2022 Vol. 44, No. 1
Display Method:
2022, 44(1): 1-10.
doi: 10.12284/hyxb2022008
Abstract:
The Bohai Sea and Yellow Sea are continental shelf areas with high production of dimethyl sulfide (DMS). Field investigation of DMS in this area is helpful to accurately assess its amount released from the ocean and its negative feedback on global climate change. Both model-based and direct measurement methods are based on DMS concentration in surface seawater and lower atmosphere, respectively, so advanced detection technology plays a decisive role in the accurate flux estimation. Gas chromatography, mass spectrometry, chemiluminescence and satellite remote sensing are commonly used observation techniques. At this paper, a method based on benzene-assisted photoionization positive ion mobility spectrometry (BAPI-PIMS) for in-situ observation of DMS in seawater is proposed. Combined with dynamic gas stripping and on-line water removal Nafion tube sampling system, the interference of environmental water vapor is eliminated. Under the optimal conditions, the linear range based on the two DMS product ions is 0.10−120 nmol/L, and the detection limit is as low as 0.065 nmol/L. Then the demonstrated method is applied to field detect DMS in the Bohai Sea and northern Yellow Sea, and the concentration of DMS in surface seawater ranged from 0.08 nmol/L to 0.96 nmol/L, while the air-sea exchange flux ranged from 0.12 μmol/(m2·d) to 17.75 μmol/(m2·d). Lastly, the difference between DMS detected on field and in lab and the main impact factors are discussed via the correlation analysis and canonical correspondence analysis, and results show that nutrients and phytoplankton community are the main factors during the seawater preservation, indicating the important significance of field observation method established currently for accurate evaluation of DMS release from the ocean.
The Bohai Sea and Yellow Sea are continental shelf areas with high production of dimethyl sulfide (DMS). Field investigation of DMS in this area is helpful to accurately assess its amount released from the ocean and its negative feedback on global climate change. Both model-based and direct measurement methods are based on DMS concentration in surface seawater and lower atmosphere, respectively, so advanced detection technology plays a decisive role in the accurate flux estimation. Gas chromatography, mass spectrometry, chemiluminescence and satellite remote sensing are commonly used observation techniques. At this paper, a method based on benzene-assisted photoionization positive ion mobility spectrometry (BAPI-PIMS) for in-situ observation of DMS in seawater is proposed. Combined with dynamic gas stripping and on-line water removal Nafion tube sampling system, the interference of environmental water vapor is eliminated. Under the optimal conditions, the linear range based on the two DMS product ions is 0.10−120 nmol/L, and the detection limit is as low as 0.065 nmol/L. Then the demonstrated method is applied to field detect DMS in the Bohai Sea and northern Yellow Sea, and the concentration of DMS in surface seawater ranged from 0.08 nmol/L to 0.96 nmol/L, while the air-sea exchange flux ranged from 0.12 μmol/(m2·d) to 17.75 μmol/(m2·d). Lastly, the difference between DMS detected on field and in lab and the main impact factors are discussed via the correlation analysis and canonical correspondence analysis, and results show that nutrients and phytoplankton community are the main factors during the seawater preservation, indicating the important significance of field observation method established currently for accurate evaluation of DMS release from the ocean.
2022, 44(1): 137-146.
doi: 10.12284/hyxb2022004
Abstract:
Based on the investigations of surface sediments at six sampling stations of nine cruises carried out in the sea around the Yongxing Island of Xisha from 2009 to 2017, the background values of seven heavy metals are determined through the process of mathematical statistics, the contents and inter-annual variations of heavy metals are analyzed, and the contents of the heavy metals are evaluated by means of single factor standard index and potential ecological risk index. The results show that the background values of heavy metals in the sediments of the study area are low, the average level of them meet the first class of marine sediment quality, and the quality of sediment is excellent. The inter-annual variations of seven heavy metals in the sediments of the study area are slightly different and generally significant and affected obviously by the development activities on the Yongxing Island. From 2009 to 2017, the contents of Zn, Cd, Cu, Cr, As and Hg are to increase first and then decrease, while the content of Pb is to increase. The assessment by means of potential ecological risk index shows that the multi year average of potential ecological risk indexes are in the order of Cd, Hg, As, Cu, Pb, Cr, Zn, and Cd and Hg are the main potential ecological risk factors of the study area.
