2017 Vol. 39, No. 8
Display Method:
2017, 39(8): 1-15.
doi: 10.3969/j.issn.0253-4193.2017.08.001
Abstract:
Isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) are biomarkers of archaea. TEX86 is a sea surface temperature (SST) proxy based on the distribution of cyclic moieties of isoGDGTs and has been widely applied to reconstruct paleo-SST in numerous cases. In this study, the distributions of isoGDGTs from surface water suspened particulate matter (SPM) during the four seasons in Pearl River Estuary (PRE, water depth below 30 m) and it's coastal waters are reported. The results showed that the major sources of isoGDGTs are in situ Methanogen in freshwater, while in estuarine brackish water, the sources of isoGDGTs are in situ Thaumarchaeota and Euryarchaeota. The input of terrigenous isoGDGTs exerted an influence on freshwater in May and August, which was inconspicuous in the estuary. The ratio of GDGT-2 to GDGT-3(GDGT-[2]/[3]) and fractional abundance of GDGT-Cren' (Cren'%) were less than 4 and 4%, respectively, which are clearly different from those in surface sediments of deep basin of South China Sea (SCS). This indicates that archaeal sources of isoGDGTs in the PRE are different from those in surface sediments of SCS, which may result in the deviation of TEX86-based temperatures from actual water temperatures in PRE. The variation in fractional abundance of GDGT-2 and GDGT-3 in surface water SPM of PRE and SCS may relate to the spatial changes in relative proportion in Group Ⅰ Thaumarchaeota and Group Ⅱ Euryarchaeota. The TEX86-based temperatures of isoGDGTs were higher than actual surface water temperatures in February, whereas they were lower than actual surface water temperatures in other months in the PRE. This may be attributed to the seasonal variation of relative proportion in Group Ⅰ Thaumarchaeota and Group Ⅱ Euryarchaeota. The isoGDGTs from surface water SPM of the PRE were most and least abundant in November and August, respectively, suggesting high and low in situ aquatic Archaeal production in the two months, respectively. Statistical analysis showed that water temperature, NH4+ and dissolved oxygen (DO) concentration in water column are the most important factors affecting the distribution of isoGDGTs in PRE.
Isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) are biomarkers of archaea. TEX86 is a sea surface temperature (SST) proxy based on the distribution of cyclic moieties of isoGDGTs and has been widely applied to reconstruct paleo-SST in numerous cases. In this study, the distributions of isoGDGTs from surface water suspened particulate matter (SPM) during the four seasons in Pearl River Estuary (PRE, water depth below 30 m) and it's coastal waters are reported. The results showed that the major sources of isoGDGTs are in situ Methanogen in freshwater, while in estuarine brackish water, the sources of isoGDGTs are in situ Thaumarchaeota and Euryarchaeota. The input of terrigenous isoGDGTs exerted an influence on freshwater in May and August, which was inconspicuous in the estuary. The ratio of GDGT-2 to GDGT-3(GDGT-[2]/[3]) and fractional abundance of GDGT-Cren' (Cren'%) were less than 4 and 4%, respectively, which are clearly different from those in surface sediments of deep basin of South China Sea (SCS). This indicates that archaeal sources of isoGDGTs in the PRE are different from those in surface sediments of SCS, which may result in the deviation of TEX86-based temperatures from actual water temperatures in PRE. The variation in fractional abundance of GDGT-2 and GDGT-3 in surface water SPM of PRE and SCS may relate to the spatial changes in relative proportion in Group Ⅰ Thaumarchaeota and Group Ⅱ Euryarchaeota. The TEX86-based temperatures of isoGDGTs were higher than actual surface water temperatures in February, whereas they were lower than actual surface water temperatures in other months in the PRE. This may be attributed to the seasonal variation of relative proportion in Group Ⅰ Thaumarchaeota and Group Ⅱ Euryarchaeota. The isoGDGTs from surface water SPM of the PRE were most and least abundant in November and August, respectively, suggesting high and low in situ aquatic Archaeal production in the two months, respectively. Statistical analysis showed that water temperature, NH4+ and dissolved oxygen (DO) concentration in water column are the most important factors affecting the distribution of isoGDGTs in PRE.
