2018 Vol. 37, No. 4
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2018, 37(4): .
Abstract:
2018, 37(4): 1-11.
doi: 10.1007/s13131-018-1200-x
Abstract:
In the southwestern Yellow Sea there is a low-salinity and turbid coastal water, the Subei Coastal Water (SCW). The origins of freshwater contents and thus the dissolved terrigenous nutrients in the SCW have been debated for decades. In this study, we used a well-validated numerical model to quantify the contributions of multiple rivers, i.e., the Changjiang River in the south and the multiple Subei local rivers (SLRs) in the north, in forming this year-round low-salinity coastal water. It is found that the freshwater contents in the SCW is dominated by the Changjiang River south of 33.5°N, by the SLRs north of 34.5°N, and by both sources in 33.5°-34.5°N. Overall, the Changjiang River contributes~70% in the dry season and~80% in the wet season of the total freshwater contents in the SCW, respectively. Dynamics driving the Changjiang River Plume to flow northward is the tidal residual current, which can even overwhelm the wind effects in winter seasons. The residual currents turn offshore near the Old Yellow River Delta (OYRD) by the collision of the two tidal wave systems, which transport the freshwater from both sources into the interior Yellow Sea. Water age experiments show that it takes 50-150 d for the Changjiang River Plume to reach the SCW in the spring and summer seasons, thus there is a 2-month lag between the maximum freshwater content in SCW and the peak Changjiang River discharge. In the winter and autumn seasons, the low salinity in inner SCW is the remnant Changjiang River diluted water arrived in the previous seasons.
In the southwestern Yellow Sea there is a low-salinity and turbid coastal water, the Subei Coastal Water (SCW). The origins of freshwater contents and thus the dissolved terrigenous nutrients in the SCW have been debated for decades. In this study, we used a well-validated numerical model to quantify the contributions of multiple rivers, i.e., the Changjiang River in the south and the multiple Subei local rivers (SLRs) in the north, in forming this year-round low-salinity coastal water. It is found that the freshwater contents in the SCW is dominated by the Changjiang River south of 33.5°N, by the SLRs north of 34.5°N, and by both sources in 33.5°-34.5°N. Overall, the Changjiang River contributes~70% in the dry season and~80% in the wet season of the total freshwater contents in the SCW, respectively. Dynamics driving the Changjiang River Plume to flow northward is the tidal residual current, which can even overwhelm the wind effects in winter seasons. The residual currents turn offshore near the Old Yellow River Delta (OYRD) by the collision of the two tidal wave systems, which transport the freshwater from both sources into the interior Yellow Sea. Water age experiments show that it takes 50-150 d for the Changjiang River Plume to reach the SCW in the spring and summer seasons, thus there is a 2-month lag between the maximum freshwater content in SCW and the peak Changjiang River discharge. In the winter and autumn seasons, the low salinity in inner SCW is the remnant Changjiang River diluted water arrived in the previous seasons.
2018, 37(4): 12-21.
doi: 10.1007/s13131-018-1179-3
Abstract:
The sources and ecological risk from sixteen polycyclic aromatic hydrocarbons in surface sediment in the Liaodong Bay were investigated from 2014 to 2015. The total concentrations of PAHs ranged from 88.5 to 347.1 ng/g, and the high value occurred in the central region of the Liaodong Bay. Cluster analysis identified two site clusters representing the coastal region affected by land-based pollution and the central region of the Liaodong Bay. Principal component analysis-multiple linear regression and diagnostic ratios suggested that PAHs contaminants originated from a mixture of combustion and petroleum sources, and the major was combustion sources. Based on sediment quality guideline, naphthalene, acenaphthylene, acenaphthene, phenanthrene and dibenz[a,h]anthracene may occasionally cause adverse biological effects in some stations. The toxic equivalent concentrations of carcinogenic PAHs indicated low carcinogenic risk for the Liaodong Bay. The ecological risk and toxic pollution levels of PAHs were higher in the central region than in the coastal region along the Liaodong Bay.