Based on the investigations of surface sediments at six sampling stations of nine cruises carried out in the sea around the Yongxing Island of Xisha from 2009 to 2017, the background values of seven heavy metals are determined through the process of mathematical statistics, the contents and inter-annual variations of heavy metals are analyzed, and the contents of the heavy metals are evaluated by means of single factor standard index and potential ecological risk index. The results show that the background values of heavy metals in the sediments of the study area are low, the average level of them meet the first class of marine sediment quality, and the quality of sediment is excellent. The inter-annual variations of seven heavy metals in the sediments of the study area are slightly different and generally significant and affected obviously by the development activities on the Yongxing Island. From 2009 to 2017, the contents of Zn, Cd, Cu, Cr, As and Hg are to increase first and then decrease, while the content of Pb is to increase. The assessment by means of potential ecological risk index shows that the multi year average of potential ecological risk indexes are in the order of Cd, Hg, As, Cu, Pb, Cr, Zn, and Cd and Hg are the main potential ecological risk factors of the study area.
2022, 44(1): 147-154.
doi: 10.12284/hyxb2022024
Abstract:
Dissimilatory nitrate reduction in marine sediment is one of the key nitrogen loss processes in the ocean. Dissimilatory nitrate reduction to ammonium (DNRA), unlike denitrification and anammox by which nitrate is reduced to N2 and removed from the environment eventually, directly reduce nitrate to ammonium, could lead to eutrophication and water hypoxia afterwards. 15N labeled technique is the main method to investigate dissimilatory nitrate reduction processes in sediments. Accurate determination of 15\begin{document}${\rm {NH}}_4^+ $\end{document} ![]()
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Dissimilatory nitrate reduction in marine sediment is one of the key nitrogen loss processes in the ocean. Dissimilatory nitrate reduction to ammonium (DNRA), unlike denitrification and anammox by which nitrate is reduced to N2 and removed from the environment eventually, directly reduce nitrate to ammonium, could lead to eutrophication and water hypoxia afterwards. 15N labeled technique is the main method to investigate dissimilatory nitrate reduction processes in sediments. Accurate determination of 15
2022, 44(1): 11-21.
doi: 10.12284/hyxb2022002
Abstract:
Trichiurus haumela is one of the major commercial fish populations in the Beibu Gulf of the northwestern South China Sea. It is of great significance to estimate population parameters and assess the stock status of T. haumela for the fishery management in the Beibu Gulf. Based on the biological data of T. haumela collected in the Beibu Gulf from 2006 to 2016, the asymptotic length (Linf), the optimal length-at-first-capture (Lc_opt), relative mortality (M/k and F/k), exploitation rate (E), and relative biomass (B/B0) are estimated using the length-based Bayesian biomass estimation method (LBB). The results show that the Linf is 44.4 cm, the mean of Lc_opt is 28.5 cm, the mean of M/k and F/k are 1.32 and 2.76, the F/M is 2.20 and the E and B/B0 are 0.67 and 0.16, respectively. The anal length of the first gonadal maturation (L50%) is 28.63 cm fitted by Logistic models. The results show that the current stock of T. haumela in the Beibu Gulf is over-exploited, the extant biomass is relatively low, the length-frequency tendes to simplification and miniaturization.
Trichiurus haumela is one of the major commercial fish populations in the Beibu Gulf of the northwestern South China Sea. It is of great significance to estimate population parameters and assess the stock status of T. haumela for the fishery management in the Beibu Gulf. Based on the biological data of T. haumela collected in the Beibu Gulf from 2006 to 2016, the asymptotic length (Linf), the optimal length-at-first-capture (Lc_opt), relative mortality (M/k and F/k), exploitation rate (E), and relative biomass (B/B0) are estimated using the length-based Bayesian biomass estimation method (LBB). The results show that the Linf is 44.4 cm, the mean of Lc_opt is 28.5 cm, the mean of M/k and F/k are 1.32 and 2.76, the F/M is 2.20 and the E and B/B0 are 0.67 and 0.16, respectively. The anal length of the first gonadal maturation (L50%) is 28.63 cm fitted by Logistic models. The results show that the current stock of T. haumela in the Beibu Gulf is over-exploited, the extant biomass is relatively low, the length-frequency tendes to simplification and miniaturization.
