A benthic harmful dinoflagellate bloom caused by Prorocentrum concavum occurred at Xincun Bay,a lagoon characterized by a tropical seagrass ecosystem in the southern China,in summer 2018.Both abiotic and biotic factor...A benthic harmful dinoflagellate bloom caused by Prorocentrum concavum occurred at Xincun Bay,a lagoon characterized by a tropical seagrass ecosystem in the southern China,in summer 2018.Both abiotic and biotic factors may affect the abundance dynamics of P.concavum.One of the biotic factors,allelopathy,is known to be especially common among aquatic species and is suggested to be an economical and environmentally-friendly way to eliminate Benthic Harmful Algal Blooms(BHABs).To investigate the possible allelopathic interactions between seagrasses and P.concavum,a field survey was conducted to study the cell densities of P.concavum on four major substrates over 12 months.In laboratory,fresh Enhalus acoroides leaves and a crude aqueous extract of dry E.acoroides leaves were added to the culture of P.concavum respectively to assess possible effects on the growth and photosynthesis activities of P.concavum cells.Our results showed that the average abundance of P.concavum on E.acoroides leaves was statistically lower than that on the sediment outside the seagrass meadow and that on Thalassia hemperichii leaves.Both the growth and photosynthesis activities of P.concavum cells were inhibited in the two experiments,which can be attributed to the release and production of allelochemicals by E.acoroides.Our results offer new insights into the interaction between the submerged seagrass E.acoroides and the benthic harmful algal bloom dinoflagellate P.concavum,which can influence the abundance dynamics of P.concavum and provide an alternative for reducing potential threat of BHABs.展开更多
The mitochondrial genome(mitogenome) was 16792 bp in length, containing 13 protein coding genes(PCGs), two rRNA genes(12 S rRNA and 16 S rRNA), 22 tRNA genes, and two main non-coding regions. Among these 37 genes, 28 ...The mitochondrial genome(mitogenome) was 16792 bp in length, containing 13 protein coding genes(PCGs), two rRNA genes(12 S rRNA and 16 S rRNA), 22 tRNA genes, and two main non-coding regions. Among these 37 genes, 28 genes were encoded on the heavy strand, while 9 genes were transcribed on the light strand. The non-coding regions of A. dispar included a control region, a light strand replication and another 11 intergenic spacers. The CR of A. dispar contained 8 conserved sequence blocks(CSBs), a termination-associated sequence(TAS) and a pyrimidine tract. Phylogenetic analysis based on 12 PCGs revealed that A. dispar was genetically closest to Arius arius. The families Schilbeidae, Claroteidae, Mochokidae, and Ariidae formed a closely evolved clade. Molecular information from this research introduces mitogenomice data of A. dispar and suggests the phylogenetic relationships among Siluriformes.展开更多
The dinoflagellate genus K arenia is known for recurrent harmful blooms worldwide. However, species diversity of the genus is generally overlooked owing to the difficulty of identifying small unarmored dinoflagellates...The dinoflagellate genus K arenia is known for recurrent harmful blooms worldwide. However, species diversity of the genus is generally overlooked owing to the difficulty of identifying small unarmored dinoflagellates. We have established four clonal cultures of K arenia longicanalis isolated from the type locality, Hong Kong harbor(strain HK01) and other three locations along the Chinese coasts(strains YB01, DT01, and NJ01). The morphology of the strain was studied by light and scanning electron microscopy(LM and SEM) and the pigment composition analyzed by high-performance liquid chromatography. We provide the first molecular data of K. longicanalis based on the large subunit(LSU) rRNA gene sequence and internal transcribed spacer(ITS). The four strains showed identical LSU rDNA sequences with a similarity of 99.4% to the holotype of K arenia umbella(strain KUTN05) from Australia. In the ITS phylogeny, the sequence of K. umbella branched between the Chinese strains of K. longicanalis. A careful comparison of the morphology of K. longicanalis and K. umbella reveals the similarity in the diagnostic characters. Diff erences may appear due to the sample treatment for SEM. We conclude that K. umbella is a junior synonym of K. longicanalis.展开更多