The sources and ecological risk from sixteen polycyclic aromatic hydrocarbons in surface sediment in the Liaodong Bay were investigated from 2014 to 2015. The total concentrations of PAHs ranged from 88.5 to 347.1 ng/g, and the high value occurred in the central region of the Liaodong Bay. Cluster analysis identified two site clusters representing the coastal region affected by land-based pollution and the central region of the Liaodong Bay. Principal component analysis-multiple linear regression and diagnostic ratios suggested that PAHs contaminants originated from a mixture of combustion and petroleum sources, and the major was combustion sources. Based on sediment quality guideline, naphthalene, acenaphthylene, acenaphthene, phenanthrene and dibenz[a,h]anthracene may occasionally cause adverse biological effects in some stations. The toxic equivalent concentrations of carcinogenic PAHs indicated low carcinogenic risk for the Liaodong Bay. The ecological risk and toxic pollution levels of PAHs were higher in the central region than in the coastal region along the Liaodong Bay.
2018, 37(4): 22-33.
doi: 10.1007/s13131-018-1194-4
Abstract:
Polymetallic sulfides from two hydrothermal chimneys and talus deposit from the Vienna Woods field of Manus Basin were studied for mineralogy, elemental composition, and S-isotope ratio to understand their evolution. The factors including the nature of source fluid, mineral paragenesis, and related geochemical processes have been discussed. Mineralogy and elemental concentration of Cu and Fe-rich large chimney at the central part of this hydrothermal field was completely different from the smaller Zn-rich peripheral chimney and Fe-rich talus deposit, suggesting the variable degree of alterations generate physico-chemically different source fluids responsible for these hydrothermal structures. Similarly, S-isotope ratios also indicate chemically diverse fluids and different modes of precipitation were involved in their evolution. Distinct mineral zonings and associated elemental and isotopic compositions within individual deposit confirm paragenetic shifts were involved during their growth process.
Polymetallic sulfides from two hydrothermal chimneys and talus deposit from the Vienna Woods field of Manus Basin were studied for mineralogy, elemental composition, and S-isotope ratio to understand their evolution. The factors including the nature of source fluid, mineral paragenesis, and related geochemical processes have been discussed. Mineralogy and elemental concentration of Cu and Fe-rich large chimney at the central part of this hydrothermal field was completely different from the smaller Zn-rich peripheral chimney and Fe-rich talus deposit, suggesting the variable degree of alterations generate physico-chemically different source fluids responsible for these hydrothermal structures. Similarly, S-isotope ratios also indicate chemically diverse fluids and different modes of precipitation were involved in their evolution. Distinct mineral zonings and associated elemental and isotopic compositions within individual deposit confirm paragenetic shifts were involved during their growth process.
2018, 37(4): 34-39.
doi: 10.1007/s13131-018-1152-1
Abstract:
The chromosomes of spinyhead croaker Collichthys lucidus (Richardson, 1844) were characterized for the first time by fluorescence staining, self genomic in situ hybridization (self-GISH), and multicolor fluorescence in situ hybridization (FISH) with 18S rDNA, 5S rDNA and telomeric sequence probes. The female karyotype has exclusively 24 pairs of acrocentric chromosomes (2n=48a, NF=48), while the male one consists of 22 pairs of acrocentric chromosomes, 2 monosomic acrocentric chromosomes and a metacentric chromosome (2n=1m+46a, NF=48). The difference between female and male karyotypes indicates the presence of a sex chromosome of X1X1X2X2/X1X2Y type, where Y is the unique metacentric chromosome in the male karyotype. As revealed by FISH, 5S rDNA and 18S rDNA sites were mapped at syntenic position of the largest acrocentric chromosome (X1), and the short arms of the Y chromosome as well. An X1-chromosome specific interstitial telomeric signal (ITS) was detected overlapping the 5S rDNA sites. In addition, self-GISH revealed that the repetitive DNAs accumulated on all the putative sex chromosome. Chromosome fusion accompanied by a partial deletion in the ancestral karyotype (2n=48a) is hypothesized for the origin of such multiple sex chromosome system. The present study, as the first description of differentiated sex chromosome in family Sciaenidae, will give clues to the studies on the sex chromosome of other Sciaenids.
