Engraulis Japonicus Research Articles

Population Genomics Reveals Shallow Genetic Structure in a Connected and Ecologically Important Fish From the Northwestern Pacific Ocean

Genetic variation at the genomic level is invaluable to identify fish stock structure in fisheries management. It has been widely accepted that populations of marine fishes are highly connected owing to fewer barriers to gene flow and increased connectivity resulting from greater dispersal abilities. Since population genomic approaches have increased the accessibility and resolution of population genetic data, it further facilitates to study and detect previously unidentified structures as well as signatures for natural selection in wild populations. In the present study, restriction-site associated DNA (RAD) sequencing was applied to the samples of genome-wide single nucleotide polymorphisms (SNPs) of Engraulis japonicus, a small pelagic fish of ecological and economic importance in the northwestern Pacific. To assess population genetic structure as well as detection for local adaptation of E. japonicus, a total of 389 individuals from six regional populations of the northwestern Pacific were collected and a set of 12,627 SNPs was developed. Marginal significant genetic structure (average FST value was approximately equal to 0.002) was detected between regional populations of “the Bohai Sea population (BHS)” and the “the Japan Sea population (JPS)” as well as between “the North Yellow Sea population (NYS)” and the “the Japan Sea population (JPS)”. Moreover, no sign of local adaptation was detected, which might be the product of high gene flow among regional populations. Overall, our results improve the understanding of fine-scale population genetic structure in E. japonicus and potentially identify management unit in this species area.

A comprehensive model-based index for identification of larval retention areas: A case study for Japanese anchovy Engraulis japonicus in the Yellow Sea

Abstract Larval retention has been recognized as a key factor/process affecting the recruitment of many pelagic fish species and detection of the larval retention areas (LRAs) is thus of crucial importance for studies of both recruitment dynamics and of fisheries management. However, most studies in relation to larval retention have adopted either retention rate or time to represent retention level. In this study, a newly developed approach based on a Lagrangian particle-tracking algorithm coupled with a hydrodynamic model, thereby jointly considering both retention rate and time to quantify larvae retention level, was introduced and used to identify the prominent LRAs for Japanese anchovy Engraulis japonicus in the Yellow Sea. Four prominent LRAs were identified, two of which locating in the Southern Yellow Sea match well with the aggregation of Japanese anchovy larvae found in previous field surveys. The spatial–temporal variation of instantaneous retention rate was further analyzed and the contribution rates of spawning grounds to LRAs as well as sensitivity of pelagic larval duration to the LRAs were investigated. Meanwhile, the LRAs defined in this study can be also used to explain the aggregations of microzooplankton and green algae in the southern part of the Yellow Sea. This approach can be widely applied to other pelagic species during their planktonic stages, which may further provide implications for studies on recruitment dynamics and on marine protected areas (MPAs) in the Yellow Sea as well as in other continental shelf regions containing abundant fishery resources.

금강 하구역의 춘계와 하계에 어류플랑크톤 종조성과 출현량

Ichthyol-plankton and the environment data were collected in Geum River Estuary in spring and summer of 2016~2018. These data were collected though “National Survey of Marine Ecosystem” project. Geum River Estuary is one of the main estuaries in the West Sea of Korea. A total of 18 taxa of fish larvae were collected. Eight taxa were collected in spring, and the mean abundance was 242 ind./1,000m3. Thirteen taxa were collected during the summer, and the mean abundances was 109 ind./1,000m3. During this study, most dominant species was Gobiidae spp. (49.4%), which was followed by whiting, Sillago japonica (37.3%). Yearly species composition showed Gobiidae spp. was most dominant specie except in 2018. In 2018, Sillago japonica was dominant in spring and anchovy (Engraulis japonicus) was dominant in summer. When abnormal high water temperature period (>28℃) occurred, Gobiidae spp. was not dominant.