2017, 39(8): 16-24.
doi: 10.3969/j.issn.0253-4193.2017.08.002
Abstract:
Sorption of organic carbon (OC) on reactive iron (FeR) plays an important role in OC stabilization and preserving in sediments and soils, and thus can buffer the concentration of atmospheric CO2 on geological timescales. Based on the amount of OC associated with FeR (Fe-OC) in three cores from the South Yellow Sea determined by the dithionite reduction extraction, we quantitatively investigated the role of FeR in OC stabilization, mechanisms of OC and FeR association, and variation of Fe-OC with depth. Our results showed that Fe-OC accounted for (13.2±7.47)% of sedimentary total OC in the South Yellow Sea. This means that annually 0.72 Mt of OC buried in the sediments is sequestered by FeR, which is 0.44% of the global OC buried in the continental shelf sea annually. Molar ratios of OC to FeR (average 4.50±2.61) indicate that coprecipitation of OC with FeR plays an important role in OC stabilization, and the ratios increased with an increase in fractions of marine OC in the sediments. Stable isotopic compositions of Fe-OC (δ13CFe-OC) suggested that more labile OC is preferentially trapped by FeR, but this preferential trend decreases with an increase in OC/Fe ratio. No obvious changes in fFe-OCand δ13CFe-OC with depth were observed, which can be ascribed to low degradability of organic matter and consequently weak iron reduction.
Sorption of organic carbon (OC) on reactive iron (FeR) plays an important role in OC stabilization and preserving in sediments and soils, and thus can buffer the concentration of atmospheric CO2 on geological timescales. Based on the amount of OC associated with FeR (Fe-OC) in three cores from the South Yellow Sea determined by the dithionite reduction extraction, we quantitatively investigated the role of FeR in OC stabilization, mechanisms of OC and FeR association, and variation of Fe-OC with depth. Our results showed that Fe-OC accounted for (13.2±7.47)% of sedimentary total OC in the South Yellow Sea. This means that annually 0.72 Mt of OC buried in the sediments is sequestered by FeR, which is 0.44% of the global OC buried in the continental shelf sea annually. Molar ratios of OC to FeR (average 4.50±2.61) indicate that coprecipitation of OC with FeR plays an important role in OC stabilization, and the ratios increased with an increase in fractions of marine OC in the sediments. Stable isotopic compositions of Fe-OC (δ13CFe-OC) suggested that more labile OC is preferentially trapped by FeR, but this preferential trend decreases with an increase in OC/Fe ratio. No obvious changes in fFe-OCand δ13CFe-OC with depth were observed, which can be ascribed to low degradability of organic matter and consequently weak iron reduction.
Assessment for allowable catch of fishery resources in the South China Sea based on statistical data
2017, 39(8): 25-33.
doi: 10.3969/j.issn.0253-4193.2017.08.003
Abstract:
The scientific quantification of allowable catch is a precondition to implementing a fishing quota system. However,the allowable catches for fisheries in the South China Sea (SCS) are difficult to evaluate because of the inclusion of a wide range of fish species,the lack of crucial economic fish species,and incomplete catch statistics. This paper used a simplified production model to estimate allowable catches for eleven fish groups and the total allowable catch (TAC) in the SCS. Maximum sustainable yield (MSY) and TAC in the SCS were calculated to be 308.6×104 t and 246.9×104-277.8×104 t,respectively. MSY estimates for the eleven fish groups showed that they all have been overfished since the 1990s. The stocks of five fish groups (grouper,conger pike,pomfrets,threadfin breams,and hairtails) with low resilience were still being overfished in 2014,with grouper and conger pike being the most extreme examples. The stocks of the remaining six fish groups (Decapterus maruadsi and Trachurus japonicas,sardines,filefish,porgies,Chinese herring,and mackerel) had high resilience and were in good condition in 2014.
The scientific quantification of allowable catch is a precondition to implementing a fishing quota system. However,the allowable catches for fisheries in the South China Sea (SCS) are difficult to evaluate because of the inclusion of a wide range of fish species,the lack of crucial economic fish species,and incomplete catch statistics. This paper used a simplified production model to estimate allowable catches for eleven fish groups and the total allowable catch (TAC) in the SCS. Maximum sustainable yield (MSY) and TAC in the SCS were calculated to be 308.6×104 t and 246.9×104-277.8×104 t,respectively. MSY estimates for the eleven fish groups showed that they all have been overfished since the 1990s. The stocks of five fish groups (grouper,conger pike,pomfrets,threadfin breams,and hairtails) with low resilience were still being overfished in 2014,with grouper and conger pike being the most extreme examples. The stocks of the remaining six fish groups (Decapterus maruadsi and Trachurus japonicas,sardines,filefish,porgies,Chinese herring,and mackerel) had high resilience and were in good condition in 2014.