The chromosomes of spinyhead croaker Collichthys lucidus (Richardson, 1844) were characterized for the first time by fluorescence staining, self genomic in situ hybridization (self-GISH), and multicolor fluorescence in situ hybridization (FISH) with 18S rDNA, 5S rDNA and telomeric sequence probes. The female karyotype has exclusively 24 pairs of acrocentric chromosomes (2n=48a, NF=48), while the male one consists of 22 pairs of acrocentric chromosomes, 2 monosomic acrocentric chromosomes and a metacentric chromosome (2n=1m+46a, NF=48). The difference between female and male karyotypes indicates the presence of a sex chromosome of X1X1X2X2/X1X2Y type, where Y is the unique metacentric chromosome in the male karyotype. As revealed by FISH, 5S rDNA and 18S rDNA sites were mapped at syntenic position of the largest acrocentric chromosome (X1), and the short arms of the Y chromosome as well. An X1-chromosome specific interstitial telomeric signal (ITS) was detected overlapping the 5S rDNA sites. In addition, self-GISH revealed that the repetitive DNAs accumulated on all the putative sex chromosome. Chromosome fusion accompanied by a partial deletion in the ancestral karyotype (2n=48a) is hypothesized for the origin of such multiple sex chromosome system. The present study, as the first description of differentiated sex chromosome in family Sciaenidae, will give clues to the studies on the sex chromosome of other Sciaenids.
2018, 37(4): 40-47.
doi: 10.1007/s13131-018-1174-8
Abstract:
Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl. A total of 1 346 fishes belonging to 19 species were collected at spring tide, whereas 1 115 fishes belonging to 17 species were at neap tide. The common fish species were Nuchequula nuchalis, Acanthogobius flavimanus, Takifugu niphobles, Acentrogobius pflaumii, and Pholis nebulosa with the former three species dominating at spring tide, while the latter two species being abundant at neap tide. Diel variation in abundance was significant with higher abundance at night than day, but there were no significant differences between spring and neap tides, and between ebb and flood tides (three-way ANOVAs). Diel variation in the abundance of fishes may be influenced by tidal range and cycle, and day-night differences of food availability and behaviors of fishes indirectly. Non-metric multidimensional scaling (nMDS) ordination and analysis of similarity (ANOSIM) results revealed significant differences in species compositions both between day and night, and between spring and neap tide. Eelgrass beds are highly productive marine ecosystem, and thus, our results will contribute to conservation of seagrass ecosystem in the study area.
Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl. A total of 1 346 fishes belonging to 19 species were collected at spring tide, whereas 1 115 fishes belonging to 17 species were at neap tide. The common fish species were Nuchequula nuchalis, Acanthogobius flavimanus, Takifugu niphobles, Acentrogobius pflaumii, and Pholis nebulosa with the former three species dominating at spring tide, while the latter two species being abundant at neap tide. Diel variation in abundance was significant with higher abundance at night than day, but there were no significant differences between spring and neap tides, and between ebb and flood tides (three-way ANOVAs). Diel variation in the abundance of fishes may be influenced by tidal range and cycle, and day-night differences of food availability and behaviors of fishes indirectly. Non-metric multidimensional scaling (nMDS) ordination and analysis of similarity (ANOSIM) results revealed significant differences in species compositions both between day and night, and between spring and neap tide. Eelgrass beds are highly productive marine ecosystem, and thus, our results will contribute to conservation of seagrass ecosystem in the study area.
