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2017, 36(10): 1-7. doi: 10.1007/s13131-017-1117-9
Abstract(39) FullText HTML(11) FullText PDF(1)
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The seasonal and inter-annual variations of Arctic cyclone are investigated. An automatic cyclone tracking algorithm developed by University of Reading was applied on the basis of European Center for Medium-range Weather Forecasts (ECMWF) ERA-interim mean sea level pressure field with 6 h interval for 34 a period. The maximum number of the Arctic cyclones is counted in winter, and the minimum is in spring not in summer. About 50% of Arctic cyclones in summer generated from south of 70°N, moving into the Arctic. The number of Arctic cyclones has large inter-annual and seasonal variabilities, but no significant linear trend is detected for the period 1979–2012. The spatial distribution and linear trends of the Arctic cyclones track density show that the cyclone activity extent is the widest in summer with significant increasing trend in CRU (central Russia) subregion, and the largest track density is in winter with decreasing trend in the same subregion. The linear regressions between the cyclone track density and large-scale indices for the same period and pre-period sea ice area indices show that Arctic cyclone activities are closely linked to large-scale atmospheric circulations, such as Arctic Oscillation (AO), North Atlantic Oscillation (NAO) and Pacific-North American Pattern (PNA). Moreover, the pre-period sea ice area is significantly associated with the cyclone activities in some regions.
2017, 36(10): 8-19. doi: 10.1007/s13131-017-1068-1
Abstract(45) FullText HTML(9) FullText PDF(2)
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Multi-biomarker indexes were analyzed for two piston cores from potential cold seep areas of the South China Sea off southwestern Taiwan. Total organic carbon (TOC) normalized terrestrial (n-alkanes) and marine (brassicasterol, dinosterol, alkenones and iso-GDGTs) biomarker contents and ratios (TMBR, 1/Pmar-aq, BIT) were used to evaluate the contributions of terrestrial and marine organic matter (TOM and MOM respectively) to the sedimentary organic matter, indicating that MOM dominated the organic sources in Core MD052911 and the sedimentary organic matter in Core ORI-860-22 was mainly derived from terrestrial inputs, and different morphologies were the likely reason for TOM percentage differences. BIT results suggested that river-transported terrestrial soil organic matter was not a major source of TOM of sedimentary organic matter around these settings. Diagnostic biomarkers for methane-oxidizing archaea (MOA) were only detected in one sample at 172 cm depth of Core ORI-860-22, with abnormally high iso-GDGTs content and Methane Index (MI) value (0.94). These results indicated high anaerobic oxidation of methane (AOM) activities at or around 172 cm in Core ORI-860-22. However in Core MD052911, MOA biomarkers were not detected and MI values were lower (0.19–0.38), indicated insignificant contributions of iso-GDGTs from methanotrophic archaea and the absence of significant AOM activities. Biomarker results thus indicated that the discontinuous upward methane seepage and insufficient methane flux could not induce high AOM activities in our sampling sites. In addition, the different patterns of TEX86 and \begin{document}${\text{U}}_{37}^{{\text{K}′}}$\end{document} temperature in two cores suggested that AOM activities affected TEX86 temperature estimates with lower values in Core ORI-860-22, but not significantly on TEX86 temperature estimates in Core MD052911.
2017, 36(10): 20-30. doi: 10.1007/s13131-017-1070-7
Abstract(39) FullText HTML(8) FullText PDF(0)
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The distribution of diatoms in surface sediments in the Minjiang Estuary, southeast China, was investigated in 2009. Total 56 species and other species belonging to 25 genera were identified, among them 11 species were dominant over 5%. Dominant species included Actinocyclus ehrenbergii, Coscinodiscus curvatulus, C. divisus, C. jonesianus, C. radiatus, C. rothii, C. subtilis, Cyclotella stylorum, Epithemia hyndmanii, Hydrosera whampoensis, and Trachyneis aspera. Diatom abundance varied spatially, with the absolute abundance of diatoms ranging from 13 valves/g to 11×104 valves/g, and averaging 2.5×104 valves/g. A canonical correspondence analysis (CCA) was used to explain the relationships between diatom distribution and sediment properties in the Minjiang Estuary. CCA revealed that the major elements (Fe2O3, Na2O, CaO, MgO, TiO2, SiO2, Al2O3, and K2O) were closely related to diatom abundance. Four diatom assemblages were distinguished, representing different sediment properties, which may assist late Quaternary palaeoceanographic reconstructions of the Minjiang Estuary.
