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1.
Anchovy (Engraulis japonicus), a small pelagic fish and food of other economic fishes, is a key species in the Yellow Sea ecosystem. Understanding the mechanisms of its recruitment and biomass variation is important for the prediction and management of fishery resources. Coupled with a hydrodynamic model (POM) and a lower trophic level ecosystem model (NEMURO), an individual-based model of anchovy is developed to study the influence of physical environment on anchovy’s biomass variation. Seasonal variations of circulation, water temperature and mix-layer depth from POM are used as external forcing for NEMURO and the anchovy model. Biomasses of large zooplankton and predatory zooplankton which anchovy feeds on are output from NEMURO and are controlled by the consumption of anchovy on them. Survival fitness theory related to temperature and food is used to determine the swimming action of anchovy in the model. The simulation results agree well with observations and elucidate the influence of temperature in over-wintering migration and food in feeding migration.  相似文献   

2.
We investigated the spatio-temporal and environmental factors that affect the distribution and abundance of wintering anchovy and quantifi es the infl uences of these factors. Generalized additive models(GAMs) were developed to examine the variation in species distribution and abundance with a set of spatiotemporal and oceanographic factors, using data collected by bottom trawl surveys and remote sensing in the central and southern Yellow Sea during 2000–2011. The fi nal model accounted for 28.21% and 41.03% of the variance in anchovy distribution and abundance, respectively. The results of a two-step GAM showed that hour, longitude, latitude, temperature gradient(TGR), and chlorophyll a(Chl- a) concentration best explained the anchovy distribution(presence/absence) and that a model including year, longitude, latitude, depth, sea surface temperature(SST), and TGR best described anchovy abundance(given presence). Longitude and latitude were the most important factors affecting both distribution and abundance, but the area of high abundance tended to be east and south of the area where anchovy were most likely to be present. Hour had a signifi cant effect on distribution, but year was more important for anchovy abundance, indicating that the anchovy catch ratio varied across the day but abundance had an apparent interannual variation. With respect to environmental factors, TGR and Chl- a concentration had effects on distribution, while depth, SST, and TGR affected abundance. Changes in SST between two successive years or between any year and the 2000–2011 mean were not associated with changes in anchovy distribution or abundance. This fi nding indicated that short- and long-term water temperature changes during 2000–2011 were not of suffi cient magnitude to give rise to variation in wintering anchovy distribution or abundance in the study area. The results of this study have important implications for fi sheries management.  相似文献   

3.
Measurement of single-fish target strength in the South China Sea   总被引：4，自引：0，他引：4  
We measured the target strength (TS) of three commercial fish species: whitespotted spinefoot (Siganus canaliculatus), black porgy (Acanthopagrus schlegelii), and creek red bream (Lutjanus argentimaculatus), in the South China Sea. The TS of caged or tethered fish (n=76 total) was measured using a Simrad EY60 portable scientific echosounder at 120 kHz. We evaluated the relationship between TS and total length (TL, cm) for the three species. This is the first attempt to use split-beam acoustics to measure single-fish TS in the South China Sea by Chinese researchers. Our results will improve the accuracy and precision of acoustic abundance estimates of commercially important species and further the development of underwater acoustic survey techniques in fisheries in the South China Sea.  相似文献   

4.
Relatively short historical catch records show that anchovy populations have exhibited large variability over multi-decadal timescales. In order to understand the driving factors (anthropogenic and/or natural) of such variability, it is essential to develop long-term time series of the population prior to the occurrence of notable anthropogenic impact. Well-preserved fish scales in the sediments are regarded as useful indicators reflecting the fluctuations of fish populations over the last centuries. This study aims to validate the anchovy scale deposition rate as a proxy of local anchovy biomass in the Yellow Sea adjoining the western North Pacific. Our reconstructed results indicated that over the last 150 years, the population size of anchovy in the Yellow Sea has exhibited great fluctuations with periodicity of around 50 years, and the pattern of current recovery and collapse is similar to that of historical records. The pattern of large-scale population synchrony with remote ocean basins provides further evidence proving that fish population dynamics are strongly affected by global and basin-scale oceanic/climatic variability.  相似文献   