진해만에서 각망에 어획된 어류의 종조성 및 계절변동

Seasonal fluctuation in abundance and species composition of fish in coastal waters off Jinhae bay were investigated using seasonal samples collected by a fyke net from July, 2010 to April, 2011. A total of 1,869 fishes were sampled and classified into 23 species, 18 families, and 7 orders. The dominant species were Sebastes inermis (184 individuals, 9.8%), Nuchequula nuchalis (158 individuals, 8.5%), and Konosirus punctatus (143 individuals, 7.7%). The highest number of individuals was found in Fall (572 individuals), while the lowest number of individuals was found in Winter (416 individuals). The diversity index was the highest in winter (H’=3.005) and the lowest in fall (H’=2.953). The dominance index was the highest in fall (D=21.0%) and the lowest in spring (D=16.5%). The economically important species in Jinhae bay were Conger myriaster, Engraulis japonicus, Konosirus punctatus, Sebastes inermis, Lateolabrax japonicus, Acanthopagrus schlegelii, and Paralichthys olivaceus.

울진 연안에서 기선저인망에 어획된 어류의 종조성 및 계절변동

Seasonal fluctuation in the abundance and species composition of fish were investigated using small otter trawl in the coastal waters off Uljin, Korea, in 2016. A total of 6,017 fishes were sampled and classified into 48 species, 33 families and 11 orders. The dominant orders were Perciformes including 20 species and 16 families followed by Scorpaeniformes including 8 species and 5 families, Tetraodontiformes including 5 species and 3 families, Clupeiformes including 4 species, and 2 families, Pleuronectiformes including 4 species and 2 families, and Zeiformes including 2 species and 2 family. Among the appeared 48 species, Engraulis japonicus was the dominant species by 17.6%, followed by Hexagrammos otakii (5.3%), Pterogobius zonoleucus (5.3%), Ditrema temmincki (4.5%), and Hexagrammos agrammus (4.2%). The diversity was the highest in summer (3.26), while the lowest in winter (2.89). The evenness was the highest in winter (0.94), while the lowest in summer (0.90). The dominance was the highest in fall (27.0%), while the lowest in winter (20.9%). The richness wast the highest summer (4.67), while the lowest in winter (3.13). The similarity of community structure was 72.77% between summer and fall.

여자만 입구 해역에서 소형기선저인망에 어획된 어류의 종조성 및 군집분석

Community structure and species composition of fish in the mouth of Yeoja bay were investigated using samples collected by a small otter trwal in March and August, 2019. A total of 3,198 fishes were sampled and classified into 38 species, 27 families, and 9 orders. The dominant species was Pennahia argentata (505 individuals, 15.8%), Ilisha elongata (234 individuals, 7.3%), and Engraulis japonicus (222 individuals, 6.9%). The highest number of individuals was found in St. 2 (1,516 individuals), while the lowest number of individuals was found in St. 3 (663 individuals). The richness index was the highest in St. 2 (RI=3.69) and the lowest in St. 3 (RI=3.39). The evenness index was the highest in St. 3 (E=0.91) and the lowest in St. 2 (E=0.86). The diversity index was the highest in St. 1 (H’=2.96) and the lowest in St. 2 (H’=2.85). The dominance index was the highest in St. 2 (D=31.4%) and the lowest in St. 1 (D=23.2%).

Species Composition and Structure of Ichthyoplankton of the Northern Part of the Sea of Japan in Summer of 2017

The ichthyoplankton of the upper epipelagic zone (0–50 m) was studied in the northern part of the Sea of ​​Japan in July–August 2017. Eggs of seven fish species and larvae of five fish species from five families were recorded off the coast of Primorye; eggs of six species from five families and larvae of 12 species from seven families, in the Strait of Tartary. Eggs and larvae of four species of the Pleuronectidae family (Limanda punctatissima, Glyptocephalus stelleri, Cleisthenes herzensteini, and Acanthopsetta nadeshnyi) prevailed everywhere. Off the coast of Primorye, Cl. herzensteini dominated, and in the Strait of Tartary, L. punctatissima. In comparison with the results of the Kuril-Sakhalin expedition performed the late 1940s, the eggs of pelagic fish species, such as Engraulis japonicus, Cololabis saira, and Scomber japonicus, was found in small quantities and only in the surface water layer. The results allow us to report on slight changes in the species composition relative to the middle of the last century, on the one hand, and significant changes in the dominant species, on the other.