2018, 37(4): 48-57.
doi: 10.1007/s13131-018-1147-y
Abstract:
Seasonal variation of marine plankton spatial distribution is important in understanding the biological processes in the ocean. In this study, we studied spatial distribution of planktonic ciliate abundance and biomass in the central deep area (station depth greater than 60 m) and the coastal shallow area (station depth less than 60 m) of the southern Yellow Sea (32°–36.5°N, 121°–125°E) in spring (April) and autumn (October–November) of 2006. Our results showed that both ciliate abundance and biomass in the surface waters were higher in spring ((1 490±2 336) ind./L; (4.11±7.81) μg/L) than in autumn ((972±823) ind./L; (1.11±1.18) μg/L, calculated by carbon). Ciliate abundance and biomass in the surface waters of the coastal shallow area were similar in spring and autumn. However, in the central deep area, those values were much higher in spring ((1 878±2 893) ind./L; (5.99±10.10) μg/L) than in autumn ((738±373) ind./L; (0.74±0.76) μg/L). High values of ciliate abundance and biomass occurred in the central deep area in spring and in the coastal shallow area in autumn. Mixotrophic ciliate Laboea strobila was abundant in the central deep area in spring, when a phytoplankton bloom occurred. However, in autumn, L. strobila was abundant in the coastal shallow area. Boreal tintinnid Ptychocyli obtusa was found in spring. Both L. strobila and P. obtusa were concentrated in the surface waters when their abundance was more than 1 000 ind./L. Peaks of these species were in the subsurface waters when their abundance was less than 400 ind./L. This study showed that both high abundance and biomass of ciliates occurred in different areas in southern Yellow Sea seasonally.
Seasonal variation of marine plankton spatial distribution is important in understanding the biological processes in the ocean. In this study, we studied spatial distribution of planktonic ciliate abundance and biomass in the central deep area (station depth greater than 60 m) and the coastal shallow area (station depth less than 60 m) of the southern Yellow Sea (32°–36.5°N, 121°–125°E) in spring (April) and autumn (October–November) of 2006. Our results showed that both ciliate abundance and biomass in the surface waters were higher in spring ((1 490±2 336) ind./L; (4.11±7.81) μg/L) than in autumn ((972±823) ind./L; (1.11±1.18) μg/L, calculated by carbon). Ciliate abundance and biomass in the surface waters of the coastal shallow area were similar in spring and autumn. However, in the central deep area, those values were much higher in spring ((1 878±2 893) ind./L; (5.99±10.10) μg/L) than in autumn ((738±373) ind./L; (0.74±0.76) μg/L). High values of ciliate abundance and biomass occurred in the central deep area in spring and in the coastal shallow area in autumn. Mixotrophic ciliate Laboea strobila was abundant in the central deep area in spring, when a phytoplankton bloom occurred. However, in autumn, L. strobila was abundant in the coastal shallow area. Boreal tintinnid Ptychocyli obtusa was found in spring. Both L. strobila and P. obtusa were concentrated in the surface waters when their abundance was more than 1 000 ind./L. Peaks of these species were in the subsurface waters when their abundance was less than 400 ind./L. This study showed that both high abundance and biomass of ciliates occurred in different areas in southern Yellow Sea seasonally.
2018, 37(4): 58-68.
doi: 10.1007/s13131-017-1122-z
Abstract:
Nutrient imbalance-a mismatch in nutrient ratios between the available food supply and the demands of consumers-has the potential to be transported up food chains, exposing zooplankton to nutrient limitations. In this study, the response of Calanus sinicus (copepod), Moina mongolica (cladocera), and Brachionus plicatilis (rotifer) to nutrient-limited (no-limited, P-limited, and N-limited) food were evaluated from the perspective of growth, reproduction, and stoichiometric homoeostasis. The results indicated that the growth of three species was suppressed under nutrient-limited (especially P-limited) conditions. However, the effect of nutrient limitations on their reproduction was species-specific. For C. sinicus, the dietary UFA (unsaturated fatty acid) as a major phospholipid component affected their egg production and total FA supporting energy promoted the hatchability of eggs. Furthermore, excess carbon in the diet promoted egg production but reduced hatching success. For M. mongolica, nutritional (P and UFA) and energy (total FA) support affected their fecundity. B. plicatilis fecundity exhibited the same pattern of growth (no-limited>N-limited>P-limited). In terms of stoichiometric homeostasis, B. plicatilis's elemental compositions were less likely to be affected by nutrient limitations than M. mongolica. We suggest that the effects of nutrient imbalances could potentially become an evolutionary force affecting ecosystem structure and stability in eutrophic waters.