The effects of different types of ultraviolet(UV)radiation(UVR,wavelength=280-400 nm)and light intensities on cell growth,pigment composition,UV-absorbing compounds(UVACs),and chlorophyll a(Chl a)fluorescence were stu...The effects of different types of ultraviolet(UV)radiation(UVR,wavelength=280-400 nm)and light intensities on cell growth,pigment composition,UV-absorbing compounds(UVACs),and chlorophyll a(Chl a)fluorescence were studied in dinoflag-ellate Prorocentrum lima cultured outdoors for 16 days and indoors for 18 days.In the outdoor experiment,UVA radiation(320-400 nm)increased the growth rate of this dinoflagellate when solar light intensities were<12%;decreased growth rates were observed when intensities were>12%.Exposure to UVB radiation(280-320 nm)alleviated the negative effects of UVA.In the indoor ex-periment,UVA and low doses of UVB enhanced growth rates.Addition of low doses of UVB to UVA exposure resulted in higher contents of Chl a and photoprotective pigments compared with UVA exposure only.The results of both experiments showed that UVB is the primary signal of UVAC synthesis.High-dose UVB exposure accelerated growth rates when UVAC contents were maintained at high levels,suggesting that the latter plays a key role in UVR damage protection.Furthermore,the repair rate was en-hanced by UVB exposure after 16 days of culture.This study confirms the positive effects of UVA and UVB on the growth of P.lima,with the latter enhancing the photoprotective and recovery pathways of the species.展开更多
Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus(P...Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus(PE-rich SYN) and phycocyanin-rich Synechococcus(PC-rich SYN). The effects of environmental factors on the alternation of the different Synechococcus groups were also elucidated. PE-rich SYN was detected in three surveys, whereas PC-rich SYN was detected in May and August, but not in November. The highest abundances of PE-rich SYN and PC-rich SYN were recorded in August and May, with mean values of 74.17×103 and 189.92×103 cells m L-1, respectively. From May to November, the relative abundance of PE-rich SYN increased, whereas that of PC-rich SYN declined. PE-rich and PC-rich SYN presented similar horizontal distributions with high abundance in the southern estuary in May, and in the western estuary in August. The abundances of PE-rich and PC-rich SYN were high at 27–32℃and salinity of 10–20. PC-rich SYN was not detected at < 24℃, and PC:PE-rich SYN decreased in abundance with salinity increase. When less than 20 mg L-1, suspended particulate matter(SPM) was helpful for Synechococcus growth. PE-rich SYN decreased in abundance when the concentration of dissolved inorganic nitrogen increased in May and November, and the concentration of phosphate increased in November. However, PC-rich SYN abundance and nutrients showed no correlation. Principal component analysis and regression analysis indicated that PE-rich SYN significantly correlated with the principal components that were affected by environmental factors.展开更多
Brown tides have recurred in estuary areas globally,but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood.In this study,we investigated per...Brown tides have recurred in estuary areas globally,but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood.In this study,we investigated performance（ingestion,growth,development and reproduction） of the planktonic copepod,Pseudodiaptomus poplesia,offered either mono-algal or mixed-algal diets containing a Chinese strain of A.anophagefferens.A typical Michaelis-Menten pattern existed between ingestion rate and food level when copepod fed on the monoalgal diet of this species.Nauplii exhibited the highest maximum ingestion rate（Imax） than copepodids and adult females.In addition,Imax value was higher in nauplii feeding on A.anophagefferens than on Skeletonema costatum.When fed mixtures of A.anophagefferens and S.costatum,P.poplesia selected against A.anophagefferens cells,but less strongly at the naupliar stage.Nauplii did not undergo metamorphosis and died at late naupliar stages feeding on A.anophagefferens alone,similar to those under starvation.Furthermore,the presence of A.anophagefferens greatly reduced the reproduction rate of females in mixtures but did not influence the growth rate of copepodids.These results suggest that P.poplesia nauplii may exert grazing pressure on A.anophagefferens population during a brown tide,which,however,may not be persistent because of copepod population decline.展开更多
The abundance and temporal patterns of viable diatom resting stage cells in sediments of the East China Sea in 2006 have been investigated.The abundance of viable resting stages was enumerated with the most probable n...The abundance and temporal patterns of viable diatom resting stage cells in sediments of the East China Sea in 2006 have been investigated.The abundance of viable resting stages was enumerated with the most probable number（MPN） technique.Overall,25 diatom species（including varieties） belonging to 16 genera were detected.Viable resting stage cells were common,on the order of 103 to 106 cells/g dry mass.The abundant taxa included Skeletonema marina,S.dohrnii,Chaetoceros curvisetus and Thalassiosira spp.,with Skeletonema accounting for 83.3% of the cell.The effects of temperature（10,15,20,25 ℃）,salinity（20,25,30,35 psu） and light intensity（0,300,4 000,8 000 lux） on the germination of resting stages in sediment samples were also determined.The results showed that light intensity had a significant positive effect on the germination of diatom resting stage cells（p 〈0.01） and that diatoms could not germinate in darkness.Temperature and salinity had no noticeable effects on the germination.The present study suggests that there are abundant diatom resting cells in sediments of the East China Sea,which could serve as a ＂seed bank＂ in the phytoplankton population succession and contribute to the initiation of algal blooms.展开更多