5.
1 Introduction Natural mortality coefficient (M) is one of the key population parameters common to most analyses in fish stock assessment. Many mathematical models of fish stock dynamics include M directly or indirectly. However, until now M is the least known among the four factors affecting fish stock variation: recruitment, growth, natural death and fishing death (Quinn and Deriso, 1999). There is an extensive literature concerning the impact of errors in M on stock assessment (Mertz and…  相似文献   

6.
Diversion of the Yellow River is a unique geological event in offshore China, causing changes of the sedimentary environment in eastern China Seas. The last diversion took place in AD 1855, with the estuary diverted from the Yellow Sea into the Bohai Sea. The identification of the river diversion events in the shelf sediments would not only provide the definite ages for the sediments, but also give a clue for better understanding of the sedimentation in that area. In this study, 210 Pb, grain size, geochemical element, and foraminiferal data in core H205 from the north Yellow Sea were systematically investigated. A high-resolution sedimentary record was established, which was coupled with the Yellow River diversion and runoff changes. The results show that the foraminiferal composition and foraminiferal abundance of the sediments from the north Yellow Sea had good response to the Yellow River diversion in 1855. Before the change, shallow water assemblages dominated the foraminifera, and the abundance of each foraminiferal species was very low. After the diversion event, the abundance of most foraminifera increased sharply, with a maximum increase of 16 times, and the assemblage was still dominated by shallow water species. Furthermore, the changes in foraminiferal abundance in the core sediments corresponded well with the discharge fluctuation of the Yellow River since 1855. When the Yellow River began entering the Bohai Sea, the Yellow River water, which is rich in nutrients, along with the coastal currents affected the north Yellow Sea, increased the primary productivity in the north Yellow Sea, which is the main reason for the abrupt increase and fluctuation of foraminiferal abundance in this area. At the meantime, the East Asian winter monsoon could also promote the development of nearshore foraminiferal species by enhancing the coastal currents.  相似文献   

7.
Previous studies have indicated that the Yellow Sea underwent significant environmental changes during the Holocene, but many questions remain concerning the timing of the establishment of the modern circulation system, which would have major implications for the Yellow Sea ecosystem and carbon cycle. In this study, marine and terrestrial biomarkers were analyzed in Core YE-2 from a muddy area in the southern Yellow Sea to reconstruct Holocene environmental and phytoplankton community change. The content of three individual marine phytoplankton biomarkers (alkenones, brassicasterol and dinosterol) all display a similar trend, and their total contents during the early Holocene (362 ng/g) were lower than those during the mid-late Holocene (991 ng/g). On the other hand, the contents of terrestrial biomarkers (C27+C29+C31n-alkanes) during the early Holocene (1 661 ng/g) were about three times higher than those during the mid-late Holocene (499 ng/g). Our biomarker results suggest that the modern circulation system of the Yellow Sea was established by 5-6 ka, and resulted in higher marine productivity and lower terrestrial organic matter inputs. Biomarker ratios were used to estimate shifts in phytoplankton community structure in response to mid-Holocene (5-6 ka) environmental changes in the Yellow Sea, revealing a transition from a dinoflagellate-diatom dominant community structure during the early Holocene to a coccolithophore-dominant community structure during the mid-late Holocene.  相似文献   