2022, 44(1): 22-35.
doi: 10.12284/hyxb2022012
Abstract:
Chub mackerel (Scomber japonicus) is a major target species in the Northwest Pacific fishery. Understanding changes in its fishing grounds is of great significance for assessing population size, resource, utilization, and management of the fishery. Based on catch data of high sea light purse seine fishery of China from 2014 to 2019, the spatial and temporal patterns of chub mackerel fishing grounds in the Northwest Pacific using the global Moran index, the local hot spot analysis, center of gravity migration trajectory model, and standard deviation ellipse are analyzed in this study. The results show that: (1) catches of chub mackerel mainly concentrates in the area between 39°−44°N and 147°−155°E, the annual catches show a trend of first increase and then decrease, the annual CPUE decrease year by year, the monthly catches show a trend of first increase and then decrease, which maintaines at a high level from June to October, and the monthly CPUE increases with month. (2) The spatial autocorrelations of annually and monthly chub mackerel catches are significant, and the monthly autocorrelations are stronger than annually ones, indicated highly aggregated distribution of the fishing grounds. (3) The distributions of chub mackerel hot spots and cold spots show a certain spatial agglomeration, but their distribution patterns and the areas cover varied apparently with years and months. (4) The gravity center of fishing ground generally show northwest shift from year to year, and in term of seasonal changes, moves northwest from April to August, and then turnes back to the southwest. (5) The annual and monthly shifts in directions of fishing grounds are consistent, showing an southwest-northeast pattern with strong directivity and aggregation. The spatial correlation models used in this analysis present a new look at spatial and temporal patterns of the chub mackerel fishing grounds, which may provide useful information for the rational development and utilization of the chub mackerel resource.
Chub mackerel (Scomber japonicus) is a major target species in the Northwest Pacific fishery. Understanding changes in its fishing grounds is of great significance for assessing population size, resource, utilization, and management of the fishery. Based on catch data of high sea light purse seine fishery of China from 2014 to 2019, the spatial and temporal patterns of chub mackerel fishing grounds in the Northwest Pacific using the global Moran index, the local hot spot analysis, center of gravity migration trajectory model, and standard deviation ellipse are analyzed in this study. The results show that: (1) catches of chub mackerel mainly concentrates in the area between 39°−44°N and 147°−155°E, the annual catches show a trend of first increase and then decrease, the annual CPUE decrease year by year, the monthly catches show a trend of first increase and then decrease, which maintaines at a high level from June to October, and the monthly CPUE increases with month. (2) The spatial autocorrelations of annually and monthly chub mackerel catches are significant, and the monthly autocorrelations are stronger than annually ones, indicated highly aggregated distribution of the fishing grounds. (3) The distributions of chub mackerel hot spots and cold spots show a certain spatial agglomeration, but their distribution patterns and the areas cover varied apparently with years and months. (4) The gravity center of fishing ground generally show northwest shift from year to year, and in term of seasonal changes, moves northwest from April to August, and then turnes back to the southwest. (5) The annual and monthly shifts in directions of fishing grounds are consistent, showing an southwest-northeast pattern with strong directivity and aggregation. The spatial correlation models used in this analysis present a new look at spatial and temporal patterns of the chub mackerel fishing grounds, which may provide useful information for the rational development and utilization of the chub mackerel resource.
2022, 44(1): 36-47.
doi: 10.12284/hyxb2022010
Abstract:
The study of spatial patterns of fish populations provides reference for reasonable utilization and management of fishery resources, which depends greatly on the quality of data collected from well-designed surveys. So appropriate sampling designs are essential in fishery-independent surveys, which can greatly affect the accuracy and applicability of the survey results. Computer simulation study is conducted to investigate the effects of sampling design on the spatial pattern of fish populations based on the data collected from bottom trawl surveys in the southern waters off Shandong Peninsula in four seasons from 2016 to 2017 in this study. Four sampling methods, including simple random sampling (SRS), systematic sampling (SYS), stratified random sampling (StRS) and stratified systematic sampling (StSS) with four levels of sample sizes are considered as potential sampling designs in this simulation study. The effects of different sampling designs on the estimation of mean crowding index and poly block index (PBI) for Conger myriaster and Enedrias fangi are examined. Relative estimation error (REE) and relative bias (RB) are used to measure the performances of different sampling designs. The results show that the simulated values of spatial pattern indices from SYS and StSS are closer to the “true” values, and the performances of SRS and StRS are relatively poor. The REE of estimation of spatial pattern indices for target fish populations decreased significantly with sample size. The original spatial pattern of fish populations has a certain effect on the estimation of spatial pattern indices. The precision of estimation of PBI decreased with the increase of the “true” values of spatial pattern indices, with PBI being overestimated when it is high. Different sampling designs have a certain effect on the estimation of spatial pattern indices of fish populations, and the degree of population aggregation also affected the analysis results. Therefore, the spatial pattern indices of target fish populations could be incorporated into the survey goals in sampling designs to improve the fishery-independent surveys with multiple objectives.