To investigate the dynamics of phytoplankton size structure in the Pearl River estuary, concentrations of size-fractionated chlorophyll a (Chl a) were determined during four cruises carried out in 2008 and 2010. The d...To investigate the dynamics of phytoplankton size structure in the Pearl River estuary, concentrations of size-fractionated chlorophyll a (Chl a) were determined during four cruises carried out in 2008 and 2010. The distribution of Chl a in this geographical location showed a high degree of temporal variation. Chl a concentrations were highest in autumn, approximately three times higher than those in summer and winter. Microphytoplankton was the dominant contributor, accounting for 66.9% of the Chl a concentration in autumn 2008. In summer and spring 2008, nano-sized cells dominated the phytoplankton population throughout the study region. During the winter cruise, two different areas of water were found, characterized by (1) low salinity and high nutrient content and (2) high salinity and low nutrient content; nano- and picophytoplankton co-dominated the first area, while microphytoplankton dominated the second. It is arguable that grazing could have played a role in determining phytoplankton community size structure in winter. Nutrient concentrations were assumed not to limit phytoplankton growth during the investigation period. Size-differential capacity in competing for the resources available under different hydrodynamic conditions seemed to be the major factor in determining seasonal variation in the structure of the phytoplankton communities. High N:P ratios in the Pearl River estuary had major implications for nutrient pollution control. Our results indicated that studies of phytoplankton size structure provide greater insight into phytoplankton dynamics and are necessary to better manage water quality in the Pearl River estuary.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42076144,41876173)the Special Foundation for National Science and Technology Basic Research Program of China(No.2018FY100200).
文摘A benthic harmful dinoflagellate bloom caused by Prorocentrum concavum occurred at Xincun Bay,a lagoon characterized by a tropical seagrass ecosystem in the southern China,in summer 2018.Both abiotic and biotic factors may affect the abundance dynamics of P.concavum.One of the biotic factors,allelopathy,is known to be especially common among aquatic species and is suggested to be an economical and environmentally-friendly way to eliminate Benthic Harmful Algal Blooms(BHABs).To investigate the possible allelopathic interactions between seagrasses and P.concavum,a field survey was conducted to study the cell densities of P.concavum on four major substrates over 12 months.In laboratory,fresh Enhalus acoroides leaves and a crude aqueous extract of dry E.acoroides leaves were added to the culture of P.concavum respectively to assess possible effects on the growth and photosynthesis activities of P.concavum cells.Our results showed that the average abundance of P.concavum on E.acoroides leaves was statistically lower than that on the sediment outside the seagrass meadow and that on Thalassia hemperichii leaves.Both the growth and photosynthesis activities of P.concavum cells were inhibited in the two experiments,which can be attributed to the release and production of allelochemicals by E.acoroides.Our results offer new insights into the interaction between the submerged seagrass E.acoroides and the benthic harmful algal bloom dinoflagellate P.concavum,which can influence the abundance dynamics of P.concavum and provide an alternative for reducing potential threat of BHABs.
基金supported by the National Natural Science Foundation of China (Nos.41806127 and 41906111)the Natural Science Foundation of Guangdong Province (No.2018A030313956)。
文摘The mitochondrial genome(mitogenome) was 16792 bp in length, containing 13 protein coding genes(PCGs), two rRNA genes(12 S rRNA and 16 S rRNA), 22 tRNA genes, and two main non-coding regions. Among these 37 genes, 28 genes were encoded on the heavy strand, while 9 genes were transcribed on the light strand. The non-coding regions of A. dispar included a control region, a light strand replication and another 11 intergenic spacers. The CR of A. dispar contained 8 conserved sequence blocks(CSBs), a termination-associated sequence(TAS) and a pyrimidine tract. Phylogenetic analysis based on 12 PCGs revealed that A. dispar was genetically closest to Arius arius. The families Schilbeidae, Claroteidae, Mochokidae, and Ariidae formed a closely evolved clade. Molecular information from this research introduces mitogenomice data of A. dispar and suggests the phylogenetic relationships among Siluriformes.