8.
There were different biogeographical tintinnids in the oceans. Knowledge of their distribution pattern and mixing was important to the understanding of ecosystem functions. Yellow Sea (YS) and Bohai Sea (BS) were semi-enclosed seas influenced by warm water intrusion and YS cold bottom water. The occurrence of tintinnids in YS and BS during two cruises (summer and winter) were investigated to find out: i) whether warm-water tintinnids appeared in YS and BS; ii) whether boreal tintinnids appeared in high summer; iii) the core area of neritic tintinnids and iv) how these different biogeographical tintinnids mixed. Our results showed that tintinnid community was dominated by neritic tintinnid. We confirmed the occurrence of warm-water tintinnids in summer and winter. In summer, they intruded into BS and mainly distributed in the upper 20 m where Yellow Sea Surface Warm Water (YSSWW) developed. In winter, they were limited in the surface water of central deep region (bottom depth >50 m) of YS where were affected by Yellow Sea Warm Water (YSWW). Boreal tintinnids occurred in YS in high summer (August) and in winter, while they were not observed in BS. In summer, the highest abundance of boreal tintinnids occurred in Yellow Sea Bottom Cold Water, indicating the presence of an oversummering stock. In winter, they were concentrated in the north of YSWW. Vertically, neritic tintinnids abundance was high in the bottom layers. Horizontally, high neritic tintinnids abundance in bottom layers occurred along the 50 m isobath coinciding with the position of front systems. Front systems were the core distribution area of neritic tintinnids. High abundance areas of warm-water and boreal tintinnids were clearly separated vertically in summer, and horizontally in winter. High abundance of neritic tintinnids rarely overlapped with that of warm-water or boreal tintinnids.  相似文献   

9.
The southern Yellow Sea is an important fishing ground, providing abundant fishery resources. However, overfishing and climate change have caused a decline in the resource and damaged the ecosystem. We developed an ecosystem model to analyze the trophic interactions and ecosystem structure and function to guide sustainable development of the ecosystem. A trophic mass-balance model of the southern Yellow Sea during 2000–2001 was constructed using Ecopath with Ecosim software. We defined 22 important functional groups and studied their diet composition. The trophic levels of fish, shrimp, crabs, and cephalopods were between 2.78 and 4.39, and the mean trophic level of the fisheries was 3.24. The trophic flows within the food web occurred primarily in the lower trophic levels. The mean trophic transfer efficiency was 8.1%, of which 7.1% was from primary producers and 9.3% was from detritus within the ecosystem. The transfer efficiency between trophic levels II to III to IV to V to >V was 5.0%, 5.7%, 18.5%, and 19.7%–20.4%, respectively. Of the total flow, phytoplankton contributed 61% and detritus contributed 39%. Fishing is defined as a top predator within the ecosystem, and has a negative impact on most commercial species. Moreover, the ecosystem had a high gross efficiency of the fishery and a high value of primary production required to sustain the fishery. Together, our data suggest there is high fishing pressure in the southern Yellow Sea. Based on analysis of Odum’s ecological parameters, this ecosystem was at an immature stage. Our results provide some insights into the structure and development of this ecosystem.  相似文献   

10.
Harmful algal blooms(HABs),caused by the overgrowth of certain phytoplankton species,have negative effects on marine environments and coastal fisheries.In addition to cell-counting methods using phytoplankton nets,a hydroacoustic technique based on acoustic backscattering has been proposed for the detection of phytoplankton blooms.However,little is known of the acoustic properties of HAB species.In this study,as essential data to support this technique,we measured the acoustic properties of two HAB species,Akashiwo sanguinea and Alexandrium affine,which occur in the South Sea off the coast of Korea.Due to the small size of the target,we used ultrasound for the measurements.Experiments were conducted under laboratory and field conditions.In the laboratory experiment,the acoustic signal received from each species was directly proportional to the cell abundance.We derived a relationship between the cell abundance and acoustic signal received for each species.The measured signals were compared to predictions of a fluid sphere scattering model.When A.sanguinea blooms appeared at an abundance greater than 3 500 cells/mL,the acoustic signals varied with cell abundance,showing a good correlation.These results confirm that acoustic measurements can be used to detect HAB species.  相似文献   

11.
Lan  Jian  Wang  Yi  Wang  Gang 《中国海洋湖沼学报》2010,28(6):1275-1280
The Cold Eddy in the East China Sea (CEECS) is located about 150 km southwest of Cheju Island. This region experiences a complex current system under the influences of the Yellow Sea Warm Current (YSWC), the Yellow Sea Coastal Current (YSCC), and the northward Kuroshio residual. To identify the strength of the CEECS, a simple subsurface intensity index is developed. Because the CEECS can be traced by temperature minimum, the intensity index is determined by the difference in sea temperature averaged across cores within and surrounding the region. Based on SODA, the CEECS subsurface intensity index time series can be calculated, with which the inter-annual variation of the CEECS is analyzed.  相似文献   