Consumption of juvenile chum salmon by a seabird species during early sea life

Juvenile mortality, a key factor determining the stock sizes of salmonids, may be increased by predation both in rivers and along shores. Information on predation at sea, however, is scarce. We analysed the diet of a pelagic seabird, the rhinoceros auklet Cerorhinca monocerata, breeding on an isolated island off eastern Hokkaido, Japan, and estimated their consumption of juvenile chum salmon Oncorhynchus keta. The auklets brought juvenile chum salmon and Japanese anchovy Engraulis japonicus for their chicks and, in addition, fed on squid themselves. The fork length of most of the juvenile chum salmon was over 80 mm, indicating that they were migrating to offshore nursery area, the Sea of Okhotsk. Using a simple bioenergetics model, the consumption of juvenile chum salmon by auklets during the first half of chick-rearing period (late June to middle July) was 316.6 t in 2014 (296.4 t by adults, 20.2 t by chicks) and 11.7 t in 2015 (0 t by adults, 11.7 t by chicks). The otoliths of six out of 66 juvenile salmon found in the diet for chicks had thermal markings and indicated that these fish were released from the rivers along Pacific coast of Hokkaido. Our study first demonstrates the extent of the auklets' consumption contributing to the reduction of the survival in the open coastal area of juvenile chum salmon with the known stock origins.

기선권현망어업에서 어로기술개발에 따른 어획성능지수 변화

Anchovy (Engraulis japonicus) is the most caught species in the last three years of fish production statistics in Korea. The anchovy is caught by dragnet, set net and stow net, among which about 50~60% is caught by anchovy dragnet. For the sustainable use of anchovy, the fishing power of anchovy dragnet is very important. Therefore, the change of fishing power index were analyzed to identify the development of the vessel and gear technology that may have improved the fishing efficiency of the anchovy dragnet fishery from 1960s to 2010s. Engine output per net vessel was increased to 40 hp in 1960, to 150 hp in 1970s, to 220 hp in 1990s, to 350 hp in 2000s and to 650 hp in 2015. As the engine output of the net vessel increased, the length of the fishing net gradually increased. Fishing equipments started to be supplied with net hauler and side roller in the mid-1980s, and fish finders began to be supplied in the mid-1960s and gradually increased. Surveys on the supply and upgrading of fishing equipment utilized visiting research. Therefore the relative fishing power index in the anchovy dragnet fishery increased from 1.0 in 1980 to 1.3 in 1990, to 1.7 in 2000 and to 2.5 in 2015. The results are expected to contribute to reasonable fisheries stock management.

A dynamic energy budget–integral projection model (DEB-IPM) to predict population-level dynamics based on individual data: a case study using the small and rapidly reproducing species Engraulis japonicus — RETRACTED

The coupling of a dynamic energy budget (DEB) model with an integral projection model (IPM; i.e. generating a DEB-IPM) is a promising new method to predict the population-level dynamics of species based on individuals. In a single framework, the DEB component provides links to the individual-level physiological processes, and the IPM component provides an alternative way to investigate ecological changes in quantitative life history characteristics and population dynamics. In this paper we present a DEB-IPM to analyse a Japanese anchovy (Engraulis japonicus) population in Chinese seas. The coupled model describes the dynamics of a population of individuals, where each individual follows an energy budget. Primary model parameters (e.g. energy conductance, ὺ; allocation coefficient, κ; and volume-specific somatic maintenance, [ṗM]) were estimated. The mean population growth rate (rp) was calculated to be 3.4year–1. The predicted demographic rates (e.g. growth, survival and reproduction) were well within observed ranges, and fit within average recorded values, and captured known seasonal trends. DEB-IPMs could be a useful tool to capture the dynamics of biodiversity amidst global environmental changes.

The complete mitochondrial genome of Engraulis ringens (Engraulidae, Clupeiformes) and phylogenetic studies of Engraulidae

In this study, the complete mitochondrial genome of Engraulis ringens has been determined. The whole sequence is 16,690 bp in length and included the typical structure of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 2 non-coding regions (control region and L-strand replication origin). The overall base composition includes A 26.65%, T 26.09%, C 28.13%, G 19.13%, with a slightly A + T bias of 52.74%. Moreover, the 13 PCGs encode 3797 amino acids in total. The phylogenetic analysis of E. ringens in the Engraulidae family was constructed based on 12 PCGs encoded by the heavy strand, and the result showed that E. ringens is most closely related to Engraulis japonicus and Engraulis encrasicolus.