2017, 39(8): 34-47.
doi: 10.3969/j.issn.0253-4193.2017.08.004
Abstract:
The species composition and spatial pattern of the ichthyoplankton community and its relationship with environmental factors were analyzed using ecological diversity indices and multivariate statistical analysis. Based on the data collected from the ichthyoplankton survey, which was conducted by horizontal tows using plankton nets in the coastal waters of central and southern Yellow Sea in the spring of 2015. In total, 35 species were identified for the ichthyoplankton. Among them,there were 21 fish eggs and 23 larvae and juveniles. They belonged to 8 orders, 18 families, and 34 genera. The ichthyoplankton were dominated by species Engraulis japonicas, Platycephalus indicus, Callionymus spp. and Larimichthys polyactis. The main ecological groups were the brackish water group, coastal group and offshore type. Cluster analysis showed that the ichthyoplankton community can be divided into three station groups, including group A (mainly distributed in the Haizhou Bay) which was dominated by species of Engraulis japonicas and Callionymus spp., group B (mainly in the coastal waters of Jiangsu Province) which was dominated by species of Pseudosciaena polyactis, Setipinna taty and Collichthys lucidus, group C (mainly in the coastal and offshore waters of Jiangsu Province), which was dominated by Platycephalus indicus. Among them, Engraulis japonicas and Callionymus spp. were mainly distributed in the Haizhou Bay fishing ground. The main distribution area of Platycephalus indicus was located in Lvsi fishing ground, and Pseudosciaena polyactis was in the northern Lvsi fishing ground. The species diversity index and evenness index of group B was the highest among the three station groups. The ecotypes and thermophily of parent fishes were different in three station groups and were closely related to their habitats. The canonical correspondence analysis (CCA) suggested that the main environmental factors affecting the spatial patterns of ichthyoplankton community in the spring were depth, salinity,sea surface temperature in the coastal waters of central and southern Yellow Sea. Meanwhile, it was also affected comprehensively by many factors such as ocean currents and bottom sediment types. The results revealed the spatial pattern of ichthyoplankton communities in the central and southern Yellow Sea, providing scientific basis and technical support for conservation measures such as scientific development of aquatic germplasm resources protection area and the scientific management of fishery resources in the waters.
The species composition and spatial pattern of the ichthyoplankton community and its relationship with environmental factors were analyzed using ecological diversity indices and multivariate statistical analysis. Based on the data collected from the ichthyoplankton survey, which was conducted by horizontal tows using plankton nets in the coastal waters of central and southern Yellow Sea in the spring of 2015. In total, 35 species were identified for the ichthyoplankton. Among them,there were 21 fish eggs and 23 larvae and juveniles. They belonged to 8 orders, 18 families, and 34 genera. The ichthyoplankton were dominated by species Engraulis japonicas, Platycephalus indicus, Callionymus spp. and Larimichthys polyactis. The main ecological groups were the brackish water group, coastal group and offshore type. Cluster analysis showed that the ichthyoplankton community can be divided into three station groups, including group A (mainly distributed in the Haizhou Bay) which was dominated by species of Engraulis japonicas and Callionymus spp., group B (mainly in the coastal waters of Jiangsu Province) which was dominated by species of Pseudosciaena polyactis, Setipinna taty and Collichthys lucidus, group C (mainly in the coastal and offshore waters of Jiangsu Province), which was dominated by Platycephalus indicus. Among them, Engraulis japonicas and Callionymus spp. were mainly distributed in the Haizhou Bay fishing ground. The main distribution area of Platycephalus indicus was located in Lvsi fishing ground, and Pseudosciaena polyactis was in the northern Lvsi fishing ground. The species diversity index and evenness index of group B was the highest among the three station groups. The ecotypes and thermophily of parent fishes were different in three station groups and were closely related to their habitats. The canonical correspondence analysis (CCA) suggested that the main environmental factors affecting the spatial patterns of ichthyoplankton community in the spring were depth, salinity,sea surface temperature in the coastal waters of central and southern Yellow Sea. Meanwhile, it was also affected comprehensively by many factors such as ocean currents and bottom sediment types. The results revealed the spatial pattern of ichthyoplankton communities in the central and southern Yellow Sea, providing scientific basis and technical support for conservation measures such as scientific development of aquatic germplasm resources protection area and the scientific management of fishery resources in the waters.