Nutrient imbalance-a mismatch in nutrient ratios between the available food supply and the demands of consumers-has the potential to be transported up food chains, exposing zooplankton to nutrient limitations. In this study, the response of Calanus sinicus (copepod), Moina mongolica (cladocera), and Brachionus plicatilis (rotifer) to nutrient-limited (no-limited, P-limited, and N-limited) food were evaluated from the perspective of growth, reproduction, and stoichiometric homoeostasis. The results indicated that the growth of three species was suppressed under nutrient-limited (especially P-limited) conditions. However, the effect of nutrient limitations on their reproduction was species-specific. For C. sinicus, the dietary UFA (unsaturated fatty acid) as a major phospholipid component affected their egg production and total FA supporting energy promoted the hatchability of eggs. Furthermore, excess carbon in the diet promoted egg production but reduced hatching success. For M. mongolica, nutritional (P and UFA) and energy (total FA) support affected their fecundity. B. plicatilis fecundity exhibited the same pattern of growth (no-limited>N-limited>P-limited). In terms of stoichiometric homeostasis, B. plicatilis's elemental compositions were less likely to be affected by nutrient limitations than M. mongolica. We suggest that the effects of nutrient imbalances could potentially become an evolutionary force affecting ecosystem structure and stability in eutrophic waters.
2018, 37(4): 69-76.
doi: 10.1007/s13131-018-1168-6
Abstract:
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 mono-algal 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.
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 mono-algal 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.
2018, 37(4): 77-82.
doi: 10.1007/s13131-018-1144-1
Abstract:
Bacterial production is one of the key parameters to evaluate bacterial role in ocean carbon fluxes. Estimation of bacterial production requires the leucine-to-carbon conversion factors that change widely across environments. However, empirical leucine-to-carbon conversion factors (eCFs) are seldom determined in situ because of time consuming and little is known on regulating factors for the eCFs. During May 2015 to January 2016, fourteen dilution experiments were conducted, from the Zhujiang (Pearl River) Estuary to the coast of the northern South China Sea, to determine spatiotemporal variability in the eCFs and its potential controlling factors along an environmental gradient. The eCFs showed clear spatial variations with the highest (1.27-1.69 (kg C)/(mol Leu)) in low salinity waters (salinity<15), intermediate (1.03-1.25 (kg C)/(mol Leu)) in moderate salinity (salinity of 15-25), and the lowest (0.48-0.85 (kg C)/(mol Leu)) in high salinity waters (salinity>25). Substrate availability was responsible for spatial variability in the eCFs. In the pristine coastal waters, low eCFs was related to substrate limitation and leucine incorporated was respired to maximize the survival rather than bacterial production. Hence, the eCFs measurement was needed for estimating bacterial production accurately in various marine environments.
Bacterial production is one of the key parameters to evaluate bacterial role in ocean carbon fluxes. Estimation of bacterial production requires the leucine-to-carbon conversion factors that change widely across environments. However, empirical leucine-to-carbon conversion factors (eCFs) are seldom determined in situ because of time consuming and little is known on regulating factors for the eCFs. During May 2015 to January 2016, fourteen dilution experiments were conducted, from the Zhujiang (Pearl River) Estuary to the coast of the northern South China Sea, to determine spatiotemporal variability in the eCFs and its potential controlling factors along an environmental gradient. The eCFs showed clear spatial variations with the highest (1.27-1.69 (kg C)/(mol Leu)) in low salinity waters (salinity<15), intermediate (1.03-1.25 (kg C)/(mol Leu)) in moderate salinity (salinity of 15-25), and the lowest (0.48-0.85 (kg C)/(mol Leu)) in high salinity waters (salinity>25). Substrate availability was responsible for spatial variability in the eCFs. In the pristine coastal waters, low eCFs was related to substrate limitation and leucine incorporated was respired to maximize the survival rather than bacterial production. Hence, the eCFs measurement was needed for estimating bacterial production accurately in various marine environments.