基金Supported by the Youth Backbone Training Plan of the Beijing Academy of Science and Technology(No.201602)the National Nature Science Foundation of China(No.41606175,41576162)+1 种基金the National Key R&D Program of China(No.2017YFC1404301)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA1102030401)
文摘The dinoflagellate genus K arenia is known for recurrent harmful blooms worldwide. However, species diversity of the genus is generally overlooked owing to the difficulty of identifying small unarmored dinoflagellates. We have established four clonal cultures of K arenia longicanalis isolated from the type locality, Hong Kong harbor(strain HK01) and other three locations along the Chinese coasts(strains YB01, DT01, and NJ01). The morphology of the strain was studied by light and scanning electron microscopy(LM and SEM) and the pigment composition analyzed by high-performance liquid chromatography. We provide the first molecular data of K. longicanalis based on the large subunit(LSU) rRNA gene sequence and internal transcribed spacer(ITS). The four strains showed identical LSU rDNA sequences with a similarity of 99.4% to the holotype of K arenia umbella(strain KUTN05) from Australia. In the ITS phylogeny, the sequence of K. umbella branched between the Chinese strains of K. longicanalis. A careful comparison of the morphology of K. longicanalis and K. umbella reveals the similarity in the diagnostic characters. Diff erences may appear due to the sample treatment for SEM. We conclude that K. umbella is a junior synonym of K. longicanalis.
基金The work was supported by the National Natural Sci-ence Foundation of China(Nos.41706126,41876173 and 41606176).
文摘The effects of different types of ultraviolet(UV)radiation(UVR,wavelength=280-400 nm)and light intensities on cell growth,pigment composition,UV-absorbing compounds(UVACs),and chlorophyll a(Chl a)fluorescence were studied in dinoflag-ellate Prorocentrum lima cultured outdoors for 16 days and indoors for 18 days.In the outdoor experiment,UVA radiation(320-400 nm)increased the growth rate of this dinoflagellate when solar light intensities were<12%;decreased growth rates were observed when intensities were>12%.Exposure to UVB radiation(280-320 nm)alleviated the negative effects of UVA.In the indoor ex-periment,UVA and low doses of UVB enhanced growth rates.Addition of low doses of UVB to UVA exposure resulted in higher contents of Chl a and photoprotective pigments compared with UVA exposure only.The results of both experiments showed that UVB is the primary signal of UVAC synthesis.High-dose UVB exposure accelerated growth rates when UVAC contents were maintained at high levels,suggesting that the latter plays a key role in UVR damage protection.Furthermore,the repair rate was en-hanced by UVB exposure after 16 days of culture.This study confirms the positive effects of UVA and UVB on the growth of P.lima,with the latter enhancing the photoprotective and recovery pathways of the species.
基金supported by the National Natural Science Foundation of China (Nos. 41476098, 41276154)Special Scientific Research Funds for Central Non-profit Institutes of Yellow Sea Fisheries Research Institutes (2060302201502)
文摘Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus(PE-rich SYN) and phycocyanin-rich Synechococcus(PC-rich SYN). The effects of environmental factors on the alternation of the different Synechococcus groups were also elucidated. PE-rich SYN was detected in three surveys, whereas PC-rich SYN was detected in May and August, but not in November. The highest abundances of PE-rich SYN and PC-rich SYN were recorded in August and May, with mean values of 74.17×103 and 189.92×103 cells m L-1, respectively. From May to November, the relative abundance of PE-rich SYN increased, whereas that of PC-rich SYN declined. PE-rich and PC-rich SYN presented similar horizontal distributions with high abundance in the southern estuary in May, and in the western estuary in August. The abundances of PE-rich and PC-rich SYN were high at 27–32℃and salinity of 10–20. PC-rich SYN was not detected at < 24℃, and PC:PE-rich SYN decreased in abundance with salinity increase. When less than 20 mg L-1, suspended particulate matter(SPM) was helpful for Synechococcus growth. PE-rich SYN decreased in abundance when the concentration of dissolved inorganic nitrogen increased in May and November, and the concentration of phosphate increased in November. However, PC-rich SYN abundance and nutrients showed no correlation. Principal component analysis and regression analysis indicated that PE-rich SYN significantly correlated with the principal components that were affected by environmental factors.