12.
Anchovy(Engraulis japonicus) is an abundant fish species in the Yellow Sea,and its natural stock is decreasing rapidly in recent years. Based on the stock-recruitment(SR) data from 1987 to 2002 published in Zhao et al.(2003),the criterion BIC(Bayesian Information Criterion) is applied to selecting a suitable model from six normal and lognormal error structured SR statisti-cal models,the age-structured model is used to calculate the biological reference points(BRPs),and the precision of the SR parame-ters and BRPs are calculated using bootstrap method. The results indicate that the anchovy fishery resource in the Yellow Sea is in an over-fished state. The precaution management principle requires that the fishery should be closed immediately.  相似文献   

13.
Petroleum geological framework and hydrocarbon potential in the Yellow Sea   总被引：2，自引：0，他引：2  
Sedimentary basins in the Yellow Sea can be grouped tectonically into the North Yellow Sea Basin (NYSB), the northern basin of the South Yellow Sea (SYSNB) and the southern basin of the South Yellow Sea (SYSSB). The NYSB is connected to Anju Basin to the east. The SYSSB extends to Subei Basin to the west. The acoustic basement of basins in the North Yellow Sea and South Yellow Sea is disparate, having different stratigraphic evolution and oil accumulation features, even though they have been under the same stress regime since the Late Triassic. The acoustic basement of the NYSB features China-Korea Platform crystalline rocks, whereas those in the SYSNB and SYSSB are of the Paleozoic Yangtze Platform sedimentary layers or metamorphic rocks. Since the Late Mesozoic terrestrial strata in the eastern of the NYSB (West Korea Bay Basin) were discovered having industrial hydrocarbon accumulation, the oil potential in the Mesozoic strata in the west depression of the basin could be promising, although the petroleum exploration in the South Yellow Sea has made no break-through yet. New deep reflection data and several drilling wells have indicated the source rock of the Mesozoic in the basins of South Yellow Sea, and the Paleozoic platform marine facies in the SYSSB and Central Rise could be the other hosts of oil or natural gas. The Mesozoic hydrocarbon could be found in the Mesozoic of the foredeep basin in the SYSNB that bears potential hydrocarbon in thick Cretaceous strata, and so does the SYSSB where the same petroleum system exists to that of oil-bearing Subei Basin.  相似文献   

14.
The Yellow Sea Warm Current (YSWC) is one of the principal currents in the Yellow Sea in winter. Former examinations on current activity in the Yellow Sea have not observed a stable YSWC because of the positioning of current meters. To further understand the YSWC, a research cruise in the southern Yellow Sea was carried out in the winter of 2006/2007. Five moorings with bottom-mounted acoustic Doppler current profilers (ADCP) were deployed on the western side of the central trough of the Yellow Sea. The existence and distributional features of the YSWC were studied by analyzing three ADCP moorings in the path of the YSWC in conjunction with conductivity-temperature-depth (CTD) data over the observed area in the southern Yellow Sea. The results show the following. (1) The upper layer of the YSWC is strongly influenced by winter cold surge; its direction and speed often vary along a south-north axis when strong cold surges arrive from the north. (2) The YSWC near the bottom layer is a stable northwest flowing current with a speed of 4 to 10 cm/s. By combining the analyses of the CTD data, we speculate that the core of the YSWC may lie near the bottom. (3) On a monthly average timescale, the YSWC is stably oriented with northward flow from the sea surface to the sea floor.  相似文献   