2018, 37(4): 83-88.
doi: 10.1007/s13131-018-1182-8
Abstract:
Vibrio vulnificus is an estuarine bacterial pathogen for human. The rapid, specific and sensitive detection of V. vulnificus is urgently needed for early disease diagnosis and timely treatment of V. vulnificus infection. In the study, a loop-mediated isothermal amplification (LAMP) technique was developed for V. vulnificus detection with a set of primers, composed of two out primers and two inner primers targeted to vvhA gene. The optimal amplification temperature was 63℃ and the reaction only took 35 min. The amplification products could not only be detected by agarose gel electrophoresis with ladder-like pattern bands, but also could be visualized using calcein with naked eye directly. Forty-five strains were tested for the specificity of LAMP assay, and all the V. vulnificus strains were identified correctly while other strains were negative results. The sensitive of the new LAMP assay was 100-fold more sensitive than the conventional PCR. Meanwhile, all the V. vulnificus strains were detected correctly in spiked, clinical and environmental samples by the new LAMP assay. Compared with other well-known techniques, the new LAMP assay targeted to vvhA gene was extremely rapid, simple, sensitive and specific for V. vulnificus identification.
Vibrio vulnificus is an estuarine bacterial pathogen for human. The rapid, specific and sensitive detection of V. vulnificus is urgently needed for early disease diagnosis and timely treatment of V. vulnificus infection. In the study, a loop-mediated isothermal amplification (LAMP) technique was developed for V. vulnificus detection with a set of primers, composed of two out primers and two inner primers targeted to vvhA gene. The optimal amplification temperature was 63℃ and the reaction only took 35 min. The amplification products could not only be detected by agarose gel electrophoresis with ladder-like pattern bands, but also could be visualized using calcein with naked eye directly. Forty-five strains were tested for the specificity of LAMP assay, and all the V. vulnificus strains were identified correctly while other strains were negative results. The sensitive of the new LAMP assay was 100-fold more sensitive than the conventional PCR. Meanwhile, all the V. vulnificus strains were detected correctly in spiked, clinical and environmental samples by the new LAMP assay. Compared with other well-known techniques, the new LAMP assay targeted to vvhA gene was extremely rapid, simple, sensitive and specific for V. vulnificus identification.
2018, 37(4): 89-101.
doi: 10.1007/s13131-018-1178-4
Abstract:
Carotenoids play a crucial role in absorbing light energy for photosynthesis, as well as in protecting chlorophyll from photodamage. In contrast to the Streptophyta, few studies have examined carotenoid biosynthetic pathways in algae, owing to a shortage of datasets. As part of the 1000 Plants Project, we sequenced and assembled the transcriptomes of 41 marine macroalgal species, including 22 rhodophytes and 19 phaeophytes, and then combined the datasets with publicly available data from GenBank (National Center for Biotechnology Information) and the U.S. Department of Energy Joint Genome Institute. As a result, we identified 68 and 79 full-length homologs in the Rhodophyta and Phaeophyceae, respectively, of seven inferred carotenoid biosynthetic genes, including the genes for phytoene synthase (PSY), phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), ζ-carotene isomerase (Z-ISO), prolycopene isomerase (crtISO), lycopene β-cyclase (LCYB), and lycopene ε-cyclase (LCYE). We found that the evolutionary history of the algal carotenoid biosynthetic pathway was more complex than that of the same pathway in the Streptophyta and, more specifically, that the evolutionary history involved endosymbiotic gene transfer, gene duplication, and gene loss. Almost all of the eukaryotic algae that we examined had inherited the seven carotenoid biosynthesis genes via endosymbiotic gene transfer. Moreover, PSY, crtISO, and the ancestral lycopene cyclase gene (LCY) underwent duplication events that resulted in multiple gene copies, and the duplication and subsequent divergence of LCYB and LCYE specialized and complicated the cyclization of lycopene. Our findings also verify that the loss of LCYE in both the microphytic rhodophytes and phaeophytes explains the differences in their carotenoid patterns, when compared to the macrophytic rhodophytes. These analyses provide a molecular basis for further biochemical and physiological validation in additional algal species and should help elucidate the origin and evolution of carotenoid biosynthetic pathways.