Disentangling density‐dependent effects on egg production and survival from egg to recruitment in fish

AbstractUnderstanding of density‐dependent effects is key to achieving sustainable management of self‐regulating biological resources such as fish stocks. Traditionally, density‐dependent effects on population abundance in fish have been considered to occur from hatching to recruitment, based on the paradigm of proportionality between spawning stock biomass and total egg production. Here, we demonstrate how the existence of intraspecific and interspecific density dependence in egg production changes the current understanding of density‐dependent processes in the life history of fish, by disentangling density‐dependent effects on egg production and survival from egg to recruitment, using sardine (Sardinops melanostictus, Clupeidae) and anchovy (Engraulis japonicus, Engraulidae) as model species. For sardine, strong intraspecific density‐dependent effects occurred in egg production, but no density‐dependent effects occurred or if any they were weak enough to be masked by environmental factors from hatching to recruitment. In contrast, for anchovy, interspecific density‐dependent effects occurred in egg production. In the survival after hatching, anchovy experienced stronger intraspecific density‐dependent effects than currently recognized. This analysis could overturn the current understanding of density‐dependent effects in the life history, highlighting contrasts between the effects on individual quality and population abundance and between the model species. We propose to reconsider the basis of fisheries management and recruitment studies based on the revised understanding of density‐dependent effects in the life history of the respective species.

Comparative proteomic analysis of olfactory rosettes in anadromous Coilia nasus and resident Coilia nasus

The Japanese grenadier anchovy ( Coilia nasus ) undergoes upstream migration to spawning annually but can also be observed in freshwater resident populations. It has been hypothesized that anadromous adult C. nasus may utilize olfactory cues to locate spawning grounds. We firstly performed a comparative proteome analysis about olfactory rosettes in two populations to hunt for the proteomic changes. Among 5 408 identified proteins, 1 515 proteins (629 up-regulated and 886 down-regulated) were differentially expressed. Especially, several proteins and pathways associated with olfactory signaling were found to be significantly differential. Compared with resident C. nasus, the expressions of Golf protein and the sodium/calcium exchanger were significantly up-regulated in anadromous C. nasus. The expression of adenylate cyclase and regulator of G-protein signaling (RGS) were decreased. Our findings suggest a decrease in the expression of cGMP-dependent protein kinase (PKG) in anadromous C. nasus compared to resident C. nasus. The expression of Calmodulin (CaM) was increased and CaM-dependent protein kinase II (CaMKII) was decreased. In addition, KEGG pathway enrichment analysis of up-regulated proteins indicated statistically significant difference not only in olfactory transduction but also in the cGMP-PKG signal pathway. Furtherly, we sought out some proteins expressed in the same trend occurring in DEGs (differentially expressed genes) and DEPs (differentially expressed proteins) by doing the integrative analysis of proteome and transcriptome in olfactory rosettes of C. nasus.

Comprehensive Experimental System for a Promising Model Organism Candidate for Marine Teleosts

A comprehensive experimental system for Japanese anchovy, a promising candidate model organism for marine teleosts, was established. Through the design of a rearing/spawning facility that controls the photoperiod and water temperature, one-cell eggs were continuously obtained shortly after spawning throughout the rearing period. The stages of eggs are indispensable for microinjection experiments, and we developed an efficient and robust microinjection system for the Japanese anchovy. Embryos injected with GFP mRNA showed strong whole-body GFP fluorescence and the survival rates of injected- and non-injected embryos were not significantly different, 87.5% (28 in 32 embryos) and 90.0% (45 in 50 embryos), respectively. We verified that the Tol2 transposon system, which mediates gene transfer in vertebrates, worked efficiently in the Japanese anchovy using the transient transgenesis protocol, with GFP or DsRed as the reporter gene. Finally, we confirmed that genome-editing technologies, namely Transcription Activator-Like Effector Nucleases (TALEN) and Clustered Regulatory Interspaced Short Palindromic Repeats (CRISPR)/Cas9, were applicable to the Japanese anchovy. In practice, specific gene-disrupted fishes were generated in the F1 generation. These results demonstrated the establishment of a basic, yet comprehensive, experimental system, which could be employed to undertake experiments using the Japanese anchovy as a model organism for marine teleost fish.