The study of spatial patterns of fish populations provides reference for reasonable utilization and management of fishery resources, which depends greatly on the quality of data collected from well-designed surveys. So appropriate sampling designs are essential in fishery-independent surveys, which can greatly affect the accuracy and applicability of the survey results. Computer simulation study is conducted to investigate the effects of sampling design on the spatial pattern of fish populations based on the data collected from bottom trawl surveys in the southern waters off Shandong Peninsula in four seasons from 2016 to 2017 in this study. Four sampling methods, including simple random sampling (SRS), systematic sampling (SYS), stratified random sampling (StRS) and stratified systematic sampling (StSS) with four levels of sample sizes are considered as potential sampling designs in this simulation study. The effects of different sampling designs on the estimation of mean crowding index and poly block index (PBI) for Conger myriaster and Enedrias fangi are examined. Relative estimation error (REE) and relative bias (RB) are used to measure the performances of different sampling designs. The results show that the simulated values of spatial pattern indices from SYS and StSS are closer to the “true” values, and the performances of SRS and StRS are relatively poor. The REE of estimation of spatial pattern indices for target fish populations decreased significantly with sample size. The original spatial pattern of fish populations has a certain effect on the estimation of spatial pattern indices. The precision of estimation of PBI decreased with the increase of the “true” values of spatial pattern indices, with PBI being overestimated when it is high. Different sampling designs have a certain effect on the estimation of spatial pattern indices of fish populations, and the degree of population aggregation also affected the analysis results. Therefore, the spatial pattern indices of target fish populations could be incorporated into the survey goals in sampling designs to improve the fishery-independent surveys with multiple objectives.
2022, 44(1): 48-62.
doi: 10.12284/hyxb2022028
Abstract:
Based on the fish survey data of the offshore waters of southern Zhejiang in August 2016 (summer), November 2016 (Autumn), March 2017 (winter) and May 2017 (spring), the relationship between dominant fish species is determined by niche breadth, niche overlap, cluster analysis, variance ratio (VR) method, chi-square test, association coefficient (AC) and species pair common percentage (PC). The results show that: (1) 169 species of fish are collected, including 26 major species; (2) in the spatial dimension, the niche breadth of Scomber japonicus is the largest (2.83); the niche overlap between Sardinella zunasi and Thryssa chefuensis is the largest (0.97); in the temporal dimension, the niche breadth of Harpadon nehereus is the largest (1.34); the niche overlap of six groups is equal to 1.00; in the spatial and temporal dimension, the niche breadth of Harpadon nehereus is the largest (3.08); the niche overlap between Sardinella zunasi and Thryssa chefuensis is the largest (0.97); (3) the variance ratio analysis showed that the VR deviation is significant, and the overall positive association of the major fish is significant, among which 170 groups of species pair association reached a significant level (χ2≥3.841). The results of the AC and the PC showed that the interspecific connection tended to be positive.
Based on the fish survey data of the offshore waters of southern Zhejiang in August 2016 (summer), November 2016 (Autumn), March 2017 (winter) and May 2017 (spring), the relationship between dominant fish species is determined by niche breadth, niche overlap, cluster analysis, variance ratio (VR) method, chi-square test, association coefficient (AC) and species pair common percentage (PC). The results show that: (1) 169 species of fish are collected, including 26 major species; (2) in the spatial dimension, the niche breadth of Scomber japonicus is the largest (2.83); the niche overlap between Sardinella zunasi and Thryssa chefuensis is the largest (0.97); in the temporal dimension, the niche breadth of Harpadon nehereus is the largest (1.34); the niche overlap of six groups is equal to 1.00; in the spatial and temporal dimension, the niche breadth of Harpadon nehereus is the largest (3.08); the niche overlap between Sardinella zunasi and Thryssa chefuensis is the largest (0.97); (3) the variance ratio analysis showed that the VR deviation is significant, and the overall positive association of the major fish is significant, among which 170 groups of species pair association reached a significant level (χ2≥3.841). The results of the AC and the PC showed that the interspecific connection tended to be positive.