2017, 39(8): 48-61.
doi: 10.3969/j.issn.0253-4193.2017.08.005
Abstract:
Based on data from bottom trawl surveys in the coastal waters along the Shandong Peninsula from 2014 to 2015, the spatial and temporal distribution, structure community and dominant species of crabs were analyzed. Results showed that 20 kinds of crabs were captured during the four survey cruises, which belonged to 17 genera and 10 families. Portunus trituberculatus and Charybdis japonica were the main economic species and the others were low-value species. Charybdis immaculate, Charybdis japonica and Portunus trituberculatus were the main dominant species. The seasonal variation of the dominant species is obvious. Biomass in Laizhou Bay southern Bohai Sea and the coastal waters along the southern Shandong Peninsula changed seasonally with the highest in summer and the lowest in winter, but no significant seasonal change occurred in the coastal waters along northern Shandong Peninsula. According to the data, the average Shannon-Wiener diversity index (H'), Margalef richness index (D) and Pielou evenness index(J') in survey waters were very low, which manifest that there was a lower-level diversity of crab in this waters. Result of CLUSTER analysis showed that water depth, water temperature and salinity were the main factors affecting the community structure. By influencing the water temperature and salinity, the Bohai-Lai Longshore Current, the Yellow Sea Warm Current and the Huanghai Sea Cold Water Mass influenced the community structure. This paper showed that most of crabs in the coastal waters along the Shandong Peninsula were small, bait-type species. The crab diversity was very low.The dominant species varied.The MI was very high. The results showed clearly that the crabs' community structure were unstable.
Based on data from bottom trawl surveys in the coastal waters along the Shandong Peninsula from 2014 to 2015, the spatial and temporal distribution, structure community and dominant species of crabs were analyzed. Results showed that 20 kinds of crabs were captured during the four survey cruises, which belonged to 17 genera and 10 families. Portunus trituberculatus and Charybdis japonica were the main economic species and the others were low-value species. Charybdis immaculate, Charybdis japonica and Portunus trituberculatus were the main dominant species. The seasonal variation of the dominant species is obvious. Biomass in Laizhou Bay southern Bohai Sea and the coastal waters along the southern Shandong Peninsula changed seasonally with the highest in summer and the lowest in winter, but no significant seasonal change occurred in the coastal waters along northern Shandong Peninsula. According to the data, the average Shannon-Wiener diversity index (H'), Margalef richness index (D) and Pielou evenness index(J') in survey waters were very low, which manifest that there was a lower-level diversity of crab in this waters. Result of CLUSTER analysis showed that water depth, water temperature and salinity were the main factors affecting the community structure. By influencing the water temperature and salinity, the Bohai-Lai Longshore Current, the Yellow Sea Warm Current and the Huanghai Sea Cold Water Mass influenced the community structure. This paper showed that most of crabs in the coastal waters along the Shandong Peninsula were small, bait-type species. The crab diversity was very low.The dominant species varied.The MI was very high. The results showed clearly that the crabs' community structure were unstable.
2017, 39(8): 62-69.
doi: 10.3969/j.issn.0253-4193.2017.08.006
Abstract:
The clearance rate and filtration rate of Crassostrea hongkongensis feeding on Chaetoceros muelleri, Isochrysis galbana and Platymonas subcordiformis were examined using the lab experiments under the conditions of same density and biomass of phytoplankton by three different size of C. hongkongensis to discuss the feeding preference and impact infactors on phytoplankton of C. hongkongensis.The results showed that at temperature 28℃, the clearance rate per gram and per individual were 0.86-3.17 L/(g·h) and 1.40-8.94 L/(ind·h) respectively. The clearance rate per individual of C. hongkongensis presented as big-size> medium-size> small-size in the both case of same density and biomass of three phytoplankton, while the clearance rate per garm of C. hongkongensis was similar in spite of the size of C. hongkongensis. The changing pattern of clearance rate per individual presented as Platymonas subcordiformis > Isochrysis galbana > Chaetoceros muelleri under the condition of same density of three phytoplankton, while presented as Isochrysis galbana > Platymonas subcordiformis > Chaetoceros muelleri under the condition of same biomass of three phytoplankton. The different clearance rate of C. hongkongensison to different phytoplanton was mainly due to factors such as the food particle size, density and nutritive value.