2017, 36(10): 31-38. doi: 10.1007/s13131-017-0976-4
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Stocking density is widely recognized as a critical factor in aquaculture and a potential source of long-term stress. The influence of stocking density on growth and stress response of juvenile turbot (Scophthalmus maximus, ~3–75 g, initial to final weight) was examined in fish held under low (LD, ~0.21–5.31 kg/m2, initial to final density), medium (MD, ~0.42–10.81 kg/m2) and high stocking density (HD, ~0.63–14.27 kg/m2) for 120 days in a recirculating aquaculture system (RAS). In this trial, the growth curve for weight of juvenile turbot in RAS, all fitted by the Schnute model. No significant difference was found in growth performance among the three densities until at the final sampling (Day 120). The final weight and body weight increase (BWI) in the HD group were significantly lower than in other groups (P<0.05, weight: (75.83±2.49) g, (75.39±2.08) g, (65.72±2.86) g and BWI: (2 436.12±28.10)%, (2 421.29±4.64)%, (2 097.88±20.99)% in LD, MD and HD groups, respectively). Similarly, the specific growth rate (SGR), feed conversion ratio (FCR) and coefficient of variation for weight (CVw) were adversely affected by high stocking density (P<0.05). However, there was no difference in survival and Fulton’s condition factor (K) of turbot among the different groups. Physiological analyses demonstrated a clear increase in the plasma cortisol level and an obvious decrease in growth hormone (GH) concentration in the HD group on Day 120 (P<0.05). There was no significant effect of stocking density on plasma glucose, Cl and protein levels. All these findings would provide a reference for selecting the optimal stocking density of juvenile turbot in RAS.
2017, 36(10): 39-47. doi: 10.1007/s13131-017-1091-2
Abstract(34) FullText HTML(8) FullText PDF(0)
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Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k (growth coefficient) and t0 (zero-length age) gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞ (body length) sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and tr (inflexion age) decreased from 3.78 year in 1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as: fishing vessel power>feeding grade>sea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.
2017, 36(10): 48-59. doi: 10.1007/s13131-017-1069-0
Abstract(35) FullText HTML(6) FullText PDF(1)
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The neon flying squid Ommastrephes bartramii is an economically important species in the Northwest Pacific Ocean. The life cycle of O. bartramii is highly susceptible to climatic and oceanic factors. In this study, we have examined the impacts of climate variability and local biophysical environments on the interannual variability of the abundance of the western winter-spring cohort of O. bartramii over the period of 1995–2011. The results showed that the squid had experienced alternant positive and negative Pacific Decadal Oscillation (PDO) over the past 17 years during which five El Niño and eight La Niña events occurred. The catch per unit effort (CPUE) was positively correlated with the PDO index (PDOI) at a one-year time lag. An abnormally warm temperature during the La Niña years over the positive PDO phase provided favorable oceanographic conditions for the habitats of O. bartramii, whereas a lower temperature on the fishing ground during the El Niño years over the negative PDO phase generally corresponded to a low CPUE. The same correlation was also found between CPUE and Chl a concentration anomaly. A possible explanation was proposed that the CPUE was likely related to the climate-induced variability of the large-scale circulation in the Northwest Pacific Ocean: high squid abundance often occurred in a year with a significant northward meander of the Kuroshio Current. The Kuroshio Current advected the warmer and food-rich waters into the fishing ground, and multiple meso-scale eddies arising from current instability enhanced the food retention on the fishing ground, all of which were favorable for the life stage development of the western squid stocks. Our results help better understand the potential process that the climatic and oceanographic factors affect the abundance of the winter-spring cohort of O. bartramii in the Northwest Pacific Ocean.