15.
In this paper, the distribution patterns and abundance of pelagic tunicates in the North Yellow Sea of China during the period 2006-2007 were analyzed. Zooplankton samples were obtained with vertical towing from bottom to surface using a WP2 plankton net(200 μm mesh size; mouth area: 0.25 m2). Five species belonging to two classes were identified: Oikopleura dioica, O. longicauda and Fritillaria borealis belonging to class Appendicularia; Salpa fusiformis and Doliolum denticulatum of class Thaliacea. O. dioica and O. longicauda were the dominant species, occurring in the samples of all four seasons, with different distribution patterns. Their maximum abundance were 1664.7 ind. m-3(spring) and 1031.7 ind. m-3(spring) respectively. Following Oikopleura spp. were D. denticulatum, which was found only in autumn with an average abundance of 149.6 ind. m-3, and S. fusiformis, which was detected all the year long except for autumn with low abundance(max. abundance 289.4 ind. m-3 in summer). Only a very small amount of F. borealis was detected in summer samples, with an average abundance of 2.7 ind. m-3. The relationship between tunicates abundances and the environmental factors was analyzed using the stepwise regression model for each species. The variation of appendicularian abundance showed a significant correlation with the surface water temperature and with the concentration of Chl-a. No relationship was found between tunicates abundance and salinity, likely due to the slight changes in surface salinity of the studied area during the four seasons. Salps abundance and that of doliolids were significantly correlated to bottom water temperature, indicating that these two species(S. fusiformis and D. denticulatum) migrate vertically in the water column. In particular D. denticulatum, known to be a warm water species, showed not only an important correlation with water temperature, but also a spatial distribution connected to the warm currents in the North Yellow Sea. The occurrence of D. denticulatum represents an interesting result never found in past research work. Water temperature, algal distribution and currents were the most relevant environmental factors influencing the tunicate abundance and distribution in the North Yellow Sea. Further research is needed in order to get more information on the ecology of these organisms and to better understand their role in the ecosystem including the oceanic food web.  相似文献   

16.
In order to understand the large-scale spatial distribution characteristics of picoplankton,nanophytoplankton and virio-plankton and their relationship with environmental variables in coastal and offshore waters,flow cytometry(FCM) was used to ana-lyze microbial abundance of samples collected in summer from four depths at 36 stations in the North Yellow Sea(NYS).The data revealed spatial heterogeneity in microbial populations in the offshore and near-shore waters of the NYS during the summer.For the surface layer,picoeukaryotes were abundant in the near-shore waters,Synechococcus was abundant in the offshore areas,and bacte-rial and viral abundances were high in the near-shore waters around the Liaodong peninsula.In the near-shore waters,no significant vertical variation of picophytoplankton(0.2-2μm) abundance was found.However,the nanophytoplankton abundance was higher in the upper layers(from the surface to 10 m depth) than in the bottom layer.For the offshore waters,both pico-and nanophytoplankton(2-20μm) abundance decreased sharply with depth in the North Yellow Sea Cold Water Mass(NYSCWM).But,for the vertical dis-tribution of virus and bacteria abundance,no significant variation was observed in both near-shore and offshore waters.Autotrophic microbes were more sensitive to environmental change than heterotrophic microbes and viruses.Viruses showed a positive correla-tion with bacterial abundance,suggesting that the bacteriophage might be prominent for virioplankton(about 0.45μm) in summer in the NYS and that viral abundance might play an important role in microbial loop functions.  相似文献   

17.
The annual bloom of the green macroalgal Ulva prolifera from May through July since 2008 and another of giant jellyfish Nemopilema nomurai from June through September have been frequent events in the Yellow Sea. However, the patterns of benthic ciliate communities during and after the blooms are still not known. In combination with analyses of benthic environmental factors, we investigated the distribution and community composition of benthic ciliates in the Yellow Sea in July and November 2011. In July, ciliates had high standing crops and diversity in the northern Yellow Sea, and in the inshore area off the southern Shandong Peninsula, where large numbers of green macroalgae accumulated. In November, the abundance, biomass and diversity of ciliates were high in the sea areas off the Shandong Peninsula and Changjiang estuary, where a large quantity of jellyfish occurred in August. Neither the abundance nor the biomass had significant difference between seasons, or between different compartments of the Yellow Sea. The species number, and both Margalef and Shannon-Wiener indices of ciliates were all significantly higher in November than in July. In both seasons, prostomateans and karyorelicteans consistently constituted the first and second most important ciliate groups in biomass; and carnivorous ciliates constituted the primary feeding type in terms of biomass as well as species richness, followed by bacterivores, algivores and omnivores. Compared with that in June 2007 when no macroalgae occurred, the percentage of small-sized bacterivores (e.g. Metacystis spp., Euplotes spp. and scuticociliates) increased in July 2011. The proportion of carnivorous ciliates increased in November, and this increased dominance of carnivorous ciliates may be a response to the increase in predominance of heterotrophic nanoflagellates, which might in turn be ascribed to an effect of green macroalgal and giant jellyfish blooms in the Yellow Sea.  相似文献   