The clearance rate and filtration rate of Crassostrea hongkongensis feeding on Chaetoceros muelleri, Isochrysis galbana and Platymonas subcordiformis were examined using the lab experiments under the conditions of same density and biomass of phytoplankton by three different size of C. hongkongensis to discuss the feeding preference and impact infactors on phytoplankton of C. hongkongensis.The results showed that at temperature 28℃, the clearance rate per gram and per individual were 0.86-3.17 L/(g·h) and 1.40-8.94 L/(ind·h) respectively. The clearance rate per individual of C. hongkongensis presented as big-size> medium-size> small-size in the both case of same density and biomass of three phytoplankton, while the clearance rate per garm of C. hongkongensis was similar in spite of the size of C. hongkongensis. The changing pattern of clearance rate per individual presented as Platymonas subcordiformis > Isochrysis galbana > Chaetoceros muelleri under the condition of same density of three phytoplankton, while presented as Isochrysis galbana > Platymonas subcordiformis > Chaetoceros muelleri under the condition of same biomass of three phytoplankton. The different clearance rate of C. hongkongensison to different phytoplanton was mainly due to factors such as the food particle size, density and nutritive value.
2017, 39(8): 70-77.
doi: 10.3969/j.issn.0253-4193.2017.08.007
Abstract:
The cDNA sequence of natural resistance associated macrophage protein in Sinonovacula constricta (Sc-Nramp2) was cloned by SMART RACE techniques. The ORF of cDNA sequence, coding for a protein of amino acids, was 1 773 bp and the molecular weight was deduced for 65.86 kDa. Sc-Nramp2 protein has the typical structural features with Solute carrier family 11 member, with 10 typical transmembrane domains and 2 glycosylation site. In 3'-UTR, Sc-Nramp2 was the presence of two IRE which was similar to the vertebrate Nramp2. Homology analysis indicated that the identity of Nramp with Crassostrea gigas was 71.6%. Real-time quantitative RT-PCR analysis indicated that the mRNA was expressed in all the six tissues, including adductor muscle, mantle, hepatopancreas, foot, waterpipe and gill. Nramp was expressed with the highest expression level in the hepatopancreas, then the gill, which had extremely significant differences from other tissues(P<0.01). The expression of Nramp in the hepatopancreas injected with V. Parahaemolyticus increased significantly(P<0.01). It rose to maximum expression at the 12th hour and returned to the initial level. These results indicated that Sc-Nramp2 is involved in innate immunity of this species.
The cDNA sequence of natural resistance associated macrophage protein in Sinonovacula constricta (Sc-Nramp2) was cloned by SMART RACE techniques. The ORF of cDNA sequence, coding for a protein of amino acids, was 1 773 bp and the molecular weight was deduced for 65.86 kDa. Sc-Nramp2 protein has the typical structural features with Solute carrier family 11 member, with 10 typical transmembrane domains and 2 glycosylation site. In 3'-UTR, Sc-Nramp2 was the presence of two IRE which was similar to the vertebrate Nramp2. Homology analysis indicated that the identity of Nramp with Crassostrea gigas was 71.6%. Real-time quantitative RT-PCR analysis indicated that the mRNA was expressed in all the six tissues, including adductor muscle, mantle, hepatopancreas, foot, waterpipe and gill. Nramp was expressed with the highest expression level in the hepatopancreas, then the gill, which had extremely significant differences from other tissues(P<0.01). The expression of Nramp in the hepatopancreas injected with V. Parahaemolyticus increased significantly(P<0.01). It rose to maximum expression at the 12th hour and returned to the initial level. These results indicated that Sc-Nramp2 is involved in innate immunity of this species.
2017, 39(8): 78-88.
doi: 10.3969/j.issn.0253-4193.2017.08.008
Abstract:
The annual zooplankton data for large areas in the Northern Yellow Sea during the marine census period (1959.1-1959.12) was analyzed in comparison to the annual zooplankton data around Zhangzi Island of the year 2009 in the aspects of species composition, dominant species, biological abundance and biodiversity. The results showed that zooplankton community around Zhangzi Island of North Yellow Sea did not exhibit significant changes. Calanus sinicus and Saggita crassa were observed as firmly dominant species. Themisto gracilipes was collected constantly each month, but it was dominant only in the winter and spring. In 2009, Euphausia pacifica was sampled in each month, but did not appear as dominant species; however, in 1959, it was observed as the dominant species in April and November. The dominant position of Centropages abdominalis in 1959 was replaced by Acartia omorii in 2009 in the spring and summer.The average abundance of zooplankton increased from 78.90 ind/m3 to 131.26 ind/m3 from 1959 to 2009; the biodiversity index (H') was higher both in the summer and autumn than in the spring and winter in these two years, and the average biodiversity index value also increased.
