indicator for UV-B radiation enhancement.