Carotenoids play a crucial role in absorbing light energy for photosynthesis, as well as in protecting chlorophyll from photodamage. In contrast to the Streptophyta, few studies have examined carotenoid biosynthetic pathways in algae, owing to a shortage of datasets. As part of the 1000 Plants Project, we sequenced and assembled the transcriptomes of 41 marine macroalgal species, including 22 rhodophytes and 19 phaeophytes, and then combined the datasets with publicly available data from GenBank (National Center for Biotechnology Information) and the U.S. Department of Energy Joint Genome Institute. As a result, we identified 68 and 79 full-length homologs in the Rhodophyta and Phaeophyceae, respectively, of seven inferred carotenoid biosynthetic genes, including the genes for phytoene synthase (PSY), phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), ζ-carotene isomerase (Z-ISO), prolycopene isomerase (crtISO), lycopene β-cyclase (LCYB), and lycopene ε-cyclase (LCYE). We found that the evolutionary history of the algal carotenoid biosynthetic pathway was more complex than that of the same pathway in the Streptophyta and, more specifically, that the evolutionary history involved endosymbiotic gene transfer, gene duplication, and gene loss. Almost all of the eukaryotic algae that we examined had inherited the seven carotenoid biosynthesis genes via endosymbiotic gene transfer. Moreover, PSY, crtISO, and the ancestral lycopene cyclase gene (LCY) underwent duplication events that resulted in multiple gene copies, and the duplication and subsequent divergence of LCYB and LCYE specialized and complicated the cyclization of lycopene. Our findings also verify that the loss of LCYE in both the microphytic rhodophytes and phaeophytes explains the differences in their carotenoid patterns, when compared to the macrophytic rhodophytes. These analyses provide a molecular basis for further biochemical and physiological validation in additional algal species and should help elucidate the origin and evolution of carotenoid biosynthetic pathways.
2018, 37(4): 102-108.
doi: 10.1007/s13131-018-1169-5
Abstract:
Since 2007, large-scale green tides dominated by Ulva prolifera consecutively bloomed in the Yellow Sea and caused great economic losses. The fouling U. prolifera on the Pyropia yezoensis aquaculture rafts in the Subei Shoal was regarded as the major source of the floating biomass. However, it was still unclear about the seed source of fouling green macroalgae attached on the rafts. In this study, the field surveys and the indoor experiments were conducted to reveal the source of propagules of the fouling green macroalgae on the rafts and to study the anti-fouling material for P. yezoensis aquaculture rafts which could possibly be a feasible strategy to control the green tides in the Yellow Sea. The results showed that (1) micro-propagules of several green macroalgal species, including U. prolifera, U. linza, U. compressa, U. flexuosa, and Blidingia sp. coexisted in the waters and sediments in the Subei Shoal and their proportion remarkably changed over time; (2) the bamboo poles with peeling treatment could significantly reduce the amount of U. prolifera micro-propagules attached. This study confirmed that the micro-propagules distributed in the Subei Shoal area were the precursors of the green tides, and provided a feasible method to control the Yellow Sea large-scale green tides at the beginning.