2017, 36(10): 60-69. doi: 10.1007/s13131-017-1071-6
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The marine ecosystem of the Jiaozhou Bay has degraded significantly in fisheries productivity and its ecological roles as spawning and nursery ground for many species of commercial importance has been declining in recent years. A mass-balanced trophic model was developed using Ecopath with Ecosim to evaluate the trophic structure of the Jiaozhou Bay for improving ecosystem management. The model were parameterized based on the fisheries survey data in the Jiaozhou Bay in 2011, including 23 species groups and one detritus group according to their ecological roles. The trophic levels of these ecological groups ranged from 1 (primary producers and detritus) to 4.3 (large demersal fishes). The estimated total system throughput was 12 917.10 t/(km2·a), with 74.59% and 25.41% contribution of the total energy flows from phytoplankton and detritus, respectively. Network analyses showed that the overall transfer efficiency of the ecosystem was 14.4%, and the mean transfer efficiency was 14.5% for grazing food chain and 13.9% for detritus food chain. The system omnivory index (SOI), Finn’s cycled index (FCI) and connectance index (CI) were relatively low in this area while the total primary production/total respiration (TPP/TR) was high, indicating an immature and unstable status of the Jiaozhou Bay ecosystem. Mixed trophic impact analysis revealed that the cultured shellfish had substantial negative impacts on most functional groups. This study contributed to ecosystem-level evaluation and management planning of the Jiaozhou Bay ecosystem.
2017, 36(10): 70-78. doi: 10.1007/s13131-017-1007-1
Abstract(33) FullText HTML(7) FullText PDF(0)
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A fouling study was conducted in coastal waters southwest of the East China Sea between December 2013 and November 2014. A total of 84 species of fouling organisms belonging to 69 genera, 49 families, and 10 phyla were recorded over the entire year. The community composition was dominated by coastal warm-water species belonging to typical subtropical inner bay communities. The prosperous stage of settlement lasted from April to September, and the adhesion strength of the fouling organisms was the highest in summer. Sessile suspension feeders constituted the main core of settlement for the fouling community. Amphibalanus reticulatus was the most dominant and representative species of fouling organism, and other dominant species included Caprella equilibra, Ectopleura crocea, Anthopleura nigrescens, Stylochus ijimai, Spirobranchus kraussii, Crassostrea angulata, Perna viridis, Jassa falcata, Stenothoe valida, Sphaerozius nitidus, and Biflustra grandicella. The individuals in the fouling community showed a mutual dependence or constraint relationship due to competition for settlement space and food, and they exhibited a particular spatiotemporal distribution in accordance with adaptation to environmental factors. Temperature was the most important environmental factor determining the geographic distribution of fouling organisms. The temperature characteristics of species essentially reflect the differences in the fouling community composition in various climate zones. The species number, settlement stage, and settlement rate of fouling organisms are closely related to water temperature. Local natural environmental conditions (salinity, water currents, light, etc.) as well as human activity (such as aquaculture production) are all important factors affecting the settlement of fouling organisms.
2017, 36(10): 79-86. doi: 10.1007/s13131-017-1051-x
Abstract(31) FullText HTML(8) FullText PDF(1)
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Spatial distribution and structure of nematode assemblages in coastal sediments of the southern part of the Caspian Sea were studied in relation to environmental factors. By considering metals, organic matter, Shannon diversity index (H), maturity index (MI) and trophic diversity (ITD), ecological quality status of sediment was also determined. Fifteen nematode species belonging to eleven genera were identified at the sampling sites. Average density of nematode inhabiting in sediment of the studied area was 139.78±98.91 (ind. per 15.20 cm2). According to redundancy analysis (RDA), there was high correlation between metals and some species. Based on biological indicators, the studied area had different environmental quality. Generally, chemical and biological indices showed different results while biological indices displayed similar results in more sites.