The annual zooplankton data for large areas in the Northern Yellow Sea during the marine census period (1959.1-1959.12) was analyzed in comparison to the annual zooplankton data around Zhangzi Island of the year 2009 in the aspects of species composition, dominant species, biological abundance and biodiversity. The results showed that zooplankton community around Zhangzi Island of North Yellow Sea did not exhibit significant changes. Calanus sinicus and Saggita crassa were observed as firmly dominant species. Themisto gracilipes was collected constantly each month, but it was dominant only in the winter and spring. In 2009, Euphausia pacifica was sampled in each month, but did not appear as dominant species; however, in 1959, it was observed as the dominant species in April and November. The dominant position of Centropages abdominalis in 1959 was replaced by Acartia omorii in 2009 in the spring and summer.The average abundance of zooplankton increased from 78.90 ind/m3 to 131.26 ind/m3 from 1959 to 2009; the biodiversity index (H') was higher both in the summer and autumn than in the spring and winter in these two years, and the average biodiversity index value also increased.
2017, 39(8): 89-98.
doi: 10.3969/j.issn.0253-4193.2017.08.009
Abstract:
To explore the diversity changes of bacterial communities in mariculture water, water samples from Litopenasus vannamei culture ponds in the middle and late growth stages at the farms located at Zhangpu, Fujian Province, China, were collected. Bacterial communities were analyzed through Illumina Miseq sequencing based on 16S rRNA gene, and the water quality parameters were also detected. The results showed that the water quality factors, such as NH4+-N, COD, fluctuated greatly compared with other parameters. 19 phyla, 35 classes, 80 orders, 135 families and 254 bacterial genera were detected,which indicated a high diversity of microbial flora. Proteobacteria and Bacteroidetes are the main dominant group during culture, and while there was a certain fluctuation of microbial composition in different aquaculture periods, no obvious change law was observed. Cyanobacteria showed high abundance at the day of 67 and 115, and their abundance varied greatly during culture (0.7% to 63.9%). In addition, the abundance of probiotics and potential pathogens is low during culture. The RDA results showed that COD/NO3- and COD contents in water had the greatest influence on bacterial communities, and reduced DO can increase bacterial richness. This study revealed the change of bacterial community in the middle and late stages of L. vannamei culture, and found that water quality factors had a significant effect on microbial composition. The results provided a significant reference for the healthy aquaculture of L. vannamei.
To explore the diversity changes of bacterial communities in mariculture water, water samples from Litopenasus vannamei culture ponds in the middle and late growth stages at the farms located at Zhangpu, Fujian Province, China, were collected. Bacterial communities were analyzed through Illumina Miseq sequencing based on 16S rRNA gene, and the water quality parameters were also detected. The results showed that the water quality factors, such as NH4+-N, COD, fluctuated greatly compared with other parameters. 19 phyla, 35 classes, 80 orders, 135 families and 254 bacterial genera were detected,which indicated a high diversity of microbial flora. Proteobacteria and Bacteroidetes are the main dominant group during culture, and while there was a certain fluctuation of microbial composition in different aquaculture periods, no obvious change law was observed. Cyanobacteria showed high abundance at the day of 67 and 115, and their abundance varied greatly during culture (0.7% to 63.9%). In addition, the abundance of probiotics and potential pathogens is low during culture. The RDA results showed that COD/NO3- and COD contents in water had the greatest influence on bacterial communities, and reduced DO can increase bacterial richness. This study revealed the change of bacterial community in the middle and late stages of L. vannamei culture, and found that water quality factors had a significant effect on microbial composition. The results provided a significant reference for the healthy aquaculture of L. vannamei.
2017, 39(8): 99-114.