2022, 44(1): 63-78.
doi: 10.12284/hyxb2022020
Abstract:
In order to further interpret the community structure of nekton and explore the ecological process of community structure changes, community structure of nekton in the Minnan sea area are analyzed based on the niche preemption model (NPM), broken stick model (BSM), overlapping niche model (ONM), dominance pre-emption model (DPM) and random assignment model (RAM) a total of 5 species abundance pattern models. The results show that there are 192 species of nekton in the Minnan sea area, including 132 species of fish, 31 species of crab, 13 species of shrimp, 10 species of cephalopod, 6 species of stomatopod. The fitting effect of NPM in the abundance distribution of nekton is better than that of ONM, the dominant species have dominant position and species niche do not overlap in Minnan sea area. From the open sea to the coastal area, the distribution pattern of nekton abundance changes from DPM to NPM, the simulation result of NPM is worse, and the simulation result of BSM is better, the status of dominant species decreased, the number of species increased, and species abundance distribution tendes to uniform.The fitting effect of DPM on the abundance distribution of nekton is better than that in the deep fishing area. With the increase of latitude, the fitting effect of the abundance distribution of nekton is better gradually, the dominant position of dominant species gradually increased, the number of species become less, and species abundance distribution tendes to unevenness, however, the fitting effect of DPM on the species abundance distribution of nekton in shallow fishing areas is poor, and the dominant position of dominant species gradually declines, the number of species becomes more, and species abundance distribution tendes to uniform. Therefore, niche preemption model is suitable to study the abundance distribution patterns of nekton in the Minnan sea area.
In order to further interpret the community structure of nekton and explore the ecological process of community structure changes, community structure of nekton in the Minnan sea area are analyzed based on the niche preemption model (NPM), broken stick model (BSM), overlapping niche model (ONM), dominance pre-emption model (DPM) and random assignment model (RAM) a total of 5 species abundance pattern models. The results show that there are 192 species of nekton in the Minnan sea area, including 132 species of fish, 31 species of crab, 13 species of shrimp, 10 species of cephalopod, 6 species of stomatopod. The fitting effect of NPM in the abundance distribution of nekton is better than that of ONM, the dominant species have dominant position and species niche do not overlap in Minnan sea area. From the open sea to the coastal area, the distribution pattern of nekton abundance changes from DPM to NPM, the simulation result of NPM is worse, and the simulation result of BSM is better, the status of dominant species decreased, the number of species increased, and species abundance distribution tendes to uniform.The fitting effect of DPM on the abundance distribution of nekton is better than that in the deep fishing area. With the increase of latitude, the fitting effect of the abundance distribution of nekton is better gradually, the dominant position of dominant species gradually increased, the number of species become less, and species abundance distribution tendes to unevenness, however, the fitting effect of DPM on the species abundance distribution of nekton in shallow fishing areas is poor, and the dominant position of dominant species gradually declines, the number of species becomes more, and species abundance distribution tendes to uniform. Therefore, niche preemption model is suitable to study the abundance distribution patterns of nekton in the Minnan sea area.
2022, 44(1): 79-88.
doi: 10.12284/hyxb2022022
Abstract:
Based on the investigation data of zooplankton in the sea area near the north operation area in the Lanshan Port of Rizhao Port in May (spring) and October (autumn) 2015, the community structure characteristics of zooplankton was analysed in this paper. The results showed that 20 species and 7 taxa of zooplankton were found in the two seasons, including 12 species and 4 taxa in spring and 19 species and 6 taxa in autumn, the average abundance of zooplankton were 128.1 ind./m3 in spring and 103.3 ind./m3 in autumn, the average biomass (wet weight) were 1 129.9 mg/m3 and 954.3 mg/m3, the average Shannon-Wiener diversity index (H'), Margalef’s species richness diversity (D) and Pielou’s evenness index (J) were 2.39, 0.85, 0.87 in spring, respectively, and 2.01, 1.21, 0.62 in autumn, respectively. In spring, the dominant species were Sagitta crassa, Calanus sinicus, Labibocera euchaeta, Acartia pacifica, Pleurobrachia globosa, while in autumn, the dominant species were Acartia pacifica, Doliolum denticulatum, Sagitta crassa, Labibocera euchaeta. Cluster analysis showed that the zooplankton in the investigation area could be divided into three groups. This study could provide important basic data for further study of zooplankton community structure in the coastal waters of Rizhao.