2017, 36(10): 87-96. doi: 10.1007/s13131-017-0975-5
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An extreme persistent cold anomaly was prevailing in the South China Sea in February 2008. In order to understand the effect of the cold anomaly on zooplankton community, the zooplankton composition, abundance and biomass were analyzed in the northern South China Sea in August 2007 and August 2008. A total of 467 zooplankton species representing 16 groups were identified, with 275 species in August 2007 and 351 in August 2008. Copepods were the most dominant zooplankton group in the study area. Compared with 2007, a dramatic decline was observed in the abundance of four dominant copepod species: Subeucalanus subcrassus, Temora discaudata, Nannocalanus minor and Temora turbinata in 2008. Moreover, zooplankton abundance declined from 133.37 ind./m3 in August 2007 to 75.49 ind./m3 in August 2008. In contrast, the abundance of medusa, such as Diphyes chamissonis, and tunicate, such as Doliolum denticulatum and Dolioletta gegenbauri, increased during the same season. Cluster analysis showed that there was a difference in zooplankton community structure between the two years. These variations in zooplankton communities were indicative of an anomalous oceanographic condition along with the extreme cold event in 2008.
2017, 36(10): 97-105. doi: 10.1007/s13131-017-0970-x
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The biomass and size fraction of phytoplankton in terms of chlorophyll a (Chl a) was measured during four cruises conducted in April, July, October 2013 and January 2014 in mariculture area, the Sanggou Bay, China. Results show that total Chl a levels in the surface seawater of the Sanggou Bay generally range from 0.10 to 20.46 μg/L, with an average value of 2.13 μg/L. Nano-phytoplankton was the most important size-fraction and accounted for about 65.1% of total Chl a. In order to evaluate the importance of the " protozoan trophic link” for energy transfer from the microbial loop to filter-feeding feeders, Zhikong scallop Chlamys farreri was then offered a natural planktonic community as potential prey. Results show that scallops obtained carbon source from natural plankton with the rate of 11 033.05 μg/(g·d). Protists (nanoflagellates and ciliates) were the dominant source of carbon retained by scallop (48.78%). The microbial loop provided 58.45% of the carbon source for farmed scallops. These results indicate that the microbial loop represent a valuable trophic resource in mariculture system of the Sanggou Bay.
2017, 36(10): 106-114. doi: 10.1007/s13131-017-1055-6
Abstract(37) FullText HTML(10) FullText PDF(4)
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A better understanding of bacterioplankton community shifts following change in marine environments is critical to predict the marine ecosystem function. In order to get a snapshot of the microbial taxonomy profiling of a wide range marine area, a quick, convenient and low cost method would be favorable. In this study, we developed a 16S rRNA gene-based microarray using ARB software, which contained 447 probes targeting 160 families of marine bacteria. The specificity, sensitivity and quantitative capability of this microarray were assessed by single cloned 16S rRNA genes. The reliability of this microarray was tested by eight environmental samples. The results showed that the microarray was specific, only 1.16% false results were detected in five single-clone hybridization tests. The microarray could detect DNA samples as few as 1 ng/μL and the signal intensity could reflect the relative abundance of the bacteria in the range of 1 ng/μL to 100 ng/μL of DNA concentration. Hybridization with environmental samples showed that it can discriminate bacterioplankton communities by sites and time. High throughput sequencing results from the eight samples confirmed the hybridization results. It indicated that this developed microarray could be used as a convenient tool to monitor the bacterioplankton community in marine environment.
2017, 36(10): 115-119. doi: 10.1007/s13131-017-1050-y
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Vibrio harveyi, known as a pathogenic bacterium caused severe secondary bacterial infections of the large yellow croaker Larimichthys crocea, was identified as an endosymbiont in the marine parasitic ciliate protozoan Cryptocaryon irritans. Meta 16S sequencing method was used to identify the bacterial flora in C. irritans, and V. harveyi was isolated via culture-dependent method. Vibrio harveyi was observed in cytoplasm of C. irritans at the stage of tomont both by transmission electron microscopy and by Fluorescence in situ hybridization; no signal, however, was detected in nucleus area. The relationship between V. harveyi and C. irritans and the role of endosymbiotic V. harveyi in C. irritans merit further investigation.
2017, 36(10): 120-121. doi: 10.1007/s13131-017-1119-7
Abstract(18) FullText HTML(5) FullText PDF(0)
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