광양만에서 소형 저인망으로 어획된 어류의 종조성 및 양적 변동

Species composition and seasonal variation in Kwangyang bay were investigated 6 times from October, 1999 to August, 2000. The fishes caught by a small otter trawl were identified into 10,017 individuals, 72 species, 61 Genus, 38 families and 9 orders. Perciformes were dominant identified into 31 species, 28 Genus and 17 families. Followed by Scorpaeniformes (12 species, 8 genus and 6 families) and Pleuronectiformes (9 species, 8 genus and 4 families) and Clupeiformes (7 species, 6 genus and 3 families) were caught in the study period. During the study, most dominant species was Leiognathus nuchalis by 6,257 individuals (62.46%) of the total, followed by Konosirus punctatus by 937 individuals (9.35%), Engraulis japonicus by 612 individuals (6.11%). The diversity was the highest in February (H’=1.931), while the lowest in April (H’= 1.001). The evenness was the highest in February (E=0.645), while the lowest in April (E=0.268). The dominance was the highest in April (d=0.858), while the lowest in February (d= 0.521). The richness was the highest in April (E=4.860), while the lowest in February (E=2.834). The similarity of community structure was 64.36% between June and August, which was the most similar in monthly similarity.

아산만 연안에서 소형 저인망에 어획되는 어류의 종조성 및 계절 변동

Seasonal fluctuations in the abundance and species composition of fishes in coastal waters off Asan bay were investigated from April, 2012 to January, 2013. A total of 3,057 fishes were sampled and classified into 71 species, 35 families, and 11 orders. Of the 11 orders, Perciformes, Scorpaeniformes, and Pleuronectiformes accounted for approximately 61.97% of the fishes in this area. Of 71 species identified, Engraulis japonicus, Leiognathus nuchalis, Trichiurus japonicus, Pholis fangi, and Konosirus punctatus accounted for 36.57% of collected fishes. The highest number of individuals was found in July, while the lowest in January. The richness index was highest in July (RI=7.103) and the lowest in January(RI=4.708). The eveness index was the highest in July(E=0.912) and the lowest in October(E=0.766). The diversity index was the highest in July(H’=1.429) and the lowest in October(H’=2.862).

거문도 연안에서 저인망에 어획되는 어류의 종조성 및 양적 변동

The fishes were caught by otter trawl from November, 2007 to October, 2008 in coastal waters off Geomundo. A total of 4,645 fishes were sampled and classified into 76 species, 40 families, and 12 orders. Of the 12 orders, Clupeiformes, Gadiformes, Perciformes accounted for approximately 83.7% of the fishes in this area. Of 76 species identified, Argyrosomus argentatus, Acanthogobius flavimanus, Nuchequula nuchalis, Coelorinchus japonicus, Engraulis japonicus accounted for 54.6% of the fishes collected. The highest number of individuals was found in summer, while the lowest in autumn. The richness index was highest in spring(RI=7.934) and lowest in winter(RI=6.701). The eveness index was highest in spring(E=0.740) and lowest in winter(E=0.690). The diversity index was highest in spring(H’=3.005) and lowest in winter(H’=2.671).

Seasonal variations of the ichthyoplankton assemblage in the Yangtze Estuary and its relationship with environmental factors.

Seasonal variations of the ichthyoplankton assemblage and its relationship with the environment were analyzed based on four seasonal surveys during 2012. Historical data was collected to be compared with results from previous years in order to indicate the seasonal and inter-annual variation of the ichthyoplankton assemblage in the Yangtze Estuary and the adjacent waters. A total of 3,688 individuals belonging to 5 orders, 9 families, and 15 species were collected. No samples were collected in the winter cruise. In 2012, all samples were separated into four ecotypes, which is comparable with the historical data from previous years. The Engraulis japonicus was the most abundant species of all teleost fishes. The E. japonicus was captured in every season and contributed the most to the abundance of ichthyoplankton, which was greater than that of previous years. This result may be due to the periodic fluctuations of E. japonicus or from the displacement of spawning grounds offshore for environmental reasons. The diversity indices of the assemblage were significantly different among seasons, with the number and abundance of the species peaking in the spring, while richness, evenness and diversity indices peaked in the autumn. The species richness of the ichthyoplankton varied from 0.74 to 1.62, the Pielou evenness index varied from 0.10 to 0.49 and the Shannon–Wiener index varied from 0.19 to 1.04. The results of CCA analysis showed that the major factors affecting the ichthyoplankton assemblage differed throughout the seasons. Chla was the key factor affecting the ichthyoplankton in 2012. These seasonal and inter-annual variations likely resulted from migrations associated with fish spawning as well as the environment. Compared with data from previous studies, the relationship between the assemblage structure of ichthyoplankton and corresponding environmental variables have undergone a decline.