Based on the investigation data of zooplankton in the sea area near the north operation area in the Lanshan Port of Rizhao Port in May (spring) and October (autumn) 2015, the community structure characteristics of zooplankton was analysed in this paper. The results showed that 20 species and 7 taxa of zooplankton were found in the two seasons, including 12 species and 4 taxa in spring and 19 species and 6 taxa in autumn, the average abundance of zooplankton were 128.1 ind./m3 in spring and 103.3 ind./m3 in autumn, the average biomass (wet weight) were 1 129.9 mg/m3 and 954.3 mg/m3, the average Shannon-Wiener diversity index (H'), Margalef’s species richness diversity (D) and Pielou’s evenness index (J) were 2.39, 0.85, 0.87 in spring, respectively, and 2.01, 1.21, 0.62 in autumn, respectively. In spring, the dominant species were Sagitta crassa, Calanus sinicus, Labibocera euchaeta, Acartia pacifica, Pleurobrachia globosa, while in autumn, the dominant species were Acartia pacifica, Doliolum denticulatum, Sagitta crassa, Labibocera euchaeta. Cluster analysis showed that the zooplankton in the investigation area could be divided into three groups. This study could provide important basic data for further study of zooplankton community structure in the coastal waters of Rizhao.
2022, 44(1): 89-100.
doi: 10.12284/hyxb2022016
Abstract:
To examine the benthos food web structure in the Xiaoqing River Estuary adjacent sea area, four potential food sources, including sediment organic matter (SOM), suspended particulate organic matter (POM), zooplankton and phytoplankton, and 35 aquatic organisms are collected in October 2020. Carbon and nitrogen stable isotope technique and Bayesian mixing model (MixSIAR) are used to analyze the food web structure and the trophic relationship of benthos. The results show that the δ13C and δ15N values of potential food sources varies from −25.56‰ to −17.91‰ and 2.43‰ to 10.33‰, respectively. Moreover, the δ13C and δ15N values of benthos varies from −23.48‰ to −18.31‰ and 8.79‰ to 18.01‰, respectively. The trophic levels of the main consumers rang from 1.65 (Arcuatula senhousia) to 3.54 (Ctenotrypauchen chinensis). Trophic relationship analysis showes that there are two main energy transfer pathways in the Xiaoqing River Estuary adjacent sea area. One is the planktonic food chain with plankton as the major energy source, in which bivalves (except Solen brevissimus), small shrimps, and polychaetes are the main primary consumers. The other is the benthic food chain with SOM as the major energy source, in which Solen brevissimus and gastropods are the main primary consumers. On the whole, there is a certain degree of niche overlap and fierce competition among species in the Xiaoqing River Estuary adjacent sea area.
To examine the benthos food web structure in the Xiaoqing River Estuary adjacent sea area, four potential food sources, including sediment organic matter (SOM), suspended particulate organic matter (POM), zooplankton and phytoplankton, and 35 aquatic organisms are collected in October 2020. Carbon and nitrogen stable isotope technique and Bayesian mixing model (MixSIAR) are used to analyze the food web structure and the trophic relationship of benthos. The results show that the δ13C and δ15N values of potential food sources varies from −25.56‰ to −17.91‰ and 2.43‰ to 10.33‰, respectively. Moreover, the δ13C and δ15N values of benthos varies from −23.48‰ to −18.31‰ and 8.79‰ to 18.01‰, respectively. The trophic levels of the main consumers rang from 1.65 (Arcuatula senhousia) to 3.54 (Ctenotrypauchen chinensis). Trophic relationship analysis showes that there are two main energy transfer pathways in the Xiaoqing River Estuary adjacent sea area. One is the planktonic food chain with plankton as the major energy source, in which bivalves (except Solen brevissimus), small shrimps, and polychaetes are the main primary consumers. The other is the benthic food chain with SOM as the major energy source, in which Solen brevissimus and gastropods are the main primary consumers. On the whole, there is a certain degree of niche overlap and fierce competition among species in the Xiaoqing River Estuary adjacent sea area.