基金The National Natural Science Foundation of China under contract No.41276153the Joint Project of National Nature Science Foundation of China-Guangdong under contract No.U1301235+1 种基金the Public Science and Technology Research Funds Projects of Ocean under contract Nos 201305003-2 and 201305010-4the Fundamental Research Funds for the Central Universities
文摘Brown tides have recurred in estuary areas globally,but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood.In this study,we investigated performance（ingestion,growth,development and reproduction） of the planktonic copepod,Pseudodiaptomus poplesia,offered either mono-algal or mixed-algal diets containing a Chinese strain of A.anophagefferens.A typical Michaelis-Menten pattern existed between ingestion rate and food level when copepod fed on the monoalgal diet of this species.Nauplii exhibited the highest maximum ingestion rate（Imax） than copepodids and adult females.In addition,Imax value was higher in nauplii feeding on A.anophagefferens than on Skeletonema costatum.When fed mixtures of A.anophagefferens and S.costatum,P.poplesia selected against A.anophagefferens cells,but less strongly at the naupliar stage.Nauplii did not undergo metamorphosis and died at late naupliar stages feeding on A.anophagefferens alone,similar to those under starvation.Furthermore,the presence of A.anophagefferens greatly reduced the reproduction rate of females in mixtures but did not influence the growth rate of copepodids.These results suggest that P.poplesia nauplii may exert grazing pressure on A.anophagefferens population during a brown tide,which,however,may not be persistent because of copepod population decline.
基金The Joint Funds of the National Natural Science Foundation of China-Guangdong Province under contract No.U0733006973the National Basic Research Priorities Programme under contract No. 2001CB409704
文摘The abundance and temporal patterns of viable diatom resting stage cells in sediments of the East China Sea in 2006 have been investigated.The abundance of viable resting stages was enumerated with the most probable number（MPN） technique.Overall,25 diatom species（including varieties） belonging to 16 genera were detected.Viable resting stage cells were common,on the order of 103 to 106 cells/g dry mass.The abundant taxa included Skeletonema marina,S.dohrnii,Chaetoceros curvisetus and Thalassiosira spp.,with Skeletonema accounting for 83.3% of the cell.The effects of temperature（10,15,20,25 ℃）,salinity（20,25,30,35 psu） and light intensity（0,300,4 000,8 000 lux） on the germination of resting stages in sediment samples were also determined.The results showed that light intensity had a significant positive effect on the germination of diatom resting stage cells（p 〈0.01） and that diatoms could not germinate in darkness.Temperature and salinity had no noticeable effects on the germination.The present study suggests that there are abundant diatom resting cells in sediments of the East China Sea,which could serve as a ＂seed bank＂ in the phytoplankton population succession and contribute to the initiation of algal blooms.
基金supported by the National Basic Research Program of China (2010CB428702)Public Science and Technology Research Funds Projects of Ocean(201005015)National Science & Technology Pillar Program of China(2012BAC07B05)
文摘To investigate the dynamics of phytoplankton size structure in the Pearl River estuary, concentrations of size-fractionated chlorophyll a (Chl a) were determined during four cruises carried out in 2008 and 2010. The distribution of Chl a in this geographical location showed a high degree of temporal variation. Chl a concentrations were highest in autumn, approximately three times higher than those in summer and winter. Microphytoplankton was the dominant contributor, accounting for 66.9% of the Chl a concentration in autumn 2008. In summer and spring 2008, nano-sized cells dominated the phytoplankton population throughout the study region. During the winter cruise, two different areas of water were found, characterized by (1) low salinity and high nutrient content and (2) high salinity and low nutrient content; nano- and picophytoplankton co-dominated the first area, while microphytoplankton dominated the second. It is arguable that grazing could have played a role in determining phytoplankton community size structure in winter. Nutrient concentrations were assumed not to limit phytoplankton growth during the investigation period. Size-differential capacity in competing for the resources available under different hydrodynamic conditions seemed to be the major factor in determining seasonal variation in the structure of the phytoplankton communities. High N:P ratios in the Pearl River estuary had major implications for nutrient pollution control. Our results indicated that studies of phytoplankton size structure provide greater insight into phytoplankton dynamics and are necessary to better manage water quality in the Pearl River estuary.