doi: 10.3969/j.issn.0253-4193.2017.08.010
Abstract:
A series of cell morphology and structure changes were displayed during the development of reproductive structure of gametophyte and tetrasporaphyte of Gracilariopsis lemaneiformis. In this study, the gametophyte and different strains of tetrasporophyte were used to make continuous free hand section, in order to observe the development of the gametophyte and the formation of tetraspores in different strains of G. lemaneiformis. The result showed that the development of male and female gametophytes undertook seedling phage (SP), hair cell phage (HCP) and sexual mature phage (SMP). There was no significant difference between male and female gametophyte in SP and HCP. The male and female gametophyte were differentiable after entering SMP when the reproductive apparatus formed. The tetraspores were derived from the epidermal cells of tetrasprophyte, the initial tetrasporogonium was scarlet, and 5-10 μm in diameter. It later grew to 20-25 μm in diameter and became mature. The mature tetrasporogonium divided into four initial tetraspores gathered together, and then the tetraspores were released out of the matrix and became globular. During the development of tetraspores, the density of floridean starch granules decreased in medullary part. Cultivar 981 formed more deformed tetraspores, which may be one of the reasons leading to the low fertility of cultivar 981. The layers of epidermal cells, the numbers and the volume of medullary cells changed continuously from the basal to the tip part. Pit connections existed wildly in the epidermal, cortical and medullary cells, however varying by size, numbers and length between different layers. The released tetraspores were observed attaching on the tetrasporophyte, and the holdfast grew to cover the tetrasporophyte or invaded into the wound tissue of tetrasporophyte, which may cause gametophyte and tetrasporophyte generation promiscuous and lead to the genetic complexity of G. lemaneiformis.
A series of cell morphology and structure changes were displayed during the development of reproductive structure of gametophyte and tetrasporaphyte of Gracilariopsis lemaneiformis. In this study, the gametophyte and different strains of tetrasporophyte were used to make continuous free hand section, in order to observe the development of the gametophyte and the formation of tetraspores in different strains of G. lemaneiformis. The result showed that the development of male and female gametophytes undertook seedling phage (SP), hair cell phage (HCP) and sexual mature phage (SMP). There was no significant difference between male and female gametophyte in SP and HCP. The male and female gametophyte were differentiable after entering SMP when the reproductive apparatus formed. The tetraspores were derived from the epidermal cells of tetrasprophyte, the initial tetrasporogonium was scarlet, and 5-10 μm in diameter. It later grew to 20-25 μm in diameter and became mature. The mature tetrasporogonium divided into four initial tetraspores gathered together, and then the tetraspores were released out of the matrix and became globular. During the development of tetraspores, the density of floridean starch granules decreased in medullary part. Cultivar 981 formed more deformed tetraspores, which may be one of the reasons leading to the low fertility of cultivar 981. The layers of epidermal cells, the numbers and the volume of medullary cells changed continuously from the basal to the tip part. Pit connections existed wildly in the epidermal, cortical and medullary cells, however varying by size, numbers and length between different layers. The released tetraspores were observed attaching on the tetrasporophyte, and the holdfast grew to cover the tetrasporophyte or invaded into the wound tissue of tetrasporophyte, which may cause gametophyte and tetrasporophyte generation promiscuous and lead to the genetic complexity of G. lemaneiformis.
2017, 39(8): 115-128.
doi: 10.3969/j.issn.0253-4193.2017.08.011
Abstract:
Phosphorus is an important biogenic element playing a key role in primary production in estuarine and coastal environments. Knowledge of the speciation and transformation of phosphorus in sediments contributes to a better understanding of the ecosystem dynamics in these regions. Surface sediment samples were collected in the Changjiang Estuary and adjacent shelf in March, 2013, and were separated into different size fractions via water elutriation. P speciation was analyzed by a modified sequential extraction method (SEDEX) to obtain six sedimentary P forms:exchangeable or loosely-sorbed P(Ex-P), organic P(Or-P), Fe-bound P(Fe-P), authigenic P(Au-P),detrital P(De-P) and refractory P(Re-P) in order to investigate the distribution and transformation of different phosphorus forms in the sediments of this area. The total phosphorus (TP) in sediments ranged from 14.0-18.4 μmol/g, and De-P was the major form and accounted for 54.5% of the TP, followed by Or-P and Re-P, which accounted for 15.1% and 13.1%, respectively. The contents of phosphorus forms in different size fractions were different. Ex-P, Or-P, Fe-P, Au-P and Re-P decreased gradually with increasing grain size, while De-P was concentrated in coarser particles (more than 32 μm). Based on the mass distribution of phosphorus speciation, less than 32 μm fractions gradually increased from Changjiang Estuary to Zhe-Min Coast and decreased seaward, while the variation tendency of more than 32 μm fractions was opposite, reflecting the selective transport of phosphorus of different forms. With the increase of particle size, TOC to Or-P (TOC/Or-P) ratios first decreased and then increased. High TOC/Or-P values in the larger size fractions were possibly caused by the high terrestrial OC contributions in this fraction, while in fine particles, high TOC/Or-P values are largely attributed to the more efficient transformation and remobilization of Or-P, indicating preferential regeneration of Or-P relative to OC. This study shows that a more comprehensive understanding of the phosphorus cycle in these dynamic estuarine and coastal environments can be obtained from a size fractionation perspective.