2022, 44(1): 101-112.
doi: 10.12284/hyxb2022018
Abstract:
In order to study the relationship between daily increment of statolith and environment of neon flying squid (Ommastrephes bartramii) for different cohorts in the North Pacific during feeding ground, we explore the relationship between daily increment of statolith microstructure and environmental variables by gradient forest method (GFM) and generalized additive model (GAM) based on the samples collected in the North Pacific from 2010 to 2016. The results show that the life cycle of O. bartramii is about one year. The age of the autumn cohort ranges from 165 d to 345 d, and the age of winter-spring cohort ranges from 95 d to 271 d, respectively. Sea water temperature at the depth of 100 m (Temp_100), sea surface temperature (SST), sea surface salinity (SSS) and mixed layer depth (MLD) are the key environmental variables for the daily growth of autumn cohort. Temp_100, MLD, sea surface height (SSH) and chlorophyll a concentration (CHL) are the key environment variables for the daily growth of winter-spring cohort. GAM analysis shows that the daily increment width of statolith is significantly correlated with the key environmental variables selected by GFM (p<0.01). Key environmental variables of different cohorts suggest that the growth of O.bartrarnii is significantly affected by water temperature and prey abundance.
In order to study the relationship between daily increment of statolith and environment of neon flying squid (Ommastrephes bartramii) for different cohorts in the North Pacific during feeding ground, we explore the relationship between daily increment of statolith microstructure and environmental variables by gradient forest method (GFM) and generalized additive model (GAM) based on the samples collected in the North Pacific from 2010 to 2016. The results show that the life cycle of O. bartramii is about one year. The age of the autumn cohort ranges from 165 d to 345 d, and the age of winter-spring cohort ranges from 95 d to 271 d, respectively. Sea water temperature at the depth of 100 m (Temp_100), sea surface temperature (SST), sea surface salinity (SSS) and mixed layer depth (MLD) are the key environmental variables for the daily growth of autumn cohort. Temp_100, MLD, sea surface height (SSH) and chlorophyll a concentration (CHL) are the key environment variables for the daily growth of winter-spring cohort. GAM analysis shows that the daily increment width of statolith is significantly correlated with the key environmental variables selected by GFM (p<0.01). Key environmental variables of different cohorts suggest that the growth of O.bartrarnii is significantly affected by water temperature and prey abundance.
2022, 44(1): 113-124.
doi: 10.12284/hyxb2022006
Abstract:
In order to mine single nucleotide polymorphism (SNP) sites relates to hypoxia stress and study the function of the gene SNP-Unigene from Rachycentron canadum. SOAPsnp software is mainly used to detect the SNP of the intestinal transcriptome sequencing results of cobia juveniles under hypoxia stress conditions, and then annotation of them in the databases of GO, KOG, and KEGG are compared. The results show that the transcriptome SNP locus are distributed on 26 120 SNP-Unigene, with a total of 431 845 SNP sites are detected, the average frequency of SNP occurrence is about 1/171 bp. SNP-Unigene functional annotation showes that the cobia is mainly involved in signal transduction, infectious disease, cancer and endocrine system under hypoxia stress. Further, 3 417 SNP-Unigene are annotated to 35 immune-related pathways including MAPK signaling pathway. Based on the transcriptome differential gene analysis, the distribution of SNP sites of 18 immune-related genes in 7 important immune pathways is examined. At the same time, the distribution of SNP sites of 8 differential genes such as PIK3CA in the HIF-1 signaling pathway is also detected. The research results will lay the foundation for further mining of the molecular genetic markers of immune and hypoxia-related SNPs, and provide a scientific reference for the in-depth study of cobia’s hypoxia adaptation mechanism.