18.
Sub-tidal barotropic current variations coupled with residual sea level fluctuation in the Bohai and Yellow Seas during wintertime are addressed in this study.The temporal evolution and spatial distribution of current fluctuation are investigated using moored acoustic Doppler current profiler data in a three-dimensional numerical model.It is found that a southward current followed by a northward current occurred in the northern Yellow Sea during the fluctuation,concurrent with a significant outflow followed by inflow through the Bohai Strait.The process is consistent from surface to bottom and is coupled with remarkable residual sea level fluctuation.This quasi three-day fluctuation with amplitude 0.2-0.3 m/s leads to 1 m/1.2 m drawdown in the northern Yellow and Bohai Seas,respectively,strongly influencing water exchange between those seas.Because this a prominent feature in the seas,it is necessary to evaluate its effect on fluctuation during winter in future studies,in particular,the northward current during the recovery phase of sea level in the Bohai and Yellow Seas regarding seasonal variation.  相似文献   

19.
Assemblages of benthic foraminifera in a sediment core (C02) near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the Holocene marine transgression. It appears that during the early Holocene (11.2–10.1 kyr BP), the faunal was dominated by low salinity and shallow water species Cribrononion subincertum, Buccella frigida and Ammonia beccarii, reflecting a near coast depositional environment. A rapid increase of the relative abundance of Ammonia compressiuscula between 10.1–9.3 kyr BP indicates that the sea level rose rapidly during that time period. From 9.3–7.7 kyr BP, the benthic foraminiferal assemblage was dominated by high percentage of A. compressiscula, suggesting that the sea level was relatively stable. An obvious transition of benthic foraminifera, from the A. compressiuscula-dominated assemblage to an Ammonia ketienziensis-dominated assemblage, occurred between 7.7–6.2 kyr BP, possibly corresponding to a second sea level rapid rise period in the Yellow Sea during the Holocene. This transition may correspond to the gradually strengthened Yellow Sea warm current (YSWC) and finally is established the modern-type circulation in the Yellow Sea. It may also mark the formation of the Yellow Sea cold bottom water (YSCBW) during that period. Since then, the benthic foraminiferal assemblage based on core C02 was dominated by typical YSCBW species, A. ketienziensis, Astrononion italicum and Hanzawaia nipponica, at 6.2–4 kyr BP. A non-deposition period occurred since ～4 kyr BP, which possibly related to the hydrology changes caused by the East Asia monsoon. The two obvious benthic foraminiferal transitions recorded in core C02 during the early and middle Holocene provide evidence that the Yellow Sea has undergone a two-phase rapid sea level rise during the Holocene marine transgression.  相似文献   

20.
To investigate the genetic variation and population structure of Pacific herring in the Yellow Sea and the genetic differentiation between the Yellow Sea and the Sea of Japan,fragments of 479-bp mitochondrial DNA control region were sequenced for 110 individuals collected from three different periods in the Yellow Sea and one locality in the Sea of Japan.High haplotype diversity and moderate nucleotide diversity were observed in Pacific herring.AMOVA and exact test of population differentiation showed no significant genetic differentiations among the three populations of the Yellow Sea and suggested the populations can be treated as a single panmictic stock in the Yellow Sea.However,a large and significant genetic differentiation(WST50.11;P50.00) was detected between the populations in the Yellow Sea and the Sea of Japan.The high sea water temperature in the Tsushima Strait was thought a barrier to block the gene exchange between populations of the two sea areas.The neutrality tests and mismatch distribution indicated recent population expansion in Pacific herring.  相似文献   

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