Since 2007, large-scale green tides dominated by Ulva prolifera consecutively bloomed in the Yellow Sea and caused great economic losses. The fouling U. prolifera on the Pyropia yezoensis aquaculture rafts in the Subei Shoal was regarded as the major source of the floating biomass. However, it was still unclear about the seed source of fouling green macroalgae attached on the rafts. In this study, the field surveys and the indoor experiments were conducted to reveal the source of propagules of the fouling green macroalgae on the rafts and to study the anti-fouling material for P. yezoensis aquaculture rafts which could possibly be a feasible strategy to control the green tides in the Yellow Sea. The results showed that (1) micro-propagules of several green macroalgal species, including U. prolifera, U. linza, U. compressa, U. flexuosa, and Blidingia sp. coexisted in the waters and sediments in the Subei Shoal and their proportion remarkably changed over time; (2) the bamboo poles with peeling treatment could significantly reduce the amount of U. prolifera micro-propagules attached. This study confirmed that the micro-propagules distributed in the Subei Shoal area were the precursors of the green tides, and provided a feasible method to control the Yellow Sea large-scale green tides at the beginning.
2018, 37(4): 109-121.
doi: 10.1007/s13131-017-1129-5
Abstract:
Global warming has caused Arctic sea ice to rapidly retreat, which is affecting phytoplankton, the primary producers at the base of the food chain, as well as the entire ecosystem. However, few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted. This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions. Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean (67.0°-88°26'N, 152°-178°54'W) were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30, 2010 during China's fourth Arctic expedition. Using these samples, the species composition, spatial distribution, and regional disparities of phytoplankton during different stages of ice melt were assessed. A total of 157 phytoplankton taxa (>5 μm) belonging to 69 genera were identified in the study area. The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii, accounting for 31.23% and 14.12% of the total phytoplankton abundance, respectively. The average abundance during the departure trip and the return trip were 797.07×102 cells/L and 84.94×102 cells/L, respectively. The highest abundance was observed at Sta. R09 in the north of Herald Shoal, where Navicula pelagica was the dominant species accounting for 59.42% of the abundance. The vertical distribution of phytoplankton abundance displayed regional differences, and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline, thermocline, and nutricline. The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips. The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt, and there was shift in dominant species from centric to pennate diatoms. Results of canonical correspondence analysis (CCA) showed that there were two distinct communities of phytoplankton in the western Arctic Ocean, and water temperature, ice coverage and silicate concentration were the most important environmental factors affecting phytoplankton distribution in the surveyed sea. These findings will help predict the responses of phytoplankton to the rapid melting of Arctic sea ice.
Global warming has caused Arctic sea ice to rapidly retreat, which is affecting phytoplankton, the primary producers at the base of the food chain, as well as the entire ecosystem. However, few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted. This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions. Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean (67.0°-88°26'N, 152°-178°54'W) were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30, 2010 during China's fourth Arctic expedition. Using these samples, the species composition, spatial distribution, and regional disparities of phytoplankton during different stages of ice melt were assessed. A total of 157 phytoplankton taxa (>5 μm) belonging to 69 genera were identified in the study area. The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii, accounting for 31.23% and 14.12% of the total phytoplankton abundance, respectively. The average abundance during the departure trip and the return trip were 797.07×102 cells/L and 84.94×102 cells/L, respectively. The highest abundance was observed at Sta. R09 in the north of Herald Shoal, where Navicula pelagica was the dominant species accounting for 59.42% of the abundance. The vertical distribution of phytoplankton abundance displayed regional differences, and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline, thermocline, and nutricline. The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips. The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt, and there was shift in dominant species from centric to pennate diatoms. Results of canonical correspondence analysis (CCA) showed that there were two distinct communities of phytoplankton in the western Arctic Ocean, and water temperature, ice coverage and silicate concentration were the most important environmental factors affecting phytoplankton distribution in the surveyed sea. These findings will help predict the responses of phytoplankton to the rapid melting of Arctic sea ice.