Uniqueness measure based on the weighted trophic field overlap of species in the food web

With the application of the topological network concept to study food webs, species uniqueness in terms of irreplaceability has begun to be considered when identifying important species in the ecosystem. Based on the uniqueness method of quantifying the interactions and trophic field overlap of species in food webs, we propose using the weighted trophic field overlap (WTO) to determine the uniqueness of species in a topological network by considering the proportions of prey in the diets of predators. This proposed method involves measuring the uniqueness of species structurally and mathematically to overcome the deficiencies of the traditional method (the sum of trophic field overlap, STO), which only relies on the topological structure of the food web. We compared the species ranking results obtained via the WTO and STO methods using the Wilcoxon signed-rank test and compared the Spearman rank correlation coefficients between them and three other topological indices. In this study, we focused on the food web of Haizhou Bay ecosystem. The results showed that Leptochela gracilis, Acetes sp., Alpheus japonicus, Engraulis japonicus, and Alpheus distinguendus were the most unique species in the food web of Haizhou Bay. They had the lowest WTO values, and three of these species were not identified as unique by the traditional method. However, they play important roles as prey in Haizhou Bay ecosystem and have high interaction strengths with other species in the food web weighted by the proportion of prey, which are not recognized by the traditional method. The proposed index is sensitive to changes in the diets of predators since slight fluctuations may cause the index to vary considerably. The proposed methodology could be extended to other marine ecosystems to identify unique species from a practical and dynamic perspective and will contribute to the protection of unique species that maintain the trophic diversity of food webs and ecosystem robustness.

基于SURF指数识别海州湾食物网的关键饵料生物

PDF HTML阅读 XML下载 导出引用 引用提醒 基于SURF指数识别海州湾食物网的关键饵料生物 DOI: 10.5846/stxb201811012365 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31772852）；国家重点研发计划（2017YFE0104400）；山东省支持青岛海洋科学与技术试点国家实验室重大科技专项（2018SDKJ0501-2） Identification of keystone prey species in Haizhou Bay food web based on SURF index Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:关键种（keystone species）在生态系统中发挥着不可替代的重要作用，对于群落结构的稳定与演替起着决定性的作用。基于2011年3-12月在海州湾及其邻近海域进行的渔业资源底拖网调查资料以及胃含物分析数据和参考历史文献数据，以物种间的摄食关系作为基础，采用SURF（Supportive Role to Fishery ecosystems）指数识别海州湾食物网中的关键饵料生物。在矩阵中分析每个物种作为饵料生物为捕食者提供的摄食比例及捕食者数量，计算每个物种的关键指标（SURFi）的值，结果表明前五位数值较高的物种是细鳌虾（Leptochela gracilis）、毛虾（Acetes sp.）、疣背宽额虾（Latreutes planirostris）、日本鼓虾（Alpheus japonicus）和鳀鱼（Engraulis japonicus），它们是海州湾的关键饵料生物，在整个食物网中起到关键的控制作用，它们的数量波动会对海州湾其他物种产生直接或间接的影响。加强关键饵料生物的保护，对于维持海州湾生态系统的健康和稳定至关重要。 Abstract:Keystone species play an irreplaceable role in ecosystems and play a decisive role in the stability and succession of community structures. Based on the bottom trawl surveys from March to December in 2011 in Haizhou Bay and adjacent waters and reference historical literature, SURF (Supportive Role to Fishery ecosystems) index was calculated to identify keystone prey species in Haizhou Bay food web. In the matrix, we analyzed the ratio of food intake and predators for each species, and calculated the value of each species' key indicator (SURFi). The top five prey species were Leptochela gracilis, Acetes sp., Latreutes planirostris, Alpheus japonicus and Engraulis japonicus, which are keystone prey species in the Haizhou Bay ecosystem. As key prey species, they have relatively low trophic levels, which not only affect energy flow and mass transfer, but also control species diversity in the ecosystem. They play key roles in the control of the entire food web, and their fluctuations may have direct or indirect effects on other species in the Haizhou Bay food web. Therefore, it is critical to protect the key prey species for maintaining the health and stability of Haizhou Bay ecosystem. 参考文献 相似文献 引证文献