In order to mine single nucleotide polymorphism (SNP) sites relates to hypoxia stress and study the function of the gene SNP-Unigene from Rachycentron canadum. SOAPsnp software is mainly used to detect the SNP of the intestinal transcriptome sequencing results of cobia juveniles under hypoxia stress conditions, and then annotation of them in the databases of GO, KOG, and KEGG are compared. The results show that the transcriptome SNP locus are distributed on 26 120 SNP-Unigene, with a total of 431 845 SNP sites are detected, the average frequency of SNP occurrence is about 1/171 bp. SNP-Unigene functional annotation showes that the cobia is mainly involved in signal transduction, infectious disease, cancer and endocrine system under hypoxia stress. Further, 3 417 SNP-Unigene are annotated to 35 immune-related pathways including MAPK signaling pathway. Based on the transcriptome differential gene analysis, the distribution of SNP sites of 18 immune-related genes in 7 important immune pathways is examined. At the same time, the distribution of SNP sites of 8 differential genes such as PIK3CA in the HIF-1 signaling pathway is also detected. The research results will lay the foundation for further mining of the molecular genetic markers of immune and hypoxia-related SNPs, and provide a scientific reference for the in-depth study of cobia’s hypoxia adaptation mechanism.
2022, 44(1): 125-136.
doi: 10.12284/hyxb2022014
Abstract:
The wetland vegetation is an important part of coastal wetlands, and its dynamic changes affect the structures and functions of wetland ecosystem. Therefore, it is of great significance to monitor and evaluate the long-term changes of wetland vegetation by remote sensing technology for the management of coastal resources and ecological protection. In this paper, we used multi-temporal Landsat satellite images as data sources, combined object-oriented method and random forest algorithm to achieve accurate classification of typical wetland vegetation in the Current Huanghe River Estuary Reserve, and revealed the spatiotemporal variation characteristics of Phragmites australis, Suaeda salsa and Spartina alterniflora in the study area from 2000 to 2020. It has been verified that the overall accuracy of wetland vegetation mapping is between 84.74% and 92.39%, and the Kappa coefficient is between 0.81 and 0.91. The results of long time series classification show that Phragmites australis is the dominant species in the Current Huanghe Estuary Reserve, and its distribution area is maintained at more than 6% and the overall growth is steady. The area of Suaeda salsa shows a decreasing trend since 2006. The dominance degree of Suaeda salsa is decreasing continuously and the degree of fragmentation is severe. The area of Spartina alterniflora increased year by year from 211.85 hm2 in 2002 to 5267.79 hm2 in 2020. The expansion process of Spartina alterniflora in the reserve could be divided into three stages: in the initial expansion period before 2008, the growth of Spartina alterniflora was unstable; from 2008 to 2014, there was a rapid expansion stage, with an average annual expansion rate of 54%, which showed that the seaward expansion invaded the plain and the landward expansion invaded the habitat of Suaeda salsa in space; since 2014, Spartina alterniflora has been growing slowly, entering a stable growth period, and the annual average expansion rate is only 9%.
The wetland vegetation is an important part of coastal wetlands, and its dynamic changes affect the structures and functions of wetland ecosystem. Therefore, it is of great significance to monitor and evaluate the long-term changes of wetland vegetation by remote sensing technology for the management of coastal resources and ecological protection. In this paper, we used multi-temporal Landsat satellite images as data sources, combined object-oriented method and random forest algorithm to achieve accurate classification of typical wetland vegetation in the Current Huanghe River Estuary Reserve, and revealed the spatiotemporal variation characteristics of Phragmites australis, Suaeda salsa and Spartina alterniflora in the study area from 2000 to 2020. It has been verified that the overall accuracy of wetland vegetation mapping is between 84.74% and 92.39%, and the Kappa coefficient is between 0.81 and 0.91. The results of long time series classification show that Phragmites australis is the dominant species in the Current Huanghe Estuary Reserve, and its distribution area is maintained at more than 6% and the overall growth is steady. The area of Suaeda salsa shows a decreasing trend since 2006. The dominance degree of Suaeda salsa is decreasing continuously and the degree of fragmentation is severe. The area of Spartina alterniflora increased year by year from 211.85 hm2 in 2002 to 5267.79 hm2 in 2020. The expansion process of Spartina alterniflora in the reserve could be divided into three stages: in the initial expansion period before 2008, the growth of Spartina alterniflora was unstable; from 2008 to 2014, there was a rapid expansion stage, with an average annual expansion rate of 54%, which showed that the seaward expansion invaded the plain and the landward expansion invaded the habitat of Suaeda salsa in space; since 2014, Spartina alterniflora has been growing slowly, entering a stable growth period, and the annual average expansion rate is only 9%.
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