Phosphorus is an important biogenic element playing a key role in primary production in estuarine and coastal environments. Knowledge of the speciation and transformation of phosphorus in sediments contributes to a better understanding of the ecosystem dynamics in these regions. Surface sediment samples were collected in the Changjiang Estuary and adjacent shelf in March, 2013, and were separated into different size fractions via water elutriation. P speciation was analyzed by a modified sequential extraction method (SEDEX) to obtain six sedimentary P forms:exchangeable or loosely-sorbed P(Ex-P), organic P(Or-P), Fe-bound P(Fe-P), authigenic P(Au-P),detrital P(De-P) and refractory P(Re-P) in order to investigate the distribution and transformation of different phosphorus forms in the sediments of this area. The total phosphorus (TP) in sediments ranged from 14.0-18.4 μmol/g, and De-P was the major form and accounted for 54.5% of the TP, followed by Or-P and Re-P, which accounted for 15.1% and 13.1%, respectively. The contents of phosphorus forms in different size fractions were different. Ex-P, Or-P, Fe-P, Au-P and Re-P decreased gradually with increasing grain size, while De-P was concentrated in coarser particles (more than 32 μm). Based on the mass distribution of phosphorus speciation, less than 32 μm fractions gradually increased from Changjiang Estuary to Zhe-Min Coast and decreased seaward, while the variation tendency of more than 32 μm fractions was opposite, reflecting the selective transport of phosphorus of different forms. With the increase of particle size, TOC to Or-P (TOC/Or-P) ratios first decreased and then increased. High TOC/Or-P values in the larger size fractions were possibly caused by the high terrestrial OC contributions in this fraction, while in fine particles, high TOC/Or-P values are largely attributed to the more efficient transformation and remobilization of Or-P, indicating preferential regeneration of Or-P relative to OC. This study shows that a more comprehensive understanding of the phosphorus cycle in these dynamic estuarine and coastal environments can be obtained from a size fractionation perspective.
2017, 39(8): 129-135.
doi: 10.3969/j.issn.0253-4193.2017.08.012
Abstract:
In order to estimate the effects of temperature and algae concentration on the energy budget of clam Sinonovacula constricta. Adult clams were exposed to various treatments under three temperatures and three algae concentration conditions. The ingestion, respiration, defecation, excretion of energy budget of S.constricta were detected. Results showed that (1) with the increase of bait-algae concentration, the feeding, respiration and excretion of S.constricta were increased. The feeding energy had a peak change, while the respiration and excretion energy increased slowly. (2)The carbon source obtained from Isochrysis sphaeric by S.constricta was mainly consumed through breathing, and excretion of dejection, with a small part being discharged by metabolic waste. And the remaining carbon was mainly used for growth and development. (3) One-way ANOVA analysis showed that the ingestion rate and the oxygen consumption were significantly influenced by bait-algae concentration and temperature (P<0.05). In 23℃ seawater, the ingestion rate and the oxygen consumption rate of S.constricta reached the maximum in 3.0×105 cells/mL bait-algae concentration,and the oxygen rate and ammonia excretion rate reached the maximum when the temperature was at 23℃.
In order to estimate the effects of temperature and algae concentration on the energy budget of clam Sinonovacula constricta. Adult clams were exposed to various treatments under three temperatures and three algae concentration conditions. The ingestion, respiration, defecation, excretion of energy budget of S.constricta were detected. Results showed that (1) with the increase of bait-algae concentration, the feeding, respiration and excretion of S.constricta were increased. The feeding energy had a peak change, while the respiration and excretion energy increased slowly. (2)The carbon source obtained from Isochrysis sphaeric by S.constricta was mainly consumed through breathing, and excretion of dejection, with a small part being discharged by metabolic waste. And the remaining carbon was mainly used for growth and development. (3) One-way ANOVA analysis showed that the ingestion rate and the oxygen consumption were significantly influenced by bait-algae concentration and temperature (P<0.05). In 23℃ seawater, the ingestion rate and the oxygen consumption rate of S.constricta reached the maximum in 3.0×105 cells/mL bait-algae concentration,and the oxygen rate and ammonia excretion rate reached the maximum when the temperature was at 23℃.
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